A library for encoding and decoding ETC1 textures.
The ETC1 compressed texture format is commonly
supported by OpenGL ES 2.0-capable devices.
diff --git a/api/current.xml b/api/current.xml
index 55289e5..ad5a1a7 100644
--- a/api/current.xml
+++ b/api/current.xml
@@ -88168,6 +88168,401 @@
</package>
<package name="android.opengl"
>
+<class name="ETC1"
+ extends="java.lang.Object"
+ abstract="false"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<constructor name="ETC1"
+ type="android.opengl.ETC1"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</constructor>
+<method name="decodeBlock"
+ return="void"
+ abstract="false"
+ native="true"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="in" type="java.nio.Buffer">
+</parameter>
+<parameter name="out" type="java.nio.Buffer">
+</parameter>
+</method>
+<method name="decodeImage"
+ return="void"
+ abstract="false"
+ native="true"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="in" type="java.nio.Buffer">
+</parameter>
+<parameter name="out" type="java.nio.Buffer">
+</parameter>
+<parameter name="width" type="int">
+</parameter>
+<parameter name="height" type="int">
+</parameter>
+<parameter name="pixelSize" type="int">
+</parameter>
+<parameter name="stride" type="int">
+</parameter>
+</method>
+<method name="encodeBlock"
+ return="void"
+ abstract="false"
+ native="true"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="in" type="java.nio.Buffer">
+</parameter>
+<parameter name="validPixelMask" type="int">
+</parameter>
+<parameter name="out" type="java.nio.Buffer">
+</parameter>
+</method>
+<method name="encodeImage"
+ return="void"
+ abstract="false"
+ native="true"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="in" type="java.nio.Buffer">
+</parameter>
+<parameter name="width" type="int">
+</parameter>
+<parameter name="height" type="int">
+</parameter>
+<parameter name="pixelSize" type="int">
+</parameter>
+<parameter name="stride" type="int">
+</parameter>
+<parameter name="out" type="java.nio.Buffer">
+</parameter>
+</method>
+<method name="formatHeader"
+ return="void"
+ abstract="false"
+ native="true"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="header" type="java.nio.Buffer">
+</parameter>
+<parameter name="width" type="int">
+</parameter>
+<parameter name="height" type="int">
+</parameter>
+</method>
+<method name="getEncodedDataSize"
+ return="int"
+ abstract="false"
+ native="true"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="width" type="int">
+</parameter>
+<parameter name="height" type="int">
+</parameter>
+</method>
+<method name="getHeight"
+ return="int"
+ abstract="false"
+ native="true"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="header" type="java.nio.Buffer">
+</parameter>
+</method>
+<method name="getWidth"
+ return="int"
+ abstract="false"
+ native="true"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="header" type="java.nio.Buffer">
+</parameter>
+</method>
+<method name="isValid"
+ return="boolean"
+ abstract="false"
+ native="true"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="header" type="java.nio.Buffer">
+</parameter>
+</method>
+<field name="DECODED_BLOCK_SIZE"
+ type="int"
+ transient="false"
+ volatile="false"
+ value="48"
+ static="true"
+ final="true"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</field>
+<field name="ENCODED_BLOCK_SIZE"
+ type="int"
+ transient="false"
+ volatile="false"
+ value="8"
+ static="true"
+ final="true"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</field>
+<field name="ETC1_RGB8_OES"
+ type="int"
+ transient="false"
+ volatile="false"
+ value="36196"
+ static="true"
+ final="true"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</field>
+<field name="ETC_PKM_HEADER_SIZE"
+ type="int"
+ transient="false"
+ volatile="false"
+ value="16"
+ static="true"
+ final="true"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</field>
+</class>
+<class name="ETC1Util"
+ extends="java.lang.Object"
+ abstract="false"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<constructor name="ETC1Util"
+ type="android.opengl.ETC1Util"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</constructor>
+<method name="compressTexture"
+ return="android.opengl.ETC1Util.ETC1Texture"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="input" type="java.nio.Buffer">
+</parameter>
+<parameter name="width" type="int">
+</parameter>
+<parameter name="height" type="int">
+</parameter>
+<parameter name="pixelSize" type="int">
+</parameter>
+<parameter name="stride" type="int">
+</parameter>
+</method>
+<method name="createTexture"
+ return="android.opengl.ETC1Util.ETC1Texture"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="input" type="java.io.InputStream">
+</parameter>
+<exception name="IOException" type="java.io.IOException">
+</exception>
+</method>
+<method name="isETC1Supported"
+ return="boolean"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</method>
+<method name="loadTexture"
+ return="void"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="target" type="int">
+</parameter>
+<parameter name="level" type="int">
+</parameter>
+<parameter name="border" type="int">
+</parameter>
+<parameter name="fallbackFormat" type="int">
+</parameter>
+<parameter name="fallbackType" type="int">
+</parameter>
+<parameter name="input" type="java.io.InputStream">
+</parameter>
+<exception name="IOException" type="java.io.IOException">
+</exception>
+</method>
+<method name="loadTexture"
+ return="void"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="target" type="int">
+</parameter>
+<parameter name="level" type="int">
+</parameter>
+<parameter name="border" type="int">
+</parameter>
+<parameter name="fallbackFormat" type="int">
+</parameter>
+<parameter name="fallbackType" type="int">
+</parameter>
+<parameter name="texture" type="android.opengl.ETC1Util.ETC1Texture">
+</parameter>
+</method>
+<method name="writeTexture"
+ return="void"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="texture" type="android.opengl.ETC1Util.ETC1Texture">
+</parameter>
+<parameter name="output" type="java.io.OutputStream">
+</parameter>
+<exception name="IOException" type="java.io.IOException">
+</exception>
+</method>
+</class>
+<class name="ETC1Util.ETC1Texture"
+ extends="java.lang.Object"
+ abstract="false"
+ static="true"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<constructor name="ETC1Util.ETC1Texture"
+ type="android.opengl.ETC1Util.ETC1Texture"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="width" type="int">
+</parameter>
+<parameter name="height" type="int">
+</parameter>
+<parameter name="data" type="java.nio.ByteBuffer">
+</parameter>
+</constructor>
+<method name="getData"
+ return="java.nio.ByteBuffer"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</method>
+<method name="getHeight"
+ return="int"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</method>
+<method name="getWidth"
+ return="int"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</method>
+</class>
<class name="GLDebugHelper"
extends="java.lang.Object"
abstract="false"
diff --git a/core/jni/Android.mk b/core/jni/Android.mk
index c92a86c..67a0bda 100644
--- a/core/jni/Android.mk
+++ b/core/jni/Android.mk
@@ -165,6 +165,7 @@
libEGL \
libGLESv1_CM \
libGLESv2 \
+ libETC1 \
libhardware \
libhardware_legacy \
libsonivox \
diff --git a/core/jni/android/opengl/util.cpp b/core/jni/android/opengl/util.cpp
index 4041346..589b255 100644
--- a/core/jni/android/opengl/util.cpp
+++ b/core/jni/android/opengl/util.cpp
@@ -23,6 +23,7 @@
#include <dlfcn.h>
#include <GLES/gl.h>
+#include <ETC1/etc1.h>
#include <core/SkBitmap.h>
@@ -39,6 +40,7 @@
static jclass gIAEClass;
static jclass gUOEClass;
+static jclass gAIOOBEClass;
static inline
void mx4transform(float x, float y, float z, float w, const float* pM, float* pDest) {
@@ -712,6 +714,297 @@
}
/*
+ * ETC1 methods.
