vcl/source/bitmap/BitmapSobelGreyFilter.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  */
  10
  11 #include <sal/config.h>
  12
  13 #include <vcl/bitmap.hxx>
  14 #include <vcl/bitmapex.hxx>
  15 #include <vcl/BitmapSobelGreyFilter.hxx>
  16
  17 #include <bitmap/BitmapWriteAccess.hxx>
  18
  19 #include <algorithm>
  20
  21 BitmapEx BitmapSobelGreyFilter::execute(BitmapEx const& rBitmapEx) const
  22 {
  23     Bitmap aBitmap(rBitmapEx.GetBitmap());
  24
  25     if (!aBitmap.ImplMakeGreyscales())
  26         return BitmapEx();
  27
  28     Bitmap::ScopedReadAccess pReadAcc(aBitmap);
  29     if (!pReadAcc)
  30         return BitmapEx();
  31
  32     Bitmap aNewBmp(aBitmap.GetSizePixel(), vcl::PixelFormat::N8_BPP, &pReadAcc->GetPalette());
  33     BitmapScopedWriteAccess pWriteAcc(aNewBmp);
  34     if (!pWriteAcc)
  35         return BitmapEx();
  36
  37     BitmapColor aGrey(sal_uInt8(0));
  38     const sal_Int32 nWidth = pWriteAcc->Width();
  39     const sal_Int32 nHeight = pWriteAcc->Height();
  40     const sal_Int32 nMask111 = -1, nMask121 = 0, nMask131 = 1;
  41     const sal_Int32 nMask211 = -2, nMask221 = 0, nMask231 = 2;
  42     const sal_Int32 nMask311 = -1, nMask321 = 0, nMask331 = 1;
  43     const sal_Int32 nMask112 = 1, nMask122 = 2, nMask132 = 1;
  44     const sal_Int32 nMask212 = 0, nMask222 = 0, nMask232 = 0;
  45     const sal_Int32 nMask312 = -1, nMask322 = -2, nMask332 = -1;
  46     sal_Int32 nGrey11, nGrey12, nGrey13;
  47     sal_Int32 nGrey21, nGrey22, nGrey23;
  48     sal_Int32 nGrey31, nGrey32, nGrey33;
  49     std::unique_ptr<long[]> pHMap(new long[nWidth + 2]);
  50     std::unique_ptr<long[]> pVMap(new long[nHeight + 2]);
  51     sal_Int32 nX, nY, nSum1, nSum2;
  52
  53     // fill mapping tables
  54     pHMap[0] = 0;
  55
  56     for (nX = 1; nX <= nWidth; nX++)
  57     {
  58         pHMap[nX] = nX - 1;
  59     }
  60
  61     pHMap[nWidth + 1] = nWidth - 1;
  62
  63     pVMap[0] = 0;
  64
  65     for (nY = 1; nY <= nHeight; nY++)
  66     {
  67         pVMap[nY] = nY - 1;
  68     }
  69
  70     pVMap[nHeight + 1] = nHeight - 1;
  71
  72     for (nY = 0; nY < nHeight; nY++)
  73     {
  74         nGrey11 = pReadAcc->GetPixel(pVMap[nY], pHMap[0]).GetIndex();
  75         nGrey12 = pReadAcc->GetPixel(pVMap[nY], pHMap[1]).GetIndex();
  76         nGrey13 = pReadAcc->GetPixel(pVMap[nY], pHMap[2]).GetIndex();
  77         nGrey21 = pReadAcc->GetPixel(pVMap[nY + 1], pHMap[0]).GetIndex();
  78         nGrey22 = pReadAcc->GetPixel(pVMap[nY + 1], pHMap[1]).GetIndex();
  79         nGrey23 = pReadAcc->GetPixel(pVMap[nY + 1], pHMap[2]).GetIndex();
  80         nGrey31 = pReadAcc->GetPixel(pVMap[nY + 2], pHMap[0]).GetIndex();
  81         nGrey32 = pReadAcc->GetPixel(pVMap[nY + 2], pHMap[1]).GetIndex();
  82         nGrey33 = pReadAcc->GetPixel(pVMap[nY + 2], pHMap[2]).GetIndex();
  83
  84         Scanline pScanline = pWriteAcc->GetScanline(nY);
  85         for (nX = 0; nX < nWidth; nX++)
  86         {
  87             nSum1 = nSum2 = 0;
  88
  89             nSum1 += nMask111 * nGrey11;
  90             nSum2 += nMask112 * nGrey11;
  91
  92             nSum1 += nMask121 * nGrey12;
  93             nSum2 += nMask122 * nGrey12;
  94
  95             nSum1 += nMask131 * nGrey13;
  96             nSum2 += nMask132 * nGrey13;
  97
  98             nSum1 += nMask211 * nGrey21;
  99             nSum2 += nMask212 * nGrey21;
 100
 101             nSum1 += nMask221 * nGrey22;
 102             nSum2 += nMask222 * nGrey22;
 103
 104             nSum1 += nMask231 * nGrey23;
 105             nSum2 += nMask232 * nGrey23;
 106
 107             nSum1 += nMask311 * nGrey31;
 108             nSum2 += nMask312 * nGrey31;
 109
 110             nSum1 += nMask321 * nGrey32;
 111             nSum2 += nMask322 * nGrey32;
 112
 113             nSum1 += nMask331 * nGrey33;
 114             nSum2 += nMask332 * nGrey33;
 115
 116             nSum1 = static_cast<sal_Int32>(std::hypot(nSum1, nSum2));
 117
 118             aGrey.SetIndex(
 119                 ~static_cast<sal_uInt8>(std::clamp(nSum1, sal_Int32(0), sal_Int32(255))));
 120             pWriteAcc->SetPixelOnData(pScanline, nX, aGrey);
 121
 122             if (nX < (nWidth - 1))
 123             {
 124                 const sal_Int32 nNextX = pHMap[nX + 3];
 125
 126                 nGrey11 = nGrey12;
 127                 nGrey12 = nGrey13;
 128                 nGrey13 = pReadAcc->GetPixel(pVMap[nY], nNextX).GetIndex();
 129                 nGrey21 = nGrey22;
 130                 nGrey22 = nGrey23;
 131                 nGrey23 = pReadAcc->GetPixel(pVMap[nY + 1], nNextX).GetIndex();
 132                 nGrey31 = nGrey32;
 133                 nGrey32 = nGrey33;
 134                 nGrey33 = pReadAcc->GetPixel(pVMap[nY + 2], nNextX).GetIndex();
 135             }
 136         }
 137     }
 138
 139     pHMap.reset();
 140     pVMap.reset();
 141     pWriteAcc.reset();
 142     pReadAcc.reset();
 143
 144     const MapMode aMap(aBitmap.GetPrefMapMode());
 145     const Size aPrefSize(aBitmap.GetPrefSize());
 146
 147     aBitmap = aNewBmp;
 148
 149     aBitmap.SetPrefMapMode(aMap);
 150     aBitmap.SetPrefSize(aPrefSize);
 151
 152     return BitmapEx(aBitmap);
 153 }
 154
 155 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */