[Lazarus] TImage Canvas not growing with Image? GTK2

[Hans-Peter Diettrich]

theo schrieb:

> I saw people are using/recommending TImage.Canvas for drawing because
> drawing is non-volatile, unlike TPaintBox.

An implementation can use either a fixed-size bitmap, so that painting 
is non-volatile, or recreate the bitmap with every change in size, so 
that previous content is almost lost.

Fixed-size images, like bitmaps, eventually can be stretch-drawn to the 
actual extent. Then one can draw into the bitmap, but only within its 
fixed size.

Truly scalable (vector...) images are not based on a bitmap, and cannot 
be updated by bitmap-specific graphics commands (LineTo...).


When you re-create your graphics after every change in size, it should 
be possible to use any "volatile" component (TPanel...) and set its 
DoubleBuffered property to True.

DoDi