/// <summary>
/// For big images the scale that is just one step larger than the specified window will be used.
/// </summary>
/// <param name="envelope"></param>
/// <param name="window"></param>
/// <returns></returns>
public override Bitmap GetBitmap(IEnvelope envelope, Rectangle window)
{
if (window.Width == 0 || window.Height == 0) return null;
if (_header == null) return null;
if (_header.ImageHeaders == null) return null;
if (_header.ImageHeaders[0] == null) return null;
Rectangle expWindow = window.ExpandBy(1);
IEnvelope expEnvelope = envelope.Reproportion(window, expWindow);
IEnvelope env = expEnvelope.Intersection(Bounds.Envelope);
if (env == null || env.IsNull || env.Height == 0 || env.Width == 0) return null;
int fractionW = (int)((env.Width/expEnvelope.Width)*expWindow.Width);
int fractionH = (int) ((env.Height/expEnvelope.Height)*expWindow.Height);
PyramidImageHeader he = _header.ImageHeaders[0];
int scale;
double cwa = expWindow.Width/expEnvelope.Width;
double cha = expWindow.Height/expEnvelope.Height;
for(scale = 0; scale < _header.ImageHeaders.Length; scale++)
{
PyramidImageHeader ph = _header.ImageHeaders[scale];
if(cwa > ph.NumColumns/Bounds.Width || cha > ph.NumRows/Bounds.Height)
{
if(scale > 0)scale -= 1;
break;
}
he = ph;
}
// Get the cell coordinates of the part of the source bitmap to read
int x = (int)((he.NumColumns / Bounds.Width) * (env.X - he.Affine[0]));
int y = (int)((he.NumRows / Bounds.Height) * (he.Affine[3] - env.Y));
int w = (int)((he.NumColumns / Bounds.Width) * env.Width);
int h = (int)((he.NumRows / Bounds.Height) * env.Height);
if (w == 0 || h == 0) return null;
byte[] vals = ReadWindow(y, x, h, w, scale);
Bitmap bmp = new Bitmap(w, h);
BitmapData bData = bmp.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
Marshal.Copy(vals, 0, bData.Scan0, vals.Length);
bmp.UnlockBits(bData);
// Use the cell coordinates to determine the affine coefficients for the cells retrieved.
double[] affine = new double[6];
Array.Copy(he.Affine, affine, 6);
affine[0] = affine[0] + x*affine[1] + y*affine[2];
affine[3] = affine[3] + x*affine[4] + y*affine[5];
Bitmap result = new Bitmap(window.Width, window.Height);
Graphics g = Graphics.FromImage(result);
double imageToWorldW = affine[1];
double imageToWorldH = affine[5];
float cw = (float)(imageToWorldW * (window.Width / envelope.Width)); // cell width
float ch = -(float)(imageToWorldH * (window.Height / envelope.Height)); // cell height
//float sx = cw * (float)(_worldFile.Affine[2] / _worldFile.Affine[1]);
//float sy = ch * (float)(_worldFile.Affine[4] / _worldFile.Affine[5]);
const float sx = 0;
const float sy = 0;
float l = (float)(affine[0]);
float t = (float)(affine[3]);
float dx = (float)((l - envelope.Minimum.X) * (window.Width / envelope.Width));
float dy = (float)((envelope.Maximum.Y - t) * (window.Height / envelope.Height));
g.Transform = new Matrix(cw, sx, sy, ch, dx, dy);
g.PixelOffsetMode = PixelOffsetMode.Half;
if (cw > 1 || ch > 1) g.InterpolationMode = InterpolationMode.NearestNeighbor;
g.DrawImage(bmp, new PointF(0, 0));
bmp.Dispose();
g.Dispose();
return result;
}