Double buffering with Panel

Question

Double buffering the whole form can be done by setting the value of the "AllPaintingInWmPaint", "UserPaint" and "DoubleBuffer" ControlStyles to "true" (this.SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint | ControlStyles.DoubleBuffer, true)).

But this can't happen with a System.Windows.Forms.Panel because the class doesn't allow me to do so. I have found one solution: http://bytes.com/topic/c-sharp/answers/267635-double-buffering-panel-control . I have also tried this: Winforms Double Buffering . It's laggy, even when it's used on a small drawing, I have some custom resources that I'm using in the form and other things because of which I won't turn the whole form into one drawing. And the second one seems to cause problems. Are there other ways to do that?

I'm asking this because I don't want the drawing on the panel to flash all the time when the form is being resized. If there is a way to get rid of the flashing without double buffering, I'll be happy to know.

Answer 1

Use a PictureBox if you don't need scrolling support, it is double-buffered by default. Getting a double-buffered scrollable panel is easy enough:

using System;
using System.Windows.Forms;

class MyPanel : Panel {
    public MyPanel() {
        this.DoubleBuffered = true;
        this.ResizeRedraw = true;
    }
}

The ResizeRedraw assignment suppresses a painting optimization for container controls. You'll need this if you do any painting in the panel. Without it, the painting smears when you resize the panel.

Double-buffering actually makes painting slower. Which can have an effect on controls that are drawn later. The hole they leave before being filled may be visible for a while, also perceived as flicker. You'll find counter-measures against the effect in this answer.

Answer 2

If acceptable you can stop refreshing the panel while resizing and enable it again after, this way you get rid of the ugly flickering.

Answer 3

I should have posted my solution a long time ago...

Well, here is my solution:

Bitmap buffer = new Bitmap(screenWidth, screenHeight);//set the size of the image
System.Drawing.Graphics gfx = Graphics.FromImage(buffer);//set the graphics to draw on the image
drawStuffWithGraphicsObject(gfx);//draw
pictureBox1.Image = buffer;//set the PictureBox's image to be the buffer

Makes me feel like a complete idiot for finding this solution years after asking this question.

I have tried this with a Panel, but it has proven to be slower when applying the new image. Somewhere I had read, that it is better to use Panel instead of PictureBox. I don't know if I have to add something to the code to speed things up for the Panel, though.