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Drawing in a window

Creating a non auto-redraw window

Create an application with a resfile containing a single window template so that, when the application is double-clicked, the window opens on the desktop and when the window closes the application quits; see Example 1.2.

By default redraws for Toolbox windows are handled automatically but this can be altered by deselecting the Auto-redraw option in the Other properties... dialogue box.

When drawing to a window it is a common policy to set the colour of its background to white. This can be done via the edit window's Colours... dialogue box.

Add a “WindowRedraw” event handler

When the auto-redraw flag is deselected the corresponding event-handler entry in the application processing menu is no longer faded. Selecting this entry places a BASIC file in !RunImage containing the procedure definition:

DEF PROCDealWith_WindowRedraw(object,a%,b%,h%) REM ------------------------------------------------- REM Current position of the lower left-hand corner of REM work area is (a%,b%). Height of work area is h% REM ------------------------------------------------- ENDPROC

Drawing a circle
The following procedure draws a circle of radius 200 at position (500,500):

DEF PROCDealWith_WindowRedraw(object,a%,b%,h%) CIRCLE FILL a%+500,b%+500,400 ENDPROC

draw/gif

The following procedures draw the circle in colour

DEF PROCDealWith_InitialEvent Colour=15 ENDPROC DEF PROCDealWith_WindowRedraw(object,a%,b%,h%) SYS “Wimp_SetColour“,Colour CIRCLE FILL a%+500,b%+500,400 ENDPROC

drawc/gif

Worked solution