Add program for linear gradient.
This change adds a new DrawLinearGradientProgram class to enable the drawing
of linear gradients. Two new vertex and fragment shaders are introduced,
based on DrawTextureProgram's shaders.
Change-Id: I885afc076bb6cef8cd3962ae21a086fa6a03bf96
diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index 1431563..731862b 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -124,6 +124,7 @@
mDrawColorProgram = new DrawColorProgram;
mDrawTextureProgram = new DrawTextureProgram;
+ mDrawLinearGradientProgram = new DrawLinearGradientProgram;
mCurrentProgram = mDrawTextureProgram;
mShader = kShaderNone;
@@ -521,6 +522,7 @@
void OpenGLRenderer::resetShader() {
mShader = OpenGLRenderer::kShaderNone;
+ mShaderKey = NULL;
mShaderBlend = false;
mShaderTileX = SkShader::kClamp_TileMode;
mShaderTileY = SkShader::kClamp_TileMode;
@@ -536,9 +538,11 @@
mShaderMatrix = matrix;
}
-void OpenGLRenderer::setupLinearGradientShader(float* bounds, uint32_t* colors,
+void OpenGLRenderer::setupLinearGradientShader(SkShader* shader, float* bounds,uint32_t* colors,
float* positions, SkShader::TileMode tileMode, SkMatrix* matrix, bool hasAlpha) {
+ // TODO: We should use a struct to describe each shader
mShader = OpenGLRenderer::kShaderLinearGradient;
+ mShaderKey = shader;
mShaderBlend = hasAlpha;
mShaderTileX = tileMode;
mShaderTileY = tileMode;
diff --git a/libs/hwui/OpenGLRenderer.h b/libs/hwui/OpenGLRenderer.h
index b3cef88..5a530eb 100644
--- a/libs/hwui/OpenGLRenderer.h
+++ b/libs/hwui/OpenGLRenderer.h
@@ -103,8 +103,8 @@
void resetShader();
void setupBitmapShader(SkBitmap* bitmap, SkShader::TileMode tileX, SkShader::TileMode tileY,
SkMatrix* matrix, bool hasAlpha);
- void setupLinearGradientShader(float* bounds, uint32_t* colors, float* positions,
- SkShader::TileMode tileMode, SkMatrix* matrix, bool hasAlpha);
+ void setupLinearGradientShader(SkShader* shader, float* bounds, uint32_t* colors,
+ float* positions, SkShader::TileMode tileMode, SkMatrix* matrix, bool hasAlpha);
private:
/**
@@ -309,6 +309,7 @@
sp<Program> mCurrentProgram;
sp<DrawColorProgram> mDrawColorProgram;
sp<DrawTextureProgram> mDrawTextureProgram;
+ sp<DrawLinearGradientProgram> mDrawLinearGradientProgram;
// Used to draw textured quads
TextureVertex mDrawTextureVertices[4];
@@ -323,6 +324,7 @@
// Skia shaders
ShaderType mShader;
+ SkShader* mShaderKey;
bool mShaderBlend;
SkShader::TileMode mShaderTileX;
SkShader::TileMode mShaderTileY;
diff --git a/libs/hwui/Program.cpp b/libs/hwui/Program.cpp
index 609b28a..6202ba3 100644
--- a/libs/hwui/Program.cpp
+++ b/libs/hwui/Program.cpp
@@ -33,6 +33,9 @@
#include "shaders/drawTexture.vert"
#include "shaders/drawTexture.frag"
+#include "shaders/drawLinearGradient.vert"
+#include "shaders/drawLinearGradient.frag"
+
///////////////////////////////////////////////////////////////////////////////
// Base program
///////////////////////////////////////////////////////////////////////////////
@@ -178,5 +181,26 @@
glDisableVertexAttribArray(texCoords);
}
+///////////////////////////////////////////////////////////////////////////////
+// Draw linear gradient
+///////////////////////////////////////////////////////////////////////////////
+
+DrawLinearGradientProgram::DrawLinearGradientProgram():
+ DrawColorProgram(gDrawLinearGradientVertexShader, gDrawLinearGradientFragmentShader) {
+ gradient = addUniform("gradient");
+ gradientLength = addUniform("gradientLength");
+ sampler = addUniform("sampler");
+}
+
+void DrawLinearGradientProgram::use() {
+ DrawColorProgram::use();
+ glActiveTexture(GL_TEXTURE0);
+ glUniform1i(sampler, 0);
+}
+
+void DrawLinearGradientProgram::remove() {
+ DrawColorProgram::remove();
+}
+
}; // namespace uirenderer
}; // namespace android
diff --git a/libs/hwui/Program.h b/libs/hwui/Program.h
index d90bcaf..d7970d9 100644
--- a/libs/hwui/Program.h
+++ b/libs/hwui/Program.h
@@ -148,6 +148,7 @@
* Name of the color uniform.
*/
int color;
+
/**
* Name of the transform uniform.
*/
@@ -189,6 +190,44 @@
int texCoords;
};
+/**
+ * Program used to draw linear gradients. In addition to everything that the
+ * DrawColorProgram supports, the following two attributes must be specified:
+ * vec2 gradient, the vector describing the linear gradient
+ * float gradientLength, the invert of the magnitude of the gradient vector
+ * sampler2D sampler, the texture sampler
+ */
+class DrawLinearGradientProgram: public DrawColorProgram {
+public:
+ DrawLinearGradientProgram();
+
+ /**
+ * Binds this program to the GL context.
+ */
+ virtual void use();
+
+ /**
+ * Marks this program as unused. This will not unbind
+ * the program from the GL context.
+ */
+ virtual void remove();
+
+ /**
+ * Name of the linear gradient vector.
+ */
+ int gradient;
+
+ /**
+ * Name of the inverse of linear gradient vector's magnitude.
+ */
+ int gradientLength;
+
+ /**
+ * Name of the texture sampler uniform.
+ */
+ int sampler;
+};
+
}; // namespace uirenderer
}; // namespace android
diff --git a/libs/hwui/shaders/drawLinearGradient.frag b/libs/hwui/shaders/drawLinearGradient.frag
new file mode 100644
index 0000000..469c662
--- /dev/null
+++ b/libs/hwui/shaders/drawLinearGradient.frag
@@ -0,0 +1,14 @@
+SHADER_SOURCE(gDrawLinearGradientFragmentShader,
+
+precision mediump float;
+
+varying float index;
+
+uniform vec4 color;
+uniform sampler2D sampler;
+
+void main(void) {
+ gl_FragColor = texture2D(sampler, vec2(index, 0.5)) * color;
+}
+
+);
diff --git a/libs/hwui/shaders/drawLinearGradient.vert b/libs/hwui/shaders/drawLinearGradient.vert
new file mode 100644
index 0000000..963dc87
--- /dev/null
+++ b/libs/hwui/shaders/drawLinearGradient.vert
@@ -0,0 +1,16 @@
+SHADER_SOURCE(gDrawLinearGradientVertexShader,
+
+attribute vec4 position;
+
+uniform float gradientLength;
+uniform vec2 gradient;
+uniform mat4 transform;
+
+varying float index;
+
+void main(void) {
+ gl_Position = transform * position;
+ index = dot(gl_Position.xy, gradient) * gradientLength;
+}
+
+);