How can I create an opacity mask in wpf that doesn't scale?

Ok, I've created a PNG-24 with transparency. It's basically a grayscale image that uses 'colors' in between black and transparent instead of black and white. I did this so I can use this as the Opacity Mask of a colored rectangle, thus rendering the image in whatever color I want using only a single graphic.

However, for the life of me, I can't get WPF to stop anti-aliasing the da*n image!!

I've set 'SnapesToDevicePixels' on the rectangle to which the brush is applied... I've set the ImageBrush's Scale to 'None'... I've set its ViewPort and the ViewBox to absolute units and sized them exactly to the source image. But no matter what I try, WPF still insists on trying to smooth things out! This is VERY frustrating!!!

So... anyone know how to use an image as an opacity mask but not lose the pixel-precise 开发者_开发问答drawing that we have done? I just want WPF to render the damn thing as we drew it, period!

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I have tried to reproduce your problem. Simply like this:

        <Rectangle Width="200" Height="200" Fill="Red">
            <Rectangle.OpacityMask>
                <ImageBrush ImageSource="/mask.png"/>
            </Rectangle.OpacityMask>
        </Rectangle>

mask.png contains a simple diagonal mask, like that half of rectange is visible and other half is 100% transparent. And recrangle is rendering pixel perfect (and aliased, as you want). I think, that you may a DPI setting, that is not native to your monitor, and WPF just can`t render images correctly.

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GOT IT! It's a layout issue that for some reason, there's no easy way to change. However, there's a value you can set called UseLayoutRounding that fixes it. I just set it at the root level (for this fauxample, a grid...)

<Grid UseLayoutRounding="True">
    ....
</Grid>

...and BAM! Works like a charm! "Sort of" like a 'SnapsToDevicePixels' but for positioning of elements (i.e. it rounds all layout-related values like left, width, etc. whereas SnapsToDevicePixels snaps the layout to the on-screen pixels when rendering.)

M