How do I keep my coordinates within the bounds of the Screen?

Question

This is my code... curX and curY are my current X and Y coordinates while tmpX and tmpY are relative X and Y values (how much the mouse has moved).

curX:= curX+tmpX;
curY:= curY+tmpY;

I use these values to move/control my cursor-shaped form.
How can I keep the cursors within the screen?

I tried limiting the values until Screen.Height and Screen.Width...here's the code.

if(curX>Screen.Width) then
  curX:=Screen.Width;
if(curY>Screen.Height) then
  curY:=Screen.Height;

but it didn't work.

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Solved it! (Sort of):

curX:= max(0, min((curX+tmpX), Screen.Width));
curY:= max(0, min((curY+tmpY), Screen.Height));

The only issue I have is that (0,0) is apparently not the upper left most (very close though, just a couple of pixels off I think) and (Screen.Width, Screen.Height) is not the upper right most (also close, the cursor disappears at the right most, though I think is one is supposed to behave that way).

Answer 1

You can create periodic boundary conditions by calculating (curX+tmpX) mod (screenSizeX) or limit the curX values with curX:= min(curX+tmpX, screenSizeX).

Answer 2

IF you limit it properly, it won't go outside your range. Post your code if you want to know why it's broken.

var1 := Inc(var1,amt);
var2 := Inc(var1,amt);
if var1 > limit1 then
    var1 := limit1;
if var2 > limit2 then
    var2 := limit2;

You must be careful to know if your limit is off all the screens in your system, not just the current screen. not everybody has one screen only. Some people have multiple screens.