将画笔转换为颜色

Question

I want to convert a Brush object to Color so that I can change any xaml button background color to its light color on button click, but System.Windows.Forms.ControlPaint.Light() takes only color as argument.

Is there some alternative to achieve this?

Answer 1

You could try getting the A,RGB values of the brush, and then pass them to System.Drawing.Color.FromARGB() Pseudo-Code:

Brush br = Brushes.Green;
byte a = ((Color)br.GetValue(SolidColorBrush.ColorProperty)).A;
byte g = ((Color)br.GetValue(SolidColorBrush.ColorProperty)).G;
byte r = ((Color)br.GetValue(SolidColorBrush.ColorProperty)).R;
byte b = ((Color)br.GetValue(SolidColorBrush.ColorProperty)).B;
System.Windows.Forms.ControlPaint.Light(
    System.Drawing.Color.FromArgb((int)a,(int)r,(int)g,(int)b));

I'm not a WPF expert, but the main thing I think you need to keep in mind is the easiest way to do what you are trying is to use System.Drawing.Color.FromArgb() or even System.Drawing.Color.FromName() .

Answer 2

You don't need to reference the huge Windows.Forms dll just to lighten a Color . In its simplest terms, you're just multiplying each value by the same factor:

private Color AdjustBrightness(double brightnessFactor)
{
    Color originalColour = Color.Red;
    Color adjustedColour = Color.FromArgb(originalColour.A, 
        (int)(originalColour.R * brightnessFactor), 
        (int)(originalColour.G * brightnessFactor), 
        (int)(originalColour.B * brightnessFactor));
    return adjustedColour;
}

This could of course be improved in several ways (and should), but you get the idea. In fact, this will throw an Exception if a value goes over 255, but I'm sure that you can take care of that. Now you just need to check what type of Brush you need to brighten:

if (brush is SolidColorBrush) 
    return new SolidColorBrush(AdjustBrightness(((SolidColorBrush)brush).Color));
else if (brush is LinearGradientBrush || brush is RadialGradientBrush) 
{
    // Go through each `GradientStop` in the `Brush` and brighten its colour
}

Answer 3

In my case I've done it like this (extension method):

public static class BrushExtension
{

    public static Color GetColor(this Brush brush)
    {
        return new Pen(brush).Color;
    }

}

And call it like Color brushColor = myBrush.GetColor();

Answer 4

Try this:

        Brush brush = Brushes.Yellow;
        Color color = ((SolidColorBrush) brush).Color;