Blank screen using DrawImage method

问题

I have to draw a bitmap image using DrawingContext.DrawImage method.

Using the code below everything is working correctly:

BitmapImage myImage = new BitmapImage();
myImage.BeginInit();
myImage.UriSource = new Uri("image.png", UriKind.Relative);
myImage.EndInit();

Rect area = new Rect(new Size(myImage.PixelWidth, myImage.PixelHeight));
DrawingVisual myVisual = new DrawingVisual();

using (DrawingContext context = myVisual.RenderOpen())
{ context.DrawImage(myImage, area); }

But only if the image does not exceed 2Mb about, i.e. the area (myImage.PixelWidth x myImage.PixelHeight) is not larger than 10000x10000. In this case the screen remains blank and no any exception is thrown (so I can not tell if there was an error).

How could I fix this problem? Thanks.

回答1:

Looks like larger images aren't yet loaded when you render them. Try the following to load the bitmap:

BitmapSource myImage = BitmapFrame.Create(
    new Uri("image.png"),
    BitmapCreateOptions.None,
    BitmapCacheOption.OnLoad);

Or this desperate attempt:

using (Stream fileStream = new FileStream("image.png", FileMode.Open))
{
    BitmapSource myImage = BitmapFrame.Create(
        fileStream, BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
}

来源：https://stackoverflow.com/questions/10715485/blank-screen-using-drawimage-method