NETCF - Optimized Repaint (onPaint)
- by Nullstr1ng
Hi Guys,
I want to ask for suggestions on how to optimize a repaint in Compact Framework? GetHashCode() didn't help because it always return a different hash code.
Anyway, I have a program which you can drag and resize an object in run time. This object is a transparent object and it has a PNG image which also dynamically resize relative to object client size.
Though I noticed, (e.g. I have 4 transparent object and I'm dragging or resizing one) all 4 of them triggers OnPaintBackground even if the 3 are not moving. Another one when am just tapping on the one object .. it sill triggers onPaintBacground(). Anyway, I don't have a problem when this events get triggered.
What I like to do is optimization and that means I only have to repaint the object when it's necessary.
Can you guys please give a suggestions?
here's my pseudo C# code
Bitmap _backBuff;
onResize() {
if(_backBuff != null) _backBuff.Dispose();
_backBuff = new Bitmap(ClientSize.Width, ClientSize.Height);
Invalidate();
}
onPaintBackground(e) /*have to use onPaintBackground because MSDN said it's faster*/ {
using(Graphics g = Graphics.FromImage(_backBuff)) {
g.Clear(Color.Black);
// draw background
....some interface calling here
....and paint the background
// draw alpha PNG
.. get hDc
.. paint PNG
.. release hDc
}
e.Graphics.DrawImage(_backBuff,0,0);
}
Thanks in advance.
