Common mistakes

Table 4.3 lists the mistakes made most often when working with graphics.

Table 4.3. Common mistakes when working with graphics

Problem	Cause	Fix
the drawing disappears after the window is minimized or covered	drawing through `CreateGraphics` in a button handler	store data in fields, draw in `OnPaint`, call `Invalidate()`
"trails" of the old drawing remain when resizing	only the new strip of the window is repainted	`ResizeRedraw = true`
flicker during animation	the frame is drawn directly on the screen	`DoubleBuffered = true` or `SetStyle(OptimizedDoubleBuffer…)`
memory and GDI objects grow, eventually an exception	pens, brushes, and fonts are not released	`using` for everything created with `new`
the chart text is upside down	text is drawn after `ScaleTransform(1, -1)`	transform points with `Matrix.TransformPoints`
an image file cannot be overwritten	`Image.FromFile` keeps the file open	a copy `new Bitmap(image)` and releasing the original
error WFO1000 in a custom control	a property without serialization configuration	the `[DefaultValue]` or `[DesignerSerializationVisibility]` attribute

Common mistakes ​