+ */
+
+static jclass nioAccessClass;
+static jclass bufferClass;
+static jmethodID getBasePointerID;
+static jmethodID getBaseArrayID;
+static jmethodID getBaseArrayOffsetID;
+static jfieldID positionID;
+static jfieldID limitID;
+static jfieldID elementSizeShiftID;
+
+/* Cache method IDs each time the class is loaded. */
+
+static void
+nativeClassInitBuffer(JNIEnv *_env)
+{
+ jclass nioAccessClassLocal = _env->FindClass("java/nio/NIOAccess");
+ nioAccessClass = (jclass) _env->NewGlobalRef(nioAccessClassLocal);
+
+ jclass bufferClassLocal = _env->FindClass("java/nio/Buffer");
+ bufferClass = (jclass) _env->NewGlobalRef(bufferClassLocal);
+
+ getBasePointerID = _env->GetStaticMethodID(nioAccessClass,
+ "getBasePointer", "(Ljava/nio/Buffer;)J");
+ getBaseArrayID = _env->GetStaticMethodID(nioAccessClass,
+ "getBaseArray", "(Ljava/nio/Buffer;)Ljava/lang/Object;");
+ getBaseArrayOffsetID = _env->GetStaticMethodID(nioAccessClass,
+ "getBaseArrayOffset", "(Ljava/nio/Buffer;)I");
+ positionID = _env->GetFieldID(bufferClass, "position", "I");
+ limitID = _env->GetFieldID(bufferClass, "limit", "I");
+ elementSizeShiftID =
+ _env->GetFieldID(bufferClass, "_elementSizeShift", "I");
+}
+
+static void *
+getPointer(JNIEnv *_env, jobject buffer, jint *remaining)
+{
+ jint position;
+ jint limit;
+ jint elementSizeShift;
+ jlong pointer;
+ jint offset;
+ void *data;
+
+ position = _env->GetIntField(buffer, positionID);
+ limit = _env->GetIntField(buffer, limitID);
+ elementSizeShift = _env->GetIntField(buffer, elementSizeShiftID);
+ *remaining = (limit - position) << elementSizeShift;
+ pointer = _env->CallStaticLongMethod(nioAccessClass,
+ getBasePointerID, buffer);
+ if (pointer != 0L) {
+ return (void *) (jint) pointer;
+ }
+ return NULL;
+}
+
+class BufferHelper {
+public:
+ BufferHelper(JNIEnv *env, jobject buffer) {
+ mEnv = env;
+ mBuffer = buffer;
+ mData = NULL;
+ mRemaining = 0;
+ }
+
+ bool checkPointer(const char* errorMessage) {
+ if (mBuffer) {
+ mData = getPointer(mEnv, mBuffer, &mRemaining);
+ if (mData == NULL) {
+ mEnv->ThrowNew(gIAEClass, errorMessage);
+ }
+ return mData != NULL;
+ } else {
+ mEnv->ThrowNew(gIAEClass, errorMessage);
+ return false;
+ }
+ }
+
+ inline void* getData() {
+ return mData;
+ }
+
+ inline jint remaining() {
+ return mRemaining;
+ }
+
+private:
+ JNIEnv* mEnv;
+ jobject mBuffer;
+ void* mData;
+ jint mRemaining;
+};
+
+/**
+ * Encode a block of pixels.
+ *
+ * @param in a pointer to a ETC1_DECODED_BLOCK_SIZE array of bytes that represent a
+ * 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
+ * value of pixel (x, y).
+ *
+ * @param validPixelMask is a 16-bit mask where bit (1 << (x + y * 4)) indicates whether
+ * the corresponding (x,y) pixel is valid. Invalid pixel color values are ignored when compressing.
+ *
+ * @param out an ETC1 compressed version of the data.
+ *
+ */
+static void etc1_encodeBlock(JNIEnv *env, jclass clazz,
+ jobject in, jint validPixelMask, jobject out) {
+ if (validPixelMask < 0 || validPixelMask > 15) {
+ env->ThrowNew(gIAEClass, "validPixelMask");
+ return;
+ }
+ BufferHelper inB(env, in);
+ BufferHelper outB(env, out);
+ if (inB.checkPointer("in") && outB.checkPointer("out")) {
+ if (inB.remaining() < ETC1_DECODED_BLOCK_SIZE) {
+ env->ThrowNew(gIAEClass, "in's remaining data < DECODED_BLOCK_SIZE");
+ } else if (outB.remaining() < ETC1_ENCODED_BLOCK_SIZE) {
+ env->ThrowNew(gIAEClass, "out's remaining data < ENCODED_BLOCK_SIZE");
+ } else {
+ etc1_encode_block((etc1_byte*) inB.getData(), validPixelMask,
+ (etc1_byte*) outB.getData());
+ }
+ }
+}
+
+/**
+ * Decode a block of pixels.
+ *
+ * @param in an ETC1 compressed version of the data.
+ *
+ * @param out a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a
+ * 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
+ * value of pixel (x, y).
+ */
+static void etc1_decodeBlock(JNIEnv *env, jclass clazz,
+ jobject in, jobject out){
+ BufferHelper inB(env, in);
+ BufferHelper outB(env, out);
+ if (inB.checkPointer("in") && outB.checkPointer("out")) {
+ if (inB.remaining() < ETC1_ENCODED_BLOCK_SIZE) {
+ env->ThrowNew(gIAEClass, "in's remaining data < ENCODED_BLOCK_SIZE");
+ } else if (outB.remaining() < ETC1_DECODED_BLOCK_SIZE) {
+ env->ThrowNew(gIAEClass, "out's remaining data < DECODED_BLOCK_SIZE");
+ } else {
+ etc1_decode_block((etc1_byte*) inB.getData(),
+ (etc1_byte*) outB.getData());
+ }
+ }
+}
+
+/**
+ * Return the size of the encoded image data (does not include size of PKM header).
+ */
+static jint etc1_getEncodedDataSize(JNIEnv *env, jclass clazz,
+ jint width, jint height) {
+ return etc1_get_encoded_data_size(width, height);
+}
+
+/**
+ * Encode an entire image.
+ * @param in pointer to the image data. Formatted such that
+ * pixel (x,y) is at pIn + pixelSize * x + stride * y + redOffset;
+ * @param out pointer to encoded data. Must be large enough to store entire encoded image.
+ */
+static void etc1_encodeImage(JNIEnv *env, jclass clazz,
+ jobject in, jint width, jint height,
+ jint pixelSize, jint stride, jobject out) {
+ if (pixelSize < 2 || pixelSize > 3) {
+ env->ThrowNew(gIAEClass, "pixelSize must be 2 or 3");
+ return;
+ }
+ BufferHelper inB(env, in);
+ BufferHelper outB(env, out);
+ if (inB.checkPointer("in") && outB.checkPointer("out")) {
+ jint imageSize = stride * height;
+ jint encodedImageSize = etc1_get_encoded_data_size(width, height);
+ if (inB.remaining() < imageSize) {
+ env->ThrowNew(gIAEClass, "in's remaining data < image size");
+ } else if (outB.remaining() < encodedImageSize) {
+ env->ThrowNew(gIAEClass, "out's remaining data < encoded image size");
+ } else {
+ int result = etc1_encode_image((etc1_byte*) inB.getData(),
+ width, height, pixelSize,
+ stride,
+ (etc1_byte*) outB.getData());
+ }
+ }
+}
+
+/**
+ * Decode an entire image.
+ * @param in the encoded data.
+ * @param out pointer to the image data. Will be written such that
+ * pixel (x,y) is at pIn + pixelSize * x + stride * y. Must be
+ * large enough to store entire image.
+ */
+static void etc1_decodeImage(JNIEnv *env, jclass clazz,
+ jobject in, jobject out,
+ jint width, jint height,
+ jint pixelSize, jint stride) {
+ if (pixelSize < 2 || pixelSize > 3) {
+ env->ThrowNew(gIAEClass, "pixelSize must be 2 or 3");
+ return;
+ }
+ BufferHelper inB(env, in);
+ BufferHelper outB(env, out);
+ if (inB.checkPointer("in") && outB.checkPointer("out")) {
+ jint imageSize = stride * height;
+ jint encodedImageSize = etc1_get_encoded_data_size(width, height);
+ if (inB.remaining() < encodedImageSize) {
+ env->ThrowNew(gIAEClass, "in's remaining data < encoded image size");
+ } else if (outB.remaining() < imageSize) {
+ env->ThrowNew(gIAEClass, "out's remaining data < image size");
+ } else {
+ int result = etc1_decode_image((etc1_byte*) inB.getData(),
+ (etc1_byte*) outB.getData(),
+ width, height, pixelSize,
+ stride);
+ }
+ }
+}
+
+/**
+ * Format a PKM header
+ */
+static void etc1_formatHeader(JNIEnv *env, jclass clazz,
+ jobject header, jint width, jint height) {
+ BufferHelper headerB(env, header);
+ if (headerB.checkPointer("header") ){
+ if (headerB.remaining() < ETC_PKM_HEADER_SIZE) {
+ env->ThrowNew(gIAEClass, "header's remaining data < ETC_PKM_HEADER_SIZE");
+ } else {
+ etc1_pkm_format_header((etc1_byte*) headerB.getData(), width, height);
+ }
+ }
+}
+
+/**
+ * Check if a PKM header is correctly formatted.
