Refactor blending and texture gl state

Change-Id: Ia6b3c8b2afd3dfcee7f3ce401d846b789612054a

6 files changed, 376 insertions, 19 deletions

diff --git a/libs/hwui/renderstate/Blend.cpp b/libs/hwui/renderstate/Blend.cpp
new file mode 100644
index 0000000..3e7b721
--- /dev/null
+++ b/libs/hwui/renderstate/Blend.cpp
@@ -0,0 +1,121 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+#include <renderstate/Blend.h>
+#include "Program.h"
+
+#include "ShadowTessellator.h"
+
+namespace android {
+namespace uirenderer {
+
+/**
+ * Structure mapping Skia xfermodes to OpenGL blending factors.
+ */
+struct Blender {
+    SkXfermode::Mode mode;
+    GLenum src;
+    GLenum dst;
+};
+
+// In this array, the index of each Blender equals the value of the first
+// entry. For instance, gBlends[1] == gBlends[SkXfermode::kSrc_Mode]
+const Blender kBlends[] = {
+    { SkXfermode::kClear_Mode,    GL_ZERO,                GL_ONE_MINUS_SRC_ALPHA },
+    { 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 },
+    { SkXfermode::kPlus_Mode,     GL_ONE,                 GL_ONE },
+    { SkXfermode::kModulate_Mode, GL_ZERO,                GL_SRC_COLOR },
+    { SkXfermode::kScreen_Mode,   GL_ONE,                 GL_ONE_MINUS_SRC_COLOR }
+};
+
+// This array contains the swapped version of each SkXfermode. For instance
+// this array's SrcOver blending mode is actually DstOver. You can refer to
+// createLayer() for more information on the purpose of this array.
+const Blender kBlendsSwap[] = {
+    { SkXfermode::kClear_Mode,    GL_ONE_MINUS_DST_ALPHA, GL_ZERO },
+    { SkXfermode::kSrc_Mode,      GL_ZERO,                GL_ONE },
+    { SkXfermode::kDst_Mode,      GL_ONE,                 GL_ZERO },
+    { SkXfermode::kSrcOver_Mode,  GL_ONE_MINUS_DST_ALPHA, GL_ONE },
+    { SkXfermode::kDstOver_Mode,  GL_ONE,                 GL_ONE_MINUS_SRC_ALPHA },
+    { SkXfermode::kSrcIn_Mode,    GL_ZERO,                GL_SRC_ALPHA },
+    { SkXfermode::kDstIn_Mode,    GL_DST_ALPHA,           GL_ZERO },
+    { SkXfermode::kSrcOut_Mode,   GL_ZERO,                GL_ONE_MINUS_SRC_ALPHA },
+    { SkXfermode::kDstOut_Mode,   GL_ONE_MINUS_DST_ALPHA, GL_ZERO },
+    { SkXfermode::kSrcATop_Mode,  GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA },
+    { SkXfermode::kDstATop_Mode,  GL_DST_ALPHA,           GL_ONE_MINUS_SRC_ALPHA },
+    { SkXfermode::kXor_Mode,      GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA },
+    { SkXfermode::kPlus_Mode,     GL_ONE,                 GL_ONE },
+    { SkXfermode::kModulate_Mode, GL_DST_COLOR,           GL_ZERO },
+    { SkXfermode::kScreen_Mode,   GL_ONE_MINUS_DST_COLOR, GL_ONE }
+};
+
+Blend::Blend()
+    : mEnabled(false)
+    , mSrcMode(GL_ZERO)
+    , mDstMode(GL_ZERO) {
+    // gl blending off by default
+}
+
+void Blend::enable(SkXfermode::Mode mode, bool swapSrcDst) {
+    // enable
+    if (!mEnabled) {
+        glEnable(GL_BLEND);
+        mEnabled = true;
+    }
+
+    // select blend mode
+    GLenum sourceMode = swapSrcDst ? kBlendsSwap[mode].src : kBlends[mode].src;
+    GLenum destMode = swapSrcDst ? kBlendsSwap[mode].dst : kBlends[mode].dst;
+
+    if (sourceMode != mSrcMode || destMode != mSrcMode) {
+        glBlendFunc(sourceMode, destMode);
+        mSrcMode = sourceMode;
+        mDstMode = destMode;
+    }
+}
+
+void Blend::disable() {
+    if (mEnabled) {
+        glDisable(GL_BLEND);
+        mEnabled = false;
+    }
+}
+
+void Blend::invalidate() {
+    syncEnabled();
+    mSrcMode = mDstMode = GL_ZERO;
+}
+
+void Blend::syncEnabled() {
+    if (mEnabled) {
+        glEnable(GL_BLEND);
+    } else {
+        glDisable(GL_BLEND);
+    }
+}
+
+} /* namespace uirenderer */
+} /* namespace android */
+
diff --git a/libs/hwui/renderstate/Blend.h b/libs/hwui/renderstate/Blend.h
new file mode 100644
index 0000000..b82b477
--- /dev/null
+++ b/libs/hwui/renderstate/Blend.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+#ifndef RENDERSTATE_BLEND_H
+#define RENDERSTATE_BLEND_H
+
+#include "Vertex.h"
+
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+#include <SkXfermode.h>
+#include <memory>
+
+namespace android {
+namespace uirenderer {
+
+class Blend {
+    friend class RenderState;
+public:
+    void enable(SkXfermode::Mode mode, bool swapSrcDst);
+    void disable();
+    void syncEnabled();
+private:
+    Blend();
+    void invalidate();
+    bool mEnabled;
+    GLenum mSrcMode;
+    GLenum mDstMode;
+};
+
+} /* namespace uirenderer */
+} /* namespace android */
+
+#endif // RENDERSTATE_BLEND_H
diff --git a/libs/hwui/renderstate/RenderState.cpp b/libs/hwui/renderstate/RenderState.cpp
index e4c8745..f913cd9 100644
--- a/libs/hwui/renderstate/RenderState.cpp
+++ b/libs/hwui/renderstate/RenderState.cpp
@@ -23,10 +23,6 @@ namespace uirenderer {
 
