1/*
2 * Copyright (c) 2006,2007,2008, Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
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15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#include "config.h"
32
33#include "platform/graphics/skia/SkiaUtils.h"
34
35#include "SkColorPriv.h"
36#include "SkRegion.h"
37#include "platform/graphics/GraphicsContext.h"
38#include "platform/graphics/ImageBuffer.h"
39
40namespace blink {
41
42static const struct CompositOpToXfermodeMode {
43    CompositeOperator mCompositOp;
44    SkXfermode::Mode m_xfermodeMode;
45} gMapCompositOpsToXfermodeModes[] = {
46    { CompositeClear,           SkXfermode::kClear_Mode },
47    { CompositeCopy,            SkXfermode::kSrc_Mode },
48    { CompositeSourceOver,      SkXfermode::kSrcOver_Mode },
49    { CompositeSourceIn,        SkXfermode::kSrcIn_Mode },
50    { CompositeSourceOut,       SkXfermode::kSrcOut_Mode },
51    { CompositeSourceAtop,      SkXfermode::kSrcATop_Mode },
52    { CompositeDestinationOver, SkXfermode::kDstOver_Mode },
53    { CompositeDestinationIn,   SkXfermode::kDstIn_Mode },
54    { CompositeDestinationOut,  SkXfermode::kDstOut_Mode },
55    { CompositeDestinationAtop, SkXfermode::kDstATop_Mode },
56    { CompositeXOR,             SkXfermode::kXor_Mode },
57    { CompositePlusDarker,      SkXfermode::kDarken_Mode },
58    { CompositePlusLighter,     SkXfermode::kPlus_Mode }
59};
60
61// keep this array in sync with WebBlendMode enum in public/platform/WebBlendMode.h
62static const SkXfermode::Mode gMapBlendOpsToXfermodeModes[] = {
63    SkXfermode::kClear_Mode, // WebBlendModeNormal
64    SkXfermode::kMultiply_Mode, // WebBlendModeMultiply
65    SkXfermode::kScreen_Mode, // WebBlendModeScreen
66    SkXfermode::kOverlay_Mode, // WebBlendModeOverlay
67    SkXfermode::kDarken_Mode, // WebBlendModeDarken
68    SkXfermode::kLighten_Mode, // WebBlendModeLighten
69    SkXfermode::kColorDodge_Mode, // WebBlendModeColorDodge
70    SkXfermode::kColorBurn_Mode, // WebBlendModeColorBurn
71    SkXfermode::kHardLight_Mode, // WebBlendModeHardLight
72    SkXfermode::kSoftLight_Mode, // WebBlendModeSoftLight
73    SkXfermode::kDifference_Mode, // WebBlendModeDifference
74    SkXfermode::kExclusion_Mode, // WebBlendModeExclusion
75    SkXfermode::kHue_Mode, // WebBlendModeHue
76    SkXfermode::kSaturation_Mode, // WebBlendModeSaturation
77    SkXfermode::kColor_Mode, // WebBlendModeColor
78    SkXfermode::kLuminosity_Mode // WebBlendModeLuminosity
79};
80
81SkXfermode::Mode WebCoreCompositeToSkiaComposite(CompositeOperator op, WebBlendMode blendMode)
82{
83    if (blendMode != WebBlendModeNormal) {
84        if (static_cast<uint8_t>(blendMode) >= SK_ARRAY_COUNT(gMapBlendOpsToXfermodeModes)) {
85            SkDEBUGF(("GraphicsContext::setPlatformCompositeOperation unknown WebBlendMode %d\n", blendMode));
86            return SkXfermode::kSrcOver_Mode;
87        }
88        return gMapBlendOpsToXfermodeModes[static_cast<uint8_t>(blendMode)];
89    }
90
91    const CompositOpToXfermodeMode* table = gMapCompositOpsToXfermodeModes;
92    if (static_cast<uint8_t>(op) >= SK_ARRAY_COUNT(gMapCompositOpsToXfermodeModes)) {
93        SkDEBUGF(("GraphicsContext::setPlatformCompositeOperation unknown CompositeOperator %d\n", op));
94        return SkXfermode::kSrcOver_Mode;
95    }
96    SkASSERT(table[static_cast<uint8_t>(op)].mCompositOp == op);
97    return table[static_cast<uint8_t>(op)].m_xfermodeMode;
98}
99
100static U8CPU InvScaleByte(U8CPU component, uint32_t scale)
101{
102    SkASSERT(component == (uint8_t)component);
103    return (component * scale + 0x8000) >> 16;
104}
105
106SkColor SkPMColorToColor(SkPMColor pm)
107{
108    if (!pm)
109        return 0;
110    unsigned a = SkGetPackedA32(pm);
111    if (!a) {
112        // A zero alpha value when there are non-zero R, G, or B channels is an
113        // invalid premultiplied color (since all channels should have been
114        // multiplied by 0 if a=0).
