如何将图片框的“居中”背景图像绘制到面板上？

Question

I was nicely supplied a code from Alex M, for painting the background image to a panel but realized that if a PictureBox 's BackgroundImage has its Center image property set, the drawn image becomes stretched but not centered. I so far have this code:

private void panel1_Paint(object sender, PaintEventArgs e)
{
    e.Graphics.DrawImage(pictureBox1.BackgroundImage, 
        new Rectangle(pictureBox1.Location, pictureBox1.Size));
}

This draws the background image to the panel but if pictureBox1 's background image property is set to CENTER, it does not paint the image in the Center of the Rectangle, but instead stretches the image to fit the rectangle.

The only possible solution I've found is here but I can't make any sense of it.

Answer 1

The reason the image is being stretched is because the second parameter to DrawImage specifies the location and size of where you're drawing the image, and you're specifying the entire area of the picture box, not the area of the image itself.

If you want to center it, try something like this:

private void panel1_Paint(object sender, PaintEventArgs e)
{
    var hPadding = (pictureBox1.Width - pictureBox1.BackgroundImage.Width) / 2;
    var vPadding = (pictureBox1.Height - pictureBox1.BackgroundImage.Height) / 2;
    var imgRect = new Rectangle(pictureBox1.Left + hPadding, pictureBox1.Top + vPadding, pictureBox1.BackgroundImage.Width, pictureBox1.BackgroundImage.Height);
    e.Graphics.DrawImage(pictureBox1.BackgroundImage, imgRect);
}