1/*
2 * Copyright 2011 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "SkBitmap.h"
9#include "SkBlurImageFilter.h"
10#include "SkColorPriv.h"
11#include "SkFlattenableBuffers.h"
12#include "SkGpuBlurUtils.h"
13#include "SkBlurImage_opts.h"
14#if SK_SUPPORT_GPU
15#include "GrContext.h"
16#include "SkImageFilterUtils.h"
17#endif
18
19SkBlurImageFilter::SkBlurImageFilter(SkFlattenableReadBuffer& buffer)
20  : INHERITED(1, buffer) {
21    fSigma.fWidth = buffer.readScalar();
22    fSigma.fHeight = buffer.readScalar();
23    buffer.validate(SkScalarIsFinite(fSigma.fWidth) &&
24                    SkScalarIsFinite(fSigma.fHeight) &&
25                    (fSigma.fWidth >= 0) &&
26                    (fSigma.fHeight >= 0));
27}
28
29SkBlurImageFilter::SkBlurImageFilter(SkScalar sigmaX,
30                                     SkScalar sigmaY,
31                                     SkImageFilter* input,
32                                     const CropRect* cropRect)
33    : INHERITED(input, cropRect), fSigma(SkSize::Make(sigmaX, sigmaY)) {
34    SkASSERT(sigmaX >= 0 && sigmaY >= 0);
35}
36
37void SkBlurImageFilter::flatten(SkFlattenableWriteBuffer& buffer) const {
38    this->INHERITED::flatten(buffer);
39    buffer.writeScalar(fSigma.fWidth);
40    buffer.writeScalar(fSigma.fHeight);
41}
42
43enum BlurDirection {
44    kX, kY
45};
46
47/**
48 *
49 * In order to make memory accesses cache-friendly, we reorder the passes to
50 * use contiguous memory reads wherever possible.
51 *
52 * For example, the 6 passes of the X-and-Y blur case are rewritten as
53 * follows. Instead of 3 passes in X and 3 passes in Y, we perform
54 * 2 passes in X, 1 pass in X transposed to Y on write, 2 passes in X,
55 * then 1 pass in X transposed to Y on write.
56 *
57 * +----+       +----+       +----+        +---+       +---+       +---+        +----+
58 * + AB + ----> | AB | ----> | AB | -----> | A | ----> | A | ----> | A | -----> | AB |
59 * +----+ blurX +----+ blurX +----+ blurXY | B | blurX | B | blurX | B | blurXY +----+
60 *                                         +---+       +---+       +---+
61 *
62 * In this way, two of the y-blurs become x-blurs applied to transposed
63 * images, and all memory reads are contiguous.
64 */
65
66template<BlurDirection srcDirection, BlurDirection dstDirection>
67static void boxBlur(const SkPMColor* src, int srcStride, SkPMColor* dst, int kernelSize,
68                    int leftOffset, int rightOffset, int width, int height)
69{
70    int rightBorder = SkMin32(rightOffset + 1, width);
71    int srcStrideX = srcDirection == kX ? 1 : srcStride;
72    int dstStrideX = dstDirection == kX ? 1 : height;
73    int srcStrideY = srcDirection == kX ? srcStride : 1;
74    int dstStrideY = dstDirection == kX ? width : 1;
75    uint32_t scale = (1 << 24) / kernelSize;
76    uint32_t half = 1 << 23;
77    for (int y = 0; y < height; ++y) {
78        int sumA = 0, sumR = 0, sumG = 0, sumB = 0;
79        const SkPMColor* p = src;
80        for (int i = 0; i < rightBorder; ++i) {
81            sumA += SkGetPackedA32(*p);
82            sumR += SkGetPackedR32(*p);
83            sumG += SkGetPackedG32(*p);
84            sumB += SkGetPackedB32(*p);
85            p += srcStrideX;
86        }
87
88        const SkPMColor* sptr = src;
89        SkColor* dptr = dst;
90        for (int x = 0; x < width; ++x) {
91            *dptr = SkPackARGB32((sumA * scale + half) >> 24,
92                                 (sumR * scale + half) >> 24,
93                                 (sumG * scale + half) >> 24,
94                                 (sumB * scale + half) >> 24);
95            if (x >= leftOffset) {
96                SkColor l = *(sptr - leftOffset * srcStrideX);
97                sumA -= SkGetPackedA32(l);
98                sumR -= SkGetPackedR32(l);
99                sumG -= SkGetPackedG32(l);
100                sumB -= SkGetPackedB32(l);
101            }
102            if (x + rightOffset + 1 < width) {
103                SkColor r = *(sptr + (rightOffset + 1) * srcStrideX);
104                sumA += SkGetPackedA32(r);
105                sumR += SkGetPackedR32(r);
106                sumG += SkGetPackedG32(r);
107                sumB += SkGetPackedB32(r);
108            }
109            sptr += srcStrideX;
110            if (srcDirection == kY) {
111                SK_PREFETCH(sptr + (rightOffset + 1) * srcStrideX);
112            }
113            dptr += dstStrideX;
114        }
115        src += srcStrideY;
116        dst += dstStrideY;
117    }
118}
119
120static void getBox3Params(SkScalar s, int *kernelSize, int* kernelSize3, int *lowOffset,
121                          int *highOffset)
122{
123    float pi = SkScalarToFloat(SK_ScalarPI);
124    int d = static_cast<int>(floorf(SkScalarToFloat(s) * 3.0f * sqrtf(2.0f * pi) / 4.0f + 0.5f));
125    *kernelSize = d;
126    if (d % 2 == 1) {
127        *lowOffset = *highOffset = (d - 1) / 2;
