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      1 
      2 /*
      3  * Copyright 2012 Google Inc.
      4  *
      5  * Use of this source code is governed by a BSD-style license that can be
      6  * found in the LICENSE file.
      7  */
      8 
      9 #ifndef SkGradientShaderPriv_DEFINED
     10 #define SkGradientShaderPriv_DEFINED
     11 
     12 #include "SkGradientShader.h"
     13 #include "SkClampRange.h"
     14 #include "SkColorPriv.h"
     15 #include "SkFlattenableBuffers.h"
     16 #include "SkMallocPixelRef.h"
     17 #include "SkUnitMapper.h"
     18 #include "SkUtils.h"
     19 #include "SkTemplates.h"
     20 #include "SkBitmapCache.h"
     21 #include "SkShader.h"
     22 
     23 #ifndef SK_DISABLE_DITHER_32BIT_GRADIENT
     24     #define USE_DITHER_32BIT_GRADIENT
     25 #endif
     26 
     27 static inline void sk_memset32_dither(uint32_t dst[], uint32_t v0, uint32_t v1,
     28                                int count) {
     29     if (count > 0) {
     30         if (v0 == v1) {
     31             sk_memset32(dst, v0, count);
     32         } else {
     33             int pairs = count >> 1;
     34             for (int i = 0; i < pairs; i++) {
     35                 *dst++ = v0;
     36                 *dst++ = v1;
     37             }
     38             if (count & 1) {
     39                 *dst = v0;
     40             }
     41         }
     42     }
     43 }
     44 
     45 //  Clamp
     46 
     47 static inline SkFixed clamp_tileproc(SkFixed x) {
     48     return SkClampMax(x, 0xFFFF);
     49 }
     50 
     51 // Repeat
     52 
     53 static inline SkFixed repeat_tileproc(SkFixed x) {
     54     return x & 0xFFFF;
     55 }
     56 
     57 // Mirror
     58 
     59 // Visual Studio 2010 (MSC_VER=1600) optimizes bit-shift code incorrectly.
     60 // See http://code.google.com/p/skia/issues/detail?id=472
     61 #if defined(_MSC_VER) && (_MSC_VER >= 1600)
     62 #pragma optimize("", off)
     63 #endif
     64 
     65 static inline SkFixed mirror_tileproc(SkFixed x) {
     66     int s = x << 15 >> 31;
     67     return (x ^ s) & 0xFFFF;
     68 }
     69 
     70 #if defined(_MSC_VER) && (_MSC_VER >= 1600)
     71 #pragma optimize("", on)
     72 #endif
     73 
     74 ///////////////////////////////////////////////////////////////////////////////
     75 
     76 typedef SkFixed (*TileProc)(SkFixed);
     77 
     78 ///////////////////////////////////////////////////////////////////////////////
     79 
     80 static const TileProc gTileProcs[] = {
     81     clamp_tileproc,
     82     repeat_tileproc,
     83     mirror_tileproc
     84 };
     85 
     86 ///////////////////////////////////////////////////////////////////////////////
     87 
     88 class SkGradientShaderBase : public SkShader {
     89 public:
     90     SkGradientShaderBase(const SkColor colors[], const SkScalar pos[],
     91                 int colorCount, SkShader::TileMode mode, SkUnitMapper* mapper);
     92     virtual ~SkGradientShaderBase();
     93 
     94     virtual bool setContext(const SkBitmap&, const SkPaint&, const SkMatrix&) SK_OVERRIDE;
     95     virtual uint32_t getFlags() SK_OVERRIDE { return fFlags; }
     96     virtual bool isOpaque() const SK_OVERRIDE;
     97 
     98     void getGradientTableBitmap(SkBitmap*) const;
     99 
    100     enum {
    101         /// Seems like enough for visual accuracy. TODO: if pos[] deserves
    102         /// it, use a larger cache.
    103         kCache16Bits    = 8,
    104         kCache16Count = (1 << kCache16Bits),
    105         kCache16Shift   = 16 - kCache16Bits,
    106         kSqrt16Shift    = 8 - kCache16Bits,
    107 
    108         /// Seems like enough for visual accuracy. TODO: if pos[] deserves
    109         /// it, use a larger cache.
    110         kCache32Bits    = 8,
    111         kCache32Count = (1 << kCache32Bits),
    112         kCache32Shift   = 16 - kCache32Bits,
    113         kSqrt32Shift    = 8 - kCache32Bits,
    114 
    115         /// This value is used to *read* the dither cache; it may be 0
    116         /// if dithering is disabled.
