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| 1 /* | |
| 2 * Copyright 2015 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 #ifndef SkCodecTools_DEFINED | |
| 9 #define SkCodecTools_DEFINED | |
| 10 | |
| 11 inline float get_scale_from_sample_size(uint32_t sampleSize) { | |
| 12 return 1.0f / (float) sampleSize; | |
| 13 } | |
| 14 | |
| 15 enum SubsetType { | |
| 16 kFullyInside_SubsetType, | |
| 17 kPartiallyInside_SubsetType, | |
| 18 kOutside_SubsetType, | |
| 19 }; | |
| 20 | |
| 21 /* | |
| 22 * Corrects image subset offsets and dimensions in order to perform a valid deco
de. | |
| 23 * Also indicates if the image subset should be placed at an offset within the | |
| 24 * output bitmap. | |
| 25 * | |
| 26 * Values of output variables are undefined if the SubsetType is kInvalid. | |
| 27 * | |
| 28 * @param imageDims Original image dimensions. | |
| 29 * @param subset As input, the subset that the client requested. | |
| 30 * As output, the image subset that we will decode. | |
| 31 * @param outX The left offset of the image subset within the output bitmap
. | |
| 32 * @param outY The top offset of the image subset within the output bitmap. | |
| 33 * | |
| 34 * @return An indication of how the subset is contained in the image. | |
| 35 * If the return value is kInvalid, values of output variables are undef
ined. | |
| 36 */ | |
| 37 inline SubsetType adjust_subset_rect(const SkISize& imageDims, SkIRect* subset,
int* outX, | |
| 38 int* outY) { | |
| 39 // These must be at least zero, we can't start decoding the image at a negat
ive coordinate. | |
| 40 int left = SkTMax(0, subset->fLeft); | |
| 41 int top = SkTMax(0, subset->fTop); | |
| 42 | |
| 43 // If input offsets are less than zero, we decode to an offset location in t
he output bitmap. | |
| 44 *outX = left - subset->fLeft; | |
| 45 *outY = top - subset->fTop; | |
| 46 | |
| 47 // Make sure we don't decode pixels past the edge of the image or past the e
dge of the subset. | |
| 48 int width = SkTMin(imageDims.width() - left, subset->width() - *outX); | |
| 49 int height = SkTMin(imageDims.height() - top, subset->height() - *outY); | |
| 50 if (width <= 0 || height <= 0) { | |
| 51 return SubsetType::kOutside_SubsetType; | |
| 52 } | |
| 53 | |
| 54 subset->setXYWH(left, top, width, height); | |
| 55 if ((*outX != 0) || (*outY != 0) || (width != subset->width()) || | |
| 56 (height != subset->height())) { | |
| 57 return SubsetType::kPartiallyInside_SubsetType; | |
| 58 } | |
| 59 | |
| 60 return SubsetType::kFullyInside_SubsetType; | |
| 61 } | |
| 62 | |
| 63 #endif // SkCodecTools_DEFINED | |
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