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How can I use window's scrolling

General and Gameplay Programming Programming

Started by Alload July 14, 2001 05:15 AM

3 comments, last by Alload 23 years, 7 months ago

Alload

Author

122

July 14, 2001 05:15 AM

Hello folks, I have to implement scrolling in my Win32 application. I read the SDK documentation, it didn''t look too hard so I wrote code at once. But my scrolling code doesn''t work at all. And I don''t know where''s the error... Here''s the global variables: SCROLLINFO si; short nScreenMaxX; short nScreenMaxY; short nScrollX = 0; short nScrollY = 0; Here''s the message handler''s part which use the scrolling: case WM_SIZE: { nScreenMaxX = LOWORD(lParam); nScreenMaxY = HIWORD(lParam); si.cbSize = sizeof(SCROLLINFO); si.fMask = SIF_ALL; si.nMin = 0; si.nMax = nScreenMaxX; si.nPage = 50; si.nPos = nScrollX; SetScrollInfo(hWnd, SB_HORZ, &si, true); InvalidateRect(hWnd, NULL, true); return 0; } case WM_HSCROLL: { short nInc; switch (LOWORD(wParam)) { case SB_PAGEUP: { nInc = si.nPage; } case SB_PAGEDOWN: { nInc = -si.nPage; } case SB_LINELEFT: { nInc = -1; } case SB_LINERIGHT: { nInc = 1; } case SB_THUMBTRACK: { nInc = HIWORD(wParam) - nScrollX; } default: { nInc = 0; } } nScrollX += nInc; si.nPos = nScrollX; SetScrollInfo(hWnd, SB_HORZ, &si, true); InvalidateRect(hWnd, NULL, true); return 0; } Does anyone see what''s going wrong?

gilady

122

July 15, 2001 12:09 AM

Hi,
Did you create the window with scroll bar style:
WS_HSCROLL | WS_VSCROLL
did you call ShowScrollBar(TRUE); ?
Maybe one of these two things is the cause of your problems.
-- Gilad

Alload

Author

122

July 15, 2001 04:58 AM

I created my window using the WS_HSCROLL and WS_VSCROLL tags, but I didn''t call the function ShowScrollBar.

I''m going to try to put it, I thought it was just a function to initialise scroll bars when they weren''t created with the window.

Thanks.

Alload

Author

122

July 15, 2001 12:27 PM

It still doesn''t work...

Nytegard

842

July 15, 2001 12:54 PM

Ah, scroll bars, the bane of windows programming (I swear, scroll bars have to be the absolute worst thing to program as far as the GUI goes).

here''s a snippet of my code that works. kind of in a rush right now, just cut and paste, so see if it makes any sense:

  //some code herecase WM_SIZE:		wmId = LOWORD(lParam);		// the width of the window		GetClientRect(hWnd,&rt);	// gets the client rectangle		// gets the maximum scrolling position		hscroll.nMax=windowlength-(rt.right-rt.left)+Paint.getStepSize();		if(wmId!=0){			hscroll.nPage=getWinRatio(wmId-STAT_OFFSET);	// gets the scrollinng thickness//			hscroll.nPage*=Paint.getStepSize();			resize=false;						// no resize		}		else{			hscroll.nPos=0;			// the offset = the maximum scroll postion			resize=true;						// resize the window								// scroll the window all the way right		}		if(windowlength<(rt.right-rt.left)){			windowoffset = 0;			hscroll.nPos = 0;			hscroll.nMax = 0;			hscroll.nMin = 0;			hscroll.nPage = 0;		}		else{			if(hscroll.nPos>hscroll.nMax){				windowoffset = hscroll.nMax;			}			else{				windowoffset=hscroll.nPos;	// the window offset = the horiztonal scroll position					}		}		SetScrollInfo(hWnd,SB_HORZ,&hscroll,false);	// set the scroll info//some more code here in the WM_SIZEcase WM_HSCROLL: //. scroll bar stuff			hscroll.fMask = SIF_ALL;			wmId	= LOWORD(wParam);	// the width of the window			GetScrollInfo(hWnd,SB_HORZ,&hscroll);	// get the scroll bar info			i=hscroll.nPos;				// keep the previous postion			switch(wmId){			case SB_LINELEFT:			// the user clicks the left button				hscroll.nPos-=Paint.getStepSize();				break;			case SB_LINERIGHT:			// the user clicks the right button				hscroll.nPos+=Paint.getStepSize();				break;			case SB_THUMBTRACK:			// the user drags the scroll bar				hscroll.nPos=hscroll.nTrackPos;				break;			case SB_PAGEDOWN:			// the user clicks to the right of the bar				hscroll.nPos+=(hscroll.nPage*Paint.getStepSize());				break;			case SB_PAGEUP:				// the user clicks to the left of the bar				hscroll.nPos-=(hscroll.nPage*Paint.getStepSize());				break;				// stop using the scroll bar			case SB_THUMBPOSITION:			case SB_ENDSCROLL:				// set the scroll info				SetScrollInfo(hWnd,SB_HORZ,&hscroll,true);				// retrieve the scroll info				GetScrollInfo(hWnd,SB_HORZ,&hscroll);				// set the window offset				windowoffset=hscroll.nPos;				// sets the scroll info				SetScrollInfo(hWnd,SB_HORZ,&hscroll,false);				// recalculate the windows if scaling is enabled				if(Paint.getScale())					calcRatio(numwindows,false);				return 0;			default:				break;			}			// set the scroll info			SetScrollInfo(hWnd,SB_HORZ,&hscroll,true);			// get the scroll info			GetScrollInfo(hWnd,SB_HORZ,&hscroll);			// if the new position != the old position, scroll the windows			// to do: ScrollWindow has been replaced by ScrollWindowEx			if(i!=hscroll.nPos){				windowoffset=i-hscroll.nPos;				ScrollWindow(Window1->gethWnd(),windowoffset,0,0,0);				ScrollWindow(Window2->gethWnd(),windowoffset,0,0,0);				ScrollWindow(Window3->gethWnd(),windowoffset,0,0,0);				windowoffset=hscroll.nPos;		// the window offset = the scroll position				SetScrollInfo(hWnd,SB_HORZ,&hscroll,false);	// set the scroll info							}			break;

How can I use window's scrolling

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