+ */
+static jboolean etc1_isValid(JNIEnv *env, jclass clazz,
+ jobject header) {
+ jboolean result = false;
+ BufferHelper headerB(env, header);
+ if (headerB.checkPointer("header") ){
+ if (headerB.remaining() < ETC_PKM_HEADER_SIZE) {
+ env->ThrowNew(gIAEClass, "header's remaining data < ETC_PKM_HEADER_SIZE");
+ } else {
+ result = etc1_pkm_is_valid((etc1_byte*) headerB.getData());
+ }
+ }
+ return result;
+}
+
+/**
+ * Read the image width from a PKM header
+ */
+static jint etc1_getWidth(JNIEnv *env, jclass clazz,
+ jobject header) {
+ jint result = 0;
+ BufferHelper headerB(env, header);
+ if (headerB.checkPointer("header") ){
+ if (headerB.remaining() < ETC_PKM_HEADER_SIZE) {
+ env->ThrowNew(gIAEClass, "header's remaining data < ETC_PKM_HEADER_SIZE");
+ } else {
+ result = etc1_pkm_get_width((etc1_byte*) headerB.getData());
+ }
+ }
+ return result;
+}
+
+/**
+ * Read the image height from a PKM header
+ */
+static int etc1_getHeight(JNIEnv *env, jclass clazz,
+ jobject header) {
+ jint result = 0;
+ BufferHelper headerB(env, header);
+ if (headerB.checkPointer("header") ){
+ if (headerB.remaining() < ETC_PKM_HEADER_SIZE) {
+ env->ThrowNew(gIAEClass, "header's remaining data < ETC_PKM_HEADER_SIZE");
+ } else {
+ result = etc1_pkm_get_height((etc1_byte*) headerB.getData());
+ }
+ }
+ return result;
+}
+
+/*
* JNI registration
*/
@@ -721,6 +1014,8 @@
env->FindClass("java/lang/IllegalArgumentException"));
gUOEClass = (jclass) env->NewGlobalRef(
env->FindClass("java/lang/UnsupportedOperationException"));
+ gAIOOBEClass = (jclass) env->NewGlobalRef(
+ env->FindClass("java/lang/ArrayIndexOutOfBoundsException"));
}
static JNINativeMethod gMatrixMethods[] = {
@@ -742,6 +1037,18 @@
{ "native_texSubImage2D", "(IIIILandroid/graphics/Bitmap;II)I", (void*)util_texSubImage2D },
};
+static JNINativeMethod gEtc1Methods[] = {
+ { "encodeBlock", "(Ljava/nio/Buffer;ILjava/nio/Buffer;)V", (void*) etc1_encodeBlock },
+ { "decodeBlock", "(Ljava/nio/Buffer;Ljava/nio/Buffer;)V", (void*) etc1_decodeBlock },
+ { "getEncodedDataSize", "(II)I", (void*) etc1_getEncodedDataSize },
+ { "encodeImage", "(Ljava/nio/Buffer;IIIILjava/nio/Buffer;)V", (void*) etc1_encodeImage },
+ { "decodeImage", "(Ljava/nio/Buffer;Ljava/nio/Buffer;IIII)V", (void*) etc1_decodeImage },
+ { "formatHeader", "(Ljava/nio/Buffer;II)V", (void*) etc1_formatHeader },
+ { "isValid", "(Ljava/nio/Buffer;)Z", (void*) etc1_isValid },
+ { "getWidth", "(Ljava/nio/Buffer;)I", (void*) etc1_getWidth },
+ { "getHeight", "(Ljava/nio/Buffer;)I", (void*) etc1_getHeight },
+};
+
typedef struct _ClassRegistrationInfo {
const char* classPath;
JNINativeMethod* methods;
@@ -752,11 +1059,13 @@
{"android/opengl/Matrix", gMatrixMethods, NELEM(gMatrixMethods)},
{"android/opengl/Visibility", gVisiblityMethods, NELEM(gVisiblityMethods)},
{"android/opengl/GLUtils", gUtilsMethods, NELEM(gUtilsMethods)},
+ {"android/opengl/ETC1", gEtc1Methods, NELEM(gEtc1Methods)},
};
int register_android_opengl_classes(JNIEnv* env)
{
lookupClasses(env);
+ nativeClassInitBuffer(env);
int result = 0;
for (int i = 0; i < NELEM(gClasses); i++) {
ClassRegistrationInfo* cri = &gClasses[i];
diff --git a/opengl/include/ETC1/etc1.h b/opengl/include/ETC1/etc1.h
new file mode 100644
index 0000000..0d38905
--- /dev/null
+++ b/opengl/include/ETC1/etc1.h
@@ -0,0 +1,106 @@
+// Copyright 2009 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef __etc1_h__
+#define __etc1_h__
+
+#define ETC1_ENCODED_BLOCK_SIZE 8
+#define ETC1_DECODED_BLOCK_SIZE 48
+
+#ifndef ETC1_RGB8_OES
+#define ETC1_RGB8_OES 0x8D64
+#endif
+
+typedef unsigned char etc1_byte;
+typedef int etc1_bool;
+typedef unsigned int etc1_uint32;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Encode a block of pixels.
+//
+// pIn is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a
+// 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
+// value of pixel (x, y).
+//
+// validPixelMask is a 16-bit mask where bit (1 << (x + y * 4)) indicates whether
+// the corresponding (x,y) pixel is valid. Invalid pixel color values are ignored when compressing.
+//
+// pOut is an ETC1 compressed version of the data.
+
+void etc1_encode_block(const etc1_byte* pIn, etc1_uint32 validPixelMask, etc1_byte* pOut);
+
+// Decode a block of pixels.
+//
+// pIn is an ETC1 compressed version of the data.
+//
+// pOut is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a
+// 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
+// value of pixel (x, y).
+
+void etc1_decode_block(const etc1_byte* pIn, etc1_byte* pOut);
+
+// Return the size of the encoded image data (does not include size of PKM header).
+
+etc1_uint32 etc1_get_encoded_data_size(etc1_uint32 width, etc1_uint32 height);
+
+// Encode an entire image.
+// pIn - pointer to the image data. Formatted such that
+// pixel (x,y) is at pIn + pixelSize * x + stride * y;
+// pOut - pointer to encoded data. Must be large enough to store entire encoded image.
+// pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image.
+// returns non-zero if there is an error.
+
+int etc1_encode_image(const etc1_byte* pIn, etc1_uint32 width, etc1_uint32 height,
+ etc1_uint32 pixelSize, etc1_uint32 stride, etc1_byte* pOut);
+
+// Decode an entire image.
+// pIn - pointer to encoded data.
+// pOut - pointer to the image data. Will be written such that
+// pixel (x,y) is at pIn + pixelSize * x + stride * y. Must be
+// large enough to store entire image.
+// pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image.
+// returns non-zero if there is an error.
+
+int etc1_decode_image(const etc1_byte* pIn, etc1_byte* pOut,
+ etc1_uint32 width, etc1_uint32 height,
+ etc1_uint32 pixelSize, etc1_uint32 stride);
+
+// Size of a PKM header, in bytes.
+
+#define ETC_PKM_HEADER_SIZE 16
+
+// Format a PKM header
+
+void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height);
+
+// Check if a PKM header is correctly formatted.
