Add SkColorSpaceXform to the public API

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2390263002

Review-Url: https://codereview.chromium.org/2390263002

1 files changed, 67 insertions, 0 deletions

diff --git a/include/core/SkColorSpaceXform.h b/include/core/SkColorSpaceXform.h
new file mode 100644
index 0000000000..15b3d49ee4
--- /dev/null
+++ b/include/core/SkColorSpaceXform.h
@@ -0,0 +1,67 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkColorSpaceXform_DEFINED
+#define SkColorSpaceXform_DEFINED
+
+#include "SkImageInfo.h"
+
+class SkColorSpace;
+
+class SkColorSpaceXform : SkNoncopyable {
+public:
+
+    /**
+     *  Create an object to handle color space conversions.
+     *
+     *  @param srcSpace The encoded color space.
+     *  @param dstSpace The destination color space.
+     *
+     */
+    static std::unique_ptr<SkColorSpaceXform> New(SkColorSpace* srcSpace, SkColorSpace* dstSpace);
+
+    enum ColorFormat {
+        kRGBA_8888_ColorFormat,
+        kBGRA_8888_ColorFormat,
+        kRGBA_F16_ColorFormat,
+        kRGBA_F32_ColorFormat,
+    };
+
+    /**
+     *  Apply the color conversion to a |src| buffer, storing the output in the |dst| buffer.
+     *
+     *  F16 and F32 are only supported as dst color formats, and only when the dst color space
+     *  is linear.  This function will return false in unsupported cases.
+     *
+     *  @param dst            Stored in the format described by |dstColorFormat|
+     *  @param src            Stored in the format described by |srcColorFormat|
+     *  @param len            Number of pixels in the buffers
+     *  @param dstColorFormat Describes color format of |dst|
+     *  @param srcColorFormat Describes color format of |src|
+     *                        Must be kRGBA_8888 or kBGRA_8888
+     *  @param alphaType      Describes alpha properties of the |dst| (and |src|)
+     *                        kUnpremul preserves input alpha values
+     *                        kPremul   performs a premultiplication and also preserves alpha values
+     *                        kOpaque   optimization hint, |dst| alphas set to 1
+     *
+     */
+    bool apply(ColorFormat dstFormat, void* dst, ColorFormat srcFormat, const void* src, int count,
+               SkAlphaType alphaType) const {
+        return this->onApply(dstFormat, dst, srcFormat, src, count, alphaType);
+    }
+
+
+    virtual ~SkColorSpaceXform() {}
+
+protected:
+    virtual bool onApply(ColorFormat dstFormat, void* dst, ColorFormat srcFormat, const void* src,
+                         int count, SkAlphaType alphaType) const = 0;
+
+    SkColorSpaceXform() {}
+};
+
+#endif