    117 #ifdef USE_DITHER_32BIT_GRADIENT
    118         kDitherStride32 = kCache32Count,
    119 #else
    120         kDitherStride32 = 0,
    121 #endif
    122         kDitherStride16 = kCache16Count,
    123     };
    124 
    125 
    126 protected:
    127     SkGradientShaderBase(SkFlattenableReadBuffer& );
    128     virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
    129     SK_DEVELOPER_TO_STRING()
    130 
    131     SkUnitMapper* fMapper;
    132     SkMatrix    fPtsToUnit;     // set by subclass
    133     SkMatrix    fDstToIndex;
    134     SkMatrix::MapXYProc fDstToIndexProc;
    135     TileMode    fTileMode;
    136     TileProc    fTileProc;
    137     int         fColorCount;
    138     uint8_t     fDstToIndexClass;
    139     uint8_t     fFlags;
    140 
    141     struct Rec {
    142         SkFixed     fPos;   // 0...1
    143         uint32_t    fScale; // (1 << 24) / range
    144     };
    145     Rec*        fRecs;
    146 
    147     const uint16_t*     getCache16() const;
    148     const SkPMColor*    getCache32() const;
    149 
    150     void commonAsAGradient(GradientInfo*) const;
    151 
    152 private:
    153     enum {
    154         kColorStorageCount = 4, // more than this many colors, and we'll use sk_malloc for the space
    155 
    156         kStorageSize = kColorStorageCount * (sizeof(SkColor) + sizeof(Rec))
    157     };
    158     SkColor     fStorage[(kStorageSize + 3) >> 2];
    159     SkColor*    fOrigColors; // original colors, before modulation by paint in setContext
    160     bool        fColorsAreOpaque;
    161 
    162     mutable uint16_t*   fCache16;   // working ptr. If this is NULL, we need to recompute the cache values
    163     mutable SkPMColor*  fCache32;   // working ptr. If this is NULL, we need to recompute the cache values
    164 
    165     mutable uint16_t*   fCache16Storage;    // storage for fCache16, allocated on demand
    166     mutable SkMallocPixelRef* fCache32PixelRef;
    167     mutable unsigned    fCacheAlpha;        // the alpha value we used when we computed the cache. larger than 8bits so we can store uninitialized value
    168 
    169     static void Build16bitCache(uint16_t[], SkColor c0, SkColor c1, int count);
    170     static void Build32bitCache(SkPMColor[], SkColor c0, SkColor c1, int count,
    171                                 U8CPU alpha);
    172     void setCacheAlpha(U8CPU alpha) const;
    173     void initCommon();
    174 
    175     typedef SkShader INHERITED;
    176 };
    177 
    178 static inline int init_dither_toggle(int x, int y) {
    179     return ((x ^ y) & 1) * SkGradientShaderBase::kDitherStride32;
    180 }
    181 
    182 static inline int next_dither_toggle(int toggle) {
    183     return toggle ^ SkGradientShaderBase::kDitherStride32;
    184 }
    185 
    186 static inline int init_dither_toggle16(int x, int y) {
    187     return ((x ^ y) & 1) * SkGradientShaderBase::kDitherStride16;
    188 }
    189 
    190 static inline int next_dither_toggle16(int toggle) {
    191     return toggle ^ SkGradientShaderBase::kDitherStride16;
    192 }
    193 
    194 ///////////////////////////////////////////////////////////////////////////////
    195 
    196 #if SK_SUPPORT_GPU
    197 
    198 #include "gl/GrGLEffect.h"
    199 #include "gl/GrGLEffectMatrix.h"
    200 
    201 class GrEffectStage;
    202 class GrBackendEffectFactory;
    203 
    204 /*
    205  * The interpretation of the texture matrix depends on the sample mode. The
    206  * texture matrix is applied both when the texture coordinates are explicit
    207  * and  when vertex positions are used as texture  coordinates. In the latter
    208  * case the texture matrix is applied to the pre-view-matrix position
    209  * values.
    210  *
    211  * Normal SampleMode
    212  *  The post-matrix texture coordinates are in normalize space with (0,0) at
    213  *  the top-left and (1,1) at the bottom right.
    214  * RadialGradient
    215  *  The matrix specifies the radial gradient parameters.
    216  *  (0,0) in the post-matrix space is center of the radial gradient.
    217  * Radial2Gradient
    218  *   Matrix transforms to space where first circle is centered at the
    219  *   origin. The second circle will be centered (x, 0) where x may be
    220  *   0 and is provided by setRadial2Params. The post-matrix space is
    221  *   normalized such that 1 is the second radius - first radius.
    222  * SweepGradient
    223  *  The angle from the origin of texture coordinates in post-matrix space
    224  *  determines the gradient value.
