Creating transparent background in WPF

I have a button with a backgroun image of color white. My button is sitting on the toolbar which has a bacground color of Blue. When the button is sitting 开发者_如何学Goon the toolbar, the button looks white, however I want it to look like blue as the the background color of toolbar is Blue.

How should I achieve this in WPF.. Please let me know.

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Are you sure you want to use an image? If the image is just a solid color, you're probably better off just setting the button's background to white and adjusting its opacity. Like:

<Button Background="White" Opacity="0.5" />

Where Opacity can be any value between 0 and 1.

EDIT: I'm not sure what you mean by "shades." Are you aware that you can set the background of a Button to a gradient? You'll want to change the colors I'm sure, but it will look something like this:

<Button>
    <Button.Background>
        <LinearGradientBrush>
            <GradientStop Color="Yellow" Offset="0.0" />
            <GradientStop Color="Orange" Offset="0.5" />
            <GradientStop Color="Red" Offset="1.0" />
         </LinearGradientBrush>
    <Button.Background>
</Button>

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You can use the System.Windows.Media.Color Transparent, like this:

<Button Background="Transparent" />

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You have to make sure your image has transparency, WPF won't try to figure out what parts in your image should be see-through and what parts should be opaque. Check that your image editor can export images with transparency, most likely to PNG.