Add minimum size for using distance fields.

src/gpu/GrDistanceFieldTextContext.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDistanceFieldTextContext.h"
 #include "GrAtlas.h"
 #include "GrBitmapTextContext.h"
@@ skipping 14 matching lines @@
 #include "SkGlyphCache.h"
 #include "SkGpuDevice.h"
 #include "SkPath.h"
 #include "SkRTConf.h"
 #include "SkStrokeRec.h"
 #include "effects/GrDistanceFieldTextureEffect.h"
 
 SK_CONF_DECLARE(bool, c_DumpFontCache, "gpu.dumpFontCache", false,
                 "Dump the contents of the font cache before every purge.");
 
-static const int kSmallDFFontSize = 32;
-static const int kSmallDFFontLimit = 32;
-static const int kMediumDFFontSize = 72;
-static const int kMediumDFFontLimit = 72;
+static const int kMinDFFontSize = 18;
+static const int kSmallDFFontSize = 40;
+static const int kSmallDFFontLimit = 40;
+static const int kMediumDFFontSize = 81;
+static const int kMediumDFFontLimit = 81;
 static const int kLargeDFFontSize = 162;
 
 static const int kVerticesPerGlyph = 4;
 static const int kIndicesPerGlyph = 6;
 
 GrDistanceFieldTextContext::GrDistanceFieldTextContext(GrContext* context,
                                                        const SkDeviceProperties& properties,
                                                        bool enable)
                                                     : GrTextContext(context, properties) {
 #if SK_FORCE_DISTANCE_FIELD_TEXT
@@ skipping 32 matching lines @@
 }
 
 bool GrDistanceFieldTextContext::canDraw(const SkPaint& paint, const SkMatrix& viewMatrix) {
     // TODO: support perspective (need getMaxScale replacement)
     if (viewMatrix.hasPerspective()) {
         return false;
     }
 
     SkScalar maxScale = viewMatrix.getMaxScale();
     SkScalar scaledTextSize = maxScale*paint.getTextSize();
+    // Hinted text looks far better at small resolutions
     // Scaling up beyond 2x yields undesireable artifacts
-    if (scaledTextSize > 2*kLargeDFFontSize) {
+    if (scaledTextSize < kMinDFFontSize || scaledTextSize > 2*kLargeDFFontSize) {
         return false;
     }
 
     if (!fEnableDFRendering && !paint.isDistanceFieldTextTEMP() &&
         scaledTextSize < kLargeDFFontSize) {
         return false;
     }
 
     // rasterizers and mask filters modify alpha, which doesn't
     // translate well to distance
@@ skipping 32 matching lines @@
 
     fVertices = NULL;
     fCurrVertex = 0;
     fAllocVertexCount = 0;
     fTotalVertexCount = 0;
 
     if (scaledTextSize <= kSmallDFFontLimit) {
         fTextRatio = textSize / kSmallDFFontSize;
         fSkPaint.setTextSize(SkIntToScalar(kSmallDFFontSize));
 #if DEBUG_TEXT_SIZE
-        fSkPaint.setColor(SkColorSetARGB(0xFF, 0x00, 0x00, 0xFF));
-        fPaint.setColor(GrColorPackRGBA(0x00, 0x00, 0xFF, 0xFF));
+        fSkPaint.setColor(SkColorSetARGB(0xFF, 0x00, 0x00, 0x7F));
+        fPaint.setColor(GrColorPackRGBA(0x00, 0x00, 0x7F, 0xFF));
 #endif
     } else if (scaledTextSize <= kMediumDFFontLimit) {
         fTextRatio = textSize / kMediumDFFontSize;
         fSkPaint.setTextSize(SkIntToScalar(kMediumDFFontSize));
 #if DEBUG_TEXT_SIZE
-        fSkPaint.setColor(SkColorSetARGB(0xFF, 0x00, 0xFF, 0x00));
-        fPaint.setColor(GrColorPackRGBA(0x00, 0xFF, 0x00, 0xFF));
+        fSkPaint.setColor(SkColorSetARGB(0xFF, 0x00, 0x3F, 0x00));
+        fPaint.setColor(GrColorPackRGBA(0x00, 0x3F, 0x00, 0xFF));
 #endif
     } else {
         fTextRatio = textSize / kLargeDFFontSize;
         fSkPaint.setTextSize(SkIntToScalar(kLargeDFFontSize));
 #if DEBUG_TEXT_SIZE
-        fSkPaint.setColor(SkColorSetARGB(0xFF, 0xFF, 0x00, 0x00));
-        fPaint.setColor(GrColorPackRGBA(0xFF, 0x00, 0x00, 0xFF));
+        fSkPaint.setColor(SkColorSetARGB(0xFF, 0x7F, 0x00, 0x00));
+        fPaint.setColor(GrColorPackRGBA(0x7F, 0x00, 0x00, 0xFF));
 #endif
     }
 
     fUseLCDText = fSkPaint.isLCDRenderText();
 
     fSkPaint.setLCDRenderText(false);
     fSkPaint.setAutohinted(false);
     fSkPaint.setHinting(SkPaint::kNormal_Hinting);
     fSkPaint.setSubpixelText(true);
 }
@@ skipping 549 matching lines @@
     }
 }
 
 inline void GrDistanceFieldTextContext::finish() {
     this->flush();
     fTotalVertexCount = 0;
 
     GrTextContext::finish();
 }