    225  */
    226 
    227  class GrTextureStripAtlas;
    228 
    229 // Base class for Gr gradient effects
    230 class GrGradientEffect : public GrEffect {
    231 public:
    232 
    233     GrGradientEffect(GrContext* ctx,
    234                      const SkGradientShaderBase& shader,
    235                      const SkMatrix& matrix,
    236                      SkShader::TileMode tileMode);
    237 
    238     virtual ~GrGradientEffect();
    239 
    240     bool useAtlas() const { return SkToBool(-1 != fRow); }
    241     SkScalar getYCoord() const { return fYCoord; };
    242     const SkMatrix& getMatrix() const { return fMatrix;}
    243 
    244     virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
    245 
    246 protected:
    247 
    248     /** Populates a pair of arrays with colors and stop info to construct a random gradient.
    249         The function decides whether stop values should be used or not. The return value indicates
    250         the number of colors, which will be capped by kMaxRandomGradientColors. colors should be
    251         sized to be at least kMaxRandomGradientColors. stops is a pointer to an array of at least
    252         size kMaxRandomGradientColors. It may be updated to NULL, indicating that NULL should be
    253         passed to the gradient factory rather than the array.
    254     */
    255     static const int kMaxRandomGradientColors = 4;
    256     static int RandomGradientParams(SkRandom* r,
    257                                     SkColor colors[kMaxRandomGradientColors],
    258                                     SkScalar** stops,
    259                                     SkShader::TileMode* tm);
    260 
    261     virtual bool onIsEqual(const GrEffect& effect) const SK_OVERRIDE;
    262 
    263 private:
    264 
    265     GrTextureAccess fTextureAccess;
    266     SkScalar fYCoord;
    267     GrTextureStripAtlas* fAtlas;
    268     int fRow;
    269     SkMatrix fMatrix;
    270     bool fIsOpaque;
    271 
    272     typedef GrEffect INHERITED;
    273 
    274 };
    275 
    276 ///////////////////////////////////////////////////////////////////////////////
    277 
    278 // Base class for GL gradient effects
    279 class GrGLGradientEffect : public GrGLEffect {
    280 public:
    281     GrGLGradientEffect(const GrBackendEffectFactory& factory);
    282     virtual ~GrGLGradientEffect();
    283 
    284     virtual void setData(const GrGLUniformManager&, const GrEffectStage&) SK_OVERRIDE;
    285 
    286 protected:
    287     /**
    288      * Subclasses must reserve the lower kMatrixKeyBitCnt of their key for use by
    289      * GrGLGradientEffect.
    290      */
    291     enum {
    292         kMatrixKeyBitCnt = GrGLEffectMatrix::kKeyBits,
    293         kMatrixKeyMask = (1 << kMatrixKeyBitCnt) - 1,
    294     };
    295 
    296     /**
    297      * Subclasses must call this. It will return a value restricted to the lower kMatrixKeyBitCnt
    298      * bits.
    299      */
    300     static EffectKey GenMatrixKey(const GrEffectStage& s);
    301 
    302     /**
    303      * Inserts code to implement the GrGradientEffect's matrix. This should be called before a
    304      * subclass emits its own code. The name of the 2D coords is output via fsCoordName and already
    305      * incorporates any perspective division. The caller can also optionally retrieve the name of
    306      * the varying inserted in the VS and its type, which may be either vec2f or vec3f depending
    307      * upon whether the matrix has perspective or not. It is not necessary to mask the key before
    308      * calling.
    309      */
    310     void setupMatrix(GrGLShaderBuilder* builder,
    311                      EffectKey key,
    312                      const char* vertexCoords,
    313                      const char** fsCoordName,
    314                      const char** vsVaryingName = NULL,
    315                      GrSLType* vsVaryingType = NULL);
    316 
    317     // Emits the uniform used as the y-coord to texture samples in derived classes. Subclasses
    318     // should call this method from their emitCode().
    319     void emitYCoordUniform(GrGLShaderBuilder* builder);
    320 
    321     // emit code that gets a fragment's color from an expression for t; for now this always uses the
    322     // texture, but for simpler cases we'll be able to lerp. Subclasses should call this method from
    323     // their emitCode().
    324     void emitColorLookup(GrGLShaderBuilder* builder,
    325                          const char* gradientTValue,
    326                          const char* outputColor,
    327                          const char* inputColor,
    328                          const GrGLShaderBuilder::TextureSampler&);
    329 
    330 private:
    331     SkScalar fCachedYCoord;
    332     GrGLUniformManager::UniformHandle fFSYUni;
    333     GrGLEffectMatrix fEffectMatrix;
    334 
    335     typedef GrGLEffect INHERITED;
    336 };
    337 
    338 #endif
    339 
    340 #endif
    341