libs/hwui/OpenGLRenderer.cpp - platform/frameworks/base - Gitiles

 /*
  * Copyright (C) 2010 The Android Open Source Project
  *
  * 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.
  */

 #define LOG_TAG "OpenGLRenderer"

 #include <stdlib.h>
 #include <stdint.h>
 #include <sys/types.h>

 #include <SkCanvas.h>

 #include <utils/Log.h>

 #include "OpenGLRenderer.h"

 namespace android {
 namespace uirenderer {

 ///////////////////////////////////////////////////////////////////////////////
 // Defines
 ///////////////////////////////////////////////////////////////////////////////

 #define MAX_TEXTURE_COUNT 128

 #define SV(x, y) { { x, y } }
 #define FV(x, y, u, v) { { x, y }, { u, v } }

 ///////////////////////////////////////////////////////////////////////////////
 // Globals
 ///////////////////////////////////////////////////////////////////////////////

 static const SimpleVertex gDrawColorVertices[] = {
         SV(0.0f, 0.0f),
         SV(1.0f, 0.0f),
         SV(0.0f, 1.0f),
         SV(1.0f, 1.0f)
 };
 static const GLsizei gDrawColorVertexStride = sizeof(SimpleVertex);
 static const GLsizei gDrawColorVertexCount = 4;

 // This array is never used directly but used as a memcpy source in the
 // OpenGLRenderer constructor
 static const TextureVertex gDrawTextureVertices[] = {
         FV(0.0f, 0.0f, 0.0f, 1.0f),
         FV(1.0f, 0.0f, 1.0f, 1.0f),
         FV(0.0f, 1.0f, 0.0f, 0.0f),
         FV(1.0f, 1.0f, 1.0f, 0.0f)
 };
 static const GLsizei gDrawTextureVertexStride = sizeof(TextureVertex);
 static const GLsizei gDrawTextureVertexCount = 4;

 // In this array, the index of each Blender equals the value of the first
 // entry. For instance, gBlends[1] == gBlends[SkXfermode::kSrc_Mode]
 static const Blender gBlends[] = {
         { SkXfermode::kClear_Mode,   GL_ZERO,                 GL_ZERO },
         { SkXfermode::kSrc_Mode,     GL_ONE,                  GL_ZERO },
         { SkXfermode::kDst_Mode,     GL_ZERO,                 GL_ONE },
         { SkXfermode::kSrcOver_Mode, GL_ONE,                  GL_ONE_MINUS_SRC_ALPHA },
         { SkXfermode::kDstOver_Mode, GL_ONE_MINUS_DST_ALPHA,  GL_ONE },
         { SkXfermode::kSrcIn_Mode,   GL_DST_ALPHA,            GL_ZERO },
         { SkXfermode::kDstIn_Mode,   GL_ZERO,                 GL_SRC_ALPHA },
         { SkXfermode::kSrcOut_Mode,  GL_ONE_MINUS_DST_ALPHA,  GL_ZERO },
         { SkXfermode::kDstOut_Mode,  GL_ZERO,                 GL_ONE_MINUS_SRC_ALPHA },
         { SkXfermode::kSrcATop_Mode, GL_DST_ALPHA,            GL_ONE_MINUS_SRC_ALPHA },
         { SkXfermode::kDstATop_Mode, GL_ONE_MINUS_DST_ALPHA,  GL_SRC_ALPHA },
         { SkXfermode::kXor_Mode,     GL_ONE_MINUS_DST_ALPHA,  GL_ONE_MINUS_SRC_ALPHA }
 };

 ///////////////////////////////////////////////////////////////////////////////
 // Constructors/destructor
 ///////////////////////////////////////////////////////////////////////////////

 OpenGLRenderer::OpenGLRenderer(): mTextureCache(MAX_TEXTURE_COUNT) {
     LOGD("Create OpenGLRenderer");

     mDrawColorShader = new DrawColorProgram;
     mDrawTextureShader = new DrawTextureProgram;

     memcpy(mDrawTextureVertices, gDrawTextureVertices, sizeof(gDrawTextureVertices));
 }

