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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 #include "SkBitmapRegionCanvas.h" | |
9 #include "SkCanvas.h" | |
10 #include "SkCodecPriv.h" | |
11 #include "SkCodecTools.h" | |
12 | |
13 SkBitmapRegionCanvas::SkBitmapRegionCanvas(SkCodec* decoder) | |
14 : INHERITED(decoder->getInfo().width(), decoder->getInfo().height()) | |
15 , fDecoder(decoder) | |
16 {} | |
17 | |
18 bool SkBitmapRegionCanvas::decodeRegion(SkBitmap* bitmap, SkBitmap::Allocator* a
llocator, | |
19 const SkIRect& desiredSubset, int sampleSize, SkColorType dstColorType, | |
20 bool requireUnpremul) { | |
21 // Reject color types not supported by this method | |
22 if (kIndex_8_SkColorType == dstColorType || kGray_8_SkColorType == dstColorT
ype) { | |
23 SkCodecPrintf("Error: Color type not supported.\n"); | |
24 return false; | |
25 } | |
26 | |
27 // Reject requests for unpremultiplied alpha | |
28 if (requireUnpremul) { | |
29 SkCodecPrintf("Error: Alpha type not supported.\n"); | |
30 return false; | |
31 } | |
32 SkAlphaType dstAlphaType = fDecoder->getInfo().alphaType(); | |
33 if (kUnpremul_SkAlphaType == dstAlphaType) { | |
34 dstAlphaType = kPremul_SkAlphaType; | |
35 } | |
36 | |
37 // FIXME: Can we add checks and support kIndex8 or unpremultiplied alpha in
special cases? | |
38 | |
39 // Fix the input sampleSize if necessary. | |
40 if (sampleSize < 1) { | |
41 sampleSize = 1; | |
42 } | |
43 | |
44 // The size of the output bitmap is determined by the size of the | |
45 // requested subset, not by the size of the intersection of the subset | |
46 // and the image dimensions. | |
47 // If inputX is negative, we will need to place decoded pixels into the | |
48 // output bitmap starting at a left offset. Call this outX. | |
49 // If outX is non-zero, subsetX must be zero. | |
50 // If inputY is negative, we will need to place decoded pixels into the | |
51 // output bitmap starting at a top offset. Call this outY. | |
52 // If outY is non-zero, subsetY must be zero. | |
53 int outX; | |
54 int outY; | |
55 SkIRect subset = desiredSubset; | |
56 SubsetType type = adjust_subset_rect(fDecoder->getInfo().dimensions(), &subs
et, &outX, &outY); | |
57 if (SubsetType::kOutside_SubsetType == type) { | |
58 return false; | |
59 } | |
60 | |
61 // Create the image info for the decode | |
62 SkImageInfo decodeInfo = SkImageInfo::Make(this->width(), this->height(), | |
63 dstColorType, dstAlphaType); | |
64 | |
65 // Start the scanline decoder | |
66 SkCodec::Result r = fDecoder->startScanlineDecode(decodeInfo); | |
67 if (SkCodec::kSuccess != r) { | |
68 SkCodecPrintf("Error: Could not start scanline decoder.\n"); | |
69 return false; | |
70 } | |
71 | |
72 // Allocate a bitmap for the unscaled decode | |
73 SkBitmap tmp; | |
74 SkImageInfo tmpInfo = decodeInfo.makeWH(this->width(), subset.height()); | |
75 if (!tmp.tryAllocPixels(tmpInfo)) { | |
76 SkCodecPrintf("Error: Could not allocate pixels.\n"); | |
77 return false; | |
78 } | |
79 | |
80 // Skip the unneeded rows | |
81 if (!fDecoder->skipScanlines(subset.y())) { | |
82 SkCodecPrintf("Error: Failed to skip scanlines.\n"); | |
83 return false; | |
84 } | |
85 | |
86 // Decode the necessary rows | |
87 fDecoder->getScanlines(tmp.getAddr(0, 0), subset.height(), tmp.rowBytes()); | |
88 | |
89 // Calculate the size of the output | |
90 const int outWidth = get_scaled_dimension(desiredSubset.width(), sampleSize)
; | |
91 const int outHeight = get_scaled_dimension(desiredSubset.height(), sampleSiz
e); | |
92 | |
93 // Initialize the destination bitmap | |
94 SkImageInfo dstInfo = decodeInfo.makeWH(outWidth, outHeight); | |
95 bitmap->setInfo(dstInfo, dstInfo.minRowBytes()); | |
96 if (!bitmap->tryAllocPixels(allocator, nullptr)) { | |
97 SkCodecPrintf("Error: Could not allocate pixels.\n"); | |
98 return false; | |
99 } | |
100 | |
101 // Zero the bitmap if the region is not completely within the image. | |
102 // TODO (msarett): Can we make this faster by implementing it to only | |
103 // zero parts of the image that we won't overwrite with | |
104 // pixels? | |
105 // TODO (msarett): This could be skipped if memory is zero initialized. | |
106 // This would matter if this code is moved to Android and | |
107 // uses Android bitmaps. | |
108 if (SubsetType::kPartiallyInside_SubsetType == type) { | |
109 bitmap->eraseColor(0); | |
110 } | |
111 | |
112 // Use a canvas to crop and scale to the destination bitmap | |
113 SkCanvas canvas(*bitmap); | |
114 // TODO (msarett): Maybe we can take advantage of the fact that SkRect uses
floats? | |
115 SkRect src = SkRect::MakeXYWH((SkScalar) subset.x(), (SkScalar) 0, | |
116 (SkScalar) subset.width(), (SkScalar) subset.height()); | |
117 SkRect dst = SkRect::MakeXYWH((SkScalar) (outX / sampleSize), (SkScalar) (ou
tY / sampleSize), | |
118 (SkScalar) get_scaled_dimension(subset.width(), sampleSize), | |
119 (SkScalar) get_scaled_dimension(subset.height(), sampleSize)); | |
120 SkPaint paint; | |
121 // Overwrite the dst with the src pixels | |
122 paint.setXfermodeMode(SkXfermode::kSrc_Mode); | |
123 // TODO (msarett): Test multiple filter qualities. kNone is the default. | |
124 canvas.drawBitmapRect(tmp, src, dst, &paint); | |
125 | |
126 return true; | |
127 } | |
128 | |
129 bool SkBitmapRegionCanvas::conversionSupported(SkColorType colorType) { | |
130 // SkCanvas does not draw to these color types. | |
131 if (kIndex_8_SkColorType == colorType || kGray_8_SkColorType == colorType) { | |
132 return false; | |
133 } | |
134 | |
135 // FIXME: Call virtual function when it lands. | |
136 SkImageInfo info = SkImageInfo::Make(0, 0, colorType, fDecoder->getInfo().al
phaType(), | |
137 fDecoder->getInfo().profileType()); | |
138 return conversion_possible(info, fDecoder->getInfo()); | |
139 } | |
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