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how to drag and drop in a grid
hey guys, i need to be able to drag and drop in a grid environment, similarly to the way the drag and drop is handled when we drag a widget onto a MainWindow in Qt designer, it lands on a grid-type background....i need to be able to do that, i currently using Qt4 and i'm using Qframe as the dropsite...will someone help me please.....
Ive done this in vb before. If you get your drag code to work, this is how u get it to snap to a grid size - if i remmeber correctly: (this works for both vertical and horizontal)
(psuedocode)
offset = currentdropx mod gridsizex
previouscolumn = currentdropx - offset
if (offset <= (gridsizex / 2))
setx(previouscolumn)
else
setx(previouscolumn + gridsizex)
Dont hold that to 100% working it may need some tweaks.
ok thanks alot but i dont understand the algorithm, is it possible for u to explain it to me? thanks in advnace
offset = currentdropx mod gridsizex // get the offset - the amount away from the last grid line where it was dropped
previouscolumn = currentdropx - offset // get the x value of the last grid line
if (offset <= (gridsizex / 2)) // if the drop placement was less than half of the width of the grid, put it to the left.
setx(previouscolumn)
else
setx(previouscolumn + gridsizex) // otherwise put it to the right
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