 OpenGLRenderer::~OpenGLRenderer() {
     LOGD("Destroy OpenGLRenderer");

     mTextureCache.clear();
 }

 ///////////////////////////////////////////////////////////////////////////////
 // Setup
 ///////////////////////////////////////////////////////////////////////////////

 void OpenGLRenderer::setViewport(int width, int height) {
     glViewport(0, 0, width, height);

     mat4 ortho;
     ortho.loadOrtho(0, width, height, 0, -1, 1);
     ortho.copyTo(mOrthoMatrix);

     mWidth = width;
     mHeight = height;
 }

 void OpenGLRenderer::prepare() {
     mSnapshot = &mFirstSnapshot;
     mSaveCount = 0;

     glDisable(GL_SCISSOR_TEST);

     glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
     glClear(GL_COLOR_BUFFER_BIT);

     glEnable(GL_SCISSOR_TEST);
     glScissor(0, 0, mWidth, mHeight);

     mSnapshot->clipRect.set(0.0f, 0.0f, mWidth, mHeight);
 }

 ///////////////////////////////////////////////////////////////////////////////
 // State management
 ///////////////////////////////////////////////////////////////////////////////

 int OpenGLRenderer::getSaveCount() const {
     return mSaveCount;
 }

 int OpenGLRenderer::save(int flags) {
     return saveSnapshot();
 }

 void OpenGLRenderer::restore() {
     if (mSaveCount == 0) return;

     if (restoreSnapshot()) {
         setScissorFromClip();
     }
 }

 void OpenGLRenderer::restoreToCount(int saveCount) {
     if (saveCount <= 0 || saveCount > mSaveCount) return;

     bool restoreClip = false;

     while (mSaveCount != saveCount - 1) {
         restoreClip |= restoreSnapshot();
     }

     if (restoreClip) {
         setScissorFromClip();
     }
 }

 int OpenGLRenderer::saveSnapshot() {
     mSnapshot = new Snapshot(mSnapshot);
     return ++mSaveCount;
 }

 bool OpenGLRenderer::restoreSnapshot() {
     bool restoreClip = mSnapshot->flags & Snapshot::kFlagClipSet;
     bool restoreLayer = mSnapshot->flags & Snapshot::kFlagIsLayer;

     sp<Snapshot> current = mSnapshot;
     sp<Snapshot> previous = mSnapshot->previous;

     if (restoreLayer) {
         composeLayer(current, previous);
     }

     mSnapshot = previous;
     mSaveCount--;

     return restoreClip;
 }

 void OpenGLRenderer::composeLayer(sp<Snapshot> current, sp<Snapshot> previous) {
     // Unbind current FBO and restore previous one
     // Most of the time, previous->fbo will be 0 to bind the default buffer
     glBindFramebuffer(GL_FRAMEBUFFER, previous->fbo);

     // Restore the clip from the previous snapshot
     const Rect& clip = previous->getMappedClip();
     glScissor(clip.left, mHeight - clip.bottom, clip.getWidth(), clip.getHeight());

     // Compute the correct texture coordinates for the FBO texture
     // The texture is currently as big as the window but drawn with
     // a quad of the appropriate size
     const Rect& layer = current->layer;
     Rect texCoords(current->layer);
     mSnapshot->transform.mapRect(texCoords);

     const float u1 = texCoords.left / float(mWidth);
     const float v1 = (mHeight - texCoords.top) / float(mHeight);
     const float u2 = texCoords.right / float(mWidth);
     const float v2 = (mHeight - texCoords.bottom) / float(mHeight);

     resetDrawTextureTexCoords(u1, v1, u2, v1);

     drawTextureRect(layer.left, layer.top, layer.right, layer.bottom,
             current->texture, current->alpha, current->mode, true);

     resetDrawTextureTexCoords(0.0f, 1.0f, 1.0f, 0.0f);

     glDeleteFramebuffers(1, &current->fbo);
     glDeleteTextures(1, &current->texture);
 }

 ///////////////////////////////////////////////////////////////////////////////
 // Layers
 ///////////////////////////////////////////////////////////////////////////////

 int OpenGLRenderer::saveLayer(float left, float top, float right, float bottom,
         const SkPaint* p, int flags) {
     int count = saveSnapshot();

     int alpha = 255;
     SkXfermode::Mode mode;

     if (p) {
         alpha = p->getAlpha();
         const bool isMode = SkXfermode::IsMode(p->getXfermode(), &mode);
         if (!isMode) {
             // Assume SRC_OVER
             mode = SkXfermode::kSrcOver_Mode;
         }
     } else {
         mode = SkXfermode::kSrcOver_Mode;
     }

     createLayer(mSnapshot, left, top, right, bottom, alpha, mode, flags);

     return count;
 }

 int OpenGLRenderer::saveLayerAlpha(float left, float top, float right, float bottom,
         int alpha, int flags) {
     int count = saveSnapshot();
     createLayer(mSnapshot, left, top, right, bottom, alpha, SkXfermode::kSrcOver_Mode, flags);
     return count;
 }

 bool OpenGLRenderer::createLayer(sp<Snapshot> snapshot, float left, float top,
         float right, float bottom, int alpha, SkXfermode::Mode mode,int flags) {
     // Generate the FBO and attach the texture
     glGenFramebuffers(1, &snapshot->fbo);
     glBindFramebuffer(GL_FRAMEBUFFER, snapshot->fbo);

