WinForms GDI Rendering not repainting correctly

Question

i have a simple WinForms app which paints some colored rectangles. however when the window is resized it is not correctly updating.

already tried to overwrite OnResize

protected override void OnResize(EventArgs e)
{
        repaintingMyStuffHere();
}

Answer 1

try this:

protected override void OnResize(EventArgs e)
{
     this.Invalidate();
     base.OnResize(e);
}

protected override void OnPaint(PaintEventArgs e) {
{
     base.OnPaint(e);
     repaintingMyStuffHere(e.Graphics);
}

if you still have the problem try to set the folowing controlstyles:

public MyClass() {
    this.SetStyle(ControlStyles.AllPaintingInWmPaint | 
                    ControlStyles.OptimizedDoubleBuffer | 
                    ControlStyles.ResizeRedraw | 
                    ControlStyles.UserPaint | 
                    ControlStyles.ResizeRedraw, 
                    true);
}

if you still have any problems please post your repaintingMyStuffHere methode.

Answer 2

To get your form/component to render property, and help improve performance, you would need to first override the OnResize() method to cause it to invalidate the form/component:

protected override void OnResize(EventArgs e)
{
    base.OnResize(e);
    this.Invalidate();
}

Then (optional, but recommended to reduce flickering) set the form/component DoubleBuffered property to true:

this.DoubleBuffered = true;