Implements a matrix convolution filter (raster path only). The filtering loop

is templated on the tiling mode for speed:  interior pixels are unconditionally
fetched; border pixels apply the appropriate tiling mode before fetching.  It
handles target, bias, divisor (as gain), and edge modes (named to be more
skia-like).  It does not handle the "preserveAlpha" semantics of
feConvolveMatrix, nor "kernelUnitLength".



git-svn-id: http://skia.googlecode.com/svn/trunk@5592 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 183 insertions, 0 deletions

diff --git a/src/effects/SkMatrixConvolutionImageFilter.cpp b/src/effects/SkMatrixConvolutionImageFilter.cpp
new file mode 100644
index 0000000000..3ff13d2236
--- /dev/null
+++ b/src/effects/SkMatrixConvolutionImageFilter.cpp
@@ -0,0 +1,183 @@
+/*
+ * Copyright 2012 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.
+ */
+
+#include "SkMatrixConvolutionImageFilter.h"
+#include "SkBitmap.h"
+#include "SkColorPriv.h"
+#include "SkFlattenableBuffers.h"
+#include "SkRect.h"
+
+SkMatrixConvolutionImageFilter::SkMatrixConvolutionImageFilter(const SkISize& kernelSize, const SkScalar* kernel, SkScalar gain, SkScalar bias, const SkIPoint& target, TileMode tileMode, SkImageFilter* input)
+  : INHERITED(input),
+    fKernelSize(kernelSize),
+    fGain(gain),
+    fBias(bias),
+    fTarget(target),
+    fTileMode(tileMode) {
+    uint32_t size = fKernelSize.fWidth * fKernelSize.fHeight;
+    fKernel = SkNEW_ARRAY(SkScalar, size);
+    memcpy(fKernel, kernel, size * sizeof(SkScalar));
+    SkASSERT(target.fX >= 0 && target.fX < kernelSize.fWidth);
+    SkASSERT(target.fY >= 0 && target.fY < kernelSize.fHeight);
+}
+
+SkMatrixConvolutionImageFilter::SkMatrixConvolutionImageFilter(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {
+    fKernelSize.fWidth = buffer.readInt();
+    fKernelSize.fHeight = buffer.readInt();
+    uint32_t size = fKernelSize.fWidth * fKernelSize.fHeight;
+    fKernel = SkNEW_ARRAY(SkScalar, size);
+    uint32_t readSize = buffer.readScalarArray(fKernel);
+    SkASSERT(readSize == size);
+    fGain = buffer.readScalar();
+    fBias = buffer.readScalar();
+    fTarget.fX = buffer.readScalar();
+    fTarget.fY = buffer.readScalar();
+    fTileMode = (TileMode) buffer.readInt();
+}
+
+void SkMatrixConvolutionImageFilter::flatten(SkFlattenableWriteBuffer& buffer) const {
+    this->INHERITED::flatten(buffer);
+    buffer.writeInt(fKernelSize.fWidth);
+    buffer.writeInt(fKernelSize.fHeight);
+    buffer.writeScalarArray(fKernel, fKernelSize.fWidth * fKernelSize.fHeight);
+    buffer.writeScalar(fGain);
+    buffer.writeScalar(fBias);
+    buffer.writeScalar(fTarget.fX);
+    buffer.writeScalar(fTarget.fY);
+    buffer.writeInt((int) fTileMode);
+}
+
+SkMatrixConvolutionImageFilter::~SkMatrixConvolutionImageFilter() {
+    delete[] fKernel;
+}
+
+class UncheckedPixelFetcher {
+public:
+    static inline SkPMColor fetch(const SkBitmap& src, int x, int y) {
+        return *src.getAddr32(x, y);
+    }
+};
+
+class ClampPixelFetcher {
+public:
+    static inline SkPMColor fetch(const SkBitmap& src, int x, int y) {
+        x = SkClampMax(x, src.width() - 1);
+        y = SkClampMax(y, src.height() - 1);
+        return *src.getAddr32(x, y);
+    }
+};
+
+class RepeatPixelFetcher {
+public:
+    static inline SkPMColor fetch(const SkBitmap& src, int x, int y) {
+        x %= src.width();
+        y %= src.height();
+        if (x < 0) {
+            x += src.width();
+        }
+        if (y < 0) {
+            y += src.height();
+        }
+        return *src.getAddr32(x, y);
+    }
+};
+
+class ClampToBlackPixelFetcher {
+public:
+    static inline SkPMColor fetch(const SkBitmap& src, int x, int y) {
+        if (x < 0 || x >= src.width() || y < 0 || y >= src.height()) {
+            return 0;
+        } else {
+            return *src.getAddr32(x, y);
+        }
+    }
+};
+
+template<class PixelFetcher>
