Android Question [B4X] [XUI] B4XCanvas - how to remove a line

A simple solution would be to use a list to add/remove the coords, and only create the path based on it, when/if needed. This will allow you for an undo-depth greater than one.

To remove the line once it is drawn, you could either just clear the canvas and redraw everything using a path created with the new list (once the last element is removed) , or redraw the last line with the background color (if it is solid)

JordiCP said:

or redraw the last line with the background color (if it is solid)

Click to expand...

that was also my first approach, but unfortunately you can still easily see the paleness line in the background.

I'll give it a try, thanks!

A cleaner approach, if you only want a 1-undo-depth, would be to draw the latest line always on a different canvas (on top of the current one).
So,

• When a new line is drawn, the previous one is removed from the temporal canvas and drawn on the final one (you keep the latest couple of coords)
• When a line is removed, just clear the temporal canvas.

Unless you are creating fast moving graphics (in which case you should probably be looking to use a game library approach), redrawing the canvas is quick enough to redraw all of the objects. Save the paths in a list, then manage the list to delete the ones you no longer want and clear and redraw them all.

It'll save problems where lines may cross or overlay at corners etc..

Thanks all!
i did it.