❔ Refresh WriteableBitmap
Hi,
I would like to use a WriteableBitmap in my application. However, the Image control does not update when the backing WriteableBitmap changes. The examples I could find online appear to use
My control looks like this:
And the relevant code within the ViewModel:
I would like to use a WriteableBitmap in my application. However, the Image control does not update when the backing WriteableBitmap changes. The examples I could find online appear to use
WriteableBitmap.AddDirtyRectWriteableBitmap.AddDirtyRect to trigger the update. But in my case this does not nothing.My control looks like this:
<UserControl ... />
<Image x:Name="bitmap"
Source="{Binding Bitmap}"
Opacity=".25">
</Image>
</UserControl><UserControl ... />
<Image x:Name="bitmap"
Source="{Binding Bitmap}"
Opacity=".25">
</Image>
</UserControl>And the relevant code within the ViewModel:
public class BitGridViewModel : ObservableBase
{
private static readonly Color trueColor = Color.FromArgb(0xAA, 0xFF, 0x00, 0x00);
private static readonly Color falseColor = Color.FromArgb(0xAA, 0xFF, 0xFF, 0xFF);
public WriteableBitmap Bitmap
{
get => _bitmap;
set => SetProperty(ref _bitmap, value);
}
private WriteableBitmap _bitmap;
...
// https://learn.microsoft.com/en-us/dotnet/api/system.windows.media.imaging.writeablebitmap?view=windowsdesktop-7.0
private static void DrawPixel(WriteableBitmap bitmap, int x, int y, Color color)
{
if (bitmap.Format != PixelFormats.Bgr32)
throw new ArgumentException();
try
{
bitmap.Lock();
unsafe
{
// determine the pixel's address within the Bitmap, depends on the Bitmap's PixelFormat
IntPtr pBackBufferAddr = bitmap.BackBuffer;
IntPtr pixelAddr = pBackBufferAddr + y * bitmap.BackBufferStride + x * 4;
// compute the pixel's color, depends on the Bitmap's PixelFormat
int colorData = (color.R << 16) | (color.G << 8) | (color.B << 0);
// set the pixel
*((int*)pixelAddr) = colorData;
}
bitmap.AddDirtyRect(new Int32Rect(0, 0, bitmap.PixelWidth, bitmap.PixelHeight));
}
finally
{
bitmap.Unlock();
}
}
}public class BitGridViewModel : ObservableBase
{
private static readonly Color trueColor = Color.FromArgb(0xAA, 0xFF, 0x00, 0x00);
private static readonly Color falseColor = Color.FromArgb(0xAA, 0xFF, 0xFF, 0xFF);
public WriteableBitmap Bitmap
{
get => _bitmap;
set => SetProperty(ref _bitmap, value);
}
private WriteableBitmap _bitmap;
...
// https://learn.microsoft.com/en-us/dotnet/api/system.windows.media.imaging.writeablebitmap?view=windowsdesktop-7.0
private static void DrawPixel(WriteableBitmap bitmap, int x, int y, Color color)
{
if (bitmap.Format != PixelFormats.Bgr32)
throw new ArgumentException();
try
{
bitmap.Lock();
unsafe
{
// determine the pixel's address within the Bitmap, depends on the Bitmap's PixelFormat
IntPtr pBackBufferAddr = bitmap.BackBuffer;
IntPtr pixelAddr = pBackBufferAddr + y * bitmap.BackBufferStride + x * 4;
// compute the pixel's color, depends on the Bitmap's PixelFormat
int colorData = (color.R << 16) | (color.G << 8) | (color.B << 0);
// set the pixel
*((int*)pixelAddr) = colorData;
}
bitmap.AddDirtyRect(new Int32Rect(0, 0, bitmap.PixelWidth, bitmap.PixelHeight));
}
finally
{
bitmap.Unlock();
}
}
}
