SkLerpXfermode.cpp revision 0f10f7bf1fb43ca6346dc220a076773b1f19a367 
1/*
2 * Copyright 2013 Google Inc.
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 "SkLerpXfermode.h"
9#include "SkColorPriv.h"
10#include "SkReadBuffer.h"
11#include "SkWriteBuffer.h"
12#include "SkString.h"
13
14SkXfermode* SkLerpXfermode::Create(SkScalar scale) {
15    int scale256 = SkScalarRoundToInt(scale * 256);
16    if (scale256 >= 256) {
17        return SkXfermode::Create(SkXfermode::kSrc_Mode);
18    } else if (scale256 <= 0) {
19        return SkXfermode::Create(SkXfermode::kDst_Mode);
20    }
21    return SkNEW_ARGS(SkLerpXfermode, (scale256));
22}
23
24SkLerpXfermode::SkLerpXfermode(unsigned scale256) : fScale256(scale256) {}
25
26SkLerpXfermode::SkLerpXfermode(SkReadBuffer& buffer)
27    : INHERITED(buffer) {
28    fScale256 = buffer.readUInt();
29}
30
31void SkLerpXfermode::flatten(SkWriteBuffer& buffer) const {
32    this->INHERITED::flatten(buffer);
33    buffer.writeUInt(fScale256);
34}
35
36void SkLerpXfermode::xfer32(SkPMColor dst[], const SkPMColor src[], int count,
37                             const SkAlpha aa[]) const {
38    const int scale = fScale256;
39
40    if (aa) {
41        for (int i = 0; i < count; ++i) {
42            unsigned a = aa[i];
43            if (a) {
44                SkPMColor dstC = dst[i];
45                SkPMColor resC = SkFastFourByteInterp256(src[i], dstC, scale);
46                if (a < 255) {
47                    resC = SkFastFourByteInterp256(resC, dstC, a + (a >> 7));
48                }
49                dst[i] = resC;
50            }
51        }
52    } else {
53        for (int i = 0; i < count; ++i) {
54            dst[i] = SkFastFourByteInterp256(src[i], dst[i], scale);
55        }
56    }
57}
58
59void SkLerpXfermode::xfer16(uint16_t dst[], const SkPMColor src[], int count,
60                             const SkAlpha aa[]) const {
61    const int scale = fScale256;
62
63    if (aa) {
64        for (int i = 0; i < count; ++i) {
65            unsigned a = aa[i];
66            if (a) {
67                SkPMColor dstC = SkPixel16ToPixel32(dst[i]);
68                SkPMColor resC = SkFastFourByteInterp256(src[i], dstC, scale);
69                if (a < 255) {
70                    resC = SkFastFourByteInterp256(resC, dstC, a + (a >> 7));
71                }
72                dst[i] = SkPixel32ToPixel16(resC);
73            }
74        }
75    } else {
76        for (int i = 0; i < count; ++i) {
77            SkPMColor dstC = SkPixel16ToPixel32(dst[i]);
78            SkPMColor resC = SkFastFourByteInterp256(src[i], dstC, scale);
79            dst[i] = SkPixel32ToPixel16(resC);
80        }
81    }
82}
83
84void SkLerpXfermode::xferA8(SkAlpha dst[], const SkPMColor src[], int count,
85                             const SkAlpha aa[]) const {
86    const int scale = fScale256;
87
88    if (aa) {
89        for (int i = 0; i < count; ++i) {
90            unsigned a = aa[i];
91            if (a) {
92                unsigned dstA = dst[i];
93                unsigned resA = SkAlphaBlend(SkGetPackedA32(src[i]), dstA, scale);
94                if (a < 255) {
95                    resA = SkAlphaBlend(resA, dstA, a + (a >> 7));
96                }
97                dst[i] = resA;
98            }
99        }
100    } else {
101        for (int i = 0; i < count; ++i) {
102            dst[i] = SkAlphaBlend(SkGetPackedA32(src[i]), dst[i], scale);
103        }
104    }
105}
106
107#ifndef SK_IGNORE_TO_STRING
108void SkLerpXfermode::toString(SkString* str) const {
109    str->printf("SkLerpXfermode: scale: %g", fScale256 / 256.0);
110}
111#endif
112