+
+etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader);
+
+// Read the image width from a PKM header
+
+etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader);
+
+// Read the image height from a PKM header
+
+etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/opengl/java/android/opengl/ETC1.java b/opengl/java/android/opengl/ETC1.java
new file mode 100644
index 0000000..677bbd4
--- /dev/null
+++ b/opengl/java/android/opengl/ETC1.java
@@ -0,0 +1,137 @@
+/*
+ * Copyright 2009 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.opengl;
+
+import java.nio.Buffer;
+
+/**
+ * Methods for encoding and decoding ETC1 textures.
+ * <p>
+ * The standard for the ETC1 texture format can be found at
+ * http://www.khronos.org/registry/gles/extensions/OES/OES_compressed_ETC1_RGB8_texture.txt
+ * <p>
+ * The PKM file format is of a 16-byte header that describes the image bounds
+ * followed by the encoded ETC1 texture data.
+ * <p>
+ * @see(ETC1Util)
+ */
+public class ETC1 {
+
+ /**
+ * Size in bytes of an encoded block.
+ */
+ public static final int ENCODED_BLOCK_SIZE = 8;
+
+ /**
+ * Size in bytes of a decoded block.
+ */
+ public static final int DECODED_BLOCK_SIZE = 48;
+
+ /**
+ * Size of a PKM file header, in bytes.
+ */
+ public static final int ETC_PKM_HEADER_SIZE = 16;
+
+ /**
+ * Accepted by the internalformat parameter of glCompressedTexImage2D.
+ */
+ public static final int ETC1_RGB8_OES = 0x8D64;
+
+ /**
+ * Encode a block of pixels.
+ *
+ * @param in a native order direct buffer of size DECODED_BLOCK_SIZE that represent a
+ * 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
+ * value of pixel (x, y).
+ *
+ * @param validPixelMask is a 16-bit mask where bit (1 << (x + y * 4)) indicates whether
+ * the corresponding (x,y) pixel is valid. Invalid pixel color values are ignored when compressing.
+ *
+ * @param out a native order direct buffer of size ENCODED_BLOCK_SIZE that receives the
+ * ETC1 compressed version of the data.
+ *
+ */
+ public static native void encodeBlock(Buffer in, int validPixelMask, Buffer out);
+
+ /**
+ * Decode a block of pixels.
+ *
+ * @param in a native order direct buffer of size ENCODED_BLOCK_SIZE that contains the
+ * ETC1 compressed version of the data.
+ *
+ * @param out a native order direct buffer of size DECODED_BLOCK_SIZE that will receive
+ * the decoded data. The data represents a
+ * 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
+ * value of pixel (x, y).
+ */
+ public static native void decodeBlock(Buffer in, Buffer out);
+
+ /**
+ * Return the size of the encoded image data (does not include size of PKM header).
+ */
+ public static native int getEncodedDataSize(int width, int height);
+
+ /**
+ * Encode an entire image.
+ * @param in a native order direct buffer of the image data. Formatted such that
+ * pixel (x,y) is at pIn + pixelSize * x + stride * y;
+ * @param out a native order direct buffer of the encoded data.
+ * Must be large enough to store entire encoded image.
+ * @param pixelSize must be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image,
+ * 3 is a GL_BYTE RGB image.
+ */
+ public static native void encodeImage(Buffer in, int width, int height,
+ int pixelSize, int stride, Buffer out);
+
+ /**
+ * Decode an entire image.
+ * @param in native order direct buffer of the encoded data.
+ * @param out native order direct buffer of the image data. Will be written such that
+ * pixel (x,y) is at pIn + pixelSize * x + stride * y. Must be
+ * large enough to store entire image.
+ * @param pixelSize must be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image,
+ * 3 is a GL_BYTE RGB image.
+ */
+ public static native void decodeImage(Buffer in, Buffer out,
+ int width, int height, int pixelSize, int stride);
+
+ /**
+ * Format a PKM header
+ * @param header native order direct buffer of the header.
+ * @param width the width of the image in pixels.
+ * @param height the height of the image in pixels.
+ */
+ public static native void formatHeader(Buffer header, int width, int height);
+
+ /**
+ * Check if a PKM header is correctly formatted.
+ * @param header native order direct buffer of the header.
+ */
+ public static native boolean isValid(Buffer header);
+
+ /**
+ * Read the image width from a PKM header
+ * @param header native order direct buffer of the header.
+ */
+ public static native int getWidth(Buffer header);
+
+ /**
+ * Read the image height from a PKM header
+ * @param header native order direct buffer of the header.
+ */
+ public static native int getHeight(Buffer header);
+}
diff --git a/opengl/java/android/opengl/ETC1Util.java b/opengl/java/android/opengl/ETC1Util.java
new file mode 100644
index 0000000..56e2f23
--- /dev/null
+++ b/opengl/java/android/opengl/ETC1Util.java
@@ -0,0 +1,228 @@
+/*
+ * Copyright 2009 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.opengl;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.Buffer;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
+/**
+ * Utility methods for using ETC1 compressed textures.
+ *
+ */
+public class ETC1Util {
+ /**
+ * Convenience method to load an ETC1 texture whether or not the active OpenGL context
+ * supports the ETC1 texture compression format.
+ * @param target the texture target.
+ * @param level the texture level
+ * @param border the border size. Typically 0.
+ * @param fallbackFormat the format to use if ETC1 texture compression is not supported.
+ * Must be GL_RGB.
+ * @param fallbackType the type to use if ETC1 texture compression is not supported.
+ * Can be either GL_UNSIGNED_SHORT_5_6_5, which implies 16-bits-per-pixel,
+ * or GL_UNSIGNED_BYTE, which implies 24-bits-per-pixel.
+ * @param input the input stream containing an ETC1 texture in PKM format.
+ * @throws IOException
+ */
+ public static void loadTexture(int target, int level, int border,
+ int fallbackFormat, int fallbackType, InputStream input)
+ throws IOException {
+ loadTexture(target, level, border, fallbackFormat, fallbackType, createTexture(input));
+ }
+
+ /**
+ * Convenience method to load an ETC1 texture whether or not the active OpenGL context
+ * supports the ETC1 texture compression format.
+ * @param target the texture target.
+ * @param level the texture level
+ * @param border the border size. Typically 0.
+ * @param fallbackFormat the format to use if ETC1 texture compression is not supported.
+ * Must be GL_RGB.
+ * @param fallbackType the type to use if ETC1 texture compression is not supported.
+ * Can be either GL_UNSIGNED_SHORT_5_6_5, which implies 16-bits-per-pixel,
+ * or GL_UNSIGNED_BYTE, which implies 24-bits-per-pixel.
+ * @param texture the ETC1 to load.
+ */
+ public static void loadTexture(int target, int level, int border,
+ int fallbackFormat, int fallbackType, ETC1Texture texture) {
+ if (fallbackFormat != GLES10.GL_RGB) {
+ throw new IllegalArgumentException("fallbackFormat must be GL_RGB");
+ }
+ if (! (fallbackType == GLES10.GL_UNSIGNED_SHORT_5_6_5
+ || fallbackType == GLES10.GL_UNSIGNED_BYTE)) {
+ throw new IllegalArgumentException("Unsupported fallbackType");
+ }
+
+ int width = texture.getWidth();
+ int height = texture.getHeight();
+ Buffer data = texture.getData();
+ if (isETC1Supported()) {
+ int imageSize = data.remaining();
+ GLES10.glCompressedTexImage2D(target, level, ETC1.ETC1_RGB8_OES, width, height,
+ border, imageSize, data);
+ } else {
+ boolean useShorts = fallbackType != GLES10.GL_UNSIGNED_BYTE;
+ int pixelSize = useShorts ? 2 : 3;
+ int stride = pixelSize * width;
+ ByteBuffer decodedData = ByteBuffer.allocateDirect(stride*height)
+ .order(ByteOrder.nativeOrder());
+ ETC1.decodeImage(data, decodedData, width, height, pixelSize, stride);
+ GLES10.glTexImage2D(target, level, fallbackFormat, width, height, border,
+ fallbackFormat, fallbackType, decodedData);
+ }
+ }
+
+ /**
+ * Check if ETC1 texture compression is supported by the active OpenGL ES context.
