Undo drawing

Targets iOS
1

I am trying to add an undo feature to part of a drawing module which I thought would be straight forward…
I have a picture array that I store the current image and when an addition is made to the drawing I add a picture to the array.
Problem is when I do this the whole array gets updated with the new image? How do I just put an instance in the array that isn’t updated?

2

hey can you share some code or pseudo code to understand your code structure and help you…

3

Mapimage is the picture property that is drawn to in the paint event.
UndiMapimage() is the picture array

In the Pointerup event after drawing on the canvas I add the updated image to
UndoMapImage.Add(MapImage)

4

You need to clone the picture before you add it to the array otherwise you will just be adding a reference to the same picture which will always contain the latest content.

One way to clone is to create a new picture and draw the source picture into it.

1 Like
5

if you have MBS

UndoMapImage.Add(MapImage.clonembs)

if not

var mapimagecopy as new picture (MapImage.width,MapImage.height)
mapimagecopy.graphics.drawpicture mapimage,0,0
UndoMapImage.Add(MapImage)
1 Like
6

Thanks both of those worked