Add flag for SkGpuSurface creation to enable distance fields.

BUG=skia:2173
R=bsalomon@google.com, reed@google.com, bungeman@google.com

Author: jvanverth@google.com

Review URL: https://codereview.chromium.org/261783004

git-svn-id: http://skia.googlecode.com/svn/trunk@14525 2bbb7eff-a529-9590-31e7-b0007b416f81

include/core/SkSurface.h

@@ -55,16 +55,32 @@ public:
         return NewRaster(SkImageInfo::MakeN32Premul(width, height));
     }
 
+    /**
+     *  Text rendering modes that can be passed to NewRenderTarget*
+     */
+    enum TextRenderMode {
+        /**
+         *  This will use the standard text rendering method
+         */
+        kStandard_TextRenderMode,
+        /**
+         *  This will use signed distance fields for text rendering when possible
+         */
+        kDistanceField_TextRenderMode,
+    };
+
     /**
      *  Return a new surface using the specified render target.
      */
-    static SkSurface* NewRenderTargetDirect(GrRenderTarget*);
+    static SkSurface* NewRenderTargetDirect(GrRenderTarget*,
+                                            TextRenderMode trm = kStandard_TextRenderMode);
 
     /**
      *  Return a new surface whose contents will be drawn to an offscreen
      *  render target, allocated by the surface.
      */
-    static SkSurface* NewRenderTarget(GrContext*, const SkImageInfo&, int sampleCount = 0);
+    static SkSurface* NewRenderTarget(GrContext*, const SkImageInfo&, int sampleCount = 0,
+                                      TextRenderMode trm = kStandard_TextRenderMode);
 
     /**
      *  Return a new surface whose contents will be drawn to an offscreen
@@ -78,7 +94,8 @@ public:
      *  Note: Scratch textures count against the GrContext's cached resource
      *  budget.
      */
-    static SkSurface* NewScratchRenderTarget(GrContext*, const SkImageInfo&, int sampleCount = 0);
+    static SkSurface* NewScratchRenderTarget(GrContext*, const SkImageInfo&, int sampleCount = 0,
+                                             TextRenderMode trm = kStandard_TextRenderMode);
 
     int width() const { return fWidth; }
     int height() const { return fHeight; }

include/gpu/SkGpuDevice.h

@@ -32,6 +32,7 @@ public:
     enum Flags {
         kNeedClear_Flag = 1 << 0,  //!< Surface requires an initial clear
         kCached_Flag    = 1 << 1,  //!< Surface is cached and needs to be unlocked when released
+        kDFFonts_Flag   = 1 << 2,  //!< Surface should render fonts using signed distance fields
     };
 
     /**

src/gpu/GrDistanceFieldTextContext.cpp

@@ -33,15 +33,15 @@ static const int kLargeDFFontSize = 128;
 SK_CONF_DECLARE(bool, c_DumpFontCache, "gpu.dumpFontCache", false,
                 "Dump the contents of the font cache before every purge.");
 
-#if SK_FORCE_DISTANCEFIELD_FONTS
-static const bool kForceDistanceFieldFonts = true;
-#else
-static const bool kForceDistanceFieldFonts = false;
-#endif
-
 GrDistanceFieldTextContext::GrDistanceFieldTextContext(GrContext* context,
-                                                       const SkDeviceProperties& properties)
+                                                       const SkDeviceProperties& properties,
+                                                       bool enable)
                                                     : GrTextContext(context, properties) {
+#if SK_FORCE_DISTANCEFIELD_FONTS
+    fEnableDFRendering = true;
+#else
+    fEnableDFRendering = enable;
+#endif
     fStrike = NULL;
 
     fCurrTexture = NULL;
@@ -56,7 +56,7 @@ GrDistanceFieldTextContext::~GrDistanceFieldTextContext() {
 }
 
 bool GrDistanceFieldTextContext::canDraw(const SkPaint& paint) {
-    if (!kForceDistanceFieldFonts && !paint.isDistanceFieldTextTEMP()) {
+    if (!fEnableDFRendering && !paint.isDistanceFieldTextTEMP()) {
         return false;
     }
 

src/gpu/GrDistanceFieldTextContext.h

@@ -17,7 +17,7 @@ class GrTextStrike;
  */
 class GrDistanceFieldTextContext : public GrTextContext {
 public:
-    GrDistanceFieldTextContext(GrContext*, const SkDeviceProperties&);
+    GrDistanceFieldTextContext(GrContext*, const SkDeviceProperties&, bool enable);
     virtual ~GrDistanceFieldTextContext();
 
     virtual void drawText(const GrPaint&, const SkPaint&, const char text[], size_t byteLength,
@@ -33,6 +33,7 @@ private:
     GrTextStrike*           fStrike;
     SkScalar                fTextRatio;
     bool                    fUseLCDText;
+    bool                    fEnableDFRendering;
 
     void init(const GrPaint&, const SkPaint&);
     void drawPackedGlyph(GrGlyph::PackedID, SkFixed left, SkFixed top, GrFontScaler*);

src/gpu/SkGpuDevice.cpp

@@ -190,7 +190,9 @@ void SkGpuDevice::initFromRenderTarget(GrContext* context,
     fContext = context;
     fContext->ref();
 
