extend SkShader to report a luminance-color to be used for gamma correction
BUG=skia:590
R=bungeman@google.com
Author: reed@google.com
Review URL: https://codereview.chromium.org/492963002
diff --git a/include/core/SkShader.h b/include/core/SkShader.h
index 1e71577..8530023 100644
--- a/include/core/SkShader.h
+++ b/include/core/SkShader.h
@@ -386,6 +386,16 @@
const SkMatrix* localMatrixOrNull, GrColor* paintColor,
GrEffect** effect) const;
+ /**
+ * If the shader can represent its "average" luminance in a single color, return true and
+ * if color is not NULL, return that color. If it cannot, return false and ignore the color
+ * parameter.
+ *
+ * Note: if this returns true, the returned color will always be opaque, as only the RGB
+ * components are used to compute luminance.
+ */
+ bool asLuminanceColor(SkColor*) const;
+
#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
/**
* If the shader is a custom shader which has data the caller might want, call this function
@@ -402,6 +412,12 @@
*/
static SkShader* CreateEmptyShader();
+ /**
+ * Call this to create a new shader that just draws the specified color. This should always
+ * draw the same as a paint with this color (and no shader).
+ */
+ static SkShader* CreateColorShader(SkColor);
+
/** Call this to create a new shader that will draw with the specified bitmap.
*
* If the bitmap cannot be used (e.g. has no pixels, or its dimensions
@@ -474,6 +490,9 @@
*/
virtual Context* onCreateContext(const ContextRec&, void* storage) const;
+ virtual bool onAsLuminanceColor(SkColor*) const {
+ return false;
+ }
private:
// This is essentially const, but not officially so it can be modified in
// constructors.