+ * @returns true if the active OpenGL ES context supports ETC1 texture compression.
+ */
+ public static boolean isETC1Supported() {
+ int[] results = new int[20];
+ GLES10.glGetIntegerv(GLES10.GL_NUM_COMPRESSED_TEXTURE_FORMATS, results, 0);
+ int numFormats = results[0];
+ if (numFormats > results.length) {
+ results = new int[numFormats];
+ }
+ GLES10.glGetIntegerv(GLES10.GL_COMPRESSED_TEXTURE_FORMATS, results, 0);
+ for (int i = 0; i < numFormats; i++) {
+ if (results[i] == ETC1.ETC1_RGB8_OES) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /**
+ * A utility class encapsulating a compressed ETC1 texture.
+ */
+ public static class ETC1Texture {
+ public ETC1Texture(int width, int height, ByteBuffer data) {
+ mWidth = width;
+ mHeight = height;
+ mData = data;
+ }
+
+ /**
+ * Get the width of the texture in pixels.
+ * @return the width of the texture in pixels.
+ */
+ public int getWidth() { return mWidth; }
+
+ /**
+ * Get the height of the texture in pixels.
+ * @return the width of the texture in pixels.
+ */
+ public int getHeight() { return mHeight; }
+
+ /**
+ * Get the compressed data of the texture.
+ * @return the texture data.
+ */
+ public ByteBuffer getData() { return mData; }
+
+ private int mWidth;
+ private int mHeight;
+ private ByteBuffer mData;
+ }
+
+ /**
+ * Create a new ETC1Texture from an input stream containing a PKM formatted compressed texture.
+ * @param input an input stream containing a PKM formatted compressed texture.
+ * @return an ETC1Texture read from the input stream.
+ * @throws IOException
+ */
+ public static ETC1Texture createTexture(InputStream input) throws IOException {
+ int width = 0;
+ int height = 0;
+ byte[] ioBuffer = new byte[4096];
+ {
+ if (input.read(ioBuffer, 0, ETC1.ETC_PKM_HEADER_SIZE) != ETC1.ETC_PKM_HEADER_SIZE) {
+ throw new IOException("Unable to read PKM file header.");
+ }
+ ByteBuffer headerBuffer = ByteBuffer.allocateDirect(ETC1.ETC_PKM_HEADER_SIZE)
+ .order(ByteOrder.nativeOrder());
+ headerBuffer.put(ioBuffer, 0, ETC1.ETC_PKM_HEADER_SIZE).position(0);
+ if (!ETC1.isValid(headerBuffer)) {
+ throw new IOException("Not a PKM file.");
+ }
+ width = ETC1.getWidth(headerBuffer);
+ height = ETC1.getHeight(headerBuffer);
+ }
+ int encodedSize = ETC1.getEncodedDataSize(width, height);
+ ByteBuffer dataBuffer = ByteBuffer.allocateDirect(encodedSize).order(ByteOrder.nativeOrder());
+ for (int i = 0; i < encodedSize; ) {
+ int chunkSize = Math.min(ioBuffer.length, encodedSize - i);
+ if (input.read(ioBuffer, 0, chunkSize) != chunkSize) {
+ throw new IOException("Unable to read PKM file data.");
+ }
+ dataBuffer.put(ioBuffer, 0, chunkSize);
+ i += chunkSize;
+ }
+ dataBuffer.position(0);
+ return new ETC1Texture(width, height, dataBuffer);
+ }
+
+ /**
+ * Helper function that compresses an image into an ETC1Texture.
+ * @param input a native order direct buffer containing the image data
+ * @param width the width of the image in pixels
+ * @param height the height of the image in pixels
+ * @param pixelSize the size of a pixel in bytes (2 or 3)
+ * @param stride the width of a line of the image in bytes
+ * @return the ETC1 texture.
+ */
+ public static ETC1Texture compressTexture(Buffer input, int width, int height, int pixelSize, int stride){
+ int encodedImageSize = ETC1.getEncodedDataSize(width, height);
+ ByteBuffer compressedImage = ByteBuffer.allocateDirect(encodedImageSize).
+ order(ByteOrder.nativeOrder());
+ ETC1.encodeImage(input, width, height, 3, stride, compressedImage);
+ return new ETC1Texture(width, height, compressedImage);
+ }
+
+ /**
+ * Helper function that writes an ETC1Texture to an output stream formatted as a PKM file.
+ * @param texture the input texture.
+ * @param output the stream to write the formatted texture data to.
+ * @throws IOException
+ */
+ public static void writeTexture(ETC1Texture texture, OutputStream output) throws IOException {
+ ByteBuffer dataBuffer = texture.getData();
+ int originalPosition = dataBuffer.position();
+ try {
+ int width = texture.getWidth();
+ int height = texture.getHeight();
+ ByteBuffer header = ByteBuffer.allocateDirect(ETC1.ETC_PKM_HEADER_SIZE).order(ByteOrder.nativeOrder());
+ ETC1.formatHeader(header, width, height);
+ byte[] ioBuffer = new byte[4096];
+ header.get(ioBuffer, 0, ETC1.ETC_PKM_HEADER_SIZE);
+ output.write(ioBuffer, 0, ETC1.ETC_PKM_HEADER_SIZE);
+ int encodedSize = ETC1.getEncodedDataSize(width, height);
+ for (int i = 0; i < encodedSize; ) {
+ int chunkSize = Math.min(ioBuffer.length, encodedSize - i);
+ dataBuffer.get(ioBuffer, 0, chunkSize);
+ output.write(ioBuffer, 0, chunkSize);
+ i += chunkSize;
+ }
+ } finally {
+ dataBuffer.position(originalPosition);
+ }
+ }
+}
diff --git a/opengl/libs/Android.mk b/opengl/libs/Android.mk
index 6d20e80..7353385 100644
--- a/opengl/libs/Android.mk
+++ b/opengl/libs/Android.mk
@@ -120,3 +120,33 @@
endif
include $(BUILD_SHARED_LIBRARY)
+
+###############################################################################
+# Build the ETC1 host static library
+#
+
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES:= \
+ ETC1/etc1.cpp \
+#
+
+LOCAL_LDLIBS := -lpthread -ldl
+LOCAL_MODULE:= libETC1
+
+include $(BUILD_HOST_STATIC_LIBRARY)
+
+###############################################################################
+# Build the ETC1 device library
+#
+
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES:= \
+ ETC1/etc1.cpp \
+#
+
+LOCAL_LDLIBS := -lpthread -ldl
+LOCAL_MODULE:= libETC1
+
+include $(BUILD_SHARED_LIBRARY)
diff --git a/opengl/libs/ETC1/etc1.cpp b/opengl/libs/ETC1/etc1.cpp
new file mode 100644
index 0000000..5ed2c3c
--- /dev/null
+++ b/opengl/libs/ETC1/etc1.cpp
@@ -0,0 +1,670 @@
+// Copyright 2009 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <ETC1/etc1.h>
+
+#include <string.h>
+
+/* From http://www.khronos.org/registry/gles/extensions/OES/OES_compressed_ETC1_RGB8_texture.txt
+
+ The number of bits that represent a 4x4 texel block is 64 bits if
+ <internalformat> is given by ETC1_RGB8_OES.
