Hide SkEncodedInfo

Bug: skia:7353
Bug: skia:6839

This contains information that is not necessary for clients to know. The
Color enum tells the number of components in the input, but this is only
interesting internally (to the SkSwizzler).

Similarly, the Alpha enum differs from SkAlphaType in that it has
kBinary instead of kPremul. This is useful information only internally
for determining whether the SkColorSpaceXform needs to premultiply.

The bitsPerComponent is potentially useful for a client; Android (in
SkAndroidCodec) uses it to determine the SkColorType. Rather than
exposing bitsPerComponent, use it to make the same decision that Android
would have made - 16 bits per component means to set the info to F16. Add
a test that computeOutputColorType behaves as expected.

Switch conversionSupported to use an SkColorType, which is enough info.

Replace the SkEncodedInfo::Alpha field on SkCodec::FrameInfo with an
SkAlphaType.

SkCodec still needs an SkEncodedInfo, so move its header (which is
already not SK_API) to include/private.

Change-Id: Ie2cf11339bf999ebfd4390c0f448f7edd6feabda
Reviewed-on: https://skia-review.googlesource.com/79260
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Leon Scroggins <scroggo@google.com>

1 files changed, 173 insertions, 0 deletions

diff --git a/include/private/SkEncodedInfo.h b/include/private/SkEncodedInfo.h
new file mode 100644
index 0000000000..638f03dc11
--- /dev/null
+++ b/include/private/SkEncodedInfo.h
@@ -0,0 +1,173 @@
+/*
+ * 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"
+
+class SkColorSpace;
+
+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,
+    };
+
+    /*
+     * 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,
+    };
+
+    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, sk_sp<SkColorSpace> colorSpace) const {
+        auto ct = kGray_Color == fColor ? kGray_8_SkColorType   :
+                  fBitsPerComponent > 8 ? kRGBA_F16_SkColorType :
+                                          kN32_SkColorType      ;
+        auto alpha = kOpaque_Alpha == fAlpha ? kOpaque_SkAlphaType
+                                             : kUnpremul_SkAlphaType;
+        return SkImageInfo::Make(width, height, ct, alpha, std::move(colorSpace));
+    }
+
+    Color color() const { return fColor; }
+    Alpha alpha() const { return fAlpha; }
+    bool opaque() const { return fAlpha == kOpaque_Alpha; }
+
+    uint8_t bitsPerComponent() const { return fBitsPerComponent; }
+
+    uint8_t bitsPerPixel() const {
+        switch (fColor) {
+            case kGray_Color:
+                return fBitsPerComponent;
+            case kGrayAlpha_Color:
+                return 2 * fBitsPerComponent;
+            case kPalette_Color:
+                return fBitsPerComponent;
+            case kRGB_Color:
+            case kBGR_Color:
+            case kYUV_Color:
+                return 3 * fBitsPerComponent;
+            case kRGBA_Color:
+            case kBGRA_Color:
+            case kBGRX_Color:
+            case kYUVA_Color:
+            case kInvertedCMYK_Color:
+            case kYCCK_Color:
+                return 4 * fBitsPerComponent;
+            default:
+                SkASSERT(false);
+                return 0;
+        }
+    }
+
+private:
+
+    SkEncodedInfo(Color color, Alpha alpha, uint8_t bitsPerComponent)
+        : fColor(color)
+        , fAlpha(alpha)
+        , fBitsPerComponent(bitsPerComponent)
+    {}
+
+    Color   fColor;
+    Alpha   fAlpha;
+    uint8_t fBitsPerComponent;
+};
+
+#endif