Shimmering colours

[davidgraham]

I am displaying 256 boxes on a dialog using FillRec.
When the dialog is first displayed the whole dialog shimmers, but if I move the dialog it stops and is the display is OK.

Any ideas how I can stop this?

Thanks,

David

[davidgraham]

Jugoslav,

Here is the code for drawing the 256 colours (in fact 16 colours drawn 16 times at present). The main call are CreateSolidBrush, FillRect & DeteObject - all the rest is drawing the rectangles in the correct place.

grad_inc & the *.gcb files contain global variables.

Regards,

David

 
integer*4 function SetColourProc(hwnd, message, wParam, lParam)  
!********************************************************** 
!MS$ATTRIBUTES STDCALL, ALIAS : '_SetColourProc@16' :: SetColourProc 
use dfwin 
use grad_inc 
 
include 'resource.fd' 
include 'rgbcol.gcb'	! api_rgb,api_rgbc,api_lsc 
include 'apipar.gcb'	! hdc,x/yClientView,yClientOffset,hpen 
 
common/SetColourc/jSetColour 
integer*2	jSetColour 
 
TYPE(T_RECT)   rect1,rectC,rectD,rectB 
 
integer*4	hwnd, message, wParam, lParam 
integer*4 iret,hdcDlg,iCtrl,hdcClr,hbr,col,row,hColours,CWidth,CHeight 
integer*4 XColour,YColour 
integer*4	hSR 
integer*2	c,r,b 
real*4	width,height 
logical*4	lret 
 
! Unreferenced variables 
lparam = lparam 
 
select case (message) 
     case (#0053)			! WM_HELP 
      call help 
		 
    case (WM_INITDIALOG) 
	hdcDlg=GetDC(hWnd) 
	SetColourProc=1 
	return 
 
    case (WM_SHOWWINDOW) 
	if (wParam) then 
                 	iret=ShowCursor(.TRUE.) 
		hColours=GetDlgItem(hwnd,IDC_COLOURS) 
	endif 
        SetColourProc = 1 
        return 
 
case (WM_PAINT) 
	lret=GetWindowRect(hColours,rectC) 
	lret=GetWindowRect(hwnd,rectD) 
	hdcClr = GetDC (hwnd) 
 
	lret=GetClientRect(hwnd,rect1) 
	col=16 
	row=16 
	XColour=rectC%left-rectD%left 
	YColour=rectC%top-rectD%top 
	CWidth=rectC%right-rectC%left-7 
	CHeight=rectC%bottom-rectC%top-15 
	width=real(CWidth)/(real(col)+(real(col)+1.0)/2.0) 
	height=real(CHeight)/(real(row)+(real(row)+1.0)/2.0) 
 
	do b=1,256				! 256 colours 
		c=imod(b-1,col)+1	! column 
		r=int2((b-1)/row)+1	! row 
		rect1%left=(int4(c)*(1.5)-1.0)*width+Xcolour 
		rect1%right=rect1%left+width 
		rect1%top=(int4*(1.5)-1.0)*height+Ycolour-10 
		rect1%bottom=rect1%Top+height 
		hbr = CreateSolidBrush (RGB(api_rgb(1,c),api_rgb(2,c),api_rgb(3,c))) 
		lret = FillRect (hdcClr, rect1, hbr) 
		lret = DeleteObject (hbr)			 
	end do 
 
case (WM_COMMAND)                       ! message: received a command 
	iCtrl=LoWord(wParam) 
	select case (iCtrl) 
				 
case (IDOK)				! OK 
	lret=EndDialog(hWnd,1) 
            SetColourProc = 1 
 
case (IDCANCEL)		! System menu close command? 
            lret = EndDialog(hWnd, 0) 
            SetColourProc = 1 
 
end select 
 
case default 
	SetColourProc=0 
	end select 
     
               return 
 
	end function SetColourProc 

[Jugoslav_Dujic]

IMO it's quite incommon to do the drawing directly on
dialog's hDC. Even as you wrote it, its atypical for standard
WM_PAINT handling. You can try two things:

1) Add

 
type(T_PAINSTRUCT) ps 
... 
      IF (GetUpdateRect(hWnd,Rect,.FALSE.)) THEN 
            hdcClr=BeginPaint(hWnd,ps) 
... 
            bSt=EndPaint(hWnd,ps) 
      END IF 

(also remove line hDcClr=GetDC(...))

I think that dialog shimmers because noone has ever
validated the update region, so Windows keep on
sending WM_PAINT until the region is validated another
way. ValidateRect documentation says that, quote,

"The BeginPaint function automatically validates the entire client area. Neither the ValidateRect nor ValidateRgn function should be called if a portion of the update region must be validated before the next WM_PAINT message is generated. Windows continues to generate WM_PAINT messages until the current update region is validated."

b) Nevertheless, I think it's clearer to do the drawing in an owner-
drawn static control. So, make IDC_COLOURS an owner-drawn static control
Unfortunately, Visual Studio 5 (nor 6, as I checked) does not have "Owner drawn" check-box for static control on property sheet. You have to edit .rc file manually later - add SS_OWNERDRAW style to your control:

CONTROL "",IDC_COLOURS,"Static",SS_OWNERDRAW,11,16,116,120

then, instead of WM_PAINT, process WM_DRAWITEM in SetColourProc:

 
TYPE(T_DRAWITEMSTRUCT)::      DIS;  POINTER(pDIS,DIS) 
... 
CASE(WM_DRAWITEM) 
      pDIS=lParam 
      hdcClr=DIS%hDC 
... 

and leave the rest of the code more or less the same.
Owner-drawn controls are very powerful for obtaining nice
effects with controls.

HTH

Jugoslav

[davidgraham]

Thanks, I used the BeginPaint / EndPaint and the colours are now OK.

David