     // Generate the texture in which the FBO will draw
     glGenTextures(1, &snapshot->texture);
     glBindTexture(GL_TEXTURE_2D, snapshot->texture);

     // The FBO will not be scaled, so we can use lower quality filtering
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

     // TODO ***** IMPORTANT *****
     // Creating a texture-backed FBO works only if the texture is the same size
     // as the original rendering buffer (in this case, mWidth and mHeight.)
     // This is expensive and wasteful and must be fixed.
     // TODO Additionally we should use an FBO cache

     const GLsizei width = mWidth; //right - left;
     const GLsizei height = mHeight; //bottom - right;

     const GLint format = (flags & SkCanvas::kHasAlphaLayer_SaveFlag) ? GL_RGBA : GL_RGB;
     glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, NULL);
     glBindTexture(GL_TEXTURE_2D, 0);

     // Bind texture to FBO
     glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
             snapshot->texture, 0);

     GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
     if (status != GL_FRAMEBUFFER_COMPLETE) {
         LOGD("Framebuffer incomplete %d", status);

         glDeleteFramebuffers(1, &snapshot->fbo);
         glDeleteTextures(1, &snapshot->texture);

         return false;
     }

     snapshot->flags |= Snapshot::kFlagIsLayer;
     snapshot->mode = mode;
     snapshot->alpha = alpha / 255.0f;
     snapshot->layer.set(left, top, right, bottom);

     return true;
 }

 ///////////////////////////////////////////////////////////////////////////////
 // Transforms
 ///////////////////////////////////////////////////////////////////////////////

 void OpenGLRenderer::translate(float dx, float dy) {
     mSnapshot->transform.translate(dx, dy, 0.0f);
     mSnapshot->flags |= Snapshot::kFlagDirtyTransform;
 }

 void OpenGLRenderer::rotate(float degrees) {
     mSnapshot->transform.rotate(degrees, 0.0f, 0.0f, 1.0f);
     mSnapshot->flags |= Snapshot::kFlagDirtyTransform;
 }

 void OpenGLRenderer::scale(float sx, float sy) {
     mSnapshot->transform.scale(sx, sy, 1.0f);
     mSnapshot->flags |= Snapshot::kFlagDirtyTransform;
 }

 void OpenGLRenderer::setMatrix(SkMatrix* matrix) {
     mSnapshot->transform.load(*matrix);
     mSnapshot->flags |= Snapshot::kFlagDirtyTransform;
 }

 void OpenGLRenderer::getMatrix(SkMatrix* matrix) {
     mSnapshot->transform.copyTo(*matrix);
 }

 void OpenGLRenderer::concatMatrix(SkMatrix* matrix) {
     mat4 m(*matrix);
     mSnapshot->transform.multiply(m);
     mSnapshot->flags |= Snapshot::kFlagDirtyTransform;
 }

 ///////////////////////////////////////////////////////////////////////////////
 // Clipping
 ///////////////////////////////////////////////////////////////////////////////

 void OpenGLRenderer::setScissorFromClip() {
     const Rect& clip = mSnapshot->getMappedClip();
     glScissor(clip.left, mHeight - clip.bottom, clip.getWidth(), clip.getHeight());
 }

 const Rect& OpenGLRenderer::getClipBounds() {
     return mSnapshot->clipRect;
 }

 bool OpenGLRenderer::quickReject(float left, float top, float right, float bottom) {
     /*
      * The documentation of quickReject() indicates that the specified rect
      * is transformed before being compared to the clip rect. However, the
      * clip rect is not stored transformed in the snapshot and can thus be
      * compared directly
      *
      * The following code can be used instead to performed a mapped comparison:
      *
      *     mSnapshot->transform.mapRect(r);
      *     const Rect& clip = mSnapshot->getMappedClip();
      *     return !clip.intersects(r);
      */
     Rect r(left, top, right, bottom);
     return !mSnapshot->clipRect.intersects(r);
 }

 bool OpenGLRenderer::clipRect(float left, float top, float right, float bottom) {
     bool clipped = mSnapshot->clipRect.intersect(left, top, right, bottom);
     if (clipped) {
         mSnapshot->flags |= Snapshot::kFlagClipSet;
         setScissorFromClip();
     }
     return clipped;
 }

 ///////////////////////////////////////////////////////////////////////////////
 // Drawing
 ///////////////////////////////////////////////////////////////////////////////

 void OpenGLRenderer::drawBitmap(const SkBitmap* bitmap, float left, float top, const SkPaint* paint) {
     LOGD("Drawing bitmap!");
 }

 void OpenGLRenderer::drawColor(int color, SkXfermode::Mode mode) {
     const Rect& clip = mSnapshot->clipRect;
     drawColorRect(clip.left, clip.top, clip.right, clip.bottom, color, mode);
 }

 void OpenGLRenderer::drawRect(float left, float top, float right, float bottom, const SkPaint* p) {
     SkXfermode::Mode mode;

     const bool isMode = SkXfermode::IsMode(p->getXfermode(), &mode);
     if (!isMode) {
         // Assume SRC_OVER
         mode = SkXfermode::kSrcOver_Mode;
     }