 RenderState::RenderState(renderthread::RenderThread& thread)
         : mRenderThread(thread)
-        , mCaches(nullptr)
-        , mMeshState(nullptr)
-        , mScissor(nullptr)
-        , mStencil(nullptr)
         , mViewportWidth(0)
         , mViewportHeight(0)
         , mFramebuffer(0) {
@@ -34,13 +30,14 @@ RenderState::RenderState(renderthread::RenderThread& thread)
 }
 
 RenderState::~RenderState() {
-    LOG_ALWAYS_FATAL_IF(mMeshState || mScissor || mStencil,
+    LOG_ALWAYS_FATAL_IF(mBlend || mMeshState || mScissor || mStencil,
             "State object lifecycle not managed correctly");
 }
 
 void RenderState::onGLContextCreated() {
-    LOG_ALWAYS_FATAL_IF(mMeshState || mScissor || mStencil,
+    LOG_ALWAYS_FATAL_IF(mBlend || mMeshState || mScissor || mStencil,
             "State object lifecycle not managed correctly");
+    mBlend = new Blend();
     mMeshState = new MeshState();
     mScissor = new Scissor();
     mStencil = new Stencil();
@@ -92,6 +89,10 @@ void RenderState::onGLContextDestroyed() {
     std::for_each(mActiveLayers.begin(), mActiveLayers.end(), layerLostGlContext);
     mAssetAtlas.terminate();
 
