Declare Function SubtractRect Lib "user32.dll" (lprcDst As RECT, lprcSrc1 As RECT, lprcSrc2 As RECT) As Long
Platforms: Win 32s, Win 95/98, Win NT
SubtractRect subtracts a smaller rectangle from a larger one. Rectangle subtraction is defined as follows. The large and small rectangles must intersect completely along one entire side, neither extanding farther along that side than the other. In other words, they must share a common side. If this is true, then all of the large rectangle that is not also part of the small rectangle is also a rectangle. This rectangle is the subtraction rectangle. This rectangle is put into the variable passed as lprcDst. If the two rectangles fail to meet the criteria, lprcDst is set equal to the large rectangle and the function returns 0. If subtraction is possible, the function returns 1.
Example:
' A demonstration of rectangle subtract. target = big - small.
' big = (20,30)-(70,80). small = (20,30)-(40,80). Note that the left side of the two rectangles is
' common. target will be set to (41,30)-(70,80).
Dim target As RECT, big As RECT, small As RECT
Dim retval As Long ' return value
' Set the big and small rectangles
retval = SetRect(big, 20, 30, 70, 80) ' big = (20,30)-(70,80)
retval = SetRect(small, 20, 30, 40, 80) ' small = (20,30)-(40,80)
' Subtract small from big and put the result into target
retval = SubtractRect(target, big, small) ' now target = (41,30)-(70,80)See Also: IntersectRect, UnionRect
Category: Rectangles
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