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Commit f008799d authored by Dan Stoza's avatar Dan Stoza
Browse files

SF: Skip render-to-texture for color transforms 

In cases where SurfaceFlinger is applying a color matrix (usually for
accessibility features), we previously would perform a render-to-
texture for the initial composition, and then apply the matrix during
a copy to the framebuffer. This changes that behavior to just apply the
matrix during composition without a render-to-texture pass.

This may result in a perceived change of the image in cases with alpha
blending, since the blending is performed at a different stage of the
pipeline and the system effectively performs non-linear blends.
However, neither this nor the prior render-to-texture pass is strictly
correct in that regard, and this approach is less error-prone and
likely faster.

Change-Id: I2110ff0374f61d76df7b087dde8a1ed98990440c
parent 7fc3ef0e

services/surfaceflinger/RenderEngine/Description.cpp

+4 −0
Original line number Diff line number Diff line
@@ -88,5 +88,9 @@ void Description::setColorMatrix(const mat4& mtx) { 
    mColorMatrixEnabled = (mtx != identity);

}



const mat4& Description::getColorMatrix() const {

    return mColorMatrix;

}





} /* namespace android */

services/surfaceflinger/RenderEngine/Description.h

+1 −0
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ public: 
    void setColor(GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha);

    void setProjectionMatrix(const mat4& mtx);

    void setColorMatrix(const mat4& mtx);

    const mat4& getColorMatrix() const;



private:

    bool mUniformsDirty;

services/surfaceflinger/RenderEngine/GLES11RenderEngine.cpp

+0 −8
Original line number Diff line number Diff line
@@ -262,14 +262,6 @@ void GLES11RenderEngine::drawMesh(const Mesh& mesh) { 
    }

}



void GLES11RenderEngine::beginGroup(const mat4& /*colorTransform*/) {

    // doesn't do anything in GLES 1.1

}



void GLES11RenderEngine::endGroup() {

    // doesn't do anything in GLES 1.1

}



void GLES11RenderEngine::dump(String8& result) {

    RenderEngine::dump(result);

}

services/surfaceflinger/RenderEngine/GLES11RenderEngine.h

+0 −3
Original line number Diff line number Diff line
@@ -62,9 +62,6 @@ protected: 


    virtual void drawMesh(const Mesh& mesh);



    virtual void beginGroup(const mat4& colorTransform);

    virtual void endGroup();



    virtual size_t getMaxTextureSize() const;

    virtual size_t getMaxViewportDims() const;

};

services/surfaceflinger/RenderEngine/GLES20RenderEngine.cpp

+6 −72
Original line number Diff line number Diff line
@@ -169,6 +169,12 @@ void GLES20RenderEngine::setupLayerBlackedOut() { 
    mState.setTexture(texture);

}



mat4 GLES20RenderEngine::setupColorTransform(const mat4& colorTransform) {

    mat4 oldTransform = mState.getColorMatrix();

    mState.setColorMatrix(colorTransform);

    return oldTransform;

}



void GLES20RenderEngine::disableTexturing() {

    mState.disableTexture();

}
@@ -237,78 +243,6 @@ void GLES20RenderEngine::drawMesh(const Mesh& mesh) { 
    }

}



void GLES20RenderEngine::beginGroup(const mat4& colorTransform) {



    GLuint tname, name;

    // create the texture

    glGenTextures(1, &tname);

    glBindTexture(GL_TEXTURE_2D, tname);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, mVpWidth, mVpHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);



    // create a Framebuffer Object to render into

    glGenFramebuffers(1, &name);

    glBindFramebuffer(GL_FRAMEBUFFER, name);

    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tname, 0);



    Group group;

    group.texture = tname;

    group.fbo = name;

    group.width = mVpWidth;

    group.height = mVpHeight;

    group.colorTransform = colorTransform;



    mGroupStack.push(group);

}



void GLES20RenderEngine::endGroup() {



    const Group group(mGroupStack.top());

    mGroupStack.pop();



    // activate the previous render target

    GLuint fbo = 0;

    if (!mGroupStack.isEmpty()) {

        fbo = mGroupStack.top().fbo;

    }

    glBindFramebuffer(GL_FRAMEBUFFER, fbo);



    // set our state

    Texture texture(Texture::TEXTURE_2D, group.texture);

    texture.setDimensions(group.width, group.height);

    glBindTexture(GL_TEXTURE_2D, group.texture);



    mState.setPlaneAlpha(1.0f);

    mState.setPremultipliedAlpha(true);

    mState.setOpaque(false);

    mState.setTexture(texture);

    mState.setColorMatrix(group.colorTransform);

    glDisable(GL_BLEND);



    Mesh mesh(Mesh::TRIANGLE_FAN, 4, 2, 2);

    Mesh::VertexArray<vec2> position(mesh.getPositionArray<vec2>());

    Mesh::VertexArray<vec2> texCoord(mesh.getTexCoordArray<vec2>());

    position[0] = vec2(0, 0);

    position[1] = vec2(group.width, 0);

    position[2] = vec2(group.width, group.height);

    position[3] = vec2(0, group.height);

    texCoord[0] = vec2(0, 0);

    texCoord[1] = vec2(1, 0);

    texCoord[2] = vec2(1, 1);

    texCoord[3] = vec2(0, 1);

    drawMesh(mesh);



    // reset color matrix

    mState.setColorMatrix(mat4());



    // free our fbo and texture

    glDeleteFramebuffers(1, &group.fbo);

    glDeleteTextures(1, &group.texture);

}



void GLES20RenderEngine::dump(String8& result) {

    RenderEngine::dump(result);

}