Add discard API to SkCanvas, plumb it to glDiscardFramebuffer()

include/gpu/GrColor.h

 
 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 
 #ifndef GrColor_DEFINED
 #define GrColor_DEFINED
 
 #include "GrTypes.h"
 
 /**
- *  GrColor is 4 bytes for R, G, B, A, in a compile-time specific order. The
- *  components are stored premultiplied.
+ * GrColor is 4 bytes for R, G, B, A, in a specific order defined below. The components are stored
+ * premultiplied.
  */
 typedef uint32_t GrColor;
 
-
 // shift amount to assign a component to a GrColor int
 // These shift values are chosen for compatibility with GL attrib arrays
 // ES doesn't allow BGRA vertex attrib order so if they were not in this order
-// we'd have to swizzle in shaders. Note the assumption that the cpu is little
-// endian.
-#define GrColor_SHIFT_R     0
-#define GrColor_SHIFT_G     8
-#define GrColor_SHIFT_B     16
-#define GrColor_SHIFT_A     24
+// we'd have to swizzle in shaders.
+#ifdef SK_CPU_BENDIAN
+    #define GrColor_SHIFT_R     24
+    #define GrColor_SHIFT_G     16
+    #define GrColor_SHIFT_B     8
+    #define GrColor_SHIFT_A     0
+#else
+    #define GrColor_SHIFT_R     0
+    #define GrColor_SHIFT_G     8
+    #define GrColor_SHIFT_B     16
+    #define GrColor_SHIFT_A     24
+#endif
 
 /**
  *  Pack 4 components (RGBA) into a GrColor int
  */
 static inline GrColor GrColorPackRGBA(unsigned r, unsigned g,
                                       unsigned b, unsigned a) {
     SkASSERT((uint8_t)r == r);
     SkASSERT((uint8_t)g == g);
     SkASSERT((uint8_t)b == b);
     SkASSERT((uint8_t)a == a);
     return  (r << GrColor_SHIFT_R) |
             (g << GrColor_SHIFT_G) |
             (b << GrColor_SHIFT_B) |
             (a << GrColor_SHIFT_A);
 }
 
 // extract a component (byte) from a GrColor int
 
 #define GrColorUnpackR(color)   (((color) >> GrColor_SHIFT_R) & 0xFF)
 #define GrColorUnpackG(color)   (((color) >> GrColor_SHIFT_G) & 0xFF)
 #define GrColorUnpackB(color)   (((color) >> GrColor_SHIFT_B) & 0xFF)
 #define GrColorUnpackA(color)   (((color) >> GrColor_SHIFT_A) & 0xFF)
 
 /**
  *  Since premultiplied means that alpha >= color, we construct a color with
  *  each component==255 and alpha == 0 to be "illegal"
  */
 #define GrColor_ILLEGAL     (~(0xFF << GrColor_SHIFT_A))
 
+/**
+ * Assert in debug builds that a GrColor is premultiplied.
+ */
+static inline void GrColorIsPMAssert(GrColor c) {
+#ifdef SK_DEBUG
+    unsigned a = GrColorUnpackA(c);
+    unsigned r = GrColorUnpackR(c);
+    unsigned g = GrColorUnpackG(c);
+    unsigned b = GrColorUnpackB(c);
+
+    SkASSERT(r <= a);
+    SkASSERT(g <= a);
+    SkASSERT(b <= a);
+#endif
+}
+
 /** Converts a GrColor to an rgba array of GrGLfloat */
 static inline void GrColorToRGBAFloat(GrColor color, float rgba[4]) {
     static const float ONE_OVER_255 = 1.f / 255.f;
     rgba[0] = GrColorUnpackR(color) * ONE_OVER_255;
     rgba[1] = GrColorUnpackG(color) * ONE_OVER_255;
     rgba[2] = GrColorUnpackB(color) * ONE_OVER_255;
     rgba[3] = GrColorUnpackA(color) * ONE_OVER_255;
 }
 
 /**
@@ skipping 47 matching lines @@
     GR_STATIC_ASSERT(1 == kAlpha_8_GrPixelConfig);
     GR_STATIC_ASSERT(2 == kIndex_8_GrPixelConfig);
     GR_STATIC_ASSERT(3 == kRGB_565_GrPixelConfig);
     GR_STATIC_ASSERT(4 == kRGBA_4444_GrPixelConfig);
     GR_STATIC_ASSERT(5 == kRGBA_8888_GrPixelConfig);
     GR_STATIC_ASSERT(6 == kBGRA_8888_GrPixelConfig);
     GR_STATIC_ASSERT(SK_ARRAY_COUNT(kFlags) == kGrPixelConfigCnt);
 }
 
 #endif