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dirty rectangles

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  • dirty rectangles

    PBWIn 9 - see thread http://www.powerbasic.com/support/pb...292#post309292
    Code:
    ' To demonstrate "dirty regions" - invalidating then redrawing regions
    ' rather than the whole client area
    ' It's a faster way of refreshing the display if only a small part needs
    ' to be redrawn.
    '
    ' Thanks to Chris Boss for pointing this technique out to me.
    '
    ' Chris Holbrook Feb 2009
    '
    ' Place the cursor on the dialog's client area, and hold the left button
    ' down then drag the mouse a little way. Release the left button, and the
    ' area defined will be overwritten by a region of corresponding size from the
    ' top left of the dialog's client area.
    '
    #compile exe
    #dim all
    #debug display on
    
    #include "win32api.inc"
    global ghD              as dword ' window handle for dialog
    global ghStatic         as dword ' window handle for label control
    global gHCDC            as dword ' memory DC
    global ghMemBMP         as dword ' compatible bitmap
    global gOriginalProc    as dword ' original WndProc for label control
    '-----------------------------------------------------------------
    function LBCB ( byval hWnd as dword, byval wMsg as dword, byval wParam as dword, byval lParam as long) as long
        local hdc, hbrush, holdbrush as dword
        local i, W, H as long
        local r as rect
        local PS as PAINTSTRUCT
        local s as string
        static paintcount as long
        static OrgX, OrgY, DestX, DestY as long
        
        select case wMsg
            case %wm_user + 400                     ' initialisation
                's = "starting..."
                'sendmessage ghD, %wm_settext, 0, byval strptr(s)
                'sleep 1000
                hdc = getdc(ghStatic)               ' set up the comaptible memory DC and bitmap
                gHCDC = createcompatibleDC(hDC)
                getclientrect ghStatic, byval varptr(r)
                W = r.nright - r.nleft
                H = r.nbottom - r.ntop
                ghMemBMP = CreateCompatibleBitmap(hdc, W, H)
                selectobject(gHCDC, ghMemBMP)
                setbkmode gHCDC, %transparent
                patblt gHCDC, 0, 0, W, H, %WHITENESS
                '
                s = "@@@@@@@@ABCDEFGHIJKLMNOPQRSYUVWXYZabcdefghijklmnopqrstuvwxyz" ' draw text on memory DC
                for i = 0 to 21
                    'movetoEx ghCDC, i * 25, 2, byval 0
                    TextOut ghCDC, 2, i * 18, byval strptr(s), len(s)
                next
                invalidaterect ghStatic, byval 0, 0
            '
            case %wm_lbuttondown
                DestX = 0: DestY = 0
                's = "drawing"
                'sendmessage ghD, %wm_settext, 0, byval strptr(s)
                OrgX = lo(word,lparam)
                OrgY = hi(word,lparam)
            '
            case %wm_lbuttonup
                DestX = lo(word,lparam)
                DestY = hi(word,lparam)
                setrect r, min(OrgX, DestX), min(OrgY, DestY), max(DestX, OrgX), max(DestY,OrgY)
                invalidatergn (ghStatic, CreateRectRgnIndirect(byval varptr(r)), 0)
            '
            case %wm_paint
                hDC = BeginPaint(ghStatic, PS)
                local lBGColor as long
                lBGColor = rnd(0, &HFFFFFF)
                bitblt HDC, PS.rcPaint.nleft, PS.rcPaint.ntop, _
                            PS.rcPaint.nright - PS.rcPaint.nleft, _
                            PS.rcPaint.nbottom - PS.rcPaint.ntop, gHCDC, _
                            0, 0, %SRCCOPY
                endpaint ghStatic, ps
                function = 1
                exit function
        end select
        function = CallWindowProc(gOriginalProc, hWnd, wMsg, wParam, lParam)
       
    end function
    '-----------------------------------------------------------------
    function pbmain () as long
        dialog new pixels, 0, "dirty rectangles                                                Chris Holbrook Feb 2009", 100, 100, 500, 400, %ws_sysmenu to ghD
        control add label, ghD, 101, "", 0, 0, 500, 400, %ss_notify
        ghStatic = getDlgItem(ghD, 101)
        gOriginalProc  = SetWindowLong(ghStatic, %GWL_WNDPROC, codeptr(LBCB)) ' Subclasses Graphic control
        sendmessage ghStatic, %wm_user + 400, 0, 0 ' initialise WndProc
    
        dialog show modal ghD
    
    end function
    Last edited by Chris Holbrook; 11 Feb 2009, 05:30 PM.
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