+void SkMatrixConvolutionImageFilter::filterPixels(const SkBitmap& src, SkBitmap* result, const SkIRect& rect) {
+    for (int y = rect.fTop; y < rect.fBottom; ++y) {
+        SkPMColor* dptr = result->getAddr32(rect.fLeft, y);
+        for (int x = rect.fLeft; x < rect.fRight; ++x) {
+            SkScalar sumA = 0, sumR = 0, sumG = 0, sumB = 0;
+            for (int cy = 0; cy < fKernelSize.fHeight; cy++) {
+                for (int cx = 0; cx < fKernelSize.fWidth; cx++) {
+                    SkPMColor s = PixelFetcher::fetch(src, x + cx - fTarget.fX, y + cy - fTarget.fY);
+                    SkScalar k = fKernel[cy * fKernelSize.fWidth + cx];
+                    sumA += SkScalarMul(SkIntToScalar(SkGetPackedA32(s)), k);
+                    sumR += SkScalarMul(SkIntToScalar(SkGetPackedR32(s)), k);
+                    sumG += SkScalarMul(SkIntToScalar(SkGetPackedG32(s)), k);
+                    sumB += SkScalarMul(SkIntToScalar(SkGetPackedB32(s)), k);
+                }
+            }
+            int a = SkScalarFloorToInt(SkScalarMul(sumA, fGain) + fBias);
+            int r = SkScalarFloorToInt(SkScalarMul(sumR, fGain) + fBias);
+            int g = SkScalarFloorToInt(SkScalarMul(sumG, fGain) + fBias);
+            int b = SkScalarFloorToInt(SkScalarMul(sumB, fGain) + fBias);
+            *dptr++ = SkPackARGB32(SkClampMax(a, 255),
+                                   SkClampMax(r, 255),
+                                   SkClampMax(g, 255),
+                                   SkClampMax(b, 255));
+        }
+    }
+}
+
+void SkMatrixConvolutionImageFilter::filterInteriorPixels(const SkBitmap& src, SkBitmap* result, const SkIRect& rect) {
+    filterPixels<UncheckedPixelFetcher>(src, result, rect);
+}
+
+void SkMatrixConvolutionImageFilter::filterBorderPixels(const SkBitmap& src, SkBitmap* result, const SkIRect& rect) {
+    switch (fTileMode) {
+        case kClamp_TileMode:
+            filterPixels<ClampPixelFetcher>(src, result, rect);
+            break;
+        case kRepeat_TileMode:
+            filterPixels<RepeatPixelFetcher>(src, result, rect);
+            break;
+        case kClampToBlack_TileMode:
+            filterPixels<ClampToBlackPixelFetcher>(src, result, rect);
+            break;
+    }
+}
+
+bool SkMatrixConvolutionImageFilter::onFilterImage(Proxy* proxy,
+                                                   const SkBitmap& source,
+                                                   const SkMatrix& matrix,
+                                                   SkBitmap* result,
+                                                   SkIPoint* loc) {
+    SkBitmap src = this->getInputResult(proxy, source, matrix, loc);
+    if (src.config() != SkBitmap::kARGB_8888_Config) {
+        return false;
+    }
+
+    SkAutoLockPixels alp(src);
+    if (!src.getPixels()) {
+        return false;
+    }
+
+    result->setConfig(src.config(), src.width(), src.height());
+    result->allocPixels();
+
+    SkIRect interior = SkIRect::MakeXYWH(fTarget.fX, fTarget.fY,
+                                         src.width() - fKernelSize.fWidth + 1,
+                                         src.height() - fKernelSize.fHeight + 1);
+    SkIRect top = SkIRect::MakeWH(src.width(), fTarget.fY);
+    SkIRect bottom = SkIRect::MakeLTRB(0, interior.bottom(),
+                                       src.width(), src.height());
+    SkIRect left = SkIRect::MakeXYWH(0, interior.top(),
+                                     fTarget.fX, interior.height());
+    SkIRect right = SkIRect::MakeLTRB(interior.right(), interior.top(),
+                                      src.width(), interior.bottom());
+    filterBorderPixels(src, result, top);
+    filterBorderPixels(src, result, left);
+    filterInteriorPixels(src, result, interior);
+    filterBorderPixels(src, result, right);
+    filterBorderPixels(src, result, bottom);
+    return true;
+}
+
+SK_DEFINE_FLATTENABLE_REGISTRAR(SkMatrixConvolutionImageFilter)
+