GlowButton - A Glowing Button Control

Download source code - 709.7 KB

Just a Quickie...

Recently I came across the KMP Player software, and was looking over some of the graphic elements (and if you want to see some really good graphics work, I recommend you check it out). One of the elements that I need for a project was a simple glowing button control, used for the player controls, nothing too fancy, just an image that changes color and glows when hovered.

Getting an image to change color is rather trivial, it is done by modifying the color matrices of an ImageAttribute:

private void DrawColoredImage(Graphics g, Image img, Rectangle bounds, Color clr)
{
     using (ImageAttributes ia = new ImageAttributes())
     {
         ColorMatrix cm = new ColorMatrix();
         // convert and refactor color palette
         cm.Matrix00 = ParseColor(clr.R);
         cm.Matrix11 = ParseColor(clr.G);
         cm.Matrix22 = ParseColor(clr.B);
         cm.Matrix33 = ParseColor(clr.A);
         cm.Matrix44 = 1f;
         // set matrix
         ia.SetColorMatrix(cm);
         // draw
         g.DrawImage(img, bounds, 0, 0, img.Width, 
                     img.Height, GraphicsUnit.Pixel, ia);
     }
}

The ParseColor in the example code simply converts byte to float values.

Getting the glow effect is also done using the ImageAttributes class. The image is first inflated, then the color palette and Alpha values are altered, then the clean image is drawn overtop. All this is done by first drawing the control elements into a buffer bitmap:

private void DrawButton()
{
    if (this.Image == null)
        return;

    Rectangle bounds = new Rectangle(0, 0, this.Width, this.Height);
    Rectangle imageBounds = GetImageBounds(bounds, this.Image);

    // draw into a buffer
    using (Graphics g = Graphics.FromImage(_bmpBuffer))
    {
        ...
    }
    // draw the buffer
    using (Graphics g = Graphics.FromHwnd(this.Handle))
        DrawImage(g, _bmpBuffer, bounds);
}

The control comes with most of the properties exposed, like various color states, and optional focus mask and border. Here's a list of the properties:

Checked: Checkbox state
CheckedBorderColor: The checked border color
CheckStyle: Checkbox style
FocusedMask: Draw a focused mask
ImageDisabledColor: The image disabled color
ImageFocusedColor: The image focused color
ImageGlowColor: The border glow color
ImageHoverColor: The image hover color
ImagePressedColor: The image pressed color
ImageGlowFactor: Glow factor depth
FocusOnHover: Focus on button hover