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Unified 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, 4 months ago
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Index: src/core/SkDeviceLooper.h
diff --git a/src/core/SkDeviceLooper.h b/src/core/SkDeviceLooper.h
new file mode 100644
index 0000000000000000000000000000000000000000..405173dda48b9be68adb9ad2e0566644ca92d39e
--- /dev/null
+++ b/src/core/SkDeviceLooper.h
@@ -0,0 +1,96 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkDeviceLooper_DEFINED
+#define SkDeviceLooper_DEFINED
+
+#include "SkBitmap.h"
+#include "SkMatrix.h"
+#include "SkRasterClip.h"
+
+/**
+ * Helper class to manage "tiling" a large coordinate space into managable
+ * chunks, where managable means areas that are <= some max critical coordinate
+ * size.
+ *
+ * The constructor takes an antialiasing bool, which affects what this maximum
+ * allowable size is: If we're drawing BW, then we need coordinates to stay
+ * safely within fixed-point range (we use +- 16K, to give ourselves room to
+ * add/subtract two fixed values and still be in range. If we're drawing AA,
+ * then we reduce that size by the amount that the supersampler scan converter
+ * needs (at the moment, that is 4X, so the "safe" range is +- 4K).
+ *
+ * For performance reasons, the class first checks to see if any help is needed
+ * at all, and if not (i.e. the specified bounds and base bitmap area already
+ * in the safe-zone, then the class does nothing (effectively).
+ */
+class SkDeviceLooper {
+public:
+ SkDeviceLooper(const SkBitmap& base, const SkRasterClip&,
+ const SkIRect& bounds, bool aa);
+ ~SkDeviceLooper();
+
+ const SkBitmap& getBitmap() const {
+ SkASSERT(kDone_State != fState);
+ SkASSERT(fCurrBitmap);
+ return *fCurrBitmap;
+ }
+
+ const SkRasterClip& getRC() const {
+ SkASSERT(kDone_State != fState);
+ SkASSERT(fCurrRC);
+ return *fCurrRC;
+ }
+
+ void mapRect(SkRect* dst, const SkRect& src) const;
+ void mapMatrix(SkMatrix* dst, const SkMatrix& src) const;
+
+ /**
+ * Call next to setup the looper to return a valid coordinate chunk.
+ * Each time this returns true, it is safe to call mapRect() and
+ * mapMatrix(), to convert from "global" coordinate values to ones that
+ * are local to this chunk.
+ *
+ * When next() returns false, the list of chunks is done, and mapRect()
+ * and mapMatrix() should no longer be called.
+ */
+ bool next();
+
+private:
+ const SkBitmap& fBaseBitmap;
+ const SkRasterClip& fBaseRC;
+
+ enum State {
+ kDone_State, // iteration is complete, getters will assert
+ kSimple_State, // no translate/clip mods needed
+ kComplex_State
+ };
+
+ // storage for our tiled versions. Perhaps could use SkTLazy
+ SkBitmap fSubsetBitmap;
+ SkRasterClip fSubsetRC;
+
+ const SkBitmap* fCurrBitmap;
+ const SkRasterClip* fCurrRC;
+ SkIRect fClippedBounds;
+ SkIPoint fCurrOffset;
+ int fDelta;
+ State fState;
+
+ enum Delta {
+ kBW_Delta = 1 << 14, // 16K, gives room to spare for fixedpoint
+ kAA_Delta = kBW_Delta >> 2 // supersample 4x
+ };
+
+ bool fitsInDelta(const SkIRect& r) const {
+ return r.right() < fDelta && r.bottom() < fDelta;
+ }
+
+ bool computeCurrBitmapAndClip();
+};
+
+#endif
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