+    mCaches->terminate();
+
+    delete mBlend;
+    mBlend = nullptr;
     delete mMeshState;
     mMeshState = nullptr;
     delete mScissor;
@@ -132,7 +133,7 @@ void RenderState::interruptForFunctorInvoke() {
             mCaches->currentProgram = nullptr;
         }
     }
-    mCaches->resetActiveTexture();
+    mCaches->textureState().resetActiveTexture();
     meshState().unbindMeshBuffer();
     meshState().unbindIndicesBuffer();
     meshState().resetVertexPointers();
@@ -148,14 +149,10 @@ void RenderState::resumeFromFunctorInvoke() {
     glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
 
     scissor().invalidate();
+    blend().invalidate();
 
-    mCaches->activeTexture(0);
-    mCaches->resetBoundTextures();
-
-    mCaches->blend = true;
-    glEnable(GL_BLEND);
-    glBlendFunc(mCaches->lastSrcMode, mCaches->lastDstMode);
-    glBlendEquation(GL_FUNC_ADD);
+    mCaches->textureState().activateTexture(0);
+    mCaches->textureState().resetBoundTextures();
 }
 
 void RenderState::debugOverdraw(bool enable, bool clear) {
diff --git a/libs/hwui/renderstate/RenderState.h b/libs/hwui/renderstate/RenderState.h
index d1ee64a..4180f44 100644
--- a/libs/hwui/renderstate/RenderState.h
+++ b/libs/hwui/renderstate/RenderState.h
@@ -24,7 +24,7 @@
 #include <utils/RefBase.h>
 
 #include <private/hwui/DrawGlInfo.h>
-
+#include <renderstate/Blend.h>
 #include "AssetAtlas.h"
 #include "Caches.h"
 #include "renderstate/MeshState.h"
@@ -84,6 +84,7 @@ public:
     void postDecStrong(VirtualLightRefBase* object);
 
     AssetAtlas& assetAtlas() { return mAssetAtlas; }
+    Blend& blend() { return *mBlend; }
     MeshState& meshState() { return *mMeshState; }
     Scissor& scissor() { return *mScissor; }
     Stencil& stencil() { return *mStencil; }
@@ -100,11 +101,12 @@ private:
 
 
     renderthread::RenderThread& mRenderThread;
-    Caches* mCaches;
+    Caches* mCaches = nullptr;
 
-    MeshState* mMeshState;
-    Scissor* mScissor;
-    Stencil* mStencil;
+    Blend* mBlend = nullptr;
+    MeshState* mMeshState = nullptr;
+    Scissor* mScissor = nullptr;
+    Stencil* mStencil = nullptr;
 
