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

src/core/SkBitmapProcState.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 "SkBitmapProcState.h"
 #include "SkColorPriv.h"
 #include "SkFilterProc.h"
@@ skipping 380 matching lines @@
     // a nearby mipmap level.  If it does, it will adjust the working
     // matrix as well as the working bitmap.  It may also adjust the filter
     // quality to avoid re-filtering an already perfectly scaled image.
     if (!this->possiblyScaleImage()) {
         if (!this->lockBaseBitmap()) {
             return false;
         }
     }
     // The above logic should have always assigned fBitmap, but in case it
     // didn't, we check for that now...
+    // TODO(dominikg): Can we just use an SkASSERT(fBitmap)?

[scroggo, 2014/03/24 21:24:46]

I think humper@ is the right person to ask that question.

Did you try running it with the assert?

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

Works fine on the tests.

     if (NULL == fBitmap) {
         return false;
     }
 
     bool trivialMatrix = (fInvMatrix.getType() & ~SkMatrix::kTranslate_Mask) == 0;
     bool clampClamp = SkShader::kClamp_TileMode == fTileModeX &&
                       SkShader::kClamp_TileMode == fTileModeY;
 
     if (!(clampClamp || trivialMatrix)) {
         fInvMatrix.postIDiv(fOrigBitmap.width(), fOrigBitmap.height());
@@ skipping 62 matching lines @@
         if (fInvType <= SkMatrix::kTranslate_Mask ||
                 !valid_for_filtering(fBitmap->width() | fBitmap->height())) {
             fFilterLevel = SkPaint::kNone_FilterLevel;
         }
     }
 
     // At this point, we know exactly what kind of sampling the per-scanline
     // shader will perform.
 
     fMatrixProc = this->chooseMatrixProc(trivialMatrix);
+    // TODO(dominikg): SkASSERT(fMatrixProc) instead? chooseMatrixProc never returns NULL.

[scroggo, 2014/03/24 21:24:46]

If chooseMatrixProc never returns NULL, then I think it's okay to change to
SkASSERT (though perhaps it should be a separate change?).

[Dominik Grewe, 2014/03/26 17:22:22]

I was trying to reduce the cases where this function could fail so that we can
create a short validation method, but maybe we won't need that in the end.

     if (NULL == fMatrixProc) {
         return false;
     }
 
     ///////////////////////////////////////////////////////////////////////
 
     // No need to do this if we're doing HQ sampling; if filter quality is
     // still set to HQ by the time we get here, then we must have installed
     // the shader procs above and can skip all this.
 
@@ skipping 21 matching lines @@
                 index |= 16;
                 break;
             case SkBitmap::kARGB_4444_Config:
                 index |= 24;
                 break;
             case SkBitmap::kA8_Config:
                 index |= 32;
                 fPaintPMColor = SkPreMultiplyColor(paint.getColor());
                 break;
             default:
+                // TODO(dominikg): Should we ever get here? SkASSERT(false) instead?
                 return false;
         }
 
     #if !SK_ARM_NEON_IS_ALWAYS
         static const SampleProc32 gSkBitmapProcStateSample32[] = {
             S32_opaque_D32_nofilter_DXDY,
             S32_alpha_D32_nofilter_DXDY,
             S32_opaque_D32_nofilter_DX,
             S32_alpha_D32_nofilter_DX,
             S32_opaque_D32_filter_DXDY,
@@ skipping 499 matching lines @@
     } else {
         size >>= 2;
     }
 
     if (fFilterLevel != SkPaint::kNone_FilterLevel) {
         size >>= 1;
     }
 
     return size;
 }