+
+ The data for a block is a number of bytes,
+
+ {q0, q1, q2, q3, q4, q5, q6, q7}
+
+ where byte q0 is located at the lowest memory address and q7 at
+ the highest. The 64 bits specifying the block is then represented
+ by the following 64 bit integer:
+
+ int64bit = 256*(256*(256*(256*(256*(256*(256*q0+q1)+q2)+q3)+q4)+q5)+q6)+q7;
+
+ ETC1_RGB8_OES:
+
+ a) bit layout in bits 63 through 32 if diffbit = 0
+
+ 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48
+ -----------------------------------------------
+ | base col1 | base col2 | base col1 | base col2 |
+ | R1 (4bits)| R2 (4bits)| G1 (4bits)| G2 (4bits)|
+ -----------------------------------------------
+
+ 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32
+ ---------------------------------------------------
+ | base col1 | base col2 | table | table |diff|flip|
+ | B1 (4bits)| B2 (4bits)| cw 1 | cw 2 |bit |bit |
+ ---------------------------------------------------
+
+
+ b) bit layout in bits 63 through 32 if diffbit = 1
+
+ 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48
+ -----------------------------------------------
+ | base col1 | dcol 2 | base col1 | dcol 2 |
+ | R1' (5 bits) | dR2 | G1' (5 bits) | dG2 |
+ -----------------------------------------------
+
+ 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32
+ ---------------------------------------------------
+ | base col 1 | dcol 2 | table | table |diff|flip|
+ | B1' (5 bits) | dB2 | cw 1 | cw 2 |bit |bit |
+ ---------------------------------------------------
+
+
+ c) bit layout in bits 31 through 0 (in both cases)
+
+ 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
+ -----------------------------------------------
+ | most significant pixel index bits |
+ | p| o| n| m| l| k| j| i| h| g| f| e| d| c| b| a|
+ -----------------------------------------------
+
+ 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
+ --------------------------------------------------
+ | least significant pixel index bits |
+ | p| o| n| m| l| k| j| i| h| g| f| e| d| c | b | a |
+ --------------------------------------------------
+
+
+ Add table 3.17.2: Intensity modifier sets for ETC1 compressed textures:
+
+ table codeword modifier table
+ ------------------ ----------------------
+ 0 -8 -2 2 8
+ 1 -17 -5 5 17
+ 2 -29 -9 9 29
+ 3 -42 -13 13 42
+ 4 -60 -18 18 60
+ 5 -80 -24 24 80
+ 6 -106 -33 33 106
+ 7 -183 -47 47 183
+
+
+ Add table 3.17.3 Mapping from pixel index values to modifier values for
+ ETC1 compressed textures:
+
+ pixel index value
+ ---------------
+ msb lsb resulting modifier value
+ ----- ----- -------------------------
+ 1 1 -b (large negative value)
+ 1 0 -a (small negative value)
+ 0 0 a (small positive value)
+ 0 1 b (large positive value)
+
+
+ */
+
+static const int kModifierTable[] = {
+/* 0 */2, 8, -2, -8,
+/* 1 */5, 17, -5, -17,
+/* 2 */9, 29, -9, -29,
+/* 3 */13, 42, -13, -42,
+/* 4 */18, 60, -18, -60,
+/* 5 */24, 80, -24, -80,
+/* 6 */33, 106, -33, -106,
+/* 7 */47, 183, -47, -183 };
+
+static const int kLookup[8] = { 0, 1, 2, 3, -4, -3, -2, -1 };
+
+static inline etc1_byte clamp(int x) {
+ return (etc1_byte) (x >= 0 ? (x < 255 ? x : 255) : 0);
+}
+
+static
+inline int convert4To8(int b) {
+ int c = b & 0xf;
+ return (c << 4) | c;
+}
+
+static
+inline int convert5To8(int b) {
+ int c = b & 0x1f;
+ return (c << 3) | (c >> 2);
+}
+
+static
+inline int convert6To8(int b) {
+ int c = b & 0x3f;
+ return (c << 2) | (c >> 4);
+}
+
+static
+inline int divideBy255(int d) {
+ return (d + 128 + (d >> 8)) >> 8;
+}
+
+static
+inline int convert8To4(int b) {
+ int c = b & 0xff;
+ return divideBy255(b * 15);
+}
+
+static
+inline int convert8To5(int b) {
+ int c = b & 0xff;
+ return divideBy255(b * 31);
+}
+
+static
+inline int convertDiff(int base, int diff) {
+ return convert5To8((0x1f & base) + kLookup[0x7 & diff]);
+}
+
+static
+void decode_subblock(etc1_byte* pOut, int r, int g, int b, const int* table,
+ etc1_uint32 low, bool second, bool flipped) {
+ int baseX = 0;
+ int baseY = 0;
+ if (second) {
+ if (flipped) {
+ baseY = 2;
+ } else {
+ baseX = 2;
+ }
+ }
+ for (int i = 0; i < 8; i++) {
+ int x, y;
+ if (flipped) {
+ x = baseX + (i >> 1);
+ y = baseY + (i & 1);
+ } else {
+ x = baseX + (i >> 2);
+ y = baseY + (i & 3);
+ }
+ int k = y + (x * 4);
+ int offset = ((low >> k) & 1) | ((low >> (k + 15)) & 2);
+ int delta = table[offset];
+ etc1_byte* q = pOut + 3 * (x + 4 * y);
+ *q++ = clamp(r + delta);
+ *q++ = clamp(g + delta);
+ *q++ = clamp(b + delta);
+ }
+}
+
+// Input is an ETC1 compressed version of the data.
+// Output is a 4 x 4 square of 3-byte pixels in form R, G, B
+
+void etc1_decode_block(const etc1_byte* pIn, etc1_byte* pOut) {
+ etc1_uint32 high = (pIn[0] << 24) | (pIn[1] << 16) | (pIn[2] << 8) | pIn[3];
+ etc1_uint32 low = (pIn[4] << 24) | (pIn[5] << 16) | (pIn[6] << 8) | pIn[7];
+ int r1, r2, g1, g2, b1, b2;
+ if (high & 2) {
+ // differential
+ int rBase = high >> 27;
+ int gBase = high >> 19;
+ int bBase = high >> 11;
+ r1 = convert5To8(rBase);
+ r2 = convertDiff(rBase, high >> 24);
+ g1 = convert5To8(gBase);
+ g2 = convertDiff(gBase, high >> 16);
+ b1 = convert5To8(bBase);
+ b2 = convertDiff(bBase, high >> 8);
+ } else {
+ // not differential
+ r1 = convert4To8(high >> 28);
+ r2 = convert4To8(high >> 24);
+ g1 = convert4To8(high >> 20);
+ g2 = convert4To8(high >> 16);
+ b1 = convert4To8(high >> 12);
+ b2 = convert4To8(high >> 8);
+ }
+ int tableIndexA = 7 & (high >> 5);
+ int tableIndexB = 7 & (high >> 2);
+ const int* tableA = kModifierTable + tableIndexA * 4;
+ const int* tableB = kModifierTable + tableIndexB * 4;
+ bool flipped = (high & 1) != 0;
+ decode_subblock(pOut, r1, g1, b1, tableA, low, false, flipped);
+ decode_subblock(pOut, r2, g2, b2, tableB, low, true, flipped);
+}
+
+typedef struct {
+ etc1_uint32 high;
+ etc1_uint32 low;
+ etc1_uint32 score; // Lower is more accurate
+} etc_compressed;
+
+static
+inline void take_best(etc_compressed* a, const etc_compressed* b) {
+ if (a->score > b->score) {
+ *a = *b;
+ }
+}
+
+static
+void etc_average_colors_subblock(const etc1_byte* pIn, etc1_uint32 inMask,
+ etc1_byte* pColors, bool flipped, bool second) {
+ int r = 0;
+ int g = 0;
+ int b = 0;
+
+ if (flipped) {
+ int by = 0;
+ if (second) {
+ by = 2;
+ }
+ for (int y = 0; y < 2; y++) {
+ int yy = by + y;
+ for (int x = 0; x < 4; x++) {
+ int i = x + 4 * yy;
+ if (inMask & (1 << i)) {
+ const etc1_byte* p = pIn + i * 3;
+ r += *(p++);
+ g += *(p++);
