add SkBitmap::installPixelRef()

include/core/SkImageInfo.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageInfo_DEFINED
 #define SkImageInfo_DEFINED
 
@@ skipping 91 matching lines @@
 
 /**
  *  Describe an image's dimensions and pixel type.
  */
 struct SkImageInfo {
     int         fWidth;
     int         fHeight;
     SkColorType fColorType;
     SkAlphaType fAlphaType;
 
+    static SkImageInfo Make(int width, int height, SkColorType ct, SkAlphaType at) {
+        SkASSERT(width >= 0);
+        SkASSERT(height >= 0);
+        SkImageInfo info = {
+            width, height, ct, at
+        };
+        return info;
+    }
+    
+    static SkImageInfo MakePM(int width, int height, SkAlphaType at) {
+        SkASSERT(width >= 0);
+        SkASSERT(height >= 0);
+        SkImageInfo info = {
+            width, height, kPMColor_SkColorType, at
+        };
+        return info;
+    }
+    
+    static SkImageInfo MakePMPremul(int width, int height) {

[scroggo, 2014/01/09 00:02:11]

Not a big fan of this name... Any chance we can change kPMColor_SkColorType to
something else, since it no longer means premul? Or maybe we just need to retcon
PM to something else?

[reed1, 2014/01/13 16:27:26]

Suggestions?

kNativeARGB32_ColorType?

[scroggo, 2014/01/13 17:48:48]

sgtm

+        SkASSERT(width >= 0);
+        SkASSERT(height >= 0);
+        SkImageInfo info = {
+            width, height, kPMColor_SkColorType, kPremul_SkAlphaType
+        };
+        return info;
+    }
+    
+    static SkImageInfo MakePMOpaque(int width, int height) {
+        SkASSERT(width >= 0);
+        SkASSERT(height >= 0);
+        SkImageInfo info = {
+            width, height, kPMColor_SkColorType, kOpaque_SkAlphaType
+        };
+        return info;
+    }
+    
+    static SkImageInfo MakeA8(int width, int height) {
+        SkASSERT(width >= 0);
+        SkASSERT(height >= 0);
+        SkImageInfo info = {
+            width, height, kAlpha_8_SkColorType, kPremul_SkAlphaType
+        };
+        return info;
+    }
+    
     bool isOpaque() const {
         return SkAlphaTypeIsOpaque(fAlphaType);
     }
 
     int bytesPerPixel() const {
         return SkColorTypeBytesPerPixel(fColorType);
     }
 
     size_t minRowBytes() const {
         return fWidth * this->bytesPerPixel();
@@ skipping 11 matching lines @@
 
     size_t getSafeSize(size_t rowBytes) const {
         if (0 == fHeight) {
             return 0;
         }
         return (fHeight - 1) * rowBytes + fWidth * this->bytesPerPixel();
     }
 };
 
 #endif