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 "SkReadBuffer.h"
12#include "SkWriteBuffer.h"
13#include "SkGpuBlurUtils.h"
14#include "SkBlurImage_opts.h"
15#if SK_SUPPORT_GPU
16#include "GrContext.h"
17#endif
18
19// This rather arbitrary-looking value results in a maximum box blur kernel size
20// of 1000 pixels on the raster path, which matches the WebKit and Firefox
21// implementations. Since the GPU path does not compute a box blur, putting
22// the limit on sigma ensures consistent behaviour between the GPU and
23// raster paths.
24#define MAX_SIGMA SkIntToScalar(532)
25
26SkBlurImageFilter::SkBlurImageFilter(SkReadBuffer& buffer)
27  : INHERITED(1, buffer) {
28    fSigma.fWidth = buffer.readScalar();
29    fSigma.fHeight = buffer.readScalar();
30    buffer.validate(SkScalarIsFinite(fSigma.fWidth) &&
31                    SkScalarIsFinite(fSigma.fHeight) &&
32                    (fSigma.fWidth >= 0) &&
33                    (fSigma.fHeight >= 0));
34}
35
36SkBlurImageFilter::SkBlurImageFilter(SkScalar sigmaX,
37                                     SkScalar sigmaY,
38                                     SkImageFilter* input,
39                                     const CropRect* cropRect)
40    : INHERITED(input, cropRect), fSigma(SkSize::Make(sigmaX, sigmaY)) {
41    SkASSERT(sigmaX >= 0 && sigmaY >= 0);
42}
43
44void SkBlurImageFilter::flatten(SkWriteBuffer& buffer) const {
45    this->INHERITED::flatten(buffer);
46    buffer.writeScalar(fSigma.fWidth);
47    buffer.writeScalar(fSigma.fHeight);
48}
49
50enum BlurDirection {
51    kX, kY
52};
53
54/**
55 *
56 * In order to make memory accesses cache-friendly, we reorder the passes to
57 * use contiguous memory reads wherever possible.
58 *
59 * For example, the 6 passes of the X-and-Y blur case are rewritten as
60 * follows. Instead of 3 passes in X and 3 passes in Y, we perform
61 * 2 passes in X, 1 pass in X transposed to Y on write, 2 passes in X,
62 * then 1 pass in X transposed to Y on write.
63 *
64 * +----+       +----+       +----+        +---+       +---+       +---+        +----+
65 * + AB + ----> | AB | ----> | AB | -----> | A | ----> | A | ----> | A | -----> | AB |
66 * +----+ blurX +----+ blurX +----+ blurXY | B | blurX | B | blurX | B | blurXY +----+
67 *                                         +---+       +---+       +---+
68 *
69 * In this way, two of the y-blurs become x-blurs applied to transposed
70 * images, and all memory reads are contiguous.
71 */
72
73template<BlurDirection srcDirection, BlurDirection dstDirection>
74static void boxBlur(const SkPMColor* src, int srcStride, SkPMColor* dst, int kernelSize,
75                    int leftOffset, int rightOffset, int width, int height)
76{
77    int rightBorder = SkMin32(rightOffset + 1, width);
78    int srcStrideX = srcDirection == kX ? 1 : srcStride;
79    int dstStrideX = dstDirection == kX ? 1 : height;
80    int srcStrideY = srcDirection == kX ? srcStride : 1;
81    int dstStrideY = dstDirection == kX ? width : 1;
82    uint32_t scale = (1 << 24) / kernelSize;
83    uint32_t half = 1 << 23;
84    for (int y = 0; y < height; ++y) {
85        int sumA = 0, sumR = 0, sumG = 0, sumB = 0;
86        const SkPMColor* p = src;
87        for (int i = 0; i < rightBorder; ++i) {
88            sumA += SkGetPackedA32(*p);
89            sumR += SkGetPackedR32(*p);
90            sumG += SkGetPackedG32(*p);
91            sumB += SkGetPackedB32(*p);
92            p += srcStrideX;
93        }
94
95        const SkPMColor* sptr = src;
96        SkColor* dptr = dst;
97        for (int x = 0; x < width; ++x) {
98            *dptr = SkPackARGB32((sumA * scale + half) >> 24,
99                                 (sumR * scale + half) >> 24,
100                                 (sumG * scale + half) >> 24,
101                                 (sumB * scale + half) >> 24);