+ b += *(p++);
+ }
+ }
+ }
+ } else {
+ int bx = 0;
+ if (second) {
+ bx = 2;
+ }
+ for (int y = 0; y < 4; y++) {
+ for (int x = 0; x < 2; x++) {
+ int xx = bx + x;
+ int i = xx + 4 * y;
+ if (inMask & (1 << i)) {
+ const etc1_byte* p = pIn + i * 3;
+ r += *(p++);
+ g += *(p++);
+ b += *(p++);
+ }
+ }
+ }
+ }
+ pColors[0] = (etc1_byte)((r + 4) >> 3);
+ pColors[1] = (etc1_byte)((g + 4) >> 3);
+ pColors[2] = (etc1_byte)((b + 4) >> 3);
+}
+
+static
+inline int square(int x) {
+ return x * x;
+}
+
+static etc1_uint32 chooseModifier(const etc1_byte* pBaseColors,
+ const etc1_byte* pIn, etc1_uint32 *pLow, int bitIndex,
+ const int* pModifierTable) {
+ etc1_uint32 bestScore = ~0;
+ int bestIndex = 0;
+ int pixelR = pIn[0];
+ int pixelG = pIn[1];
+ int pixelB = pIn[2];
+ int r = pBaseColors[0];
+ int g = pBaseColors[1];
+ int b = pBaseColors[2];
+ for (int i = 0; i < 4; i++) {
+ int modifier = pModifierTable[i];
+ int decodedG = clamp(g + modifier);
+ etc1_uint32 score = (etc1_uint32) (6 * square(decodedG - pixelG));
+ if (score >= bestScore) {
+ continue;
+ }
+ int decodedR = clamp(r + modifier);
+ score += (etc1_uint32) (3 * square(decodedR - pixelR));
+ if (score >= bestScore) {
+ continue;
+ }
+ int decodedB = clamp(b + modifier);
+ score += (etc1_uint32) square(decodedB - pixelB);
+ if (score < bestScore) {
+ bestScore = score;
+ bestIndex = i;
+ }
+ }
+ etc1_uint32 lowMask = (((bestIndex >> 1) << 16) | (bestIndex & 1))
+ << bitIndex;
+ *pLow |= lowMask;
+ return bestScore;
+}
+
+static
+void etc_encode_subblock_helper(const etc1_byte* pIn, etc1_uint32 inMask,
+ etc_compressed* pCompressed, bool flipped, bool second,
+ const etc1_byte* pBaseColors, const int* pModifierTable) {
+ int score = pCompressed->score;
+ if (flipped) {
+ int by = 0;
+ if (second) {
+ by = 2;
+ }
+ for (int y = 0; y < 2; y++) {
+ int yy = by + y;
+ for (int x = 0; x < 4; x++) {
+ int i = x + 4 * yy;
+ if (inMask & (1 << i)) {
+ score += chooseModifier(pBaseColors, pIn + i * 3,
+ &pCompressed->low, yy + x * 4, pModifierTable);
+ }
+ }
+ }
+ } else {
+ int bx = 0;
+ if (second) {
+ bx = 2;
+ }
+ for (int y = 0; y < 4; y++) {
+ for (int x = 0; x < 2; x++) {
+ int xx = bx + x;
+ int i = xx + 4 * y;
+ if (inMask & (1 << i)) {
+ score += chooseModifier(pBaseColors, pIn + i * 3,
+ &pCompressed->low, y + xx * 4, pModifierTable);
+ }
+ }
+ }
+ }
+ pCompressed->score = score;
+}
+
+static bool inRange4bitSigned(int color) {
+ return color >= -4 && color <= 3;
+}
+
+static void etc_encodeBaseColors(etc1_byte* pBaseColors,
+ const etc1_byte* pColors, etc_compressed* pCompressed) {
+ int r1, g1, b1, r2, g2, b2; // 8 bit base colors for sub-blocks
+ bool differential;
+ {
+ int r51 = convert8To5(pColors[0]);
+ int g51 = convert8To5(pColors[1]);
+ int b51 = convert8To5(pColors[2]);
+ int r52 = convert8To5(pColors[3]);
+ int g52 = convert8To5(pColors[4]);
+ int b52 = convert8To5(pColors[5]);
+
+ r1 = convert5To8(r51);
+ g1 = convert5To8(g51);
+ b1 = convert5To8(b51);
+
+ int dr = r52 - r51;
+ int dg = g52 - g51;
+ int db = b52 - b51;
+
+ differential = inRange4bitSigned(dr) && inRange4bitSigned(dg)
+ && inRange4bitSigned(db);
+ if (differential) {
+ r2 = convert5To8(r51 + dr);
+ g2 = convert5To8(g51 + dg);
+ b2 = convert5To8(b51 + db);
+ pCompressed->high |= (r51 << 27) | ((7 & dr) << 24) | (g51 << 19)
+ | ((7 & dg) << 16) | (b51 << 11) | ((7 & db) << 8) | 2;
+ }
+ }
+
+ if (!differential) {
+ int r41 = convert8To4(pColors[0]);
+ int g41 = convert8To4(pColors[1]);
+ int b41 = convert8To4(pColors[2]);
+ int r42 = convert8To4(pColors[3]);
+ int g42 = convert8To4(pColors[4]);
+ int b42 = convert8To4(pColors[5]);
+ r1 = convert4To8(r41);
+ g1 = convert4To8(g41);
+ b1 = convert4To8(b41);
+ r2 = convert4To8(r42);
+ g2 = convert4To8(g42);
+ b2 = convert4To8(b42);
+ pCompressed->high |= (r41 << 28) | (r42 << 24) | (g41 << 20) | (g42
+ << 16) | (b41 << 12) | (b42 << 8);
+ }
+ pBaseColors[0] = r1;
+ pBaseColors[1] = g1;
+ pBaseColors[2] = b1;
+ pBaseColors[3] = r2;
+ pBaseColors[4] = g2;
+ pBaseColors[5] = b2;
+}
+
+static
+void etc_encode_block_helper(const etc1_byte* pIn, etc1_uint32 inMask,
+ const etc1_byte* pColors, etc_compressed* pCompressed, bool flipped) {
+ pCompressed->score = ~0;
+ pCompressed->high = (flipped ? 1 : 0);
+ pCompressed->low = 0;
+
+ etc1_byte pBaseColors[6];
+
+ etc_encodeBaseColors(pBaseColors, pColors, pCompressed);
+
+ int originalHigh = pCompressed->high;
+
+ const int* pModifierTable = kModifierTable;
+ for (int i = 0; i < 8; i++, pModifierTable += 4) {
+ etc_compressed temp;
+ temp.score = 0;
+ temp.high = originalHigh | (i << 5);
+ temp.low = 0;
+ etc_encode_subblock_helper(pIn, inMask, &temp, flipped, false,
+ pBaseColors, pModifierTable);
+ take_best(pCompressed, &temp);
+ }
+ pModifierTable = kModifierTable;
+ etc_compressed firstHalf = *pCompressed;
+ for (int i = 0; i < 8; i++, pModifierTable += 4) {
+ etc_compressed temp;
+ temp.score = firstHalf.score;
+ temp.high = firstHalf.high | (i << 2);
+ temp.low = firstHalf.low;
+ etc_encode_subblock_helper(pIn, inMask, &temp, flipped, true,
+ pBaseColors + 3, pModifierTable);
+ if (i == 0) {
+ *pCompressed = temp;
+ } else {
+ take_best(pCompressed, &temp);
+ }
+ }
+}
+
+static void writeBigEndian(etc1_byte* pOut, etc1_uint32 d) {
+ pOut[0] = (etc1_byte)(d >> 24);
+ pOut[1] = (etc1_byte)(d >> 16);
+ pOut[2] = (etc1_byte)(d >> 8);
+ pOut[3] = (etc1_byte) d;
+}
+
+// Input is a 4 x 4 square of 3-byte pixels in form R, G, B
+// inmask is a 16-bit mask where bit (1 << (x + y * 4)) tells whether the corresponding (x,y)
+// pixel is valid or not. Invalid pixel color values are ignored when compressing.
+// Output is an ETC1 compressed version of the data.
+
+void etc1_encode_block(const etc1_byte* pIn, etc1_uint32 inMask,
+ etc1_byte* pOut) {
+ etc1_byte colors[6];
+ etc1_byte flippedColors[6];
+ etc_average_colors_subblock(pIn, inMask, colors, false, false);
+ etc_average_colors_subblock(pIn, inMask, colors + 3, false, true);
+ etc_average_colors_subblock(pIn, inMask, flippedColors, true, false);
+ etc_average_colors_subblock(pIn, inMask, flippedColors + 3, true, true);
+
+ etc_compressed a, b;
+ etc_encode_block_helper(pIn, inMask, colors, &a, false);
+ etc_encode_block_helper(pIn, inMask, flippedColors, &b, true);
+ take_best(&a, &b);
+ writeBigEndian(pOut, a.high);
+ writeBigEndian(pOut + 4, a.low);
+}
+
+// Return the size of the encoded image data (does not include size of PKM header).
