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