Extract most of the mutable state of SkShader into a separate Context object.

src/core/SkBitmapProcShader.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkColorPriv.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
@@ skipping 16 matching lines @@
                 return true;
         default:
             break;
     }
     return false;
 }
 
 SkBitmapProcShader::SkBitmapProcShader(const SkBitmap& src,
                                        TileMode tmx, TileMode tmy) {
     fRawBitmap = src;
-    fState.fTileModeX = (uint8_t)tmx;
-    fState.fTileModeY = (uint8_t)tmy;
-    fFlags = 0; // computed in setContext
+    fTileModeX = (uint8_t)tmx;
+    fTileModeY = (uint8_t)tmy;
 }
 
 SkBitmapProcShader::SkBitmapProcShader(SkReadBuffer& buffer)
         : INHERITED(buffer) {
     buffer.readBitmap(&fRawBitmap);
     fRawBitmap.setImmutable();
-    fState.fTileModeX = buffer.readUInt();
-    fState.fTileModeY = buffer.readUInt();
-    fFlags = 0; // computed in setContext
+    fTileModeX = buffer.readUInt();
+    fTileModeY = buffer.readUInt();
 }
 
 SkShader::BitmapType SkBitmapProcShader::asABitmap(SkBitmap* texture,
                                                    SkMatrix* texM,
                                                    TileMode xy[]) const {
     if (texture) {
         *texture = fRawBitmap;
     }
     if (texM) {
         texM->reset();
     }
     if (xy) {
-        xy[0] = (TileMode)fState.fTileModeX;
-        xy[1] = (TileMode)fState.fTileModeY;
+        xy[0] = (TileMode)fTileModeX;
+        xy[1] = (TileMode)fTileModeY;
     }
     return kDefault_BitmapType;
 }
 
 void SkBitmapProcShader::flatten(SkWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
 
     buffer.writeBitmap(fRawBitmap);
-    buffer.writeUInt(fState.fTileModeX);
-    buffer.writeUInt(fState.fTileModeY);
+    buffer.writeUInt(fTileModeX);
+    buffer.writeUInt(fTileModeY);
 }
 
 static bool only_scale_and_translate(const SkMatrix& matrix) {
     unsigned mask = SkMatrix::kTranslate_Mask | SkMatrix::kScale_Mask;
     return (matrix.getType() & ~mask) == 0;
 }
 
 bool SkBitmapProcShader::isOpaque() const {
     return fRawBitmap.isOpaque();
 }
 
 static bool valid_for_drawing(const SkBitmap& bm) {
     if (0 == bm.width() || 0 == bm.height()) {
         return false;   // nothing to draw
     }
     if (NULL == bm.pixelRef()) {
         return false;   // no pixels to read
     }
     if (kIndex_8_SkColorType == bm.colorType()) {
         // ugh, I have to lock-pixels to inspect the colortable
         SkAutoLockPixels alp(bm);
         if (!bm.getColorTable()) {
             return false;
         }
     }
     return true;
 }
 
-bool SkBitmapProcShader::setContext(const SkBitmap& device,
-                                    const SkPaint& paint,
-                                    const SkMatrix& matrix) {
+bool SkBitmapProcShader::validContext(const SkBitmap& device,
+                                      const SkPaint& paint,
+                                      const SkMatrix& matrix) const {
     if (!fRawBitmap.getTexture() && !valid_for_drawing(fRawBitmap)) {
         return false;
     }
 
-    // do this first, so we have a correct inverse matrix
-    if (!this->INHERITED::setContext(device, paint, matrix)) {
+    // Do this first, so we know the matrix can be inverted.
+    if (!this->INHERITED::validContext(device, paint, matrix)) {
         return false;
     }
 
-    fState.fOrigBitmap = fRawBitmap;
-    if (!fState.chooseProcs(this->getTotalInverse(), paint)) {
-        this->INHERITED::endContext();
+    // TODO(dominikg): Can we avoid re-computing the inverse?

[scroggo, 2014/03/26 23:13:09]

One way would be for validContext to have an out parameter that returns the
inverse.

[Dominik Grewe, 2014/03/27 14:27:20]

I gave that a try. PTAL.

+    SkMatrix inverse;
+    SkASSERT(matrix.invert(&inverse));

[scroggo, 2014/03/26 23:13:09]

As in the SkTriColorShader, this should be SkAssertResult and it should take
into account the localMatrix.

+
+    SkBitmapProcState state;
+    state.fTileModeX = fTileModeX;
+    state.fTileModeY = fTileModeY;
+    state.fOrigBitmap = fRawBitmap;
+    // TODO(dominikg): Could we have a more light-weight method instead of chooseProcs that only
+    //                 validates the inputs?
+    if (!state.chooseProcs(inverse, paint)) {
         return false;
     }
 
+    return true;
+}
+
+SkShader::Context* SkBitmapProcShader::createContext(const SkBitmap& device, const SkPaint& paint,
+                                                     const SkMatrix& matrix, void* storage) const {
+    if (!this->validContext(device, paint, matrix)) {
+        return NULL;
+    }
+
+    return SkNEW_PLACEMENT_ARGS(storage, BitmapProcShaderContext, (*this, device, paint, matrix));
+}
+
+size_t SkBitmapProcShader::contextSize() const {
+    return sizeof(BitmapProcShaderContext);
+}
+
+SkBitmapProcShader::BitmapProcShaderContext::BitmapProcShaderContext(
+        const SkBitmapProcShader& shader, const SkBitmap& device,
+        const SkPaint& paint, const SkMatrix& matrix) 
+    : INHERITED(shader, device, paint, matrix) {
+
+    fState.fTileModeX = shader.fTileModeX;
+    fState.fTileModeY = shader.fTileModeY;
+    fState.fOrigBitmap = shader.fRawBitmap;
+    SkASSERT(fState.chooseProcs(this->getTotalInverse(), paint));
+
     const SkBitmap& bitmap = *fState.fBitmap;
     bool bitmapIsOpaque = bitmap.isOpaque();
 
