Greg,
Glad that worked. When I do these types of auto-size / auto-location exercists I like to draw it out on a piece of paper and then map my coordinates, helps me visualize but I was a draftsman back in the day (yes that dates me).
If you want to center something then take the width of the area that you have available, lets just say you have the full screen. so App.Width. Then subtract the width of the component (gallery in your case - Gallery.Width) and divide it by 2 (equal spacing on each side). So, what you end up with is an expression in the Gallery.X property of;
(App.Width - Self.Width )/2
You would apply the same for vertical centering using Height in the Gallery.Y property.
(App.Height - Self.Height )/2
To get a bit more complicated but you get the basis of the pattern. Let's say you have 3 objects you wanted evenly distributed across the a screen but the area was between and X of 500 and and X of 1000.
Your available area width is 500. and lets say you want the objects aligned with the left and right edges (no spacing).
The inter-control spacing is (500 - Control1.Width - Control2.Width - Control3.Width)/2
Since you will reuse this spacing in multiple expressions, in the screen Visible you can create a variable to hold the number;
UpdateContext({varControlSpacing: (500 - Control1.Width - Control2.Width - Control3.Width)/2})
Then the X property for each control would be
Control1.X set to 0
Control2.X set to Control1.X + Control1.Width + varControlSpacing
Control2.3 set to Control2.X + Control2.Width + varControlSpacing
Hope this helps you.
Mike
