Centralize decision about whether to do bicubic filtering, and fallbacks to mip, bilerp, or nearest

src/gpu/SkGpuDevice.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 "SkGpuDevice.h"
 
 #include "effects/GrBicubicEffect.h"
@@ skipping 1152 matching lines @@
     // the view matrix rather than a local matrix.
     SkMatrix m;
     m.setScale(dstSize.fWidth / srcRect.width(),
                dstSize.fHeight / srcRect.height());
     fContext->concatMatrix(m);
 
     GrTextureParams params;
     SkPaint::FilterLevel paintFilterLevel = paint.getFilterLevel();
     GrTextureParams::FilterMode textureFilterMode;
 
-    int tileFilterPad;
     bool doBicubic = false;
 
     switch(paintFilterLevel) {
         case SkPaint::kNone_FilterLevel:
-            tileFilterPad = 0;
             textureFilterMode = GrTextureParams::kNone_FilterMode;
             break;
         case SkPaint::kLow_FilterLevel:
-            tileFilterPad = 1;
             textureFilterMode = GrTextureParams::kBilerp_FilterMode;
             break;
         case SkPaint::kMedium_FilterLevel:
-            tileFilterPad = 1;
             if (fContext->getMatrix().getMinScale() < SK_Scalar1) {
                 textureFilterMode = GrTextureParams::kMipMap_FilterMode;
             } else {
                 // Don't trigger MIP level generation unnecessarily.
                 textureFilterMode = GrTextureParams::kBilerp_FilterMode;
             }
             break;
         case SkPaint::kHigh_FilterLevel:
             // Minification can look bad with the bicubic effect.
-            if (fContext->getMatrix().getMinScale() >= SK_Scalar1) {
-                // We will install an effect that does the filtering in the shader.
-                textureFilterMode = GrTextureParams::kNone_FilterMode;
-                tileFilterPad = GrBicubicEffect::kFilterTexelPad;
-                doBicubic = true;
-            } else {
-                textureFilterMode = GrTextureParams::kMipMap_FilterMode;
-                tileFilterPad = 1;
-            }
+            doBicubic =
+                GrBicubicEffect::ShouldUseBicubic(fContext->getMatrix(), &textureFilterMode);
             break;
         default:
             SkErrorInternals::SetError( kInvalidPaint_SkError,
                                         "Sorry, I don't understand the filtering "
                                         "mode you asked for.  Falling back to "
                                         "MIPMaps.");
-            tileFilterPad = 1;
             textureFilterMode = GrTextureParams::kMipMap_FilterMode;
             break;
     }
 
+    int tileFilterPad;
+    if (doBicubic) {
+        tileFilterPad = GrBicubicEffect::kFilterTexelPad;
+    } else if (GrTextureParams::kNone_FilterMode == textureFilterMode) {
+        tileFilterPad = 0;
+    } else {
+        tileFilterPad = 1;
+    }
     params.setFilterMode(textureFilterMode);
 
     int maxTileSize = fContext->getMaxTextureSize() - 2 * tileFilterPad;
     int tileSize;
 
     SkIRect clippedSrcRect;
     if (this->shouldTileBitmap(bitmap, params, srcRectPtr, maxTileSize, &tileSize,
                                &clippedSrcRect)) {
         this->drawTiledBitmap(bitmap, srcRect, clippedSrcRect, params, paint, flags, tileSize,
                               doBicubic);
@@ skipping 764 matching lines @@
         GrCachedLayer* layer = fContext->getLayerCache()->findLayerOrCreate(picture, i);
 
         if (NULL != layer->getTexture()) {
             fContext->unlockScratchTexture(layer->getTexture());
             layer->setTexture(NULL);
         }
     }
 
     return true;
 }