Question

I am extracting system default icons (16 * 16 only) for some extensions like XLS, XLSX, PDF etc and trying to show that in Image Control. I am noticing that if I take dump of those icons on disk, they look sharp but the icons in my ListBox look somewhat blurred.

Any ideas what could be going on here ? I have tried a lot of suggestions from the posts I read from but couldn’t make the problem go

Code Snippet:

Case1 – I am extracting the icon of file through Win32 Pinvoke – result -> blurrred icons

private const uint SHGFI_ICON = 0x100;
    private const uint SHGFI_LARGEICON = 0x0;
    private const uint SHGFI_SMALLICON = 0x1;
    private const int FILE_ATTRIBUTE_NORMAL = 0x80;
    private const uint SHGFI_USEFILEATTRIBUTES = 0x000000010;
    [StructLayout(LayoutKind.Sequential)]
    private struct SHFILEINFO
    {
        public IntPtr hIcon;
        public IntPtr iIcon;
        public uint dwAttributes;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
        public string szDisplayName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
        public string szTypeName;
    };
    [DllImport("shell32.dll")]
    private static extern IntPtr SHGetFileInfo(string pszPath, uint dwFileAttributes,   
   ref SHFILEINFO psfi, uint cbSizeFileInfo, uint uFlags);

private static Icon Extract(string fileName)
{
var shinfo = new SHFILEINFO();

IntPtr hIcon = SHGetFileInfo(fileName, 0, ref shinfo, (uint)Marshal.SizeOf(shinfo), SHGFI_ICON | SHGFI_SMALLICON);
//The icon is returned in the hIcon member of the shinfo struct
var icon = (Icon)Icon.FromHandle(shinfo.hIcon).Clone();
DestroyIcon(shinfo.hIcon);
return icon;
}
[DllImport("User32.dll")]
public static extern int DestroyIcon(IntPtr hIcon);

Case2 – Dumping Icon objects created above to disk and viewing them in explorer -> the icons are of excellent quality

string filePath = string.Format("C:\\temp\\Icons\\{0}.ico", iconName.Substring(1));
var stream = new FileStream(filePath, FileMode.OpenOrCreate);
iconObject.ExtensionSource.ToBitmap().Save(stream, ImageFormat.Bmp);
stream.Close();

ListBox xaml –

<Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <StackPanel Orientation="Horizontal"
                    Grid.Row="0"
                    Margin="10">
            <TextBox Text="{Binding ExtensionNames, Mode=TwoWay}"
                     ToolTip="Comma Separated List of Extensions, Tab out to persist changes.."
                     Margin="5"/>
            <Button Content="Dump All Icons" 
                    Click="Button_DumpAllIconsClick" 
                    Width="100"
                    ToolTip="Dump Path: C:\temp\Icons"
                    Margin="5"/>

        </StackPanel>
        <ListBox ItemsSource="{Binding Icons}"
                 Grid.Row="1"
                 Margin="2">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal"
                                HorizontalAlignment="Stretch"
                                Margin="5">
                        <TextBlock Text="{Binding ExtensionName}"
                                       FontWeight="Bold"
                                       FontSize="20"/>
                        <Image Source="{Binding Path=ExtensionSource,
                                                Converter={ExtractIconWPF:IconToImageSourceConverter}}"
                               Margin="5"/>
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
            <ListBox.ItemContainerStyle>
                <Style TargetType="ListBoxItem">
                    <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
                </Style>
            </ListBox.ItemContainerStyle>
        </ListBox>
</Grid>

How I am converting Icon to ImageSource object:

var stream = GetIconStream(iconObject);
ImageSource source = GetBitMapImage(stream);

public static Stream GetIconStream(Icon icon)
{
var iconStream = new MemoryStream();

var bitmap = icon.ToBitmap();
bitmap.Save(iconStream, ImageFormat.Png);

return iconStream;
}

public static ImageSource GetBitMapImage(Stream iconStream)
{
var bi = new BitmapImage();

bi.BeginInit();
bi.StreamSource = iconStream;
bi.EndInit();

return bi;
}

Any pointers will be highly appreciated!

Thanks

Answer 1

Sharing what helped in my case for others who face similar problem.

Setting this property on Image helped a ton in removing the blur:

RenderOptions.BitmapScalingMode="NearestNeighbor"

In other case, we were showing the image in a grid cell which was 20 * 20, so we ended up removing the default Image stretch with below setting. That made a lot of diff too.

Stretch = Stretch.None