     // Skia draws using the color's alpha channel if < 255
     // Otherwise, it uses the paint's alpha
     int color = p->getColor();
     if (((color >> 24) & 0xFF) == 255) {
         color |= p->getAlpha() << 24;
     }

     drawColorRect(left, top, right, bottom, color, mode);
 }

 void OpenGLRenderer::drawColorRect(float left, float top, float right, float bottom,
         int color, SkXfermode::Mode mode) {
     const int alpha = (color >> 24) & 0xFF;
     const bool blend = alpha < 255 || mode != SkXfermode::kSrcOver_Mode;

     const GLfloat a = alpha                  / 255.0f;
     const GLfloat r = ((color >> 16) & 0xFF) / 255.0f;
     const GLfloat g = ((color >>  8) & 0xFF) / 255.0f;
     const GLfloat b = ((color      ) & 0xFF) / 255.0f;

     if (blend) {
         glEnable(GL_BLEND);
         glBlendFunc(gBlends[mode].src, gBlends[mode].dst);
     }

     mModelView.loadTranslate(left, top, 0.0f);
     mModelView.scale(right - left, bottom - top, 1.0f);

     mDrawColorShader->use(&mOrthoMatrix[0], &mModelView.data[0], &mSnapshot->transform.data[0]);

     const GLvoid* p = &gDrawColorVertices[0].position[0];

     glEnableVertexAttribArray(mDrawColorShader->position);
     glVertexAttribPointer(mDrawColorShader->position, 2, GL_FLOAT, GL_FALSE,
             gDrawColorVertexStride, p);
     glVertexAttrib4f(mDrawColorShader->color, r, g, b, a);

     glDrawArrays(GL_TRIANGLE_STRIP, 0, gDrawColorVertexCount);

     glDisableVertexAttribArray(mDrawColorShader->position);

     if (blend) {
         glDisable(GL_BLEND);
     }
 }

 void OpenGLRenderer::drawTextureRect(float left, float top, float right, float bottom,
         GLuint texture, float alpha, SkXfermode::Mode mode, bool isPremultiplied) {
     mModelView.loadTranslate(left, top, 0.0f);
     mModelView.scale(right - left, bottom - top, 1.0f);

     mDrawTextureShader->use(&mOrthoMatrix[0], &mModelView.data[0], &mSnapshot->transform.data[0]);

     GLenum sourceMode = gBlends[mode].src;
     if (!isPremultiplied && sourceMode == GL_ONE) {
         sourceMode = GL_SRC_ALPHA;
     }

     // TODO: Try to disable blending when the texture is opaque and alpha == 1.0f
     glEnable(GL_BLEND);
     glBlendFunc(sourceMode, gBlends[mode].dst);

     glBindTexture(GL_TEXTURE_2D, texture);

     glActiveTexture(GL_TEXTURE0);
     glUniform1i(mDrawTextureShader->sampler, 0);

     const GLvoid* p = &mDrawTextureVertices[0].position[0];
     const GLvoid* t = &mDrawTextureVertices[0].texture[0];

     glEnableVertexAttribArray(mDrawTextureShader->position);
     glVertexAttribPointer(mDrawTextureShader->position, 2, GL_FLOAT, GL_FALSE,
             gDrawTextureVertexStride, p);

     glEnableVertexAttribArray(mDrawTextureShader->texCoords);
     glVertexAttribPointer(mDrawTextureShader->texCoords, 2, GL_FLOAT, GL_FALSE,
             gDrawTextureVertexStride, t);

     glVertexAttrib4f(mDrawTextureShader->color, 1.0f, 1.0f, 1.0f, alpha);

     glDrawArrays(GL_TRIANGLE_STRIP, 0, gDrawTextureVertexCount);

     glDisableVertexAttribArray(mDrawTextureShader->position);
     glDisableVertexAttribArray(mDrawTextureShader->texCoords);

     glBindTexture(GL_TEXTURE_2D, 0);
     glDisable(GL_BLEND);
 }

 void OpenGLRenderer::resetDrawTextureTexCoords(float u1, float v1, float u2, float v2) {
     mDrawTextureVertices[0].texture[0] = u1;
     mDrawTextureVertices[0].texture[1] = v2;
     mDrawTextureVertices[1].texture[0] = u2;
     mDrawTextureVertices[1].texture[1] = v2;
     mDrawTextureVertices[2].texture[0] = u1;
     mDrawTextureVertices[2].texture[1] = v1;
     mDrawTextureVertices[3].texture[0] = u2;
     mDrawTextureVertices[3].texture[1] = v1;
 }

