[Moonlight-list] Help with WriteableBitmap

[Tony Alexander Hild]

Hi,

I have made a simple program to test the WriteableBitmap.
btnTest_Click calls the Invert function.


             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
             Width="1000" Height="650"
             x:Class="HelloMoon.Page"
>
    <Grid x:Name="LayoutRoot" Background="Black">
        <TextBlock x:Name="tblText" FontSize="30" Foreground="White">Hello Moon!</TextBlock>
    <Button x:Name="btnTest" Width="200" VerticalAlignment="Top" Height="50" Canvas.Top="0" Canvas.Left="100" Click="btnTest_Click" Content="Click me!"></Button>
    <Image x:Name="MyBitmap" Source="/test;component/2.png"
               Width="512"
               Height="512" />

    </Grid>
</UserControl>

        private void Invert ()
        {
            const int imageWidth = 512;
            const int imageHeight = 512;

            WriteableBitmap b = new WriteableBitmap ((BitmapSource)MyBitmap.Source);
            //WriteableBitmap b = new WriteableBitmap (imageWidth, imageHeight, PixelFormats.Bgr32);

            for (int x = 0; x < imageWidth; x++) {
                for (int y = 0; y < imageHeight; y++) {
                    int color = b.Pixels[y * imageWidth + x];
                    if (color == 0) {
                        // generate a color in Pbgra32 format
                        byte[] components = {
                            255,
                            255,
                            255,
                            0
                        };
                        int pixelValue = BitConverter.ToInt32 (components, 0);
                        b.Pixels[y * imageWidth + x] = pixelValue;

                    } else {
                        b.Pixels[y * imageWidth + x] = b.Pixels[y * imageWidth + x] = 0;
                    }
                }
            }

            b.Invalidate ();
            MyBitmap.Source = b;

        }


I also modified the constructor of WriteableBitmap:

        public WriteableBitmap (BitmapSource source) : base(NativeMethods.writeable_bitmap_new (), true)
        {
            rendered = true;
            PixelWidth = source.PixelWidth;
            PixelHeight = source.PixelHeight;
            PixelFormat = PixelFormats.Pbgra32;
            if (source != null)
                NativeMethods.writeable_bitmap_initialize_from_bitmap_source (native, source.native);
        }

But source.PixelWidth/Height always is 0, so i get this error:


Value must be greater than zeroException Details: System.ArgumentException: Value must be greater than zero

Stack Trace:


   at Mono.NativeMethods.CreateManagedException (MoonError err) [0x00000] 
   at Mono.NativeMethods.dependency_object_set_value (IntPtr instance, IntPtr property, Mono.Value& value) [0x00000] 
   at Mono.NativeDependencyObjectHelper.SetValue (INativeDependencyObjectWrapper wrapper, System.Windows.DependencyProperty dp, System.Object value) [0x00000] 
   at System.Windows.DependencyObject.SetValueImpl (System.Windows.DependencyProperty dp, System.Object value) [0x00000] 
   at System.Windows.DependencyObject.SetValue (System.Windows.DependencyProperty dp, System.Object value) [0x00000] 
   at System.Windows.Media.Imaging.BitmapSource.set_PixelWidth (Int32 value) [0x00000] 
   at System.Windows.Media.Imaging.WriteableBitmap..ctor (System.Windows.Media.Imaging.BitmapSource source) [0x00000] 
   at HelloMoon.Page.Invert () [0x00000] 
   at HelloMoon.Page.btnTest_Click (System.Object sender, System.Windows.RoutedEventArgs e) [0x00000] 
   at System.Windows.Controls.Primitives.ButtonBase.OnClick () [0x00000] 
   at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp (System.Windows.Input.MouseButtonEventArgs e) [0x00000] 
   at System.Windows.Controls.Control.InvokeMouseLeftButtonUp (System.Windows.Input.MouseButtonEventArgs e) [0x00000] 
   at Mono.Events.mouse_left_button_up_callback (IntPtr target, IntPtr calldata, IntPtr closure) [0x00000] 
   at Mono.Events+<CreateSafeHandler>c__AnonStorey1.<>m__2 (IntPtr a, IntPtr b, IntPtr c) [0x00000]  
But as the BitmapSource is already rendered, it should have the Height and Width properties set.

What I'm doing wrong?
I'm using trunk version, from mono, mcs, libgdi and moon.


Tony



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