reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 1 | /* libs/graphics/effects/SkShaderExtras.cpp |
| 2 | ** |
| 3 | ** Copyright 2006, The Android Open Source Project |
| 4 | ** |
| 5 | ** Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | ** you may not use this file except in compliance with the License. |
| 7 | ** You may obtain a copy of the License at |
| 8 | ** |
| 9 | ** http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | ** |
| 11 | ** Unless required by applicable law or agreed to in writing, software |
| 12 | ** distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | ** See the License for the specific language governing permissions and |
| 15 | ** limitations under the License. |
| 16 | */ |
| 17 | |
| 18 | #include "SkComposeShader.h" |
| 19 | #include "SkColorFilter.h" |
| 20 | #include "SkColorPriv.h" |
| 21 | #include "SkXfermode.h" |
| 22 | |
| 23 | ////////////////////////////////////////////////////////////////////////////////////// |
| 24 | |
| 25 | SkComposeShader::SkComposeShader(SkShader* sA, SkShader* sB, SkXfermode* mode) |
| 26 | { |
| 27 | fShaderA = sA; sA->ref(); |
| 28 | fShaderB = sB; sB->ref(); |
| 29 | // mode may be null |
| 30 | fMode = mode; mode->safeRef(); |
| 31 | } |
| 32 | |
| 33 | SkComposeShader::SkComposeShader(SkFlattenableReadBuffer& buffer) : |
| 34 | INHERITED(buffer) |
| 35 | { |
| 36 | fShaderA = static_cast<SkShader*>(buffer.readFlattenable()); |
| 37 | fShaderB = static_cast<SkShader*>(buffer.readFlattenable()); |
| 38 | fMode = static_cast<SkXfermode*>(buffer.readFlattenable()); |
| 39 | } |
| 40 | |
| 41 | SkComposeShader::~SkComposeShader() |
| 42 | { |
| 43 | fMode->safeUnref(); // may be null |
| 44 | fShaderB->unref(); |
| 45 | fShaderA->unref(); |
| 46 | } |
| 47 | |
| 48 | void SkComposeShader::beginSession() |
| 49 | { |
| 50 | this->INHERITED::beginSession(); |
| 51 | fShaderA->beginSession(); |
| 52 | fShaderB->beginSession(); |
| 53 | } |
| 54 | |
| 55 | void SkComposeShader::endSession() |
| 56 | { |
| 57 | fShaderA->endSession(); |
| 58 | fShaderB->endSession(); |
| 59 | this->INHERITED::endSession(); |
| 60 | } |
| 61 | |
| 62 | class SkAutoAlphaRestore { |
| 63 | public: |
| 64 | SkAutoAlphaRestore(SkPaint* paint, uint8_t newAlpha) |
| 65 | { |
| 66 | fAlpha = paint->getAlpha(); |
| 67 | fPaint = paint; |
| 68 | paint->setAlpha(newAlpha); |
| 69 | } |
| 70 | ~SkAutoAlphaRestore() |
| 71 | { |
| 72 | fPaint->setAlpha(fAlpha); |
| 73 | } |
| 74 | private: |
| 75 | SkPaint* fPaint; |
| 76 | uint8_t fAlpha; |
| 77 | }; |
| 78 | |
| 79 | void SkComposeShader::flatten(SkFlattenableWriteBuffer& buffer) |
| 80 | { |
| 81 | this->INHERITED::flatten(buffer); |
| 82 | buffer.writeFlattenable(fShaderA); |
| 83 | buffer.writeFlattenable(fShaderB); |
| 84 | buffer.writeFlattenable(fMode); |
| 85 | } |
| 86 | |
| 87 | /* We call setContext on our two worker shaders. However, we |
| 88 | always let them see opaque alpha, and if the paint really |
| 89 | is translucent, then we apply that after the fact. |
| 90 | */ |
| 91 | bool SkComposeShader::setContext(const SkBitmap& device, |
| 92 | const SkPaint& paint, |
| 93 | const SkMatrix& matrix) |
| 94 | { |
| 95 | if (!this->INHERITED::setContext(device, paint, matrix)) |
| 96 | return false; |
| 97 | |
| 98 | // we preconcat our localMatrix (if any) with the device matrix |
| 99 | // before calling our sub-shaders |
| 100 | |
| 101 | SkMatrix tmpM; |
| 102 | |
| 103 | (void)this->getLocalMatrix(&tmpM); |
| 104 | tmpM.setConcat(matrix, tmpM); |
| 105 | |
| 106 | SkAutoAlphaRestore restore(const_cast<SkPaint*>(&paint), 0xFF); |
| 107 | |
| 108 | return fShaderA->setContext(device, paint, tmpM) && |
| 109 | fShaderB->setContext(device, paint, tmpM); |
| 110 | } |
| 111 | |
| 112 | // larger is better (fewer times we have to loop), but we shouldn't |
| 113 | // take up too much stack-space (each element is 4 bytes) |
| 114 | #define TMP_COLOR_COUNT 64 |
| 115 | |
| 116 | void SkComposeShader::shadeSpan(int x, int y, SkPMColor result[], int count) |
| 117 | { |
| 118 | SkShader* shaderA = fShaderA; |
| 119 | SkShader* shaderB = fShaderB; |
| 120 | SkXfermode* mode = fMode; |
| 121 | unsigned scale = SkAlpha255To256(this->getPaintAlpha()); |
| 122 | |
| 123 | SkPMColor tmp[TMP_COLOR_COUNT]; |
| 124 | |
| 125 | if (NULL == mode) // implied SRC_OVER |
| 126 | { |
| 127 | do { |
| 128 | int n = count; |
| 129 | if (n > TMP_COLOR_COUNT) |
| 130 | n = TMP_COLOR_COUNT; |
| 131 | |
| 132 | shaderA->shadeSpan(x, y, result, n); |
| 133 | shaderB->shadeSpan(x, y, tmp, n); |
| 134 | |
| 135 | if (256 == scale) |
| 136 | { |
| 137 | for (int i = 0; i < n; i++) |
| 138 | result[i] = SkPMSrcOver(tmp[i], result[i]); |
| 139 | } |
| 140 | else |
| 141 | { |
| 142 | for (int i = 0; i < n; i++) |
| 143 | result[i] = SkAlphaMulQ(SkPMSrcOver(tmp[i], result[i]), scale); |
| 144 | } |
| 145 | |
| 146 | result += n; |
| 147 | x += n; |
| 148 | count -= n; |
| 149 | } while (count > 0); |
| 150 | } |
| 151 | else // use mode for the composition |
| 152 | { |
| 153 | do { |
| 154 | int n = count; |
| 155 | if (n > TMP_COLOR_COUNT) |
| 156 | n = TMP_COLOR_COUNT; |
| 157 | |
| 158 | shaderA->shadeSpan(x, y, result, n); |
| 159 | shaderB->shadeSpan(x, y, tmp, n); |
| 160 | mode->xfer32(result, tmp, n, NULL); |
| 161 | |
| 162 | if (256 == scale) |
| 163 | { |
| 164 | for (int i = 0; i < n; i++) |
| 165 | result[i] = SkAlphaMulQ(result[i], scale); |
| 166 | } |
| 167 | |
| 168 | result += n; |
| 169 | x += n; |
| 170 | count -= n; |
| 171 | } while (count > 0); |
| 172 | } |
| 173 | } |
| 174 | |