Line data Source code
1 : /******************************************************************************
2 : *
3 : * Project: GDAL Core
4 : * Purpose: Implementation of GDALRescaledAlphaBand, a class implementing
5 : * a band mask based from a non-GDT_Byte alpha band
6 : * Author: Even Rouault, <even dot rouault at spatialys dot com>
7 : *
8 : ******************************************************************************
9 : * Copyright (c) 2014, Even Rouault <even dot rouault at spatialys dot com>
10 : *
11 : * Permission is hereby granted, free of charge, to any person obtaining a
12 : * copy of this software and associated documentation files (the "Software"),
13 : * to deal in the Software without restriction, including without limitation
14 : * the rights to use, copy, modify, merge, publish, distribute, sublicense,
15 : * and/or sell copies of the Software, and to permit persons to whom the
16 : * Software is furnished to do so, subject to the following conditions:
17 : *
18 : * The above copyright notice and this permission notice shall be included
19 : * in all copies or substantial portions of the Software.
20 : *
21 : * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
22 : * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
23 : * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
24 : * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
25 : * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
26 : * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
27 : * DEALINGS IN THE SOFTWARE.
28 : ****************************************************************************/
29 :
30 : #include "cpl_port.h"
31 : #include "gdal_priv.h"
32 :
33 : #include <cstddef>
34 :
35 : #include "cpl_error.h"
36 : #include "cpl_vsi.h"
37 : #include "gdal.h"
38 :
39 : //! @cond Doxygen_Suppress
40 : /************************************************************************/
41 : /* GDALRescaledAlphaBand() */
42 : /************************************************************************/
43 :
44 58 : GDALRescaledAlphaBand::GDALRescaledAlphaBand(GDALRasterBand *poParentIn)
45 58 : : poParent(poParentIn), pTemp(nullptr)
46 : {
47 58 : CPLAssert(poParent->GetRasterDataType() == GDT_UInt16);
48 :
49 : // Defined in GDALRasterBand.
50 58 : poDS = nullptr;
51 58 : nBand = 0;
52 :
53 58 : nRasterXSize = poParent->GetXSize();
54 58 : nRasterYSize = poParent->GetYSize();
55 :
56 58 : eDataType = GDT_Byte;
57 58 : poParent->GetBlockSize(&nBlockXSize, &nBlockYSize);
58 58 : }
59 :
60 : /************************************************************************/
61 : /* ~GDALRescaledAlphaBand() */
62 : /************************************************************************/
63 :
64 116 : GDALRescaledAlphaBand::~GDALRescaledAlphaBand()
65 : {
66 58 : VSIFree(pTemp);
67 116 : }
68 :
69 : /************************************************************************/
70 : /* IReadBlock() */
71 : /************************************************************************/
72 :
73 1 : CPLErr GDALRescaledAlphaBand::IReadBlock(int nXBlockOff, int nYBlockOff,
74 : void *pImage)
75 : {
76 1 : int nXSizeRequest = nBlockXSize;
77 1 : if (nXBlockOff * nBlockXSize + nBlockXSize > nRasterXSize)
78 0 : nXSizeRequest = nRasterXSize - nXBlockOff * nBlockXSize;
79 1 : int nYSizeRequest = nBlockYSize;
80 1 : if (nYBlockOff * nBlockYSize + nBlockYSize > nRasterYSize)
81 0 : nYSizeRequest = nRasterYSize - nYBlockOff * nBlockYSize;
82 :
83 : GDALRasterIOExtraArg sExtraArg;
84 1 : INIT_RASTERIO_EXTRA_ARG(sExtraArg);
85 :
86 1 : return IRasterIO(GF_Read, nXBlockOff * nBlockXSize,
87 1 : nYBlockOff * nBlockYSize, nXSizeRequest, nYSizeRequest,
88 : pImage, nXSizeRequest, nYSizeRequest, GDT_Byte, 1,
89 2 : nBlockXSize, &sExtraArg);
90 : }
91 :
92 : /************************************************************************/
93 : /* IRasterIO() */
94 : /************************************************************************/
95 :
96 204 : CPLErr GDALRescaledAlphaBand::IRasterIO(
97 : GDALRWFlag eRWFlag, int nXOff, int nYOff, int nXSize, int nYSize,
98 : void *pData, int nBufXSize, int nBufYSize, GDALDataType eBufType,
99 : GSpacing nPixelSpace, GSpacing nLineSpace, GDALRasterIOExtraArg *psExtraArg)
100 : {
101 : // Optimization in common use case.
102 : // This avoids triggering the block cache on this band, which helps
103 : // reducing the global block cache consumption.
104 204 : if (eRWFlag == GF_Read && eBufType == GDT_Byte && nXSize == nBufXSize &&
105 204 : nYSize == nBufYSize && nPixelSpace == 1)
106 : {
107 204 : if (pTemp == nullptr)
108 : {
109 12 : pTemp = VSI_MALLOC2_VERBOSE(sizeof(GUInt16), nRasterXSize);
110 12 : if (pTemp == nullptr)
111 : {
112 0 : return CE_Failure;
113 : }
114 : }
115 417 : for (int j = 0; j < nBufYSize; j++)
116 : {
117 : const CPLErr eErr =
118 213 : poParent->RasterIO(GF_Read, nXOff, nYOff + j, nXSize, 1, pTemp,
119 : nBufXSize, 1, GDT_UInt16, 0, 0, nullptr);
120 213 : if (eErr != CE_None)
121 0 : return eErr;
122 :
123 213 : GByte *pabyImage = static_cast<GByte *>(pData) + j * nLineSpace;
124 213 : GUInt16 *pSrc = static_cast<GUInt16 *>(pTemp);
125 :
126 5216 : for (int i = 0; i < nBufXSize; i++)
127 : {
128 : // In case the dynamics was actually 0-255 and not 0-65535 as
129 : // expected, we want to make sure non-zero alpha will still
130 : // be non-zero.
131 5003 : if (pSrc[i] > 0 && pSrc[i] < 257)
132 4001 : pabyImage[i] = 1;
133 : else
134 1002 : pabyImage[i] = static_cast<GByte>((pSrc[i] * 255) / 65535);
135 : }
136 : }
137 204 : return CE_None;
138 : }
139 :
140 0 : return GDALRasterBand::IRasterIO(eRWFlag, nXOff, nYOff, nXSize, nYSize,
141 : pData, nBufXSize, nBufYSize, eBufType,
142 0 : nPixelSpace, nLineSpace, psExtraArg);
143 : }
144 :
145 : //! @endcond
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