102            if (x >= leftOffset) {
103                SkColor l = *(sptr - leftOffset * srcStrideX);
104                sumA -= SkGetPackedA32(l);
105                sumR -= SkGetPackedR32(l);
106                sumG -= SkGetPackedG32(l);
107                sumB -= SkGetPackedB32(l);
108            }
109            if (x + rightOffset + 1 < width) {
110                SkColor r = *(sptr + (rightOffset + 1) * srcStrideX);
111                sumA += SkGetPackedA32(r);
112                sumR += SkGetPackedR32(r);
113                sumG += SkGetPackedG32(r);
114                sumB += SkGetPackedB32(r);
115            }
116            sptr += srcStrideX;
117            if (srcDirection == kY) {
118                SK_PREFETCH(sptr + (rightOffset + 1) * srcStrideX);
119            }
120            dptr += dstStrideX;
121        }
122        src += srcStrideY;
123        dst += dstStrideY;
124    }
125}
126
127static void getBox3Params(SkScalar s, int *kernelSize, int* kernelSize3, int *lowOffset,
128                          int *highOffset)
129{
130    float pi = SkScalarToFloat(SK_ScalarPI);
131    int d = static_cast<int>(floorf(SkScalarToFloat(s) * 3.0f * sqrtf(2.0f * pi) / 4.0f + 0.5f));
132    *kernelSize = d;
133    if (d % 2 == 1) {
134        *lowOffset = *highOffset = (d - 1) / 2;
135        *kernelSize3 = d;
136    } else {
137        *highOffset = d / 2;
138        *lowOffset = *highOffset - 1;
139        *kernelSize3 = d + 1;
140    }
141}
142
143bool SkBlurImageFilter::onFilterImage(Proxy* proxy,
144                                      const SkBitmap& source, const Context& ctx,
145                                      SkBitmap* dst, SkIPoint* offset) const {
146    SkBitmap src = source;
147    SkIPoint srcOffset = SkIPoint::Make(0, 0);
148    if (getInput(0) && !getInput(0)->filterImage(proxy, source, ctx, &src, &srcOffset)) {
149        return false;
150    }
151
152    if (src.colorType() != kN32_SkColorType) {
153        return false;
154    }
155
156    SkIRect srcBounds, dstBounds;
157    if (!this->applyCropRect(ctx, proxy, src, &srcOffset, &srcBounds, &src)) {
158        return false;
159    }
160
161    SkAutoLockPixels alp(src);
162    if (!src.getPixels()) {
163        return false;
164    }
165
166    if (!dst->allocPixels(src.info().makeWH(srcBounds.width(), srcBounds.height()))) {
167        return false;
168    }
169    dst->getBounds(&dstBounds);
170
171    SkVector sigma = SkVector::Make(fSigma.width(), fSigma.height());
172    ctx.ctm().mapVectors(&sigma, 1);
173    sigma.fX = SkMinScalar(sigma.fX, MAX_SIGMA);
174    sigma.fY = SkMinScalar(sigma.fY, MAX_SIGMA);
175
176    int kernelSizeX, kernelSizeX3, lowOffsetX, highOffsetX;
177    int kernelSizeY, kernelSizeY3, lowOffsetY, highOffsetY;
178    getBox3Params(sigma.x(), &kernelSizeX, &kernelSizeX3, &lowOffsetX, &highOffsetX);
179    getBox3Params(sigma.y(), &kernelSizeY, &kernelSizeY3, &lowOffsetY, &highOffsetY);
180
181    if (kernelSizeX < 0 || kernelSizeY < 0) {
182        return false;
183    }
184
185    if (kernelSizeX == 0 && kernelSizeY == 0) {
186        src.copyTo(dst, dst->colorType());
187        offset->fX = srcBounds.fLeft;
188        offset->fY = srcBounds.fTop;
189        return true;
190    }
191
192    SkBitmap temp;
193    if (!temp.allocPixels(dst->info())) {
194        return false;
195    }
196
197    offset->fX = srcBounds.fLeft;
198    offset->fY = srcBounds.fTop;
199    srcBounds.offset(-srcOffset);
200    const SkPMColor* s = src.getAddr32(srcBounds.left(), srcBounds.top());
201    SkPMColor* t = temp.getAddr32(0, 0);
202    SkPMColor* d = dst->getAddr32(0, 0);
203    int w = dstBounds.width(), h = dstBounds.height();
204    int sw = src.rowBytesAsPixels();
205    SkBoxBlurProc boxBlurX, boxBlurY, boxBlurXY, boxBlurYX;
206    if (!SkBoxBlurGetPlatformProcs(&boxBlurX, &boxBlurY, &boxBlurXY, &boxBlurYX)) {
