Add an option to create unpremultiplied bitmaps.
Currently they cannot be used directly by Skia, but
the pixels can be used elsewhere.
SkImageDecoder:
Add functions to require unpremultiplied output
and query the presence of the requirement
SkImageDecoder_libpng:
SkImageDecoder_libwebp:
SkImageDecoder_WIC:
Respect the requirement for unpremultiplied output.
TODO: Fix SkImageDecoder_CG.
SkScaledBitmapSampler:
Add procs to skip premultiplication and a boolean
parameter to use those procs.
ImageDecodingTest:
Test unpremultiplied bitmap decoding.
SampleUnpremul:
Add a sample which allows visually comparing between the
unpremultiplied version (copied into a premultiplied bitmap,
since drawing unpremultiplied is not currently supported)
and a premultiplied version of image files.
gm.h:
Add a getter for the resource path, so Samples can use it.
As of patch set 13, https://codereview.chromium.org/16816016/
and https://codereview.chromium.org/16983004/, which were
approved separately.
R=reed@google.com
Review URL: https://codereview.chromium.org/16410009
git-svn-id: http://skia.googlecode.com/svn/trunk@9612 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/ImageDecodingTest.cpp b/tests/ImageDecodingTest.cpp
new file mode 100644
index 0000000..f30a0b2
--- /dev/null
+++ b/tests/ImageDecodingTest.cpp
@@ -0,0 +1,157 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkBitmap.h"
+#include "SkColorPriv.h"
+#include "SkForceLinking.h"
+#include "SkImageDecoder.h"
+#include "SkOSFile.h"
+#include "SkStream.h"
+#include "SkString.h"
+#include "Test.h"
+
+__SK_FORCE_IMAGE_DECODER_LINKING;
+
+/**
+ * Interprets c as an unpremultiplied color, and returns the
+ * premultiplied equivalent.
+ */
+static SkPMColor premultiply_unpmcolor(SkPMColor c) {
+ U8CPU a = SkGetPackedA32(c);
+ U8CPU r = SkGetPackedR32(c);
+ U8CPU g = SkGetPackedG32(c);
+ U8CPU b = SkGetPackedB32(c);
+ return SkPreMultiplyARGB(a, r, g, b);
+}
+
+/**
+ * Return true if this stream format should be skipped, due
+ * to do being an opaque format or not a valid format.
+ */
+static bool skip_image_format(SkImageDecoder::Format format) {
+ switch (format) {
+ case SkImageDecoder::kPNG_Format:
+ case SkImageDecoder::kWEBP_Format:
+ return false;
+ // Skip unknown since it will not be decoded anyway.
+ case SkImageDecoder::kUnknown_Format:
+ // Technically ICO and BMP supports alpha channels, but our image
+ // decoders do not, so skip them as well.
+ case SkImageDecoder::kICO_Format:
+ case SkImageDecoder::kBMP_Format:
+ // The rest of these are opaque.
+ case SkImageDecoder::kWBMP_Format:
+ case SkImageDecoder::kGIF_Format:
+ case SkImageDecoder::kJPEG_Format:
+ return true;
+ }
+ SkASSERT(false);
+ return true;
+}
+
+/**
+ * Test decoding an image in premultiplied mode and unpremultiplied mode and compare
+ * them.
+ */
+static void compare_unpremul(skiatest::Reporter* reporter, const SkString& filename) {
+ // Decode a resource:
+ SkBitmap bm8888;
+ SkBitmap bm8888Unpremul;
+
+ SkFILEStream stream(filename.c_str());
+
+ SkImageDecoder::Format format = SkImageDecoder::GetStreamFormat(&stream);
+ if (skip_image_format(format)) {
+ return;
+ }
+
+ SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(&stream));
+ if (NULL == decoder.get()) {
+ SkDebugf("couldn't decode %s\n", filename.c_str());
+ return;
+ }
+
+ bool success = decoder->decode(&stream, &bm8888, SkBitmap::kARGB_8888_Config,
+ SkImageDecoder::kDecodePixels_Mode);
+ if (!success) {
+ return;
+ }
+
+ success = stream.rewind();
+ REPORTER_ASSERT(reporter, success);
+ if (!success) {
+ return;
+ }
+
+ decoder->setRequireUnpremultipliedColors(true);
+ success = decoder->decode(&stream, &bm8888Unpremul, SkBitmap::kARGB_8888_Config,
+ SkImageDecoder::kDecodePixels_Mode);
+ if (!success) {
+ return;
+ }
+
+ bool dimensionsMatch = bm8888.width() == bm8888Unpremul.width()
+ && bm8888.height() == bm8888Unpremul.height();
+ REPORTER_ASSERT(reporter, dimensionsMatch);
+ if (!dimensionsMatch) {
+ return;
+ }
+
+ // Only do the comparison if the two bitmaps are both 8888.
+ if (bm8888.config() != SkBitmap::kARGB_8888_Config
+ || bm8888Unpremul.config() != SkBitmap::kARGB_8888_Config) {
+ return;
+ }
+
+ // Now compare the two bitmaps.
+ for (int i = 0; i < bm8888.width(); ++i) {
+ for (int j = 0; j < bm8888.height(); ++j) {
+ // "c0" is the color of the premultiplied bitmap at (i, j).
+ const SkPMColor c0 = *bm8888.getAddr32(i, j);
+ // "c1" is the result of premultiplying the color of the unpremultiplied
+ // bitmap at (i, j).
+ const SkPMColor c1 = premultiply_unpmcolor(*bm8888Unpremul.getAddr32(i, j));
+ // Compute the difference for each component.
+ int da = SkAbs32(SkGetPackedA32(c0) - SkGetPackedA32(c1));
+ int dr = SkAbs32(SkGetPackedR32(c0) - SkGetPackedR32(c1));
+ int dg = SkAbs32(SkGetPackedG32(c0) - SkGetPackedG32(c1));
+ int db = SkAbs32(SkGetPackedB32(c0) - SkGetPackedB32(c1));
+
+ // Alpha component must be exactly the same.
+ REPORTER_ASSERT(reporter, 0 == da);
+ // Other components may differ if rounding is done differently,
+ // but currently that is not the case. If an image fails here
+ // in the future, we can change these to account for differences.
+ REPORTER_ASSERT(reporter, 0 == dr);
+ REPORTER_ASSERT(reporter, 0 == dg);
+ REPORTER_ASSERT(reporter, 0 == db);
+ }
+ }
+}
+
+static void test_imageDecodingTests(skiatest::Reporter* reporter) {
+ // This test cannot run if there is no resource path.
+ SkString resourcePath = skiatest::Test::GetResourcePath();
+ if (resourcePath.isEmpty()) {
+ return;
+ }
+ SkOSFile::Iter iter(resourcePath.c_str());
+ SkString basename;
+ if (iter.next(&basename)) {
+ do {
+ SkString filename = SkOSPath::SkPathJoin(resourcePath.c_str(), basename.c_str());
+ //SkDebugf("about to decode \"%s\"\n", filename.c_str());
+ compare_unpremul(reporter, filename);
+ } while (iter.next(&basename));
+ } else {
+ SkDebugf("Failed to find any files :(\n");
+ }
+}
+
+#include "TestClassDef.h"
+DEFINE_TESTCLASS("ImageDecoding", ImageDecodingTestClass,
+ test_imageDecodingTests)