michael@0: /*
michael@0:  * Copyright 2013 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #ifndef SkDeviceLooper_DEFINED
michael@0: #define SkDeviceLooper_DEFINED
michael@0: 
michael@0: #include "SkBitmap.h"
michael@0: #include "SkMatrix.h"
michael@0: #include "SkRasterClip.h"
michael@0: 
michael@0: /**
michael@0:  *  Helper class to manage "tiling" a large coordinate space into managable
michael@0:  *  chunks, where managable means areas that are <= some max critical coordinate
michael@0:  *  size.
michael@0:  *
michael@0:  *  The constructor takes an antialiasing bool, which affects what this maximum
michael@0:  *  allowable size is: If we're drawing BW, then we need coordinates to stay
michael@0:  *  safely within fixed-point range (we use +- 16K, to give ourselves room to
michael@0:  *  add/subtract two fixed values and still be in range. If we're drawing AA,
michael@0:  *  then we reduce that size by the amount that the supersampler scan converter
michael@0:  *  needs (at the moment, that is 4X, so the "safe" range is +- 4K).
michael@0:  *
michael@0:  *  For performance reasons, the class first checks to see if any help is needed
michael@0:  *  at all, and if not (i.e. the specified bounds and base bitmap area already
michael@0:  *  in the safe-zone, then the class does nothing (effectively).
michael@0:  */
michael@0: class SkDeviceLooper {
michael@0: public:
michael@0:     SkDeviceLooper(const SkBitmap& base, const SkRasterClip&,
michael@0:                    const SkIRect& bounds, bool aa);
michael@0:     ~SkDeviceLooper();
michael@0: 
michael@0:     const SkBitmap& getBitmap() const {
michael@0:         SkASSERT(kDone_State != fState);
michael@0:         SkASSERT(fCurrBitmap);
michael@0:         return *fCurrBitmap;
michael@0:     }
michael@0: 
michael@0:     const SkRasterClip& getRC() const {
michael@0:         SkASSERT(kDone_State != fState);
michael@0:         SkASSERT(fCurrRC);
michael@0:         return *fCurrRC;
michael@0:     }
michael@0: 
michael@0:     void mapRect(SkRect* dst, const SkRect& src) const;
michael@0:     void mapMatrix(SkMatrix* dst, const SkMatrix& src) const;
michael@0: 
michael@0:     /**
michael@0:      *  Call next to setup the looper to return a valid coordinate chunk.
michael@0:      *  Each time this returns true, it is safe to call mapRect() and
michael@0:      *  mapMatrix(), to convert from "global" coordinate values to ones that
michael@0:      *  are local to this chunk.
michael@0:      *
michael@0:      *  When next() returns false, the list of chunks is done, and mapRect()
michael@0:      *  and mapMatrix() should no longer be called.
michael@0:      */
michael@0:     bool next();
michael@0: 
michael@0: private:
michael@0:     const SkBitmap&     fBaseBitmap;
michael@0:     const SkRasterClip& fBaseRC;
michael@0: 
michael@0:     enum State {
michael@0:         kDone_State,    // iteration is complete, getters will assert
michael@0:         kSimple_State,  // no translate/clip mods needed
michael@0:         kComplex_State
michael@0:     };
michael@0: 
michael@0:     // storage for our tiled versions. Perhaps could use SkTLazy
michael@0:     SkBitmap            fSubsetBitmap;
michael@0:     SkRasterClip        fSubsetRC;
michael@0: 
michael@0:     const SkBitmap*     fCurrBitmap;
michael@0:     const SkRasterClip* fCurrRC;
michael@0:     SkIRect             fClippedBounds;
michael@0:     SkIPoint            fCurrOffset;
michael@0:     int                 fDelta;
michael@0:     State               fState;
michael@0: 
michael@0:     enum Delta {
michael@0:         kBW_Delta = 1 << 14,        // 16K, gives room to spare for fixedpoint
michael@0:         kAA_Delta = kBW_Delta >> 2  // supersample 4x
michael@0:     };
michael@0: 
michael@0:     bool fitsInDelta(const SkIRect& r) const {
michael@0:         return r.right() < fDelta && r.bottom() < fDelta;
michael@0:     }
michael@0: 
michael@0:     bool computeCurrBitmapAndClip();
michael@0: };
michael@0: 
michael@0: #endif