 }; // namespace uirenderer
 }; // namespace android
	/*
	* Copyright (C) 2010 The Android Open Source Project
	*
	* 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.
	*/

	#define LOG_TAG "OpenGLRenderer"

	#include <stdlib.h>
	#include <stdint.h>
	#include <sys/types.h>

	#include <SkCanvas.h>

	#include <utils/Log.h>

	#include "OpenGLRenderer.h"

	namespace android {
	namespace uirenderer {

	///////////////////////////////////////////////////////////////////////////////
	// Defines
	///////////////////////////////////////////////////////////////////////////////

	#define MAX_TEXTURE_COUNT 128

	#define SV(x, y) { { x, y } }
	#define FV(x, y, u, v) { { x, y }, { u, v } }

	///////////////////////////////////////////////////////////////////////////////
	// Globals
	///////////////////////////////////////////////////////////////////////////////

	static const SimpleVertex gDrawColorVertices[] = {
	SV(0.0f, 0.0f),
	SV(1.0f, 0.0f),
	SV(0.0f, 1.0f),
	SV(1.0f, 1.0f)
	};
	static const GLsizei gDrawColorVertexStride = sizeof(SimpleVertex);
	static const GLsizei gDrawColorVertexCount = 4;

	// This array is never used directly but used as a memcpy source in the
	// OpenGLRenderer constructor
	static const TextureVertex gDrawTextureVertices[] = {
	FV(0.0f, 0.0f, 0.0f, 1.0f),
	FV(1.0f, 0.0f, 1.0f, 1.0f),
	FV(0.0f, 1.0f, 0.0f, 0.0f),
	FV(1.0f, 1.0f, 1.0f, 0.0f)
	};
	static const GLsizei gDrawTextureVertexStride = sizeof(TextureVertex);
	static const GLsizei gDrawTextureVertexCount = 4;

	// In this array, the index of each Blender equals the value of the first
	// entry. For instance, gBlends[1] == gBlends[SkXfermode::kSrc_Mode]
	static const Blender gBlends[] = {
	{ SkXfermode::kClear_Mode, GL_ZERO, GL_ZERO },
	{ SkXfermode::kSrc_Mode, GL_ONE, GL_ZERO },
	{ SkXfermode::kDst_Mode, GL_ZERO, GL_ONE },
	{ SkXfermode::kSrcOver_Mode, GL_ONE, GL_ONE_MINUS_SRC_ALPHA },
	{ SkXfermode::kDstOver_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE },
	{ SkXfermode::kSrcIn_Mode, GL_DST_ALPHA, GL_ZERO },
	{ SkXfermode::kDstIn_Mode, GL_ZERO, GL_SRC_ALPHA },
	{ SkXfermode::kSrcOut_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ZERO },
	{ SkXfermode::kDstOut_Mode, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA },
	{ SkXfermode::kSrcATop_Mode, GL_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA },
	{ SkXfermode::kDstATop_Mode, GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA },
	{ SkXfermode::kXor_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA }
	};

	///////////////////////////////////////////////////////////////////////////////
	// Constructors/destructor
	///////////////////////////////////////////////////////////////////////////////

	OpenGLRenderer::OpenGLRenderer(): mTextureCache(MAX_TEXTURE_COUNT) {
	LOGD("Create OpenGLRenderer");

	mDrawColorShader = new DrawColorProgram;
	mDrawTextureShader = new DrawTextureProgram;

	memcpy(mDrawTextureVertices, gDrawTextureVertices, sizeof(gDrawTextureVertices));
	}

	OpenGLRenderer::~OpenGLRenderer() {
	LOGD("Destroy OpenGLRenderer");

	mTextureCache.clear();
	}

	///////////////////////////////////////////////////////////////////////////////
	// Setup
	///////////////////////////////////////////////////////////////////////////////

	void OpenGLRenderer::setViewport(int width, int height) {
	glViewport(0, 0, width, height);

	mat4 ortho;
	ortho.loadOrtho(0, width, height, 0, -1, 1);
	ortho.copyTo(mOrthoMatrix);

	mWidth = width;
	mHeight = height;
	}

	void OpenGLRenderer::prepare() {
	mSnapshot = &mFirstSnapshot;
	mSaveCount = 0;

	glDisable(GL_SCISSOR_TEST);