207        boxBlurX = boxBlur<kX, kX>;
208        boxBlurY = boxBlur<kY, kY>;
209        boxBlurXY = boxBlur<kX, kY>;
210        boxBlurYX = boxBlur<kY, kX>;
211    }
212
213    if (kernelSizeX > 0 && kernelSizeY > 0) {
214        boxBlurX(s,  sw, t, kernelSizeX,  lowOffsetX,  highOffsetX, w, h);
215        boxBlurX(t,  w,  d, kernelSizeX,  highOffsetX, lowOffsetX,  w, h);
216        boxBlurXY(d, w,  t, kernelSizeX3, highOffsetX, highOffsetX, w, h);
217        boxBlurX(t,  h,  d, kernelSizeY,  lowOffsetY,  highOffsetY, h, w);
218        boxBlurX(d,  h,  t, kernelSizeY,  highOffsetY, lowOffsetY,  h, w);
219        boxBlurXY(t, h,  d, kernelSizeY3, highOffsetY, highOffsetY, h, w);
220    } else if (kernelSizeX > 0) {
221        boxBlurX(s,  sw, d, kernelSizeX,  lowOffsetX,  highOffsetX, w, h);
222        boxBlurX(d,  w,  t, kernelSizeX,  highOffsetX, lowOffsetX,  w, h);
223        boxBlurX(t,  w,  d, kernelSizeX3, highOffsetX, highOffsetX, w, h);
224    } else if (kernelSizeY > 0) {
225        boxBlurYX(s, sw, d, kernelSizeY,  lowOffsetY,  highOffsetY, h, w);
226        boxBlurX(d,  h,  t, kernelSizeY,  highOffsetY, lowOffsetY,  h, w);
227        boxBlurXY(t, h,  d, kernelSizeY3, highOffsetY, highOffsetY, h, w);
228    }
229    return true;
230}
231
232
233void SkBlurImageFilter::computeFastBounds(const SkRect& src, SkRect* dst) const {
234    if (getInput(0)) {
235        getInput(0)->computeFastBounds(src, dst);
236    } else {
237        *dst = src;
238    }
239
240    dst->outset(SkScalarMul(fSigma.width(), SkIntToScalar(3)),
241                SkScalarMul(fSigma.height(), SkIntToScalar(3)));
242}
243
244bool SkBlurImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
245                                       SkIRect* dst) const {
246    SkIRect bounds = src;
247    if (getInput(0) && !getInput(0)->filterBounds(src, ctm, &bounds)) {
248        return false;
249    }
250    SkVector sigma = SkVector::Make(fSigma.width(), fSigma.height());
251    ctm.mapVectors(&sigma, 1);
252    bounds.outset(SkScalarCeilToInt(SkScalarMul(sigma.x(), SkIntToScalar(3))),
253                  SkScalarCeilToInt(SkScalarMul(sigma.y(), SkIntToScalar(3))));
254    *dst = bounds;
255    return true;
256}
257
258bool SkBlurImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const Context& ctx,
259                                       SkBitmap* result, SkIPoint* offset) const {
260#if SK_SUPPORT_GPU
261    SkBitmap input = src;
262    SkIPoint srcOffset = SkIPoint::Make(0, 0);
263    if (getInput(0) && !getInput(0)->getInputResultGPU(proxy, src, ctx, &input, &srcOffset)) {
264        return false;
265    }
266    SkIRect rect;
267    if (!this->applyCropRect(ctx, proxy, input, &srcOffset, &rect, &input)) {
268        return false;
269    }
270    GrTexture* source = input.getTexture();
271    SkVector sigma = SkVector::Make(fSigma.width(), fSigma.height());
272    ctx.ctm().mapVectors(&sigma, 1);
273    sigma.fX = SkMinScalar(sigma.fX, MAX_SIGMA);
274    sigma.fY = SkMinScalar(sigma.fY, MAX_SIGMA);
275    offset->fX = rect.fLeft;
276    offset->fY = rect.fTop;
277    rect.offset(-srcOffset);
278    SkAutoTUnref<GrTexture> tex(SkGpuBlurUtils::GaussianBlur(source->getContext(),
279                                                             source,
280                                                             false,
281                                                             SkRect::Make(rect),
282                                                             true,
283                                                             sigma.x(),
284                                                             sigma.y()));
285    WrapTexture(tex, rect.width(), rect.height(), result);
286    return true;
287#else
288    SkDEBUGFAIL("Should not call in GPU-less build");
289    return false;
290#endif
291}
292