IsRectEmpty Function

Declare Function IsRectEmpty Lib "user32.dll" (lpRect As RECT) As Long

Platforms: Win 32s, Win 95/98, Win NT

IsRectEmpty checks to see if a rectangle is empty. A rectangle is considered empty if its right edge is not to the right of its left edge and/or its bottom edge is not below its top edge. For example, a rectangle (50,50)-(25,100) is empty because the right edge is to the left of the left edge. The function returns 1 if the rectangle is empty and 0 if it is not.

lpRect

The rectangle to check.

Example:

' Determine if windows Form1 and Form2 are overlapping on the
' screen.  If they don't the intersection rectangle will be empty.
Dim intrect As RECT  ' receives the intersection rectangle
Dim window1 As RECT, window2 As RECT  ' receive rectangles of Form1 and Form2
Dim isempty As Long  ' will be set to 0 if intersection isn't empty, 1 if it is
Dim retval As Long  ' return value for other functions

retval = GetWindowRect(Form1.hWnd, window1)  ' get Form1's rectangle
retval = GetWindowRect(Form2.hWnd, window2)  ' get Form2's rectangle
retval = IntersectRect(intrect, window1, window2)  ' determine the intersection rectangle
isempty = IsRectEmpty(intrect)  ' determine if it is empty -- it will be if there's no intersection
If isempty = 0  ' in this case, intrect will also be empty
  Debug.Print "Windows Form1 and Form2 are not overlapping on the screen."
Else
  Debug.Print "Windows Form1 and Form2 are overlapping on the screen."
End If

Related Call: SetRectEmpty
Category: Rectangles
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