	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
	glClear(GL_COLOR_BUFFER_BIT);

	glEnable(GL_SCISSOR_TEST);
	glScissor(0, 0, mWidth, mHeight);

	mSnapshot->clipRect.set(0.0f, 0.0f, mWidth, mHeight);
	}

	///////////////////////////////////////////////////////////////////////////////
	// State management
	///////////////////////////////////////////////////////////////////////////////

	int OpenGLRenderer::getSaveCount() const {
	return mSaveCount;
	}

	int OpenGLRenderer::save(int flags) {
	return saveSnapshot();
	}

	void OpenGLRenderer::restore() {
	if (mSaveCount == 0) return;

	if (restoreSnapshot()) {
	setScissorFromClip();
	}
	}

	void OpenGLRenderer::restoreToCount(int saveCount) {
	if (saveCount <= 0 \|\| saveCount > mSaveCount) return;

	bool restoreClip = false;

	while (mSaveCount != saveCount - 1) {
	restoreClip \|= restoreSnapshot();
	}

	if (restoreClip) {
	setScissorFromClip();
	}
	}

	int OpenGLRenderer::saveSnapshot() {
	mSnapshot = new Snapshot(mSnapshot);
	return ++mSaveCount;
	}

	bool OpenGLRenderer::restoreSnapshot() {
	bool restoreClip = mSnapshot->flags & Snapshot::kFlagClipSet;
	bool restoreLayer = mSnapshot->flags & Snapshot::kFlagIsLayer;

	sp<Snapshot> current = mSnapshot;
	sp<Snapshot> previous = mSnapshot->previous;

	if (restoreLayer) {
	composeLayer(current, previous);
	}

	mSnapshot = previous;
	mSaveCount--;

	return restoreClip;
	}

	void OpenGLRenderer::composeLayer(sp<Snapshot> current, sp<Snapshot> previous) {
	// Unbind current FBO and restore previous one
	// Most of the time, previous->fbo will be 0 to bind the default buffer
	glBindFramebuffer(GL_FRAMEBUFFER, previous->fbo);

	// Restore the clip from the previous snapshot
	const Rect& clip = previous->getMappedClip();
	glScissor(clip.left, mHeight - clip.bottom, clip.getWidth(), clip.getHeight());

	// Compute the correct texture coordinates for the FBO texture
	// The texture is currently as big as the window but drawn with
	// a quad of the appropriate size
	const Rect& layer = current->layer;
	Rect texCoords(current->layer);
	mSnapshot->transform.mapRect(texCoords);

	const float u1 = texCoords.left / float(mWidth);
	const float v1 = (mHeight - texCoords.top) / float(mHeight);
	const float u2 = texCoords.right / float(mWidth);
	const float v2 = (mHeight - texCoords.bottom) / float(mHeight);

	resetDrawTextureTexCoords(u1, v1, u2, v1);

	drawTextureRect(layer.left, layer.top, layer.right, layer.bottom,
	current->texture, current->alpha, current->mode, true);

	resetDrawTextureTexCoords(0.0f, 1.0f, 1.0f, 0.0f);

	glDeleteFramebuffers(1, &current->fbo);
	glDeleteTextures(1, &current->texture);
	}

	///////////////////////////////////////////////////////////////////////////////
	// Layers
	///////////////////////////////////////////////////////////////////////////////

	int OpenGLRenderer::saveLayer(float left, float top, float right, float bottom,
	const SkPaint* p, int flags) {
	int count = saveSnapshot();

	int alpha = 255;
	SkXfermode::Mode mode;

	if (p) {
	alpha = p->getAlpha();
	const bool isMode = SkXfermode::IsMode(p->getXfermode(), &mode);
	if (!isMode) {
	// Assume SRC_OVER
	mode = SkXfermode::kSrcOver_Mode;
	}
	} else {
	mode = SkXfermode::kSrcOver_Mode;
	}

	createLayer(mSnapshot, left, top, right, bottom, alpha, mode, flags);

	return count;
	}

	int OpenGLRenderer::saveLayerAlpha(float left, float top, float right, float bottom,
	int alpha, int flags) {
	int count = saveSnapshot();
	createLayer(mSnapshot, left, top, right, bottom, alpha, SkXfermode::kSrcOver_Mode, flags);
	return count;
	}

	bool OpenGLRenderer::createLayer(sp<Snapshot> snapshot, float left, float top,
	float right, float bottom, int alpha, SkXfermode::Mode mode,int flags) {
	// Generate the FBO and attach the texture
	glGenFramebuffers(1, &snapshot->fbo);
	glBindFramebuffer(GL_FRAMEBUFFER, snapshot->fbo);

	// Generate the texture in which the FBO will draw
	glGenTextures(1, &snapshot->texture);
	glBindTexture(GL_TEXTURE_2D, snapshot->texture);

	// The FBO will not be scaled, so we can use lower quality filtering
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

