Implement a bicubic resampling image filter, with raster and GPU backends.

In order to get this to work on the GPU side, I had to modify the width and height of the drawn texture in drawSprite() and drawDevice() to use the filtered texture's dimensions, instead of the source texture.  (This wasn't a problem before since all other image filters produce results the same dimensions as their input texture.)
For now, this implementation only does axis-aligned scaling (same as the Lanczos-3 implementation in Chrome).  It's also done for correctness and clarity, not speed, so there are lots of opportunities for speedups.

Review URL: https://codereview.appspot.com/7033049

git-svn-id: http://skia.googlecode.com/svn/trunk@7275 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 55 insertions, 0 deletions

diff --git a/include/effects/SkBicubicImageFilter.h b/include/effects/SkBicubicImageFilter.h
new file mode 100644
index 0000000000..682b4600cc
--- /dev/null
+++ b/include/effects/SkBicubicImageFilter.h
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+/*
+ * Copyright 2013 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkBicubicImageFilter_DEFINED
+#define SkBicubicImageFilter_DEFINED
+
+#include "SkSingleInputImageFilter.h"
+#include "SkScalar.h"
+#include "SkSize.h"
+#include "SkPoint.h"
+
+/*! \class SkBicubicImageFilter
+    Bicubic resampling image filter.  This filter does a 16-tap bicubic
+    filter using the given matrix.
+ */
+
+class SK_API SkBicubicImageFilter : public SkSingleInputImageFilter {
+public:
+    /** Construct a (scaling-only) bicubic resampling image filter.
+        @param scale        How much to scale the image.
+        @param coefficients The 16 coefficients of the bicubic matrix.
+        @param input        The input image filter.  If NULL, the src bitmap
+                            passed to filterImage() is used instead.
+    */
+
+    SkBicubicImageFilter(const SkSize& scale, const SkScalar coefficients[16], SkImageFilter* input = NULL);
+    static SkBicubicImageFilter* CreateMitchell(const SkSize& scale, SkImageFilter* input = NULL);
+    virtual ~SkBicubicImageFilter();
+
+    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkBicubicImageFilter)
+
+protected:
+    SkBicubicImageFilter(SkFlattenableReadBuffer& buffer);
+    virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
+
+    virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
+                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+
+#if SK_SUPPORT_GPU
+    virtual bool canFilterImageGPU() const SK_OVERRIDE { return true; }
+    virtual GrTexture* filterImageGPU(Proxy* proxy, GrTexture* src,
+                                      const SkRect& rect) SK_OVERRIDE;
+#endif
+
+private:
+    SkSize    fScale;
+    SkScalar  fCoefficients[16];
+    typedef SkSingleInputImageFilter INHERITED;
+};
+
+#endif