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

1 files changed, 39 insertions, 0 deletions

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 @@ public:
      * Name of the color uniform.
      */
     int color;
+
     /**
      * Name of the transform uniform.
      */
@@ -189,6 +190,44 @@ public:
     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