private void GetPreview(GDAL.Dataset dataset, System.Drawing.Size size, Graphics g, SharpMap.Geometries.BoundingBox bbox)
{
double [] geoTrans = new double[6];
dataset.GetGeoTransform(geoTrans);
GeoTransform GT = new GeoTransform(geoTrans);
int DsWidth = dataset.RasterXSize;
int DsHeight = dataset.RasterYSize;
Bitmap bitmap = new Bitmap(size.Width, size.Height, PixelFormat.Format24bppRgb);
int iPixelSize = 3; //Format24bppRgb = byte[b,g,r]
if (dataset != null)
{
/*
* if ((float)size.Width / (float)size.Height > (float)DsWidth / (float)DsHeight)
* size.Width = size.Height * DsWidth / DsHeight;
* else
* size.Height = size.Width * DsHeight / DsWidth;
*/
double left = Math.Max(bbox.Left, _Envelope.Left);
double top = Math.Min(bbox.Top, _Envelope.Top);
double right = Math.Min(bbox.Right, _Envelope.Right);
double bottom = Math.Max(bbox.Bottom, _Envelope.Bottom);
int x1 = (int)GT.PixelX(left);
int y1 = (int)GT.PixelY(top);
int x1width = (int)GT.PixelXwidth(right - left);
int y1height = (int)GT.PixelYwidth(bottom - top);
bitmap = new Bitmap(size.Width, size.Height, PixelFormat.Format24bppRgb);
BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, size.Width, size.Height), ImageLockMode.ReadWrite, bitmap.PixelFormat);
try
{
unsafe
{
for (int i = 1; i <= (dataset.RasterCount > 3 ? 3 : dataset.RasterCount); ++i)
{
byte[] buffer = new byte[size.Width * size.Height];
GDAL.Band band = dataset.GetRasterBand(i);
//band.ReadRaster(x1, y1, x1width, y1height, buffer, size.Width, size.Height, (int)GT.HorizontalPixelResolution, (int)GT.VerticalPixelResolution);
band.ReadRaster(x1, y1, x1width, y1height, buffer, size.Width, size.Height, 0, 0);
int p_indx = 0;
int ch = 0;
if (band.GetRasterColorInterpretation() == 5)
{
ch = 0;
}
if (band.GetRasterColorInterpretation() == 4)
{
ch = 1;
}
if (band.GetRasterColorInterpretation() == 3)
{
ch = 2;
}
if (band.GetRasterColorInterpretation() != 2)
{
for (int y = 0; y < size.Height; y++)
{
byte *row = (byte *)bitmapData.Scan0 + (y * bitmapData.Stride);
for (int x = 0; x < size.Width; x++, p_indx++)
{
row[x * iPixelSize + ch] = buffer[p_indx];
}
}
}
else //8bit Grayscale
{
for (int y = 0; y < size.Height; y++)
{
byte *row = (byte *)bitmapData.Scan0 + (y * bitmapData.Stride);
for (int x = 0; x < size.Width; x++, p_indx++)
{
row[x * iPixelSize] = buffer[p_indx];
row[x * iPixelSize + 1] = buffer[p_indx];
row[x * iPixelSize + 2] = buffer[p_indx];
}
}
}
}
}
}
finally
{
bitmap.UnlockBits(bitmapData);
}
}
g.DrawImage(bitmap, new System.Drawing.Point(0, 0));
}
