Line data    Source code

       1             : /*
       2             :  * Copyright 2017 Google Inc.
       3             :  *
       4             :  * Use of this source code is governed by a BSD-style license that can be
       5             :  * found in the LICENSE file.
       6             :  */
       7             : 
       8             : #ifndef SkImageInfoPriv_DEFINED
       9             : #define SkImageInfoPriv_DEFINED
      10             : 
      11             : #include "SkImageInfo.h"
      12             : 
      13             : /**
      14             :  *  Returns true if |info| contains a valid combination of width, height, colorType, alphaType,
      15             :  *  colorSpace.  Returns false otherwise.
      16             :  */
      17           0 : static inline bool SkImageInfoIsValid(const SkImageInfo& info) {
      18           0 :     if (info.width() <= 0 || info.height() <= 0) {
      19           0 :         return false;
      20             :     }
      21             : 
      22           0 :     const int kMaxDimension = SK_MaxS32 >> 2;
      23           0 :     if (info.width() > kMaxDimension || info.height() > kMaxDimension) {
      24           0 :         return false;
      25             :     }
      26             : 
      27           0 :     if (kUnknown_SkColorType == info.colorType() || kUnknown_SkAlphaType == info.alphaType()) {
      28           0 :         return false;
      29             :     }
      30             : 
      31           0 :     if (kOpaque_SkAlphaType != info.alphaType() &&
      32           0 :        (kRGB_565_SkColorType == info.colorType() || kGray_8_SkColorType == info.colorType())) {
      33           0 :         return false;
      34             :     }
      35             : 
      36           0 :     if (kRGBA_F16_SkColorType == info.colorType() &&
      37           0 :        (!info.colorSpace() || !info.colorSpace()->gammaIsLinear())) {
      38           0 :         return false;
      39             :     }
      40             : 
      41           0 :     if (info.colorSpace() &&
      42           0 :        (!info.colorSpace()->gammaCloseToSRGB() && !info.colorSpace()->gammaIsLinear())) {
      43           0 :         return false;
      44             :     }
      45             : 
      46           0 :     return true;
      47             : }
      48             : 
      49             : /**
      50             :  *  Returns true if Skia has defined a pixel conversion from the |src| to the |dst|.
      51             :  *  Returns false otherwise.  Some discussion of false cases:
      52             :  *      We will not convert to kIndex8 unless it exactly matches the src, since color tables
      53             :  *      are immutable.
      54             :  *      We do not convert to kGray8 when the |src| is not kGray8 in the same color space.
      55             :  *      We may add this feature - it just requires some work to convert to luminance while
      56             :  *      handling color spaces correctly.  Currently no one is asking for this.
      57             :  *      We will not convert from kAlpha8 when the |dst| is not kAlpha8.  This would require
      58             :  *      inventing color information.
      59             :  *      We will not convert to kOpaque when the |src| is not kOpaque.  This could be
      60             :  *      implemented to set all the alpha values to 1, but there is still some ambiguity -
      61             :  *      should we use kPremul or kUnpremul color values with the opaque alphas?  Or should
      62             :  *      we just use whatever the |src| alpha is?  In the future, we could choose to clearly
      63             :  *      define this, but currently no one is asking for this feature.
      64             :  *      We will not convert to a particular color space if |src| is nullptr.  The color space
      65             :  *      conversion is not well-defined.
      66             :  */
      67           0 : static inline bool SkImageInfoValidConversion(const SkImageInfo& dst, const SkImageInfo& src) {
      68           0 :     if (!SkImageInfoIsValid(dst) || !SkImageInfoIsValid(src)) {
      69           0 :         return false;
      70             :     }
      71             : 
      72           0 :     if (kIndex_8_SkColorType == dst.colorType()) {
      73           0 :         if (kIndex_8_SkColorType != src.colorType()) {
      74           0 :             return false;
      75             :         }
      76             : 
      77           0 :         if ((kPremul_SkAlphaType == dst.alphaType() && kUnpremul_SkAlphaType == src.alphaType()) ||
      78           0 :             (kUnpremul_SkAlphaType == dst.alphaType() && kPremul_SkAlphaType == src.alphaType()))
      79             :         {
      80           0 :             return false;
      81             :         }
      82             : 
      83           0 :         if (dst.colorSpace() && !SkColorSpace::Equals(dst.colorSpace(), src.colorSpace())) {
      84           0 :             return false;
      85             :         }
      86             :     }
      87             : 
      88           0 :     if (kGray_8_SkColorType == dst.colorType()) {
      89           0 :         if (kGray_8_SkColorType != src.colorType()) {
      90           0 :             return false;
      91             :         }
      92             : 
      93           0 :         if (dst.colorSpace() && !SkColorSpace::Equals(dst.colorSpace(), src.colorSpace())) {
      94           0 :             return false;
      95             :         }
      96             :     }
      97             : 
      98           0 :     if (kAlpha_8_SkColorType != dst.colorType() && kAlpha_8_SkColorType == src.colorType()) {
      99           0 :         return false;
     100             :     }
     101             : 
     102           0 :     if (kOpaque_SkAlphaType == dst.alphaType() && kOpaque_SkAlphaType != src.alphaType()) {
     103           0 :         return false;
     104             :     }
     105             : 
     106           0 :     if (dst.colorSpace() && !src.colorSpace()) {
     107           0 :         return false;
     108             :     }
     109             : 
     110           0 :     return true;
     111             : }
     112             : #endif  // SkImageInfoPriv_DEFINED