     // update fFlags
     uint32_t flags = 0;
     if (bitmapIsOpaque && (255 == this->getPaintAlpha())) {
         flags |= kOpaqueAlpha_Flag;
     }
 
     switch (bitmap.colorType()) {
@@ skipping 21 matching lines @@
     // if we're only 1-pixel high, and we don't rotate, then we can claim this
     if (1 == bitmap.height() &&
             only_scale_and_translate(this->getTotalInverse())) {
         flags |= kConstInY32_Flag;
         if (flags & kHasSpan16_Flag) {
             flags |= kConstInY16_Flag;
         }
     }
 
     fFlags = flags;
-    return true;
-}
-
-void SkBitmapProcShader::endContext() {
-    fState.endContext();
-    this->INHERITED::endContext();
 }
 
 #define BUF_MAX     128
 
 #define TEST_BUFFER_OVERRITEx
 
 #ifdef TEST_BUFFER_OVERRITE
     #define TEST_BUFFER_EXTRA   32
     #define TEST_PATTERN    0x88888888
 #else
     #define TEST_BUFFER_EXTRA   0
 #endif
 
-void SkBitmapProcShader::shadeSpan(int x, int y, SkPMColor dstC[], int count) {
+void SkBitmapProcShader::BitmapProcShaderContext::shadeSpan(int x, int y, SkPMColor dstC[],
+                                                            int count) {
     const SkBitmapProcState& state = fState;
     if (state.getShaderProc32()) {
         state.getShaderProc32()(state, x, y, dstC, count);
         return;
     }
 
     uint32_t buffer[BUF_MAX + TEST_BUFFER_EXTRA];
     SkBitmapProcState::MatrixProc   mproc = state.getMatrixProc();
     SkBitmapProcState::SampleProc32 sproc = state.getSampleProc32();
     int max = fState.maxCountForBufferSize(sizeof(buffer[0]) * BUF_MAX);
@@ skipping 23 matching lines @@
 
         if ((count -= n) == 0) {
             break;
         }
         SkASSERT(count > 0);
         x += n;
         dstC += n;
     }
 }
 
-SkShader::ShadeProc SkBitmapProcShader::asAShadeProc(void** ctx) {
+SkShader::Context::ShadeProc SkBitmapProcShader::BitmapProcShaderContext::asAShadeProc(void** ctx) {
     if (fState.getShaderProc32()) {
         *ctx = &fState;
         return (ShadeProc)fState.getShaderProc32();
     }
     return NULL;
 }
 
-void SkBitmapProcShader::shadeSpan16(int x, int y, uint16_t dstC[], int count) {
+void SkBitmapProcShader::BitmapProcShaderContext::shadeSpan16(int x, int y, uint16_t dstC[],
+                                                              int count) {
     const SkBitmapProcState& state = fState;
     if (state.getShaderProc16()) {
         state.getShaderProc16()(state, x, y, dstC, count);
         return;
     }
 
     uint32_t buffer[BUF_MAX];
     SkBitmapProcState::MatrixProc   mproc = state.getMatrixProc();
     SkBitmapProcState::SampleProc16 sproc = state.getSampleProc16();
     int max = fState.maxCountForBufferSize(sizeof(buffer));
@@ skipping 93 matching lines @@
 
 #ifdef SK_DEVELOPER
 void SkBitmapProcShader::toString(SkString* str) const {
     static const char* gTileModeName[SkShader::kTileModeCount] = {
         "clamp", "repeat", "mirror"
     };
 
     str->append("BitmapShader: (");
 
     str->appendf("(%s, %s)",
-                 gTileModeName[fState.fTileModeX],
-                 gTileModeName[fState.fTileModeY]);
+                 gTileModeName[fTileModeX],
+                 gTileModeName[fTileModeY]);
 
     str->append(" ");
     fRawBitmap.toString(str);
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif
 
@@ skipping 20 matching lines @@
     SkMatrix matrix;
     matrix.setIDiv(fRawBitmap.width(), fRawBitmap.height());
 
     SkMatrix lmInverse;
     if (!this->getLocalMatrix().invert(&lmInverse)) {
         return NULL;
     }
     matrix.preConcat(lmInverse);
 
     SkShader::TileMode tm[] = {
-        (TileMode)fState.fTileModeX,
-        (TileMode)fState.fTileModeY,
+        (TileMode)fTileModeX,
+        (TileMode)fTileModeY,
     };
 
     // Must set wrap and filter on the sampler before requesting a texture. In two places below
     // we check the matrix scale factors to determine how to interpret the filter quality setting.
     // This completely ignores the complexity of the drawVertices case where explicit local coords
     // are provided by the caller.
     SkPaint::FilterLevel paintFilterLevel = paint.getFilterLevel();
     GrTextureParams::FilterMode textureFilterMode;
     switch(paintFilterLevel) {
         case SkPaint::kNone_FilterLevel:
@@ skipping 45 matching lines @@
     GrEffectRef* effect = NULL;
     if (paintFilterLevel == SkPaint::kHigh_FilterLevel) {
         effect = GrBicubicEffect::Create(texture, matrix, tm);
     } else {
         effect = GrSimpleTextureEffect::Create(texture, matrix, params);
     }
     GrUnlockAndUnrefCachedBitmapTexture(texture);
     return effect;
 }
 #endif