-    fMainTextContext = SkNEW_ARGS(GrDistanceFieldTextContext, (fContext, fLeakyProperties));
+    bool useDFFonts = !!(flags & kDFFonts_Flag);
+    fMainTextContext = SkNEW_ARGS(GrDistanceFieldTextContext, (fContext, fLeakyProperties,
+                                                               useDFFonts));
     fFallbackTextContext = SkNEW_ARGS(GrBitmapTextContext, (fContext, fLeakyProperties));
 
     fRenderTarget = NULL;

src/image/SkSurface_Gpu.cpp

@@ -14,7 +14,7 @@ class SkSurface_Gpu : public SkSurface_Base {
 public:
     SK_DECLARE_INST_COUNT(SkSurface_Gpu)
 
-    SkSurface_Gpu(GrRenderTarget*, bool cached);
+    SkSurface_Gpu(GrRenderTarget*, bool cached, TextRenderMode trm);
     virtual ~SkSurface_Gpu();
 
     virtual SkCanvas* onNewCanvas() SK_OVERRIDE;
@@ -33,9 +33,12 @@ private:
 
 ///////////////////////////////////////////////////////////////////////////////
 
-SkSurface_Gpu::SkSurface_Gpu(GrRenderTarget* renderTarget, bool cached)
+SkSurface_Gpu::SkSurface_Gpu(GrRenderTarget* renderTarget, bool cached, TextRenderMode trm)
         : INHERITED(renderTarget->width(), renderTarget->height()) {
-    fDevice = SkGpuDevice::Create(renderTarget, cached ? SkGpuDevice::kCached_Flag : 0);
+    int flags = 0;
+    flags |= cached ? SkGpuDevice::kCached_Flag : 0;
+    flags |= (kDistanceField_TextRenderMode == trm) ? SkGpuDevice::kDFFonts_Flag : 0;
+    fDevice = SkGpuDevice::Create(renderTarget, flags);
 
     if (kRGB_565_GrPixelConfig != renderTarget->config()) {
         fDevice->clear(0x0);
@@ -98,14 +101,15 @@ void SkSurface_Gpu::onDiscard() {
 
 ///////////////////////////////////////////////////////////////////////////////
 
-SkSurface* SkSurface::NewRenderTargetDirect(GrRenderTarget* target) {
+SkSurface* SkSurface::NewRenderTargetDirect(GrRenderTarget* target, TextRenderMode trm) {
     if (NULL == target) {
         return NULL;
     }
-    return SkNEW_ARGS(SkSurface_Gpu, (target, false));
+    return SkNEW_ARGS(SkSurface_Gpu, (target, false, trm));
 }
 
-SkSurface* SkSurface::NewRenderTarget(GrContext* ctx, const SkImageInfo& info, int sampleCount) {
+SkSurface* SkSurface::NewRenderTarget(GrContext* ctx, const SkImageInfo& info, int sampleCount,
+                                      TextRenderMode trm) {
     if (NULL == ctx) {
         return NULL;
     }
@@ -122,10 +126,11 @@ SkSurface* SkSurface::NewRenderTarget(GrContext* ctx, const SkImageInfo& info, i
         return NULL;
     }
 
-    return SkNEW_ARGS(SkSurface_Gpu, (tex->asRenderTarget(), false));
+    return SkNEW_ARGS(SkSurface_Gpu, (tex->asRenderTarget(), false, trm));
 }
 
-SkSurface* SkSurface::NewScratchRenderTarget(GrContext* ctx, const SkImageInfo& info, int sampleCount) {
+SkSurface* SkSurface::NewScratchRenderTarget(GrContext* ctx, const SkImageInfo& info,
+                                             int sampleCount, TextRenderMode trm) {
     if (NULL == ctx) {
         return NULL;
     }
@@ -143,5 +148,5 @@ SkSurface* SkSurface::NewScratchRenderTarget(GrContext* ctx, const SkImageInfo&
         return NULL;
     }
 
-    return SkNEW_ARGS(SkSurface_Gpu, (tex->asRenderTarget(), true));
+    return SkNEW_ARGS(SkSurface_Gpu, (tex->asRenderTarget(), true, trm));
 }