1 /*
2  * Copyright 2012 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 GrSWMaskHelper_DEFINED
9 #define GrSWMaskHelper_DEFINED
10 
11 #include "GrColor.h"
12 #include "GrRenderTargetContext.h"
13 #include "SkAutoPixmapStorage.h"
14 #include "SkBitmap.h"
15 #include "SkDraw.h"
16 #include "SkMatrix.h"
17 #include "SkRasterClip.h"
18 #include "SkRegion.h"
19 #include "SkTypes.h"
20 
21 class GrClip;
22 class GrPaint;
23 class GrShape;
24 class GrStyle;
25 class GrTexture;
26 struct GrUserStencilSettings;
27 
28 /**
29  * The GrSWMaskHelper helps generate clip masks using the software rendering
30  * path. It is intended to be used as:
31  *
32  *   GrSWMaskHelper helper(context);
33  *   helper.init(...);
34  *
35  *      draw one or more paths/rects specifying the required boolean ops
36  *
37  *   toTexture();   // to get it from the internal bitmap to the GPU
38  *
39  * The result of this process will be the final mask (on the GPU) in the
40  * upper left hand corner of the texture.
41  */
42 class GrSWMaskHelper : SkNoncopyable {
43 public:
GrSWMaskHelper()44     GrSWMaskHelper() { }
45 
46     // set up the internal state in preparation for draws. Since many masks
47     // may be accumulated in the helper during creation, "resultBounds"
48     // allows the caller to specify the region of interest - to limit the
49     // amount of work.
50     bool init(const SkIRect& resultBounds, const SkMatrix* matrix);
51 
52     // Draw a single rect into the accumulation bitmap using the specified op
53     void drawRect(const SkRect& rect, SkRegion::Op op, GrAA, uint8_t alpha);
54 
55     // Draw a single path into the accumuation bitmap using the specified op
56     void drawShape(const GrShape&, SkRegion::Op op, GrAA, uint8_t alpha);
57 
58     sk_sp<GrTextureProxy> toTextureProxy(GrContext*, SkBackingFit fit);
59 
60     // Convert mask generation results to a signed distance field
61     void toSDF(unsigned char* sdf);
62 
63     // Reset the internal bitmap
clear(uint8_t alpha)64     void clear(uint8_t alpha) {
65         fPixels.erase(SkColorSetARGB(alpha, 0xFF, 0xFF, 0xFF));
66     }
67 
68     // Canonical usage utility that draws a single path and uploads it
69     // to the GPU. The result is returned.
70     static sk_sp<GrTextureProxy> DrawShapeMaskToTexture(GrContext*,
71                                                         const GrShape&,
72                                                         const SkIRect& resultBounds,
73                                                         GrAA,
74                                                         SkBackingFit,
75                                                         const SkMatrix* matrix);
76 
77     // This utility draws a path mask generated by DrawShapeMaskToTexture using a provided paint.
78     // The rectangle is drawn in device space. The 'viewMatrix' will be used to ensure the correct
79     // local coords are provided to any fragment processors in the paint.
80     static void DrawToTargetWithShapeMask(sk_sp<GrTextureProxy>,
81                                           GrRenderTargetContext*,
82                                           GrPaint&& paint,
83                                           const GrUserStencilSettings& userStencilSettings,
84                                           const GrClip&,
85                                           const SkMatrix& viewMatrix,
86                                           const SkIPoint& textureOriginInDeviceSpace,
87                                           const SkIRect& deviceSpaceRectToDraw);
88 
89 private:
90     SkMatrix            fMatrix;
91     SkAutoPixmapStorage fPixels;
92     SkDraw              fDraw;
93     SkRasterClip        fRasterClip;
94 
95     typedef SkNoncopyable INHERITED;
96 };
97 
98 #endif // GrSWMaskHelper_DEFINED
99