+
+etc1_uint32 etc1_get_encoded_data_size(etc1_uint32 width, etc1_uint32 height) {
+ return (((width + 3) & ~3) * ((height + 3) & ~3)) >> 1;
+}
+
+// Encode an entire image.
+// pIn - pointer to the image data. Formatted such that the Red component of
+// pixel (x,y) is at pIn + pixelSize * x + stride * y + redOffset;
+// pOut - pointer to encoded data. Must be large enough to store entire encoded image.
+
+int etc1_encode_image(const etc1_byte* pIn, etc1_uint32 width, etc1_uint32 height,
+ etc1_uint32 pixelSize, etc1_uint32 stride, etc1_byte* pOut) {
+ if (pixelSize < 2 || pixelSize > 3) {
+ return -1;
+ }
+ static const unsigned short kYMask[] = { 0x0, 0xf, 0xff, 0xfff, 0xffff };
+ static const unsigned short kXMask[] = { 0x0, 0x1111, 0x3333, 0x7777,
+ 0xffff };
+ etc1_byte block[ETC1_DECODED_BLOCK_SIZE];
+ etc1_byte encoded[ETC1_ENCODED_BLOCK_SIZE];
+
+ etc1_uint32 encodedWidth = (width + 3) & ~3;
+ etc1_uint32 encodedHeight = (height + 3) & ~3;
+
+ for (etc1_uint32 y = 0; y < encodedHeight; y += 4) {
+ etc1_uint32 yEnd = height - y;
+ if (yEnd > 4) {
+ yEnd = 4;
+ }
+ int ymask = kYMask[yEnd];
+ for (etc1_uint32 x = 0; x < encodedWidth; x += 4) {
+ etc1_uint32 xEnd = width - x;
+ if (xEnd > 4) {
+ xEnd = 4;
+ }
+ int mask = ymask & kXMask[xEnd];
+ for (etc1_uint32 cy = 0; cy < yEnd; cy++) {
+ etc1_byte* q = block + (cy * 4) * 3;
+ const etc1_byte* p = pIn + pixelSize * x + stride * (y + cy);
+ if (pixelSize == 3) {
+ memcpy(q, p, xEnd * 3);
+ } else {
+ for (etc1_uint32 cx = 0; cx < xEnd; cx++) {
+ int pixel = (p[1] << 8) | p[0];
+ *q++ = convert5To8(pixel >> 11);
+ *q++ = convert6To8(pixel >> 5);
+ *q++ = convert5To8(pixel);
+ p += pixelSize;
+ }
+ }
+ }
+ etc1_encode_block(block, mask, encoded);
+ memcpy(pOut, encoded, sizeof(encoded));
+ pOut += sizeof(encoded);
+ }
+ }
+ return 0;
+}
+
+// Decode an entire image.
+// pIn - pointer to encoded data.
+// pOut - pointer to the image data. Will be written such that the Red component of
+// pixel (x,y) is at pIn + pixelSize * x + stride * y + redOffset. Must be
+// large enough to store entire image.
+
+
+int etc1_decode_image(const etc1_byte* pIn, etc1_byte* pOut,
+ etc1_uint32 width, etc1_uint32 height,
+ etc1_uint32 pixelSize, etc1_uint32 stride) {
+ if (pixelSize < 2 || pixelSize > 3) {
+ return -1;
+ }
+ etc1_byte block[ETC1_DECODED_BLOCK_SIZE];
+
+ etc1_uint32 encodedWidth = (width + 3) & ~3;
+ etc1_uint32 encodedHeight = (height + 3) & ~3;
+
+ for (etc1_uint32 y = 0; y < encodedHeight; y += 4) {
+ etc1_uint32 yEnd = height - y;
+ if (yEnd > 4) {
+ yEnd = 4;
+ }
+ for (etc1_uint32 x = 0; x < encodedWidth; x += 4) {
+ etc1_uint32 xEnd = width - x;
+ if (xEnd > 4) {
+ xEnd = 4;
+ }
+ etc1_decode_block(pIn, block);
+ pIn += ETC1_ENCODED_BLOCK_SIZE;
+ for (etc1_uint32 cy = 0; cy < yEnd; cy++) {
+ const etc1_byte* q = block + (cy * 4) * 3;
+ etc1_byte* p = pOut + pixelSize * x + stride * (y + cy);
+ if (pixelSize == 3) {
+ memcpy(p, q, xEnd * 3);
+ } else {
+ for (etc1_uint32 cx = 0; cx < xEnd; cx++) {
+ etc1_byte r = *q++;
+ etc1_byte g = *q++;
+ etc1_byte b = *q++;
+ etc1_uint32 pixel = ((r >> 3) << 11) | ((g >> 2) << 5) | (b >> 3);
+ *p++ = (etc1_byte) pixel;
+ *p++ = (etc1_byte) (pixel >> 8);
+ }
+ }
+ }
+ }
+ }
+ return 0;
+}
+
+static const char kMagic[] = { 'P', 'K', 'M', ' ', '1', '0' };
+
+static const etc1_uint32 ETC1_PKM_FORMAT_OFFSET = 6;
+static const etc1_uint32 ETC1_PKM_ENCODED_WIDTH_OFFSET = 8;
+static const etc1_uint32 ETC1_PKM_ENCODED_HEIGHT_OFFSET = 10;
+static const etc1_uint32 ETC1_PKM_WIDTH_OFFSET = 12;
+static const etc1_uint32 ETC1_PKM_HEIGHT_OFFSET = 14;
+
+static const etc1_uint32 ETC1_RGB_NO_MIPMAPS = 0;
+
+static void writeBEUint16(etc1_byte* pOut, etc1_uint32 data) {
+ pOut[0] = (etc1_byte) (data >> 8);
+ pOut[1] = (etc1_byte) data;
+}
+
+static etc1_uint32 readBEUint16(const etc1_byte* pIn) {
+ return (pIn[0] << 8) | pIn[1];
+}
+
+// Format a PKM header
+
+void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height) {
+ memcpy(pHeader, kMagic, sizeof(kMagic));
+ etc1_uint32 encodedWidth = (width + 3) & ~3;
+ etc1_uint32 encodedHeight = (height + 3) & ~3;
+ writeBEUint16(pHeader + ETC1_PKM_FORMAT_OFFSET, ETC1_RGB_NO_MIPMAPS);
+ writeBEUint16(pHeader + ETC1_PKM_ENCODED_WIDTH_OFFSET, encodedWidth);
+ writeBEUint16(pHeader + ETC1_PKM_ENCODED_HEIGHT_OFFSET, encodedHeight);
+ writeBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET, width);
+ writeBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET, height);
+}
+
+// Check if a PKM header is correctly formatted.
+
+etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader) {
+ if (memcmp(pHeader, kMagic, sizeof(kMagic))) {
+ return false;
+ }
+ etc1_uint32 format = readBEUint16(pHeader + ETC1_PKM_FORMAT_OFFSET);
+ etc1_uint32 encodedWidth = readBEUint16(pHeader + ETC1_PKM_ENCODED_WIDTH_OFFSET);
+ etc1_uint32 encodedHeight = readBEUint16(pHeader + ETC1_PKM_ENCODED_HEIGHT_OFFSET);
+ etc1_uint32 width = readBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET);
+ etc1_uint32 height = readBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET);
+ return format == ETC1_RGB_NO_MIPMAPS &&
+ encodedWidth >= width && encodedWidth - width < 4 &&
+ encodedHeight >= height && encodedHeight - height < 4;
+}
+
+// Read the image width from a PKM header
+
+etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader) {
+ return readBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET);
+}
+
+// Read the image height from a PKM header
+
+etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader){
+ return readBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET);
+}