summaryrefslogtreecommitdiff
path: root/effects/gradients/SkTwoPointConicalGradient.cpp
blob: 9d1f8f1a821441b96d0e9bf16a856e3dfcac0755 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
/*
 * Copyright 2012 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkTwoPointConicalGradient.h"

#include "SkTwoPointConicalGradient_gpu.h"

struct TwoPtRadialContext {
    const TwoPtRadial&  fRec;
    float               fRelX, fRelY;
    const float         fIncX, fIncY;
    float               fB;
    const float         fDB;

    TwoPtRadialContext(const TwoPtRadial& rec, SkScalar fx, SkScalar fy,
                       SkScalar dfx, SkScalar dfy);
    SkFixed nextT();
};

static int valid_divide(float numer, float denom, float* ratio) {
    SkASSERT(ratio);
    if (0 == denom) {
        return 0;
    }
    *ratio = numer / denom;
    return 1;
}

// Return the number of distinct real roots, and write them into roots[] in
// ascending order
static int find_quad_roots(float A, float B, float C, float roots[2], bool descendingOrder = false) {
    SkASSERT(roots);

    if (A == 0) {
        return valid_divide(-C, B, roots);
    }

    float R = B*B - 4*A*C;
    if (R < 0) {
        return 0;
    }
    R = sk_float_sqrt(R);

#if 1
    float Q = B;
    if (Q < 0) {
        Q -= R;
    } else {
        Q += R;
    }
#else
    // on 10.6 this was much slower than the above branch :(
    float Q = B + copysignf(R, B);
#endif
    Q *= -0.5f;
    if (0 == Q) {
        roots[0] = 0;
        return 1;
    }

    float r0 = Q / A;
    float r1 = C / Q;
    roots[0] = r0 < r1 ? r0 : r1;
    roots[1] = r0 > r1 ? r0 : r1;
    if (descendingOrder) {
        SkTSwap(roots[0], roots[1]);
    }
    return 2;
}

static float lerp(float x, float dx, float t) {
    return x + t * dx;
}

static float sqr(float x) { return x * x; }

void TwoPtRadial::init(const SkPoint& center0, SkScalar rad0,
                       const SkPoint& center1, SkScalar rad1,
                       bool flipped) {
    fCenterX = SkScalarToFloat(center0.fX);
    fCenterY = SkScalarToFloat(center0.fY);
    fDCenterX = SkScalarToFloat(center1.fX) - fCenterX;
    fDCenterY = SkScalarToFloat(center1.fY) - fCenterY;
    fRadius = SkScalarToFloat(rad0);
    fDRadius = SkScalarToFloat(rad1) - fRadius;

    fA = sqr(fDCenterX) + sqr(fDCenterY) - sqr(fDRadius);
    fRadius2 = sqr(fRadius);
    fRDR = fRadius * fDRadius;

    fFlipped = flipped;
}

TwoPtRadialContext::TwoPtRadialContext(const TwoPtRadial& rec, SkScalar fx, SkScalar fy,
                                       SkScalar dfx, SkScalar dfy)
    : fRec(rec)
    , fRelX(SkScalarToFloat(fx) - rec.fCenterX)
    , fRelY(SkScalarToFloat(fy) - rec.fCenterY)
    , fIncX(SkScalarToFloat(dfx))
    , fIncY(SkScalarToFloat(dfy))
    , fB(-2 * (rec.fDCenterX * fRelX + rec.fDCenterY * fRelY + rec.fRDR))
    , fDB(-2 * (rec.fDCenterX * fIncX + rec.fDCenterY * fIncY)) {}