115        SkASSERT(false);
116        // In production, return 0 to protect against division by zero.
117        return 0;
118    }
119
120    uint32_t scale = (255 << 16) / a;
121
122    return SkColorSetARGB(a,
123                          InvScaleByte(SkGetPackedR32(pm), scale),
124                          InvScaleByte(SkGetPackedG32(pm), scale),
125                          InvScaleByte(SkGetPackedB32(pm), scale));
126}
127
128bool SkPathContainsPoint(const SkPath& originalPath, const FloatPoint& point, SkPath::FillType ft)
129{
130    SkRect bounds = originalPath.getBounds();
131
132    // We can immediately return false if the point is outside the bounding
133    // rect.  We don't use bounds.contains() here, since it would exclude
134    // points on the right and bottom edges of the bounding rect, and we want
135    // to include them.
136    SkScalar fX = SkFloatToScalar(point.x());
137    SkScalar fY = SkFloatToScalar(point.y());
138    if (fX < bounds.fLeft || fX > bounds.fRight || fY < bounds.fTop || fY > bounds.fBottom)
139        return false;
140
141    // Scale the path to a large size before hit testing for two reasons:
142    // 1) Skia has trouble with coordinates close to the max signed 16-bit values, so we scale larger paths down.
143    //    TODO: when Skia is patched to work properly with large values, this will not be necessary.
144    // 2) Skia does not support analytic hit testing, so we scale paths up to do raster hit testing with subpixel accuracy.
145    SkScalar biggestCoord = std::max(std::max(std::max(bounds.fRight, bounds.fBottom), -bounds.fLeft), -bounds.fTop);
146    if (SkScalarNearlyZero(biggestCoord))
147        return false;
148    biggestCoord = std::max(std::max(biggestCoord, fX + 1), fY + 1);
149
150    const SkScalar kMaxCoordinate = SkIntToScalar(1 << 15);
151    SkScalar scale = SkScalarDiv(kMaxCoordinate, biggestCoord);
152
153    SkRegion rgn;
154    SkRegion clip;
155    SkMatrix m;
156    SkPath scaledPath(originalPath);
157
158    scaledPath.setFillType(ft);
159    m.setScale(scale, scale);
160    scaledPath.transform(m, 0);
161
162    int x = static_cast<int>(floorf(0.5f + point.x() * scale));
163    int y = static_cast<int>(floorf(0.5f + point.y() * scale));
164    clip.setRect(x - 1, y - 1, x + 1, y + 1);
165
166    return rgn.setPath(scaledPath, clip);
167}
168
169SkMatrix affineTransformToSkMatrix(const AffineTransform& source)
170{
171    SkMatrix result;
172
173    result.setScaleX(WebCoreDoubleToSkScalar(source.a()));
174    result.setSkewX(WebCoreDoubleToSkScalar(source.c()));
175    result.setTranslateX(WebCoreDoubleToSkScalar(source.e()));
176
177    result.setScaleY(WebCoreDoubleToSkScalar(source.d()));
178    result.setSkewY(WebCoreDoubleToSkScalar(source.b()));
179    result.setTranslateY(WebCoreDoubleToSkScalar(source.f()));
180
181    // FIXME: Set perspective properly.
182    result.setPerspX(0);
183    result.setPerspY(0);
184    result.set(SkMatrix::kMPersp2, SK_Scalar1);
185
186    return result;
187}
188
189bool nearlyIntegral(float value)
190{
191    return fabs(value - floorf(value)) < std::numeric_limits<float>::epsilon();
192}
193
194InterpolationQuality limitInterpolationQuality(const GraphicsContext* context, InterpolationQuality resampling)
195{
196    return std::min(resampling, context->imageInterpolationQuality());
197}
198
199InterpolationQuality computeInterpolationQuality(
200    const SkMatrix& matrix,
201    float srcWidth,
202    float srcHeight,
203    float destWidth,
204    float destHeight,
205    bool isDataComplete)
206{
207    // The percent change below which we will not resample. This usually means
208    // an off-by-one error on the web page, and just doing nearest neighbor
209    // sampling is usually good enough.
210    const float kFractionalChangeThreshold = 0.025f;
211
212    // Images smaller than this in either direction are considered "small" and
213    // are not resampled ever (see below).
214    const int kSmallImageSizeThreshold = 8;
215
216    // The amount an image can be stretched in a single direction before we
217    // say that it is being stretched so much that it must be a line or
218    // background that doesn't need resampling.
