Question

I created a gradient for my form background but Im having this issue now. In winforms, when I minimize and then maximize the form i get this:

imageshack.us/photo/my-images/35/errorbl.png.

I guess the bug is that the form has to redraw itself after maximizing and it doesn’t. Somebody knows how to solve it?

Thanks!

Calling gradient:

public Base()
    {
        InitializeComponent();

        this.Paint += new PaintEventHandler(Form_Background);

    }

Gradient method:

public void Form_Background(object sender, PaintEventArgs e)
    {
        Color c1 = Color.FromArgb(255, 252, 254, 255);
        Color c2 = Color.FromArgb(255, 247, 251, 253);
        Color c3 = Color.FromArgb(255, 228, 239, 247);
        Color c4 = Color.FromArgb(255, 217, 228, 238);
        Color c5 = Color.FromArgb(255, 200, 212, 217);
        Color c6 = Color.FromArgb(255, 177, 198, 215);
        Color c7 = Color.FromArgb(255, 166, 186, 208);

        LinearGradientBrush br = new LinearGradientBrush(this.ClientRectangle, c1, c7, 90, true);
        ColorBlend cb = new ColorBlend();
        cb.Positions = new[] { 0, (float)0.146, (float)0.317, (float)0.439, (float)0.585, (float)0.797, 1 };
        cb.Colors = new[] { c1, c2, c3, c4, c5, c6, c7 };
        br.InterpolationColors = cb;


        // paint
        e.Graphics.FillRectangle(br, this.ClientRectangle);
    }

Answer 1

The reason it does not work is that width and height of this.ClientRectangle is zero after being minimized.

You need to implement a check of the rectangle before applying any gradient and drawing with it:

Rectangle r = this.ClientRectangle;

if (r.Width > 0 && r.Height > 0) {

    //draw

}

So your code would like something like this:

public void Form_Background(object sender, PaintEventArgs e) {

    Rectangle r = this.ClientRectangle;

    if (r.Width > 0 && r.Height > 0) {

        Color c1 = Color.FromArgb(252, 254, 255);
        Color c2 = Color.FromArgb(247, 251, 253);
        Color c3 = Color.FromArgb(228, 239, 247);
        Color c4 = Color.FromArgb(217, 228, 238);
        Color c5 = Color.FromArgb(200, 212, 217);
        Color c6 = Color.FromArgb(177, 198, 215);
        Color c7 = Color.FromArgb(166, 186, 208);

        LinearGradientBrush br = new LinearGradientBrush(r, c1, c7, 90, true);
        ColorBlend cb = new ColorBlend();
        cb.Positions = new[] { 0, (float)0.146, (float)0.317, _
                                  (float)0.439, (float)0.585, _
                                  (float)0.797, 1 };

        cb.Colors = new[] { c1, c2, c3, c4, c5, c6, c7 };
        br.InterpolationColors = cb;

        // paint
        e.Graphics.FillRectangle(br, r);

        br.Dispose; //added dispose for the brush

    }
}