allow subpixel positioning w/ bitmap filtering

src/core/SkDraw.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDraw.h"
 #include "SkBlitter.h"
 #include "SkCanvas.h"
@@ skipping 1089 matching lines @@
         } else {
             proc = SkScan::HairPath;
         }
     }
     proc(*devPathPtr, *fRC, blitter.get());
 }
 
 /** For the purposes of drawing bitmaps, if a matrix is "almost" translate
     go ahead and treat it as if it were, so that subsequent code can go fast.
  */
-static bool just_translate(const SkMatrix& matrix, const SkBitmap& bitmap) {
-    unsigned bits = 0;  // TODO: find a way to allow the caller to tell us to
-                        // respect filtering.
-    return SkTreatAsSprite(matrix, bitmap.width(), bitmap.height(), bits);
+static bool just_translate(const SkMatrix& ctm, const SkBitmap& bm, SkPaint::FilterLevel filter) {
+    unsigned bits = 0;
+    switch (filter) {
+        case SkPaint::kNone_FilterLevel:
+            bits = 0;
+            break;
+        case SkPaint::kLow_FilterLevel:
+        case SkPaint::kMedium_FilterLevel:
+            bits = 4;
+            break;
+        case SkPaint::kHigh_FilterLevel:
+            bits = 4;
+            break;
+    }
+    return SkTreatAsSprite(ctm, bm.width(), bm.height(), bits);
 }
 
 void SkDraw::drawBitmapAsMask(const SkBitmap& bitmap,
                               const SkPaint& paint) const {
     SkASSERT(bitmap.colorType() == kAlpha_8_SkColorType);
 
-    if (just_translate(*fMatrix, bitmap)) {
+    if (just_translate(*fMatrix, bitmap, paint.getFilterLevel())) {
         int ix = SkScalarRoundToInt(fMatrix->getTranslateX());
         int iy = SkScalarRoundToInt(fMatrix->getTranslateY());
 
         SkAutoLockPixels alp(bitmap);
         if (!bitmap.readyToDraw()) {
             return;
         }
 
         SkMask  mask;
         mask.fBounds.set(ix, iy, ix + bitmap.width(), iy + bitmap.height());
@@ skipping 98 matching lines @@
     SkPaint paint(origPaint);
     paint.setStyle(SkPaint::kFill_Style);
 
     SkMatrix matrix;
     matrix.setConcat(*fMatrix, prematrix);
 
     if (clipped_out(matrix, *fRC, bitmap.width(), bitmap.height())) {
         return;
     }
 
-    if (bitmap.colorType() != kAlpha_8_SkColorType && just_translate(matrix, bitmap)) {
+    if (bitmap.colorType() != kAlpha_8_SkColorType && just_translate(matrix, bitmap,
+                                                                     paint.getFilterLevel())) {
         //
         // It is safe to call lock pixels now, since we know the matrix is
         // (more or less) identity.
         //
         SkAutoLockPixels alp(bitmap);
         if (!bitmap.readyToDraw()) {
             return;
         }
         int ix = SkScalarRoundToInt(matrix.getTranslateX());
         int iy = SkScalarRoundToInt(matrix.getTranslateY());
@@ skipping 1227 matching lines @@
         mask->fImage = SkMask::AllocImage(size);
         memset(mask->fImage, 0, mask->computeImageSize());
     }
 
     if (SkMask::kJustComputeBounds_CreateMode != mode) {
         draw_into_mask(*mask, devPath, style);
     }
 
     return true;
 }