use some helper Make functions to initialize SkImageInfo

BUG=
R=halcanary@google.com, scroggo@google.com

Author: reed@google.com

Review URL: https://codereview.chromium.org/137993012

git-svn-id: http://skia.googlecode.com/svn/trunk@13081 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 50 insertions, 0 deletions

diff --git a/include/core/SkImageInfo.h b/include/core/SkImageInfo.h
index 1165479f74..e37f2ef6d9 100644
--- a/include/core/SkImageInfo.h
+++ b/include/core/SkImageInfo.h
@@ -9,6 +9,7 @@
 #define SkImageInfo_DEFINED
 
 #include "SkTypes.h"
+#include "SkSize.h"
 
 class SkFlattenableWriteBuffer;
 class SkFlattenableReadBuffer;
@@ -109,6 +110,55 @@ 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;
+    }
+
+    /**
+     *  Sets colortype to the native ARGB32 type.
+     */
+    static SkImageInfo MakeN32(int width, int height, SkAlphaType at) {
+        SkASSERT(width >= 0);
+        SkASSERT(height >= 0);
+        SkImageInfo info = {
+            width, height, kPMColor_SkColorType, at
+        };
+        return info;
+    }
+
+    /**
+     *  Sets colortype to the native ARGB32 type, and the alphatype to premul.
+     */
+    static SkImageInfo MakeN32Premul(int width, int height) {
+        SkASSERT(width >= 0);
+        SkASSERT(height >= 0);
+        SkImageInfo info = {
+            width, height, kPMColor_SkColorType, kPremul_SkAlphaType
+        };
+        return info;
+    }
+    
+    /**
+     *  Sets colortype to the native ARGB32 type, and the alphatype to premul.
+     */
+    static SkImageInfo MakeN32Premul(const SkISize& size) {
+        return MakeN32Premul(size.width(), size.height());
+    }
+    
+    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);
     }