private static void SaveBitmapDirect(string filename, Dataset ds, int xOff, int yOff, int width, int height, int imageWidth, int imageHeight)
{
if (ds.RasterCount == 0)
return;
int[] bandMap = new int[4] { 1, 1, 1, 1 };
int channelCount = 1;
bool hasAlpha = false;
bool isIndexed = false;
int channelSize = 8;
ColorTable ct = null;
// Evaluate the bands and find out a proper image transfer format
for (int i = 0; i < ds.RasterCount; i++)
{
Band band = ds.GetRasterBand(i + 1);
if (Gdal.GetDataTypeSize(band.DataType) > 8)
channelSize = 16;
switch (band.GetRasterColorInterpretation())
{
case ColorInterp.GCI_AlphaBand:
channelCount = 4;
hasAlpha = true;
bandMap[3] = i + 1;
break;
case ColorInterp.GCI_BlueBand:
if (channelCount < 3)
channelCount = 3;
bandMap[0] = i + 1;
break;
case ColorInterp.GCI_RedBand:
if (channelCount < 3)
channelCount = 3;
bandMap[2] = i + 1;
break;
case ColorInterp.GCI_GreenBand:
if (channelCount < 3)
channelCount = 3;
bandMap[1] = i + 1;
break;
case ColorInterp.GCI_PaletteIndex:
ct = band.GetRasterColorTable();
isIndexed = true;
bandMap[0] = i + 1;
break;
case ColorInterp.GCI_GrayIndex:
isIndexed = true;
bandMap[0] = i + 1;
break;
default:
// we create the bandmap using the dataset ordering by default
if (i < 4 && bandMap[i] == 0)
{
if (channelCount < i)
channelCount = i;
bandMap[i] = i + 1;
}
break;
}
}
// find out the pixel format based on the gathered information
PixelFormat pixelFormat;
DataType dataType;
int pixelSpace;
if (isIndexed)
{
pixelFormat = PixelFormat.Format8bppIndexed;
dataType = DataType.GDT_Byte;
pixelSpace = 1;
}
else
{
if (channelCount == 1)
{
if (channelSize > 8)
{
pixelFormat = PixelFormat.Format16bppGrayScale;
dataType = DataType.GDT_Int16;
pixelSpace = 2;
}
else
{
pixelFormat = PixelFormat.Format24bppRgb;
channelCount = 3;
dataType = DataType.GDT_Byte;
pixelSpace = 3;
}
}
else
{
if (hasAlpha)
{
if (channelSize > 8)
{
pixelFormat = PixelFormat.Format64bppArgb;
dataType = DataType.GDT_UInt16;
pixelSpace = 8;
}
else
{
pixelFormat = PixelFormat.Format32bppArgb;
dataType = DataType.GDT_Byte;
pixelSpace = 4;
}
channelCount = 4;
}
else
{
if (channelSize > 8)
{
pixelFormat = PixelFormat.Format48bppRgb;
dataType = DataType.GDT_UInt16;
pixelSpace = 6;
}
else
{
pixelFormat = PixelFormat.Format24bppRgb;
dataType = DataType.GDT_Byte;
pixelSpace = 3;
}
channelCount = 3;
}
}
}
// Create a Bitmap to store the GDAL image in
Bitmap bitmap = new Bitmap(imageWidth, imageHeight, pixelFormat);
if (isIndexed)
{
// setting up the color table
if (ct != null)
{
int iCol = ct.GetCount();
ColorPalette pal = bitmap.Palette;
for (int i = 0; i < iCol; i++)
{
ColorEntry ce = ct.GetColorEntry(i);
pal.Entries[i] = Color.FromArgb(ce.c4, ce.c1, ce.c2, ce.c3);
}
bitmap.Palette = pal;
}
else
{
// grayscale
ColorPalette pal = bitmap.Palette;
for (int i = 0; i < 256; i++)
pal.Entries[i] = Color.FromArgb(255, i, i, i);
bitmap.Palette = pal;
}
}
// Use GDAL raster reading methods to read the image data directly into the Bitmap
BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, imageWidth, imageHeight), ImageLockMode.ReadWrite, pixelFormat);
try
{
int stride = bitmapData.Stride;
IntPtr buf = bitmapData.Scan0;
ds.ReadRaster(xOff, yOff, width, height, buf, imageWidth, imageHeight, dataType,
channelCount, bandMap, pixelSpace, stride, 1);
}
finally
{
bitmap.UnlockBits(bitmapData);
}
bitmap.Save(filename);
}
private static void LoadBitmapDirect(Dataset ds, Bitmap bitmap, int xOff, int yOff, int width, int height, int imageWidth, int imageHeight, int iOverview)
{
if (isIndexed)
{
// setting up the color table
if (ct != null)
{
int iCol = ct.GetCount();
ColorPalette pal = bitmap.Palette;
for (int i = 0; i < iCol; i++)
{
ColorEntry ce = ct.GetColorEntry(i);
pal.Entries[i] = Color.FromArgb(ce.c4, ce.c1, ce.c2, ce.c3);
}
bitmap.Palette = pal;
}
else
{
// grayscale
ColorPalette pal = bitmap.Palette;
for (int i = 0; i < 256; i++)
pal.Entries[i] = Color.FromArgb(255, i, i, i);
bitmap.Palette = pal;
}
}
// Use GDAL raster reading methods to read the image data directly into the Bitmap
BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, imageWidth, imageHeight), ImageLockMode.ReadWrite, pixelFormat);
try
{
int stride = bitmapData.Stride;
IntPtr buf = bitmapData.Scan0;
ds.ReadRaster(xOff, yOff, width, height, buf, imageWidth, imageHeight, dataType,
channelCount, bandMap, pixelSpace, stride, 1);
}
finally
{
bitmap.UnlockBits(bitmapData);
}
}
