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Side by Side Diff: src/core/SkDeviceLooper.h

Issue 23618005: fix state machine so we know simple only loops once, but we can call maprect in debug mode (Closed) Base URL: https://skia.googlecode.com/svn/trunk
Patch Set: Created 7 years, 3 months ago
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1 /*
2 * Copyright 2013 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 SkDeviceLooper_DEFINED
9 #define SkDeviceLooper_DEFINED
10
11 #include "SkBitmap.h"
12 #include "SkMatrix.h"
13 #include "SkRasterClip.h"
14
15 /**
16 * Helper class to manage "tiling" a large coordinate space into managable
17 * chunks, where managable means areas that are <= some max critical coordinate
18 * size.
19 *
20 * The constructor takes an antialiasing bool, which affects what this maximum
21 * allowable size is: If we're drawing BW, then we need coordinates to stay
22 * safely within fixed-point range (we use +- 16K, to give ourselves room to
23 * add/subtract two fixed values and still be in range. If we're drawing AA,
24 * then we reduce that size by the amount that the supersampler scan converter
25 * needs (at the moment, that is 4X, so the "safe" range is +- 4K).
26 *
27 * For performance reasons, the class first checks to see if any help is needed
28 * at all, and if not (i.e. the specified bounds and base bitmap area already
29 * in the safe-zone, then the class does nothing (effectively).
30 */
31 class SkDeviceLooper {
32 public:
33 SkDeviceLooper(const SkBitmap& base, const SkRasterClip&,
34 const SkIRect& bounds, bool aa);
35 ~SkDeviceLooper();
36
37 const SkBitmap& getBitmap() const {
38 SkASSERT(kDone_State != fState);
39 SkASSERT(fCurrBitmap);
40 return *fCurrBitmap;
41 }
42
43 const SkRasterClip& getRC() const {
44 SkASSERT(kDone_State != fState);
45 SkASSERT(fCurrRC);
46 return *fCurrRC;
47 }
48
49 void mapRect(SkRect* dst, const SkRect& src) const;
50 void mapMatrix(SkMatrix* dst, const SkMatrix& src) const;
51
52 /**
53 * Call next to setup the looper to return a valid coordinate chunk.
54 * Each time this returns true, it is safe to call mapRect() and
55 * mapMatrix(), to convert from "global" coordinate values to ones that
56 * are local to this chunk.
57 *
58 * When next() returns false, the list of chunks is done, and mapRect()
59 * and mapMatrix() should no longer be called.
60 */
61 bool next();
62
63 private:
64 const SkBitmap& fBaseBitmap;
65 const SkRasterClip& fBaseRC;
66
67 enum State {
68 kDone_State, // iteration is complete, getters will assert
69 kSimple_State, // no translate/clip mods needed
70 kComplex_State
71 };
72
73 // storage for our tiled versions. Perhaps could use SkTLazy
74 SkBitmap fSubsetBitmap;
75 SkRasterClip fSubsetRC;
76
77 const SkBitmap* fCurrBitmap;
78 const SkRasterClip* fCurrRC;
79 SkIRect fClippedBounds;
80 SkIPoint fCurrOffset;
81 int fDelta;
82 State fState;
83
84 enum Delta {
85 kBW_Delta = 1 << 14, // 16K, gives room to spare for fixedpoint
86 kAA_Delta = kBW_Delta >> 2 // supersample 4x
87 };
88
89 bool fitsInDelta(const SkIRect& r) const {
90 return r.right() < fDelta && r.bottom() < fDelta;
91 }
92
93 bool computeCurrBitmapAndClip();
94 };
95
96 #endif
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