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Unified Diff: include/codec/SkEncodedInfo.h

Issue 1820073002: Add SkEncodedInfo to report properties of encoded image data (Closed) Base URL: https://skia.googlesource.com/skia.git@master
Patch Set: Order of param eval bug Created 4 years, 8 months ago
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Index: include/codec/SkEncodedInfo.h
diff --git a/include/codec/SkEncodedInfo.h b/include/codec/SkEncodedInfo.h
new file mode 100644
index 0000000000000000000000000000000000000000..f91660529e05a26194fdf8b5084f211133298ab5
--- /dev/null
+++ b/include/codec/SkEncodedInfo.h
@@ -0,0 +1,178 @@
+/*
+ * 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 SkEncodedInfo_DEFINED
+#define SkEncodedInfo_DEFINED
+
+#include "SkImageInfo.h"
+
+struct SkEncodedInfo {
+public:
+
+ enum Alpha {
+ kOpaque_Alpha,
+ kUnpremul_Alpha,
+
+ // Each pixel is either fully opaque or fully transparent.
+ // There is no difference between requesting kPremul or kUnpremul.
+ kBinary_Alpha,
+
+ // Allows us to have a default constructor. Should be treated as
+ // invalid.
+ kUnknown_Alpha,
+ };
+
+ /*
+ * We strive to make the number of components per pixel obvious through
+ * our naming conventions.
+ * Ex: kRGB has 3 components. kRGBA has 4 components.
+ *
+ * This sometimes results in redundant Alpha and Color information.
+ * Ex: kRGB images must also be kOpaque.
+ */
+ enum Color {
+ // PNG, WBMP
+ kGray_Color,
+
+ // PNG
+ kGrayAlpha_Color,
+
+ // PNG, GIF, BMP
+ kPalette_Color,
+
+ // PNG, RAW
+ kRGB_Color,
+ kRGBA_Color,
+
+ // BMP
+ kBGR_Color,
+ kBGRX_Color,
+ kBGRA_Color,
+
+ // JPEG, WEBP
+ kYUV_Color,
+
+ // WEBP
+ kYUVA_Color,
+
+ // JPEG
+ // Photoshop actually writes inverted CMYK data into JPEGs, where zero
+ // represents 100% ink coverage. For this reason, we treat CMYK JPEGs
+ // as having inverted CMYK. libjpeg-turbo warns that this may break
+ // other applications, but the CMYK JPEGs we see on the web expect to
+ // be treated as inverted CMYK.
+ kInvertedCMYK_Color,
+ kYCCK_Color,
+
+ // Allows us to have a default constructor. Should be treated as
+ // invalid.
+ kUnknown_Color,
+ };
+
+ static SkEncodedInfo Make(Color color, Alpha alpha, int bitsPerComponent) {
+ SkASSERT(1 == bitsPerComponent ||
+ 2 == bitsPerComponent ||
+ 4 == bitsPerComponent ||
+ 8 == bitsPerComponent ||
+ 16 == bitsPerComponent);
+
+ switch (color) {
+ case kGray_Color:
+ SkASSERT(kOpaque_Alpha == alpha);
+ break;
+ case kGrayAlpha_Color:
+ SkASSERT(kOpaque_Alpha != alpha);
+ break;
+ case kPalette_Color:
+ SkASSERT(16 != bitsPerComponent);
+ break;
+ case kRGB_Color:
+ case kBGR_Color:
+ case kBGRX_Color:
+ SkASSERT(kOpaque_Alpha == alpha);
+ SkASSERT(bitsPerComponent >= 8);
+ break;
+ case kYUV_Color:
+ case kInvertedCMYK_Color:
+ case kYCCK_Color:
+ SkASSERT(kOpaque_Alpha == alpha);
+ SkASSERT(8 == bitsPerComponent);
+ break;
+ case kRGBA_Color:
+ SkASSERT(kOpaque_Alpha != alpha);
+ SkASSERT(bitsPerComponent >= 8);
+ break;
+ case kBGRA_Color:
+ case kYUVA_Color:
+ SkASSERT(kOpaque_Alpha != alpha);
+ SkASSERT(8 == bitsPerComponent);
+ break;
+ default:
+ SkASSERT(false);
+ break;
+ }
+
+ return SkEncodedInfo(color, alpha, bitsPerComponent);
+ }
+
+ /*
+ * Returns an SkImageInfo with Skia color and alpha types that are the
+ * closest possible match to the encoded info.
+ */
+ SkImageInfo makeImageInfo(int width, int height) const {
+ switch (fColor) {
+ case kGray_Color:
+ SkASSERT(kOpaque_Alpha == fAlpha);
+ return SkImageInfo::Make(width, height, kGray_8_SkColorType, kOpaque_SkAlphaType);
+ case kGrayAlpha_Color:
+ SkASSERT(kOpaque_Alpha != fAlpha);
+ return SkImageInfo::Make(width, height, kN32_SkColorType,
+ kUnpremul_SkAlphaType);
+ case kPalette_Color: {
+ SkAlphaType alphaType = (kOpaque_Alpha == fAlpha) ? kOpaque_SkAlphaType :
+ kUnpremul_SkAlphaType;
+ return SkImageInfo::Make(width, height, kIndex_8_SkColorType, alphaType);
+ }
+ case kRGB_Color:
+ case kBGR_Color:
+ case kBGRX_Color:
+ case kYUV_Color:
+ case kInvertedCMYK_Color:
+ case kYCCK_Color:
+ SkASSERT(kOpaque_Alpha == fAlpha);
+ return SkImageInfo::Make(width, height, kN32_SkColorType, kOpaque_SkAlphaType);
+ case kRGBA_Color:
+ case kBGRA_Color:
+ case kYUVA_Color:
+ SkASSERT(kOpaque_Alpha != fAlpha);
+ return SkImageInfo::Make(width, height, kN32_SkColorType, kUnpremul_SkAlphaType);
+ default:
+ SkASSERT(false);
+ return SkImageInfo::MakeUnknown();
+ }
+ }
+
+ SkEncodedInfo()
+ : fColor(kUnknown_Color)
+ , fAlpha(kUnknown_Alpha)
+ , fBitsPerComponent(0)
+ {}
+
+private:
+
+ SkEncodedInfo(Color color, Alpha alpha, uint8_t bitsPerComponent)
+ : fColor(color)
+ , fAlpha(alpha)
+ , fBitsPerComponent(bitsPerComponent)
+ {}
+
+ Color fColor;
+ Alpha fAlpha;
+ uint8_t fBitsPerComponent;
+};
+
+#endif
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