SkFixed TwoPtRadialContext::nextT() {
    float roots[2];

    float C = sqr(fRelX) + sqr(fRelY) - fRec.fRadius2;
    int countRoots = find_quad_roots(fRec.fA, fB, C, roots, fRec.fFlipped);

    fRelX += fIncX;
    fRelY += fIncY;
    fB += fDB;

    if (0 == countRoots) {
        return TwoPtRadial::kDontDrawT;
    }

    // Prefer the bigger t value if both give a radius(t) > 0
    // find_quad_roots returns the values sorted, so we start with the last
    float t = roots[countRoots - 1];
    float r = lerp(fRec.fRadius, fRec.fDRadius, t);
    if (r <= 0) {
        t = roots[0];   // might be the same as roots[countRoots-1]
        r = lerp(fRec.fRadius, fRec.fDRadius, t);
        if (r <= 0) {
            return TwoPtRadial::kDontDrawT;
        }
    }
    return SkFloatToFixed(t);
}

typedef void (*TwoPointConicalProc)(TwoPtRadialContext* rec, SkPMColor* dstC,
                                    const SkPMColor* cache, int toggle, int count);

static void twopoint_clamp(TwoPtRadialContext* rec, SkPMColor* SK_RESTRICT dstC,
                           const SkPMColor* SK_RESTRICT cache, int toggle,
                           int count) {
    for (; count > 0; --count) {
        SkFixed t = rec->nextT();
        if (TwoPtRadial::DontDrawT(t)) {
            *dstC++ = 0;
        } else {
            SkFixed index = SkClampMax(t, 0xFFFF);
            SkASSERT(index <= 0xFFFF);
            *dstC++ = cache[toggle +
                            (index >> SkGradientShaderBase::kCache32Shift)];
        }
        toggle = next_dither_toggle(toggle);
    }
}

static void twopoint_repeat(TwoPtRadialContext* rec, SkPMColor* SK_RESTRICT dstC,
                            const SkPMColor* SK_RESTRICT cache, int toggle,
                            int count) {
    for (; count > 0; --count) {
        SkFixed t = rec->nextT();
        if (TwoPtRadial::DontDrawT(t)) {
            *dstC++ = 0;
        } else {
            SkFixed index = repeat_tileproc(t);
            SkASSERT(index <= 0xFFFF);
            *dstC++ = cache[toggle +
                            (index >> SkGradientShaderBase::kCache32Shift)];
        }
        toggle = next_dither_toggle(toggle);
    }
}

static void twopoint_mirror(TwoPtRadialContext* rec, SkPMColor* SK_RESTRICT dstC,
                            const SkPMColor* SK_RESTRICT cache, int toggle,
                            int count) {
    for (; count > 0; --count) {
        SkFixed t = rec->nextT();
        if (TwoPtRadial::DontDrawT(t)) {
            *dstC++ = 0;
        } else {
            SkFixed index = mirror_tileproc(t);
            SkASSERT(index <= 0xFFFF);
            *dstC++ = cache[toggle +
                            (index >> SkGradientShaderBase::kCache32Shift)];
        }
        toggle = next_dither_toggle(toggle);
    }
}

void SkTwoPointConicalGradient::init() {
    fRec.init(fCenter1, fRadius1, fCenter2, fRadius2, fFlippedGrad);
    fPtsToUnit.reset();
}

/////////////////////////////////////////////////////////////////////

SkTwoPointConicalGradient::SkTwoPointConicalGradient(
        const SkPoint& start, SkScalar startRadius,
        const SkPoint& end, SkScalar endRadius,
        bool flippedGrad, const Descriptor& desc,
        const SkMatrix* localMatrix)
    : SkGradientShaderBase(desc, localMatrix),
    fCenter1(start),
    fCenter2(end),
    fRadius1(startRadius),
    fRadius2(endRadius),
    fFlippedGrad(flippedGrad) {
    // this is degenerate, and should be caught by our caller
    SkASSERT(fCenter1 != fCenter2 || fRadius1 != fRadius2);
    this->init();
}

bool SkTwoPointConicalGradient::isOpaque() const {
    // Because areas outside the cone are left untouched, we cannot treat the
    // shader as opaque even if the gradient itself is opaque.
    // TODO(junov): Compute whether the cone fills the plane crbug.com/222380
    return false;
}

size_t SkTwoPointConicalGradient::contextSize() const {
    return sizeof(TwoPointConicalGradientContext);
}

