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 Gr1DKernelEffect_DEFINED
9 #define Gr1DKernelEffect_DEFINED
10 
11 #include "GrSingleTextureEffect.h"
12 #include "SkMatrix.h"
13 
14 /**
15  * Base class for 1D kernel effects. The kernel operates either in X or Y and
16  * has a pixel radius. The kernel is specified in the src texture's space
17  * and the kernel center is pinned to a texel's center. The radius specifies
18  * the number of texels on either side of the center texel in X or Y that are
19  * read. Since the center pixel is also read, the total width is one larger than
20  * two times the radius.
21  */
22 
23 class Gr1DKernelEffect : public GrSingleTextureEffect {
24 
25 public:
26     enum Direction {
27         kX_Direction,
28         kY_Direction,
29     };
30 
Gr1DKernelEffect(GrTexture * texture,Direction direction,int radius)31     Gr1DKernelEffect(GrTexture* texture,
32                      Direction direction,
33                      int radius)
34         : GrSingleTextureEffect(texture, GrCoordTransform::MakeDivByTextureWHMatrix(texture))
35         , fDirection(direction)
36         , fRadius(radius) {}
37 
~Gr1DKernelEffect()38     virtual ~Gr1DKernelEffect() {};
39 
WidthFromRadius(int radius)40     static int WidthFromRadius(int radius) { return 2 * radius + 1; }
41 
radius()42     int radius() const { return fRadius; }
width()43     int width() const { return WidthFromRadius(fRadius); }
direction()44     Direction direction() const { return fDirection; }
45 
46 private:
47 
48     Direction       fDirection;
49     int             fRadius;
50 
51     typedef GrSingleTextureEffect INHERITED;
52 };
53 
54 #endif
55