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      1 /*
      2  * Copyright 2015 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef SkPaintFilterCanvas_DEFINED
      9 #define SkPaintFilterCanvas_DEFINED
     10 
     11 #include "SkNWayCanvas.h"
     12 #include "SkTLazy.h"
     13 
     14 /** \class SkPaintFilterCanvas
     15 
     16     A utility proxy base class for implementing draw/paint filters.
     17 */
     18 class SK_API SkPaintFilterCanvas : public SkNWayCanvas {
     19 public:
     20     /**
     21      * The new SkPaintFilterCanvas is configured for forwarding to the
     22      * specified canvas.  Also copies the target canvas matrix and clip bounds.
     23      */
     24     SkPaintFilterCanvas(SkCanvas* canvas);
     25 
     26     enum Type {
     27         kPaint_Type,
     28         kPoint_Type,
     29         kArc_Type,
     30         kBitmap_Type,
     31         kRect_Type,
     32         kRRect_Type,
     33         kDRRect_Type,
     34         kOval_Type,
     35         kPath_Type,
     36         kPicture_Type,
     37         kDrawable_Type,
     38         kText_Type,
     39         kTextBlob_Type,
     40         kVertices_Type,
     41         kPatch_Type,
     42 
     43         kTypeCount
     44     };
     45 
     46     // Forwarded to the wrapped canvas.
     47     SkISize getBaseLayerSize() const override { return proxy()->getBaseLayerSize(); }
     48     GrContext*  getGrContext()       override { return proxy()->getGrContext();     }
     49 
     50 protected:
     51     /**
     52      *  Called with the paint that will be used to draw the specified type.
     53      *  The implementation may modify the paint as they wish (using SkTCopyOnFirstWrite::writable).
     54      *
     55      *  The result bool is used to determine whether the draw op is to be
     56      *  executed (true) or skipped (false).
     57      *
     58      *  Note: The base implementation calls onFilter() for top-level/explicit paints only.
     59      *        To also filter encapsulated paints (e.g. SkPicture, SkTextBlob), clients may need to
     60      *        override the relevant methods (i.e. drawPicture, drawTextBlob).
     61      */
     62     virtual bool onFilter(SkTCopyOnFirstWrite<SkPaint>* paint, Type type) const = 0;
     63 
     64     void onDrawPaint(const SkPaint&) override;
     65     void onDrawPoints(PointMode, size_t count, const SkPoint pts[], const SkPaint&) override;
     66     void onDrawRect(const SkRect&, const SkPaint&) override;
     67     void onDrawRRect(const SkRRect&, const SkPaint&) override;
     68     void onDrawDRRect(const SkRRect&, const SkRRect&, const SkPaint&) override;
     69     void onDrawOval(const SkRect&, const SkPaint&) override;
     70     void onDrawArc(const SkRect&, SkScalar, SkScalar, bool, const SkPaint&) override;
     71     void onDrawPath(const SkPath&, const SkPaint&) override;
     72     void onDrawBitmap(const SkBitmap&, SkScalar left, SkScalar top, const SkPaint*) override;
     73     void onDrawBitmapRect(const SkBitmap&, const SkRect* src, const SkRect& dst, const SkPaint*,
     74                           SrcRectConstraint) override;
     75     void onDrawBitmapNine(const SkBitmap&, const SkIRect& center, const SkRect& dst,
     76                           const SkPaint*) override;
     77     void onDrawImage(const SkImage*, SkScalar left, SkScalar top, const SkPaint*) override;
     78     void onDrawImageRect(const SkImage*, const SkRect* src, const SkRect& dst,
     79                          const SkPaint*, SrcRectConstraint) override;
     80     void onDrawImageNine(const SkImage*, const SkIRect& center, const SkRect& dst,
     81                          const SkPaint*) override;
     82     void onDrawVerticesObject(const SkVertices*, SkBlendMode, const SkPaint&) override;
     83     void onDrawPatch(const SkPoint cubics[12], const SkColor colors[4],
     84                              const SkPoint texCoords[4], SkBlendMode,
     85                              const SkPaint& paint) override;
     86     void onDrawPicture(const SkPicture*, const SkMatrix*, const SkPaint*) override;
     87     void onDrawDrawable(SkDrawable*, const SkMatrix*) override;
     88 
     89     void onDrawText(const void* text, size_t byteLength, SkScalar x, SkScalar y,
     90                     const SkPaint&) override;
     91     void onDrawPosText(const void* text, size_t byteLength, const SkPoint pos[],
     92                        const SkPaint&) override;
     93     void onDrawPosTextH(const void* text, size_t byteLength, const SkScalar xpos[],
     94                         SkScalar constY, const SkPaint&) override;
     95     void onDrawTextOnPath(const void* text, size_t byteLength, const SkPath& path,
     96                           const SkMatrix* matrix, const SkPaint&) override;
     97     void onDrawTextRSXform(const void* text, size_t byteLength, const SkRSXform xform[],
     98                            const SkRect* cull, const SkPaint& paint) override;
     99     void onDrawTextBlob(const SkTextBlob* blob, SkScalar x, SkScalar y,
    100                         const SkPaint& paint) override;
    101 
    102     // Forwarded to the wrapped canvas.
    103     sk_sp<SkSurface> onNewSurface(const SkImageInfo&, const SkSurfaceProps&) override;
    104     bool onPeekPixels(SkPixmap* pixmap) override;
    105     bool onAccessTopLayerPixels(SkPixmap* pixmap) override;
    106     SkImageInfo onImageInfo() const override;
    107     bool onGetProps(SkSurfaceProps* props) const override;
    108 
    109 private:
    110     class AutoPaintFilter;
    111 
    112     SkCanvas* proxy() const { SkASSERT(fList.count() == 1); return fList[0]; }
    113 
    114     typedef SkNWayCanvas INHERITED;
    115 };
    116 
    117 #endif
    118