add SkBitmap::installPixelRef()

include/core/SkImageInfo.h

Index: include/core/SkImageInfo.h
diff --git a/include/core/SkImageInfo.h b/include/core/SkImageInfo.h
index 1165479f7484267e47dc5dfa2bba90e5a79dce56..ae5470c6c66edc121898595001ff5f29631a4d01 100644
--- a/include/core/SkImageInfo.h
+++ b/include/core/SkImageInfo.h
@@ -109,6 +109,51 @@ struct SkImageInfo {
     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);
     }