vcl OpenGL program: Cache mvp matrix to reduce ~200 api calls per frame.

Change-Id: I86ae50bd8d2148e86a6c8fc0821d3e2bc29a0cd4
(cherry picked from commit e3cd97ce0b2e153b8b6812cc66f2e7d33504a7da)
Reviewed-on: https://gerrit.libreoffice.org/18006Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
Tested-by: Tomaž Vajngerl <quikee@gmail.com>

vcl/inc/opengl/program.hxx

@@ -39,6 +39,11 @@ private:
     TextureList     maTextures;
     bool            mbBlending;
 
+    float mfLastWidth;
+    float mfLastHeight;
+    float mfLastPixelOffset;
+
+
     OpenGLProgram(const OpenGLProgram &) SAL_DELETED_FUNCTION;
 public:
     OpenGLProgram();

vcl/opengl/program.cxx

@@ -21,7 +21,10 @@ OpenGLProgram::OpenGLProgram() :
     mnPositionAttrib( SAL_MAX_UINT32 ),
     mnTexCoordAttrib( SAL_MAX_UINT32 ),
     mnAlphaCoordAttrib( SAL_MAX_UINT32 ),
-    mbBlending( false )
+    mbBlending( false ),
+    mfLastWidth(0.0),
+    mfLastHeight(0.0),
+    mfLastPixelOffset(0.0)
 {
 }
 
@@ -241,6 +244,14 @@ void OpenGLProgram::SetTransform(
 
 void OpenGLProgram::ApplyMatrix(float fWidth, float fHeight, float fPixelOffset)
 {
+
+    if (mfLastWidth == fWidth && mfLastHeight == fHeight && mfLastPixelOffset == fPixelOffset)
+        return;
+
+    mfLastWidth = fWidth;
+    mfLastHeight = fHeight;
+    mfLastPixelOffset = fPixelOffset;
+
     OString sProjectionMatrix("mvp");
     GLuint nUniform = GetUniformLocation(sProjectionMatrix);