Path: utzoo!utgpu!water!watmath!clyde!bellcore!faline!ulysses!allegra!mit-eddie!bloom-beacon!think!ames!pasteur!ucbvax!CORY.BERKELEY.EDU!dillon
From: dillon@CORY.BERKELEY.EDU.UUCP
Newsgroups: comp.sys.amiga
Subject: Re: Scrolling SuperBitMaps
Message-ID: <8801231940.AA12667@cory.Berkeley.EDU>
Date: 23 Jan 88 19:40:08 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 41
Posted: Sat Jan 23 14:40:08 1988

:In A-Talk Plus I do that in the Zoom for the Tek4014 emulator.  I have two
:horizontal and vertical scrolling gadgets that control a 1024 x 780 
:superbitmap.  When I get a GADGETDOWN, I smooth-scroll until the gadget is 
:released looping for INTUITICKS messages.  A little voodoo with ModifyIDCMP
:is also needed.  I recall that the source code for the Lines Workbench demo
:(probably by Bart) does just that.

	An easier way would be to set the FOLLOWMOUSE flag for the prop
gadget.  Then you get mouse movement events *while* the person is sliding
the gadget around.  The example code below will also handle the update as
fast as the program can take it (that is, it uses only the very latest
mousemove).  This is a somewhat different effect than INTUITICKS in that if
you have an extremely fast display update it will look smoother.

    while (mess = GetMsg(win->UserPort)) {
        switch(mess->Class) {
	GADGETDOWN:
	    if (mess->IAddress == (APTR)&MySliderGadget)
		sgisdown = 1;
	    ModifyTheStuff(mess->MouseY);
	    break;
	GADGETUP:
	    if (mess->IAddress == (APTR)&MySliderGadget) 
		sgisdown = 0;
	    ModifyTheStuff(mess->MouseY);
	    break;
	MOUSEMOVE:
	    MouseMovedFlag = 1;
	    MouseX = mess->MouseX;
	    MouseY = mess->MouseY;
	    break;
        etc....
	}
	ReplyMsg(mess);
    }
    if (MouseMovedFlag) {
	MouseMovedFlag = 0;
	if (sgisdown)
	    ModifyTheStuff(MouseY);
	/* do other stuff */
    }