SkShader::Context* SkTwoPointConicalGradient::createContext(
        const SkBitmap& device, const SkPaint& paint,
        const SkMatrix& matrix, void* storage) const {
    if (!this->validContext(device, paint, matrix)) {
        return NULL;
    }

    return SkNEW_PLACEMENT_ARGS(storage, TwoPointConicalGradientContext,
                                (*this, device, paint, matrix));
}

SkTwoPointConicalGradient::TwoPointConicalGradientContext::TwoPointConicalGradientContext(
        const SkTwoPointConicalGradient& shader, const SkBitmap& device,
        const SkPaint& paint, const SkMatrix& matrix)
    : INHERITED(shader, device, paint, matrix)
{
    // we don't have a span16 proc
    fFlags &= ~kHasSpan16_Flag;

    // in general, we might discard based on computed-radius, so clear
    // this flag (todo: sometimes we can detect that we never discard...)
    fFlags &= ~kOpaqueAlpha_Flag;
}

void SkTwoPointConicalGradient::TwoPointConicalGradientContext::shadeSpan(
        int x, int y, SkPMColor* dstCParam, int count) {
    const SkTwoPointConicalGradient& twoPointConicalGradient =
            static_cast<const SkTwoPointConicalGradient&>(fShader);

    int toggle = init_dither_toggle(x, y);

    SkASSERT(count > 0);

    SkPMColor* SK_RESTRICT dstC = dstCParam;

    SkMatrix::MapXYProc dstProc = fDstToIndexProc;

    const SkPMColor* SK_RESTRICT cache = fCache->getCache32();

    TwoPointConicalProc shadeProc = twopoint_repeat;
    if (SkShader::kClamp_TileMode == twoPointConicalGradient.fTileMode) {
        shadeProc = twopoint_clamp;
    } else if (SkShader::kMirror_TileMode == twoPointConicalGradient.fTileMode) {
        shadeProc = twopoint_mirror;
    } else {
        SkASSERT(SkShader::kRepeat_TileMode == twoPointConicalGradient.fTileMode);
    }

    if (fDstToIndexClass != kPerspective_MatrixClass) {
        SkPoint srcPt;
        dstProc(fDstToIndex, SkIntToScalar(x) + SK_ScalarHalf,
                SkIntToScalar(y) + SK_ScalarHalf, &srcPt);
        SkScalar dx, fx = srcPt.fX;
        SkScalar dy, fy = srcPt.fY;

        if (fDstToIndexClass == kFixedStepInX_MatrixClass) {
            SkFixed fixedX, fixedY;
            (void)fDstToIndex.fixedStepInX(SkIntToScalar(y), &fixedX, &fixedY);
            dx = SkFixedToScalar(fixedX);
            dy = SkFixedToScalar(fixedY);
        } else {
            SkASSERT(fDstToIndexClass == kLinear_MatrixClass);
            dx = fDstToIndex.getScaleX();
            dy = fDstToIndex.getSkewY();
        }

        TwoPtRadialContext rec(twoPointConicalGradient.fRec, fx, fy, dx, dy);
        (*shadeProc)(&rec, dstC, cache, toggle, count);
    } else {    // perspective case
        SkScalar dstX = SkIntToScalar(x) + SK_ScalarHalf;
        SkScalar dstY = SkIntToScalar(y) + SK_ScalarHalf;
        for (; count > 0; --count) {
            SkPoint srcPt;
            dstProc(fDstToIndex, dstX, dstY, &srcPt);
            TwoPtRadialContext rec(twoPointConicalGradient.fRec, srcPt.fX, srcPt.fY, 0, 0);
            (*shadeProc)(&rec, dstC, cache, toggle, 1);

            dstX += SK_Scalar1;
            toggle = next_dither_toggle(toggle);
            dstC += 1;
        }
    }
}

