1 files changed, 79 insertions, 0 deletions
diff --git a/src/core/SkImageInfoPriv.h b/src/core/SkImageInfoPriv.h
new file mode 100644
index 0000000000..029aa93e1d
--- /dev/null
+++ b/src/core/SkImageInfoPriv.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/**
+ *  Returns true if |info| contains a valid combination of width, height, colorType, alphaType,
+ *  colorSpace.  Returns false otherwise.
+ */
+static inline bool SkImageInfoIsValid(const SkImageInfo& info) {
+    if (info.width() <= 0 || info.height() <= 0) {
+        return false;
+    }
+
+    if (kUnknown_SkColorType == info.colorType() || kUnknown_SkAlphaType == info.alphaType()) {
+        return false;
+    }
+
+    if (kOpaque_SkAlphaType != info.alphaType() &&
+       (kRGB_565_SkColorType == info.colorType() || kGray_8_SkColorType == info.colorType())) {
+        return false;
+    }
+
+    if (kRGBA_F16_SkColorType == info.colorType() &&
+       (!info.colorSpace() || !info.colorSpace()->gammaIsLinear())) {
+        return false;
+    }
+
+    if (info.colorSpace() &&
+       (!info.colorSpace()->gammaCloseToSRGB() && !info.colorSpace()->gammaIsLinear())) {
+        return false;
+    }
+
+    return true;
+}
+
+/**
+ *  Returns true if Skia has defined a pixel conversion from the |src| to the |dst|.
+ *  Returns false otherwise.  Some discussion of false cases:
+ *      We will not convert to kIndex8 unless |src| is kIndex8.  This is possible only
+ *      in some cases and likley inefficient.
+ *      We do not convert to kGray8 when the |src| is not kGray8.  We may add this
+ *      feature - it just requires some work to convert to luminance while handling color
+ *      spaces correctly.  Currently no one is asking for this.
+ *      We will not convert from kAlpha8 when the |dst| is not kAlpha8.  This would require
+ *      inventing color information.
+ *      We will not convert to kOpaque when the |src| is not kOpaque.  This could be
+ *      implemented to set all the alpha values to 1, but there is still some ambiguity -
+ *      should we use kPremul or kUnpremul color values with the opaque alphas?  Or should
+ *      we just use whatever the |src| alpha is?  In the future, we could choose to clearly
+ *      define this, but currently no one is asking for this feature.
+ */
+static inline bool SkImageInfoValidConversion(const SkImageInfo& dst, const SkImageInfo& src) {
+    if (!SkImageInfoIsValid(dst) || !SkImageInfoIsValid(src)) {
+        return false;
+    }
+
+    if (kIndex_8_SkColorType == dst.colorType() && kIndex_8_SkColorType != src.colorType()) {
+        return false;
+    }
+
+    if (kGray_8_SkColorType == dst.colorType() && kGray_8_SkColorType != src.colorType()) {
+        return false;
+    }
+
+    if (kAlpha_8_SkColorType != dst.colorType() && kAlpha_8_SkColorType == src.colorType()) {
+        return false;
+    }
+
+    // FIXME (msarett): This is commented out until a fix to Chrome's gfx_unittest lands.
+    // In those tests, they write kPremul pixels to a kOpaque canvas.
+    //if (kOpaque_SkAlphaType == dst.alphaType() && kOpaque_SkAlphaType != src.alphaType()) {
+    //    return false;
+    //}
+
+    return true;
+}