1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/core/SkDeviceLooper.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,96 @@
1.4 +/*
1.5 + * Copyright 2013 Google Inc.
1.6 + *
1.7 + * Use of this source code is governed by a BSD-style license that can be
1.8 + * found in the LICENSE file.
1.9 + */
1.10 +
1.11 +#ifndef SkDeviceLooper_DEFINED
1.12 +#define SkDeviceLooper_DEFINED
1.13 +
1.14 +#include "SkBitmap.h"
1.15 +#include "SkMatrix.h"
1.16 +#include "SkRasterClip.h"
1.17 +
1.18 +/**
1.19 + * Helper class to manage "tiling" a large coordinate space into managable
1.20 + * chunks, where managable means areas that are <= some max critical coordinate
1.21 + * size.
1.22 + *
1.23 + * The constructor takes an antialiasing bool, which affects what this maximum
1.24 + * allowable size is: If we're drawing BW, then we need coordinates to stay
1.25 + * safely within fixed-point range (we use +- 16K, to give ourselves room to
1.26 + * add/subtract two fixed values and still be in range. If we're drawing AA,
1.27 + * then we reduce that size by the amount that the supersampler scan converter
1.28 + * needs (at the moment, that is 4X, so the "safe" range is +- 4K).
1.29 + *
1.30 + * For performance reasons, the class first checks to see if any help is needed
1.31 + * at all, and if not (i.e. the specified bounds and base bitmap area already
1.32 + * in the safe-zone, then the class does nothing (effectively).
1.33 + */
1.34 +class SkDeviceLooper {
1.35 +public:
1.36 + SkDeviceLooper(const SkBitmap& base, const SkRasterClip&,
1.37 + const SkIRect& bounds, bool aa);
1.38 + ~SkDeviceLooper();
1.39 +
1.40 + const SkBitmap& getBitmap() const {
1.41 + SkASSERT(kDone_State != fState);
1.42 + SkASSERT(fCurrBitmap);
1.43 + return *fCurrBitmap;
1.44 + }
1.45 +
1.46 + const SkRasterClip& getRC() const {
1.47 + SkASSERT(kDone_State != fState);
1.48 + SkASSERT(fCurrRC);
1.49 + return *fCurrRC;
1.50 + }
1.51 +
1.52 + void mapRect(SkRect* dst, const SkRect& src) const;
1.53 + void mapMatrix(SkMatrix* dst, const SkMatrix& src) const;
1.54 +
1.55 + /**
1.56 + * Call next to setup the looper to return a valid coordinate chunk.
1.57 + * Each time this returns true, it is safe to call mapRect() and
1.58 + * mapMatrix(), to convert from "global" coordinate values to ones that
1.59 + * are local to this chunk.
1.60 + *
1.61 + * When next() returns false, the list of chunks is done, and mapRect()
1.62 + * and mapMatrix() should no longer be called.
1.63 + */
1.64 + bool next();
1.65 +
1.66 +private:
1.67 + const SkBitmap& fBaseBitmap;
1.68 + const SkRasterClip& fBaseRC;
1.69 +
1.70 + enum State {
1.71 + kDone_State, // iteration is complete, getters will assert
1.72 + kSimple_State, // no translate/clip mods needed
1.73 + kComplex_State
1.74 + };
1.75 +
1.76 + // storage for our tiled versions. Perhaps could use SkTLazy
1.77 + SkBitmap fSubsetBitmap;
1.78 + SkRasterClip fSubsetRC;
1.79 +
1.80 + const SkBitmap* fCurrBitmap;
1.81 + const SkRasterClip* fCurrRC;
1.82 + SkIRect fClippedBounds;
1.83 + SkIPoint fCurrOffset;
1.84 + int fDelta;
1.85 + State fState;
1.86 +
1.87 + enum Delta {
1.88 + kBW_Delta = 1 << 14, // 16K, gives room to spare for fixedpoint
1.89 + kAA_Delta = kBW_Delta >> 2 // supersample 4x
1.90 + };
1.91 +
1.92 + bool fitsInDelta(const SkIRect& r) const {
1.93 + return r.right() < fDelta && r.bottom() < fDelta;
1.94 + }
1.95 +
1.96 + bool computeCurrBitmapAndClip();
1.97 +};
1.98 +
1.99 +#endif