SkShader::BitmapType SkTwoPointConicalGradient::asABitmap(
    SkBitmap* bitmap, SkMatrix* matrix, SkShader::TileMode* xy) const {
    SkPoint diff = fCenter2 - fCenter1;
    SkScalar diffLen = 0;

    if (bitmap) {
        this->getGradientTableBitmap(bitmap);
    }
    if (matrix) {
        diffLen = diff.length();
    }
    if (matrix) {
        if (diffLen) {
            SkScalar invDiffLen = SkScalarInvert(diffLen);
            // rotate to align circle centers with the x-axis
            matrix->setSinCos(-SkScalarMul(invDiffLen, diff.fY),
                              SkScalarMul(invDiffLen, diff.fX));
        } else {
            matrix->reset();
        }
        matrix->preTranslate(-fCenter1.fX, -fCenter1.fY);
    }
    if (xy) {
        xy[0] = fTileMode;
        xy[1] = kClamp_TileMode;
    }
    return kTwoPointConical_BitmapType;
}

// Returns the original non-sorted version of the gradient
SkShader::GradientType SkTwoPointConicalGradient::asAGradient(
    GradientInfo* info) const {
    if (info) {
        commonAsAGradient(info, fFlippedGrad);
        info->fPoint[0] = fCenter1;
        info->fPoint[1] = fCenter2;
        info->fRadius[0] = fRadius1;
        info->fRadius[1] = fRadius2;
        if (fFlippedGrad) {
            SkTSwap(info->fPoint[0], info->fPoint[1]);
            SkTSwap(info->fRadius[0], info->fRadius[1]);
        }
    }
    return kConical_GradientType;
}

SkTwoPointConicalGradient::SkTwoPointConicalGradient(
    SkReadBuffer& buffer)
    : INHERITED(buffer),
    fCenter1(buffer.readPoint()),
    fCenter2(buffer.readPoint()),
    fRadius1(buffer.readScalar()),
    fRadius2(buffer.readScalar()) {
    if (buffer.pictureVersion() >= 24 || 0 == buffer.pictureVersion()) {
        fFlippedGrad = buffer.readBool();
    } else {
        // V23_COMPATIBILITY_CODE
        // Sort gradient by radius size for old pictures
        if (fRadius2 < fRadius1) {
            SkTSwap(fCenter1, fCenter2);
            SkTSwap(fRadius1, fRadius2);
            this->flipGradientColors();
            fFlippedGrad = true;
        } else {
            fFlippedGrad = false;
        }
    }
    this->init();
};

void SkTwoPointConicalGradient::flatten(
    SkWriteBuffer& buffer) const {
    this->INHERITED::flatten(buffer);
    buffer.writePoint(fCenter1);
    buffer.writePoint(fCenter2);
    buffer.writeScalar(fRadius1);
    buffer.writeScalar(fRadius2);
    buffer.writeBool(fFlippedGrad);
}

#if SK_SUPPORT_GPU

GrEffectRef* SkTwoPointConicalGradient::asNewEffect(GrContext* context, const SkPaint&) const {
    SkASSERT(NULL != context);
    SkASSERT(fPtsToUnit.isIdentity());

    return Gr2PtConicalGradientEffect::Create(context, *this, fTileMode);
}

#else

GrEffectRef* SkTwoPointConicalGradient::asNewEffect(GrContext*, const SkPaint&) const {
    SkDEBUGFAIL("Should not call in GPU-less build");
    return NULL;
}

#endif

#ifndef SK_IGNORE_TO_STRING
void SkTwoPointConicalGradient::toString(SkString* str) const {
    str->append("SkTwoPointConicalGradient: (");

    str->append("center1: (");
    str->appendScalar(fCenter1.fX);
    str->append(", ");
    str->appendScalar(fCenter1.fY);
    str->append(") radius1: ");
    str->appendScalar(fRadius1);
    str->append(" ");

    str->append("center2: (");
    str->appendScalar(fCenter2.fX);
    str->append(", ");
    str->appendScalar(fCenter2.fY);
    str->append(") radius2: ");
    str->appendScalar(fRadius2);
    str->append(" ");

    this->INHERITED::toString(str);

    str->append(")");
}
#endif