don't support converting from alpha to non-alpha

BUG=skia:

Change-Id: Ia06bef6c0bfc03b5ca9f569c07e993da0bbd67c3
Reviewed-on: https://skia-review.googlesource.com/5288
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Mike Reed <reed@google.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/core/SkConfig8888.cpp b/src/core/SkConfig8888.cpp
index 9af36216cc..3906a9a1ef 100644
--- a/src/core/SkConfig8888.cpp
+++ b/src/core/SkConfig8888.cpp
@@ -324,6 +324,12 @@ bool SkPixelInfo::CopyPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t
         return false;
     }
 
+    if (srcInfo.colorType() == kAlpha_8_SkColorType &&
+        dstInfo.colorType() != kAlpha_8_SkColorType)
+    {
+        return false;   // can't convert from alpha to non-alpha
+    }
+
     const int width = srcInfo.width();
     const int height = srcInfo.height();