/// <summary>
/// Creates a new instance of GdalFileOverviewImage
/// </summary>
public GdalFileOverviewImage(string filename)
{
_source = new GdalImageSource(filename);
}
/// <summary>
///
/// </summary>
/// <param name="filename"></param>
/// <returns></returns>
private IImageData OpenFile(string filename)
{
GdalImage result = new GdalImage(filename);
if(result.Width > 8000 || result.Height > 8000)
{
// Firstly, if there are pyramids inside of the GDAL file itself, we can just work with this directly,
// without creating our own pyramid image.
// For now, we can't get fast, low-res versions without some kind of pyramiding happening.
// since that can take a while for huge images, I'd rather do this once, and create a kind of
// standardized file-based pyramid system. Maybe in future pyramid tiffs could be used instead?
string pyrFile = Path.ChangeExtension(filename, ".mwi");
if(File.Exists(pyrFile))
{
if(File.Exists(Path.ChangeExtension(pyrFile, ".mwh")))
{
return new PyramidImage(filename);
}
File.Delete(pyrFile);
}
GdalImageSource gs = new GdalImageSource(filename);
PyramidImage py = new PyramidImage(pyrFile, gs.Bounds);
int width = gs.Bounds.NumColumns;
int blockHeight = 64000000 / width;
if (blockHeight > gs.Bounds.NumRows) blockHeight = gs.Bounds.NumRows;
int numBlocks = (int)Math.Ceiling(gs.Bounds.NumRows/(double)blockHeight);
ProgressMeter pm = new ProgressMeter(ProgressHandler, "Copying Data To Pyramids", numBlocks* 2);
ProgressHandler.Progress("pyramid", 0, "Copying Data To Pyramids: 0% Complete");
Application.DoEvents();
for(int j = 0; j < numBlocks; j++)
{
int h = blockHeight;
if(j==numBlocks-1)
{
h = gs.Bounds.NumRows - j*blockHeight;
}
Stopwatch sw = new Stopwatch();
sw.Start();
byte[] vals = gs.ReadWindow(j*blockHeight, 0, h, width, 0);
Debug.WriteLine("Reading Value time: " + sw.ElapsedMilliseconds);
pm.CurrentValue = j * 2 + 1;
sw.Reset();
sw.Start();
py.WriteWindow(vals, j * blockHeight, 0, h, width, 0);
sw.Stop();
Debug.WriteLine("Writing Pyramid time: " + sw.ElapsedMilliseconds);
pm.CurrentValue = (j+1) * 2;
}
gs.Dispose();
pm.Reset();
py.CreatePyramids(ProgressHandler);
py.WriteHeader(pyrFile);
return py;
}
result.Open(filename);
return result;
}