128        *kernelSize3 = d;
129    } else {
130        *highOffset = d / 2;
131        *lowOffset = *highOffset - 1;
132        *kernelSize3 = d + 1;
133    }
134}
135
136bool SkBlurImageFilter::onFilterImage(Proxy* proxy,
137                                      const SkBitmap& source, const SkMatrix& ctm,
138                                      SkBitmap* dst, SkIPoint* offset) {
139    SkBitmap src = source;
140    if (getInput(0) && !getInput(0)->filterImage(proxy, source, ctm, &src, offset)) {
141        return false;
142    }
143
144    if (src.config() != SkBitmap::kARGB_8888_Config) {
145        return false;
146    }
147
148    SkAutoLockPixels alp(src);
149    if (!src.getPixels()) {
150        return false;
151    }
152
153    SkIRect srcBounds, dstBounds;
154    src.getBounds(&srcBounds);
155    if (!this->applyCropRect(&srcBounds, ctm)) {
156        return false;
157    }
158
159    dst->setConfig(src.config(), srcBounds.width(), srcBounds.height());
160    dst->getBounds(&dstBounds);
161    dst->allocPixels();
162    if (!dst->getPixels()) {
163        return false;
164    }
165
166    int kernelSizeX, kernelSizeX3, lowOffsetX, highOffsetX;
167    int kernelSizeY, kernelSizeY3, lowOffsetY, highOffsetY;
168    getBox3Params(fSigma.width(), &kernelSizeX, &kernelSizeX3, &lowOffsetX, &highOffsetX);
169    getBox3Params(fSigma.height(), &kernelSizeY, &kernelSizeY3, &lowOffsetY, &highOffsetY);
170
171    if (kernelSizeX < 0 || kernelSizeY < 0) {
172        return false;
173    }
174
175    if (kernelSizeX == 0 && kernelSizeY == 0) {
176        src.copyTo(dst, dst->config());
177        return true;
178    }
179
180    SkBitmap temp;
181    temp.setConfig(dst->config(), dst->width(), dst->height());
182    if (!temp.allocPixels()) {
183        return false;
184    }
185
186    const SkPMColor* s = src.getAddr32(srcBounds.left(), srcBounds.top());
187    SkPMColor* t = temp.getAddr32(0, 0);
188    SkPMColor* d = dst->getAddr32(0, 0);
189    int w = dstBounds.width(), h = dstBounds.height();
190    int sw = src.rowBytesAsPixels();
191    SkBoxBlurProc boxBlurX, boxBlurY, boxBlurXY, boxBlurYX;
192    if (!SkBoxBlurGetPlatformProcs(&boxBlurX, &boxBlurY, &boxBlurXY, &boxBlurYX)) {
193        boxBlurX = boxBlur<kX, kX>;
194        boxBlurY = boxBlur<kY, kY>;
195        boxBlurXY = boxBlur<kX, kY>;
196        boxBlurYX = boxBlur<kY, kX>;
197    }
198
199    if (kernelSizeX > 0 && kernelSizeY > 0) {
200        boxBlurX(s,  sw, t, kernelSizeX,  lowOffsetX,  highOffsetX, w, h);
201        boxBlurX(t,  w,  d, kernelSizeX,  highOffsetX, lowOffsetX,  w, h);
202        boxBlurXY(d, w,  t, kernelSizeX3, highOffsetX, highOffsetX, w, h);
203        boxBlurX(t,  h,  d, kernelSizeY,  lowOffsetY,  highOffsetY, h, w);
204        boxBlurX(d,  h,  t, kernelSizeY,  highOffsetY, lowOffsetY,  h, w);
205        boxBlurXY(t, h,  d, kernelSizeY3, highOffsetY, highOffsetY, h, w);
206    } else if (kernelSizeX > 0) {
207        boxBlurX(s,  sw, d, kernelSizeX,  lowOffsetX,  highOffsetX, w, h);
208        boxBlurX(d,  w,  t, kernelSizeX,  highOffsetX, lowOffsetX,  w, h);
209        boxBlurX(t,  w,  d, kernelSizeX3, highOffsetX, highOffsetX, w, h);
210    } else if (kernelSizeY > 0) {
211        boxBlurYX(s, sw, d, kernelSizeY,  lowOffsetY,  highOffsetY, h, w);
212        boxBlurX(d,  h,  t, kernelSizeY,  highOffsetY, lowOffsetY,  h, w);
213        boxBlurXY(t, h,  d, kernelSizeY3, highOffsetY, highOffsetY, h, w);
214    }
215    offset->fX += srcBounds.fLeft;
216    offset->fY += srcBounds.fTop;
217    return true;
218}
219
220bool SkBlurImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
221                                       SkBitmap* result, SkIPoint* offset) {
222#if SK_SUPPORT_GPU
223    SkBitmap input;
224    if (!SkImageFilterUtils::GetInputResultGPU(getInput(0), proxy, src, ctm, &input, offset)) {
225        return false;
226    }
227    GrTexture* source = input.getTexture();
228    SkIRect rect;
229    src.getBounds(&rect);
230    if (!this->applyCropRect(&rect, ctm)) {
231        return false;
232    }
233    SkAutoTUnref<GrTexture> tex(SkGpuBlurUtils::GaussianBlur(source->getContext(),
234                                                             source,
235                                                             false,
236                                                             SkRect::Make(rect),
237                                                             true,
238                                                             fSigma.width(),
239                                                             fSigma.height()));
240    offset->fX += rect.fLeft;
241    offset->fY += rect.fTop;
242    return SkImageFilterUtils::WrapTexture(tex, rect.width(), rect.height(), result);
243#else
244    SkDEBUGFAIL("Should not call in GPU-less build");
245    return false;
246#endif
247}
248