add helper to know when a colortype is always opaque

Now that surface creation is more picky about its imageinfo, we need to
allow clients to know when they should clean-up their alphatype (like
our own gm)

Bug: skia:
Change-Id: Ic110c75769e0154a8343d7e2160d3351f02cf48f
Reviewed-on: https://skia-review.googlesource.com/106320
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/src/core/SkImageInfo.cpp b/src/core/SkImageInfo.cpp
index b684cdfcf4..0b06334484 100644
--- a/src/core/SkImageInfo.cpp
+++ b/src/core/SkImageInfo.cpp
@@ -79,6 +79,19 @@ static SkColorType stored_to_live(unsigned stored) {
     return kUnknown_SkColorType;
 }
 
+bool SkColorTypeIsAlwaysOpaque(SkColorType ct) {
+    switch (ct) {
+        case kRGB_565_SkColorType:
+        case kRGB_888x_SkColorType:
+        case kRGB_101010x_SkColorType:
+        case kGray_8_SkColorType:
+            return true;
+        default:
+            break;
+    }
+    return false;
+}
+
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 int SkImageInfo::bytesPerPixel() const { return SkColorTypeBytesPerPixel(fColorType); }