reed@google.com | 1c028bd | 2013-08-28 15:23:19 +0000 | [diff] [blame] | 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. |
skia.committer@gmail.com | 6b00a1e | 2013-08-29 07:01:20 +0000 | [diff] [blame^] | 54 | * Each time this returns true, it is safe to call mapRect() and |
reed@google.com | 1c028bd | 2013-08-28 15:23:19 +0000 | [diff] [blame] | 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 | } |
skia.committer@gmail.com | 6b00a1e | 2013-08-29 07:01:20 +0000 | [diff] [blame^] | 92 | |
reed@google.com | 1c028bd | 2013-08-28 15:23:19 +0000 | [diff] [blame] | 93 | bool computeCurrBitmapAndClip(); |
| 94 | }; |
| 95 | |
| 96 | #endif |