// Render a cached bitmap to a drawing context.
void RenderMapArea(DrawingContext dc, CachedMapArea mapArea)
{
dc.DrawImage(mapArea.bitmap, new Rect(mapArea.portion.X, mapArea.portion.Y,
mapArea.pixelSize * mapArea.bitmap.Width, mapArea.pixelSize * mapArea.bitmap.Height));
}
// Fill in the bitmap member of a cached map area with a bitmap, created from the current map.
void CreateBitmap(CachedMapArea mapArea)
{
// Determine the size of the bitmap we need.
int height = (int) Math.Ceiling(mapArea.portion.Height / mapArea.pixelSize);
int width = (int) Math.Ceiling(mapArea.portion.Width / mapArea.pixelSize);
// Create transformation matrix from map coords to the bitmap coords
Matrix matrix = Matrix.Identity;
matrix.ScalePrepend(1 / mapArea.pixelSize, 1 / mapArea.pixelSize);
matrix.TranslatePrepend(- mapArea.portion.X, - mapArea.portion.Y);
// Get the render options.
RenderOptions renderOpts = new RenderOptions();
renderOpts.usePatternBitmaps = false;
renderOpts.minResolution = (float) mapArea.pixelSize;
// Create a visual of the map, appropriately transformed
DrawingVisual visual = new DrawingVisual();
DrawingContext dc = visual.RenderOpen();
dc.PushTransform(new MatrixTransform(matrix));
using (map.Read())
map.Draw(dc, mapArea.portion, renderOpts);
dc.Close();
// Draw it into a new bitmap.
if (mapArea.bitmap != null && mapArea.bitmap.PixelWidth >= width && mapArea.bitmap.PixelHeight >= height)
mapArea.bitmap.Clear(); // reuse the old bitmap again by clearing it.
else
mapArea.bitmap = new RenderTargetBitmap(width, height, 96.0, 96.0, PixelFormats.Pbgra32);
mapArea.bitmap.Render(visual);
// Mark as up to date.
mapArea.isUpToDate = true;
}