	// TODO *** IMPORTANT ***
	// Creating a texture-backed FBO works only if the texture is the same size
	// as the original rendering buffer (in this case, mWidth and mHeight.)
	// This is expensive and wasteful and must be fixed.
	// TODO Additionally we should use an FBO cache

	const GLsizei width = mWidth; //right - left;
	const GLsizei height = mHeight; //bottom - right;

	const GLint format = (flags & SkCanvas::kHasAlphaLayer_SaveFlag) ? GL_RGBA : GL_RGB;
	glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, NULL);
	glBindTexture(GL_TEXTURE_2D, 0);

	// Bind texture to FBO
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
	snapshot->texture, 0);

	GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
	if (status != GL_FRAMEBUFFER_COMPLETE) {
	LOGD("Framebuffer incomplete %d", status);

	glDeleteFramebuffers(1, &snapshot->fbo);
	glDeleteTextures(1, &snapshot->texture);

	return false;
	}

	snapshot->flags \|= Snapshot::kFlagIsLayer;
	snapshot->mode = mode;
	snapshot->alpha = alpha / 255.0f;
	snapshot->layer.set(left, top, right, bottom);

	return true;
	}

	///////////////////////////////////////////////////////////////////////////////
	// Transforms
	///////////////////////////////////////////////////////////////////////////////

	void OpenGLRenderer::translate(float dx, float dy) {
	mSnapshot->transform.translate(dx, dy, 0.0f);
	mSnapshot->flags \|= Snapshot::kFlagDirtyTransform;
	}

	void OpenGLRenderer::rotate(float degrees) {
	mSnapshot->transform.rotate(degrees, 0.0f, 0.0f, 1.0f);
	mSnapshot->flags \|= Snapshot::kFlagDirtyTransform;
	}

	void OpenGLRenderer::scale(float sx, float sy) {
	mSnapshot->transform.scale(sx, sy, 1.0f);
	mSnapshot->flags \|= Snapshot::kFlagDirtyTransform;
	}

	void OpenGLRenderer::setMatrix(SkMatrix* matrix) {
	mSnapshot->transform.load(*matrix);
	mSnapshot->flags \|= Snapshot::kFlagDirtyTransform;
	}

	void OpenGLRenderer::getMatrix(SkMatrix* matrix) {
	mSnapshot->transform.copyTo(*matrix);
	}

	void OpenGLRenderer::concatMatrix(SkMatrix* matrix) {
	mat4 m(*matrix);
	mSnapshot->transform.multiply(m);
	mSnapshot->flags \|= Snapshot::kFlagDirtyTransform;
	}

	///////////////////////////////////////////////////////////////////////////////
	// Clipping
	///////////////////////////////////////////////////////////////////////////////

	void OpenGLRenderer::setScissorFromClip() {
	const Rect& clip = mSnapshot->getMappedClip();
	glScissor(clip.left, mHeight - clip.bottom, clip.getWidth(), clip.getHeight());
	}

	const Rect& OpenGLRenderer::getClipBounds() {
	return mSnapshot->clipRect;
	}

	bool OpenGLRenderer::quickReject(float left, float top, float right, float bottom) {
	/*
	* The documentation of quickReject() indicates that the specified rect
	* is transformed before being compared to the clip rect. However, the
	* clip rect is not stored transformed in the snapshot and can thus be
	* compared directly
	*
	* The following code can be used instead to performed a mapped comparison:
	*
	* mSnapshot->transform.mapRect(r);
	* const Rect& clip = mSnapshot->getMappedClip();
	* return !clip.intersects(r);
	*/
	Rect r(left, top, right, bottom);
	return !mSnapshot->clipRect.intersects(r);
	}

	bool OpenGLRenderer::clipRect(float left, float top, float right, float bottom) {
	bool clipped = mSnapshot->clipRect.intersect(left, top, right, bottom);
	if (clipped) {
	mSnapshot->flags \|= Snapshot::kFlagClipSet;
	setScissorFromClip();
	}
	return clipped;
	}

	///////////////////////////////////////////////////////////////////////////////
	// Drawing
	///////////////////////////////////////////////////////////////////////////////

	void OpenGLRenderer::drawBitmap(const SkBitmap* bitmap, float left, float top, const SkPaint* paint) {
	LOGD("Drawing bitmap!");
	}

	void OpenGLRenderer::drawColor(int color, SkXfermode::Mode mode) {
	const Rect& clip = mSnapshot->clipRect;
	drawColorRect(clip.left, clip.top, clip.right, clip.bottom, color, mode);
	}

	void OpenGLRenderer::drawRect(float left, float top, float right, float bottom, const SkPaint* p) {
	SkXfermode::Mode mode;

	const bool isMode = SkXfermode::IsMode(p->getXfermode(), &mode);
	if (!isMode) {
	// Assume SRC_OVER
	mode = SkXfermode::kSrcOver_Mode;
	}