219    const float kLargeStretch = 3.0f;
220
221    // Figure out if we should resample this image. We try to prune out some
222    // common cases where resampling won't give us anything, since it is much
223    // slower than drawing stretched.
224    float diffWidth = fabs(destWidth - srcWidth);
225    float diffHeight = fabs(destHeight - srcHeight);
226    bool widthNearlyEqual = diffWidth < std::numeric_limits<float>::epsilon();
227    bool heightNearlyEqual = diffHeight < std::numeric_limits<float>::epsilon();
228    // We don't need to resample if the source and destination are the same.
229    if (widthNearlyEqual && heightNearlyEqual)
230        return InterpolationNone;
231
232    if (srcWidth <= kSmallImageSizeThreshold
233        || srcHeight <= kSmallImageSizeThreshold
234        || destWidth <= kSmallImageSizeThreshold
235        || destHeight <= kSmallImageSizeThreshold) {
236        // Small image detected.
237
238        // Resample in the case where the new size would be non-integral.
239        // This can cause noticeable breaks in repeating patterns, except
240        // when the source image is only one pixel wide in that dimension.
241        if ((!nearlyIntegral(destWidth) && srcWidth > 1 + std::numeric_limits<float>::epsilon())
242            || (!nearlyIntegral(destHeight) && srcHeight > 1 + std::numeric_limits<float>::epsilon()))
243            return InterpolationLow;
244
245        // Otherwise, don't resample small images. These are often used for
246        // borders and rules (think 1x1 images used to make lines).
247        return InterpolationNone;
248    }
249
250    if (srcHeight * kLargeStretch <= destHeight || srcWidth * kLargeStretch <= destWidth) {
251        // Large image detected.
252
253        // Don't resample if it is being stretched a lot in only one direction.
254        // This is trying to catch cases where somebody has created a border
255        // (which might be large) and then is stretching it to fill some part
256        // of the page.
257        if (widthNearlyEqual || heightNearlyEqual)
258            return InterpolationNone;
259
260        // The image is growing a lot and in more than one direction. Resampling
261        // is slow and doesn't give us very much when growing a lot.
262        return InterpolationLow;
263    }
264
265    if ((diffWidth / srcWidth < kFractionalChangeThreshold)
266        && (diffHeight / srcHeight < kFractionalChangeThreshold)) {
267        // It is disappointingly common on the web for image sizes to be off by
268        // one or two pixels. We don't bother resampling if the size difference
269        // is a small fraction of the original size.
270        return InterpolationNone;
271    }
272
273    // When the image is not yet done loading, use linear. We don't cache the
274    // partially resampled images, and as they come in incrementally, it causes
275    // us to have to resample the whole thing every time.
276    if (!isDataComplete)
277        return InterpolationLow;
278
279    // Everything else gets resampled.
280    // High quality interpolation only enabled for scaling and translation.
281    if (!(matrix.getType() & (SkMatrix::kAffine_Mask | SkMatrix::kPerspective_Mask)))
282        return InterpolationHigh;
283
284    return InterpolationLow;
285}
286
287
288bool shouldDrawAntiAliased(const GraphicsContext* context, const SkRect& destRect)
289{
290    if (!context->shouldAntialias())
291        return false;
292    const SkMatrix totalMatrix = context->getTotalMatrix();
293    // Don't disable anti-aliasing if we're rotated or skewed.
294    if (!totalMatrix.rectStaysRect())
295        return true;
296    // Disable anti-aliasing for scales or n*90 degree rotations.
297    // Allow to opt out of the optimization though for "hairline" geometry
298    // images - using the shouldAntialiasHairlineImages() GraphicsContext flag.
299    if (!context->shouldAntialiasHairlineImages())
300        return false;
301    // Check if the dimensions of the destination are "small" (less than one
302    // device pixel). To prevent sudden drop-outs. Since we know that
303    // kRectStaysRect_Mask is set, the matrix either has scale and no skew or
304    // vice versa. We can query the kAffine_Mask flag to determine which case
305    // it is.
306    // FIXME: This queries the CTM while drawing, which is generally
307    // discouraged. Always drawing with AA can negatively impact performance
308    // though - that's why it's not always on.
309    SkScalar widthExpansion, heightExpansion;
310    if (totalMatrix.getType() & SkMatrix::kAffine_Mask)
311        widthExpansion = totalMatrix[SkMatrix::kMSkewY], heightExpansion = totalMatrix[SkMatrix::kMSkewX];
312    else
313        widthExpansion = totalMatrix[SkMatrix::kMScaleX], heightExpansion = totalMatrix[SkMatrix::kMScaleY];
314    return destRect.width() * fabs(widthExpansion) < 1 || destRect.height() * fabs(heightExpansion) < 1;
315}
316
317}  // namespace blink
318