The Sinclair QL Forum

• Prepare a window save area on the heap with WSAIN and proper size (can be bigger than the screen)
• Load the full image into memory (not to the screen, use L_WSA)
• copy what fits into your window from memory into your application window (use WSARS)
• when the user scrolls, copy the new position of your partial display from the big save area to the application window using WSARS, use width and height of your window for the cutout size

tofro wrote:

• Prepare a window save area on the heap with WSAIN and proper size (can be bigger than the screen)

[*]Load the full image into memory (not to the screen, use L_WSA)

[*]copy what fits into your window from memory into your application window (use WSARS)

[*]when the user scrolls, copy the new position of your partial display from the big save area to the application window using WSARS, use width and height of your window for the cutout size[/list]
The point is that the scrollbar defines the position of the cutout from the memory image that is copied to the screen. This is like moving the cutout that is actually displayed around with the scrollbars.

Giorgio Garabello wrote: This part is clear to me as a concept, but I did not understand how to achieve technically, what commands I have to use to make the scroll?

999  REMark returns address of back buffer in address, x and y size in x% and y%
1000 DEFine PROCEDURE LoadPicture (filename$, x%, y%, address)
1010   address = L_WSA (filename$, x%, y%)
1020 ENDDefine
1025 :
1030 REMark draw part of the picture at address with a left/top offset of x|y to our window
1035 REMark note we assume here x% and y% are < 900, so we always stay within the back buffer
1100 DEFine PROCEDURE DrawPicture (channel, address, x%, y%)
1110   REMark Clear application window to black
1120   BLOCK #channel, 0, 0, 100, 100, 0
1130   REMark Now cut a 100x100 area out of the back buffer and paint it
1135  REMark note we want the back buffer to stay, so use the \ separator
1140  WSARS #channel, address \ 100, 100, 0, 0, x%, y%
1150 END DEFine
1160 :

2000 REPeat MenuLoop
2010    .....
2100   MDRAW #ch%, "menuFile",....
2105   REMark assume appWinCh was somehow established, e.g with MWLINK or MWINDOW
2100   DrawPicture (appwinCh, pictureAddress, currX, currY)
2110   menuReturn = MCALL (ch% \ ...)
2120   IF (menuReturn > 65536) THEN
2130     IF (menuReturn && $FFFF = appWinNum) THEN : REMark make sure we got the right appl. Window
2140       upper = menuReturn / 65536
2150       opCode = upper && 15
2160       pixPos = INT (upper / 16)
2165       IF pixPos <> -1 THEN
2166         REMark scrollbar arrows not hit
2170         IF opCode = 0 THEN : REMark scrollbar hit
2180           currY = 1000 * scrollbarHeighinPixels / pixPos
2185           IF currY > 900 : currY = 900
2190         ENDIF
2191       ELSE 
2192         REMark handle arrows here
2193       ENDIF
2200 :
2200       IF opCode = 4 THEN : REMark Pan bar hit
2210         currX = 1000 * panBarWidthinPixels / pixPos
2215         IF currX > 900 : currX = 900 
2220       ENDIF
....
3000 END REPeat
 

Giorgio Garabello wrote: 1) to scroll or pan the image i need to have scrollbars... how can draw it?

Giorgio Garabello wrote: 2) this work if the X/Y size of the application subwindow menu is known ..but i'vea resizable menu..there's any function that returs these value?

tofro wrote:

Giorgio Garabello wrote: 1) to scroll or pan the image i need to have scrollbars... how can draw it?

Check MAWBARR

Ok

Giorgio Garabello wrote: 2) this work if the X/Y size of the application subwindow menu is known ..but i'vea resizable menu..there's any function that returs these value?

Check PVAL - allows you to get to the size of a window

Tobias