Creating a Nonrectangular Window

Janet Terra
Creating a Nonrectangular Window | Demo 1: Drawing a Nonrectangular Window | Third Part Title

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Creating an irregular shaped window is achieved with WinAPI calls to user32.dll and gdi32.dll. The first step is to create a window without a caption. This can be achieved with the stylebits commands _WS_POPUP in the addbits parameter and _WS_CAPTION in the removebits paramater, or simply using the window_popup style. It is also advisable to keep the window in the forefront. Do this by using the stylebits command _WS_EX_TOPMOST in the extended bits parameter. Remember that any GUI window may be closed with Alt-F4.

For more detailed discussion of stylebits, see Stylebits - Windows .

Demo 1: Drawing a Nonrectangular Window

This first demo draws a circle, a rectangle, and some graphic text. The background is never added to the window. Only the actual drawings, including the graphic text, become part of the window. First, open a captionless window.

 Nomainwin 
 
 'Define the Window 
 WindowWidth = 500 
 WindowHeight = 500 
 UpperLeftX = int((DisplayWidth-WindowWidth)/2) 
 UpperLeftY = int((DisplayHeight-WindowHeight)/2) 
 graphicbox #ShapeWindow.gb, 0, 0, 500, 500 
 stylebits #ShapeWindow.gb, 0, _WS_BORDER, 0, 0 
 
 'Keep the Shaped Window in the Forefront 
 stylebits #ShapeWindow, 0, 0, _WS_EX_TOPMOST, 0 
 
 open "Shape Window" for window_popup as #ShapeWindow 
 #ShapeWindow "trapclose [closeShapeWindow]" 

Once the window is opened, handles and device controls to both the window and the graphicbox must be obtained.

 'Obtain the Handles and Device Controls 
 hBw = hWnd(#ShapeWindow) 
 hBgb = hWnd(#ShapeWindow.gb) 
 hDCw = GetDC(hBw) 
 hDCgb = GetDC(hBgb) 
 
 'The Function 
 Function GetDC(hW) 
 Calldll #user32, "GetDC", _ 
 hW as ulong, _ 
 GetDC as ulong 
 End Function 

Now you're ready to draw an image. In this first demo, the image will be drawn using API calls. These are the steps in the [drawShape] gosub.

1: The Destination - Define a region to hold the finished window. Because this region will be built upon, start with all 0's for x, y, width and height.

 'Original values for hRgn is meaningless 
 hRgn = RectRegion(0, 0, 0, 0) 
 
 'The Function 
 Function RectRegion(ulx, uly, width, height) 
 CallDLL #gdi32, "CreateRectRgn", _ 
 ulx as long, _ 
 uly as long, _ 
 width as long, _ 
 height as long, _ 
 RectRegion as ulong 
 End Function 

2: The Circle - Define the x, y, width and height values for the circle. Select a red brush, paint the designated ellipse, delete the brush.

 'hRgn1 = Elliptical Source Region 
 hRgn1 = EllipticRegion(100, 50, 200, 250) 
 'Paint the Ellipse Red 
 brushColor1 = 255 'Red Brush 
 hBrush1 = createBrush(brushColor1) 
 Call SelObject hDCw, hBrush1 
 Call PaintRegion hDCw, hRgn1 
 Call DelObject hBrush1 
 
 'The Functions and Subs 
 Function RectRegion(ulx, uly, width, height) 
 CallDLL #gdi32, "CreateRectRgn", _ 
 ulx as long, _ 
 uly as long, _ 
 width as long, _ 
 height as long, _ 
 RectRegion as ulong 
 End Function 
 
 Function EllipticRegion(ulx, uly, width, height) 
 CallDLL #gdi32, "CreateEllipticRgn", _ 
 ulx as long, _ 
 uly as long, _ 
 width as long, _ 
 height as long, _ 
 EllipticRegion as ulong 
 End Function 
 Function createBrush(brushColor) 
 Calldll #gdi32, "CreateSolidBrush", _ 
 brushColor as long, _ 
 createBrush as ulong 
 End Function 
 
 Sub PaintRegion hDC, hRgn 
 Calldll #gdi32, "PaintRgn", _ 
 hDC as ulong, _ 
 hRgn as ulong, _ 
 null as long 
 End Sub 
 
 Sub DelObject hObject 
 Calldll #gdi32, "DeleteObject",_ 
 hObject as ulong,_ 
 null as long 
 End Sub 
 
 Sub SelObject hDC, hBrush 
 Calldll #gdi32, "SelectObject", _ 
 hDC as ulong, _ 
 hBrush as ulong, _ 
 null as long 
 End Sub 

Use CombineRgn to add this painted region, hRgn1, to the destination region, hRgn.

 'Set hRgn to the Combination of itself and hRgn1 
 newRgn = CombineRgn(hRgn, hRgn, hRgn1, _RGN_OR) 

Now that region hRgn1 is a part of region hRgn, it is no longer needed. Delete that object to free memory.

 'Delete hRgn1 
 Call DelObject hRgn1 

3: The Rectangle - Define the x, y, width and height values for the rectangle. Select a blue brush, paint the designated rectangle, delete the brush.

 'hRgn2 = Rectangular Source Region 
 hRgn2 = RectRegion(150, 75, 300, 200) 
 'Paint the rectangle blue 
 brushColor2 = 255 * 256^2 'Blue Brush 
 hBrush2 = createBrush(brushColor2) 
 Call SelObject hDCw, hBrush2 
 Call PaintRegion hDCw, hRgn2 
 Call DelObject hBrush2 

Once again, use the API Call CombineRgn to add the pixels of the rectangle hRgn2 to the final destination region hRgn.

 'Set hRgn to the Combination of itself and hRgn2 
 newRgn = CombineRgn(hRgn, hRgn, hRgn2, _RGN_OR) 

The hRgn2 rectangle can now be safely deleted to free up space, as it's been added to the shaped window region hRgn.

 'Delete hRgn2 
 Call DelObject hRgn2 

4: The newly built region made up of regions hRgn1 and hRgn2 can now be set as the window.

 'Set hRgn as the Window 
 Call SetWindowRgn hBw, hRgn, 1 
 
 'The Sub 
 Sub SetWindowRgn hWnd, hRgn, redrawMode 
 Calldll #user32, "SetWindowRgn",_ 
 hWnd as ulong,_ 
 hRgn as ulong,_ 
 redrawMode as boolean,_ 
 SetWindowRgn as long 
 End Sub 

The SetBkMode of #gdi32 can be called to achieve a transparent background for text. Text can then become part of the window.

 'Set background to Transparent 
 Call SetBkMode hDCgb, 1 

ReleaseDC is again called to release memory.

 'Release memory 
 Call ReleaseDC hBgb, hDCbg 

Graphics text is accomplished with native Liberty BASIC code.

 'Format Text 
 #ShapeWindow.gb "font Courier_New 14 Bold" 
 #ShapeWindow.gb "color Black; place 120 150" 
 #ShapeWindow.gb "\Alt-F4 to Close" 
 Wait 

Run your program and a shaped window appears. Close the window with Alt-F4 or include a button for closure. The window will stay on top of other windows, but it is possible for the window to lose focus. If this happens, click on the window before pressing Alt-F4.



Click ShapedDemo1.bas for the entire program.

Third Part Title

Text here.

 'code here 

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Creating a Nonrectangular Window | Demo 1: Drawing a Nonrectangular Window | Third Part Title