	// Skia draws using the color's alpha channel if < 255
	// Otherwise, it uses the paint's alpha
	int color = p->getColor();
	if (((color >> 24) & 0xFF) == 255) {
	color \|= p->getAlpha() << 24;
	}

	drawColorRect(left, top, right, bottom, color, mode);
	}

	void OpenGLRenderer::drawColorRect(float left, float top, float right, float bottom,
	int color, SkXfermode::Mode mode) {
	const int alpha = (color >> 24) & 0xFF;
	const bool blend = alpha < 255 \|\| mode != SkXfermode::kSrcOver_Mode;

	const GLfloat a = alpha / 255.0f;
	const GLfloat r = ((color >> 16) & 0xFF) / 255.0f;
	const GLfloat g = ((color >> 8) & 0xFF) / 255.0f;
	const GLfloat b = ((color ) & 0xFF) / 255.0f;

	if (blend) {
	glEnable(GL_BLEND);
	glBlendFunc(gBlends[mode].src, gBlends[mode].dst);
	}

	mModelView.loadTranslate(left, top, 0.0f);
	mModelView.scale(right - left, bottom - top, 1.0f);

	mDrawColorShader->use(&mOrthoMatrix[0], &mModelView.data[0], &mSnapshot->transform.data[0]);

	const GLvoid* p = &gDrawColorVertices[0].position[0];

	glEnableVertexAttribArray(mDrawColorShader->position);
	glVertexAttribPointer(mDrawColorShader->position, 2, GL_FLOAT, GL_FALSE,
	gDrawColorVertexStride, p);
	glVertexAttrib4f(mDrawColorShader->color, r, g, b, a);

	glDrawArrays(GL_TRIANGLE_STRIP, 0, gDrawColorVertexCount);

	glDisableVertexAttribArray(mDrawColorShader->position);

	if (blend) {
	glDisable(GL_BLEND);
	}
	}

	void OpenGLRenderer::drawTextureRect(float left, float top, float right, float bottom,
	GLuint texture, float alpha, SkXfermode::Mode mode, bool isPremultiplied) {
	mModelView.loadTranslate(left, top, 0.0f);
	mModelView.scale(right - left, bottom - top, 1.0f);

	mDrawTextureShader->use(&mOrthoMatrix[0], &mModelView.data[0], &mSnapshot->transform.data[0]);

	GLenum sourceMode = gBlends[mode].src;
	if (!isPremultiplied && sourceMode == GL_ONE) {
	sourceMode = GL_SRC_ALPHA;
	}

	// TODO: Try to disable blending when the texture is opaque and alpha == 1.0f
	glEnable(GL_BLEND);
	glBlendFunc(sourceMode, gBlends[mode].dst);

	glBindTexture(GL_TEXTURE_2D, texture);

	glActiveTexture(GL_TEXTURE0);
	glUniform1i(mDrawTextureShader->sampler, 0);

	const GLvoid* p = &mDrawTextureVertices[0].position[0];
	const GLvoid* t = &mDrawTextureVertices[0].texture[0];

	glEnableVertexAttribArray(mDrawTextureShader->position);
	glVertexAttribPointer(mDrawTextureShader->position, 2, GL_FLOAT, GL_FALSE,
	gDrawTextureVertexStride, p);

	glEnableVertexAttribArray(mDrawTextureShader->texCoords);
	glVertexAttribPointer(mDrawTextureShader->texCoords, 2, GL_FLOAT, GL_FALSE,
	gDrawTextureVertexStride, t);

	glVertexAttrib4f(mDrawTextureShader->color, 1.0f, 1.0f, 1.0f, alpha);

	glDrawArrays(GL_TRIANGLE_STRIP, 0, gDrawTextureVertexCount);

	glDisableVertexAttribArray(mDrawTextureShader->position);
	glDisableVertexAttribArray(mDrawTextureShader->texCoords);

	glBindTexture(GL_TEXTURE_2D, 0);
	glDisable(GL_BLEND);
	}

	void OpenGLRenderer::resetDrawTextureTexCoords(float u1, float v1, float u2, float v2) {
	mDrawTextureVertices[0].texture[0] = u1;
	mDrawTextureVertices[0].texture[1] = v2;
	mDrawTextureVertices[1].texture[0] = u2;
	mDrawTextureVertices[1].texture[1] = v2;
	mDrawTextureVertices[2].texture[0] = u1;
	mDrawTextureVertices[2].texture[1] = v1;
	mDrawTextureVertices[3].texture[0] = u2;
	mDrawTextureVertices[3].texture[1] = v1;
	}

	}; // namespace uirenderer
	}; // namespace android