     AssetAtlas mAssetAtlas;
     std::set<Layer*> mActiveLayers;
diff --git a/libs/hwui/renderstate/TextureState.cpp b/libs/hwui/renderstate/TextureState.cpp
new file mode 100644
index 0000000..1a638d2
--- /dev/null
+++ b/libs/hwui/renderstate/TextureState.cpp
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+#include <renderstate/TextureState.h>
+
+namespace android {
+namespace uirenderer {
+
+// Must define as many texture units as specified by kTextureUnitsCount
+const GLenum kTextureUnits[] = {
+    GL_TEXTURE0,
+    GL_TEXTURE1,
+    GL_TEXTURE2
+};
+
+TextureState::TextureState()
+        : mTextureUnit(0) {
+    glActiveTexture(kTextureUnits[0]);
+    resetBoundTextures();
+
+    GLint maxTextureUnits;
+    glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &maxTextureUnits);
+    LOG_ALWAYS_FATAL_IF(maxTextureUnits < kTextureUnitsCount,
+        "At least %d texture units are required!", kTextureUnitsCount);
+}
+
+void TextureState::activateTexture(GLuint textureUnit) {
+    if (mTextureUnit != textureUnit) {
+        glActiveTexture(kTextureUnits[textureUnit]);
+        mTextureUnit = textureUnit;
+    }
+}
+
+void TextureState::resetActiveTexture() {
+    mTextureUnit = -1;
+}
+
+void TextureState::bindTexture(GLuint texture) {
+    if (mBoundTextures[mTextureUnit] != texture) {
+        glBindTexture(GL_TEXTURE_2D, texture);
+        mBoundTextures[mTextureUnit] = texture;
+    }
+}
+
+void TextureState::bindTexture(GLenum target, GLuint texture) {
+    if (target == GL_TEXTURE_2D) {
+        bindTexture(texture);
+    } else {
+        // GLConsumer directly calls glBindTexture() with
+        // target=GL_TEXTURE_EXTERNAL_OES, don't cache this target
+        // since the cached state could be stale
+        glBindTexture(target, texture);
+    }
+}
+
+void TextureState::deleteTexture(GLuint texture) {
+    // When glDeleteTextures() is called on a currently bound texture,
+    // OpenGL ES specifies that the texture is then considered unbound
+    // Consider the following series of calls:
+    //
+    // glGenTextures -> creates texture name 2
+    // glBindTexture(2)
+    // glDeleteTextures(2) -> 2 is now unbound
+    // glGenTextures -> can return 2 again
+    //
+    // If we don't call glBindTexture(2) after the second glGenTextures
+    // call, any texture operation will be performed on the default
+    // texture (name=0)
+
+    unbindTexture(texture);
+
+    glDeleteTextures(1, &texture);
+}
+
+void TextureState::resetBoundTextures() {
+    for (int i = 0; i < kTextureUnitsCount; i++) {
+        mBoundTextures[i] = 0;
+    }
+}
+
+void TextureState::unbindTexture(GLuint texture) {
+    for (int i = 0; i < kTextureUnitsCount; i++) {
+        if (mBoundTextures[i] == texture) {
+            mBoundTextures[i] = 0;
+        }
+    }
+}
+
+} /* namespace uirenderer */
+} /* namespace android */
+
diff --git a/libs/hwui/renderstate/TextureState.h b/libs/hwui/renderstate/TextureState.h
new file mode 100644
index 0000000..5a57b9f
--- /dev/null
+++ b/libs/hwui/renderstate/TextureState.h
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+#ifndef RENDERSTATE_TEXTURESTATE_H
+#define RENDERSTATE_TEXTURESTATE_H
+
+#include "Vertex.h"
+
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+#include <SkXfermode.h>
+#include <memory>
+
+namespace android {
+namespace uirenderer {
+
+class TextureState {
+    friend class Caches; // TODO: move to RenderState
+public:
+    /**
+     * Activate the specified texture unit. The texture unit must
+     * be specified using an integer number (0 for GL_TEXTURE0 etc.)
+     */
+    void activateTexture(GLuint textureUnit);
+
+    /**
+     * Invalidate the cached value of the active texture unit.
+     */
+    void resetActiveTexture();
+
+    /**
+     * Binds the specified texture as a GL_TEXTURE_2D texture.
+     * All texture bindings must be performed with this method or
+     * bindTexture(GLenum, GLuint).
+     */
+    void bindTexture(GLuint texture);
+
+    /**
+     * Binds the specified texture with the specified render target.
+     * All texture bindings must be performed with this method or
+     * bindTexture(GLuint).
+     */
+    void bindTexture(GLenum target, GLuint texture);
+
+    /**
+     * Deletes the specified texture and clears it from the cache
+     * of bound textures.
+     * All textures must be deleted using this method.
+     */
+    void deleteTexture(GLuint texture);
+
+    /**
+     * Signals that the cache of bound textures should be cleared.
+     * Other users of the context may have altered which textures are bound.
+     */
+    void resetBoundTextures();
+
+    /**
+     * Clear the cache of bound textures.
+     */
+    void unbindTexture(GLuint texture);
+private:
+    // total number of texture units available for use
+    static const int kTextureUnitsCount = 3;
+
+    TextureState();
+    GLuint mTextureUnit;
+
+    // Caches texture bindings for the GL_TEXTURE_2D target
+    GLuint mBoundTextures[kTextureUnitsCount];
+};
+
+} /* namespace uirenderer */
+} /* namespace android */
+
+#endif // RENDERSTATE_BLEND_H