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iOS UIScrollView + pagingEnabled, scroll half a page?

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iphoneSDKrules

macrumors newbie
Original poster
Aug 21, 2008
9
0
Hello,

can anyone tell me if it is possible, to scroll half a page in a UIScrollView with pagingEnabled = true.

As far as I know, the amount of scrolling when pagingEnabled depends on the frame size of the ScrollView, so it scrolls exactly one page.What I'd like to do is scrolling exactly half a page: my ScrollView contains two images on each 'page' and after scrolling I don't want to display the next two images, but the second image of the previous page + the first image of the next page and so on...

I'd be so glad if anyone could tell me how to do so.

thanks for your help, kate :)
 
W

walty

macrumors member
Jul 15, 2008
33
0
hm.. I have seen such scenario (as a bug) in uitableview, but not sure if it worked the same as uiscrollview.

have u tried to make the frame size of the scrollview TWICE the size of screen? in that way, the second half may never be scrolled to.
 
Z

zkiraly

macrumors newbie
Jan 15, 2009
2
0
I am also interested in the same. Right now I have a workaround in place, but being able to page arbitrary distances would be nice.

Zsolt
 
dejo

dejo

Moderator emeritus
Sep 2, 2004
15,982
452
The Centennial State
zkiraly said:
I am also interested in the same. Right now I have a workaround in place, but being able to page arbitrary distances would be nice
Click to expand...
That doesn't sound like paging to me, which, as I understand it, is scrolling non-arbitrary distances.

My suggestion to everyone would be to set pagingEnabled = NO and scrollingEnabled = NO and then capture the swipe events and then call scrollRectToVisible to scroll to where you want it. I'm not certain this will work but it's worth a shot.
 
Z

zkiraly

macrumors newbie
Jan 15, 2009
2
0
dejo said:
My suggestion to everyone would be to set pagingEnabled = NO and scrollingEnabled = NO and then capture the swipe events and then call scrollRectToVisible to scroll to where you want it. I'm not certain this will work but it's worth a shot.
Click to expand...

Thanks for the suggestion. Actually, that's what I do now. But there is no 'bounce' at the end, like in the weather app.

I think this is still 'paging.' Imagine the weather app, but zoomed out, so you see a portion of the adjoining pages as well. That's kinda what I'd like to accomplish in my own app.
 
I

iphoneSDKrules

macrumors newbie
Original poster
Aug 21, 2008
9
0
dejo said:
My suggestion to everyone would be to set pagingEnabled = NO and scrollingEnabled = NO and then capture the swipe events and then call scrollRectToVisible to scroll to where you want it. I'm not certain this will work but it's worth a shot.
Click to expand...

Thank you! That solves my problem!
I set paginEnabled + scrollingEnabled to NO and capture swipes using the touchesBegan and touchesEnded methods. Depending on a positive or negative yDistance between the two touch locations, I call the scrollRectToVisible in order to scroll half a page forward or backward, which works really well! :cool:
 
C

coconutdj

macrumors newbie
Mar 12, 2009
1
0
hi iphoneSdkRules,
i have the same problem , i want to scroll a half page, can you send me that piece of code to see hot to do this ?
" I set paginEnabled + scrollingEnabled to NO and capture swipes using the touchesBegan and touchesEnded methods. Depending on a positive or negative yDistance between the two touch locations, I call the scrollRectToVisible in order to scroll half a page forward or backward, which works really well! "

Thanks
coconut_dj@yahoo.com
 
I

iphoneSDKrules

macrumors newbie
Original poster
Aug 21, 2008
9
0
hi, this is what i did in touchesBegan & touchesEnded methods:

PHP: 
#define SCROLLOFFSET 60

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
	NSLog(@"TOUCHES BEGAN!");
	
	UITouch* touch = [touches anyObject];
	touchDown = [touch locationInView:self.view];
}

- (void)touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event
{
	NSLog(@"TOUCHES ENDED!");
	
	UITouch* touch = [touches anyObject];
	touchUp = [touch locationInView:[[self.view subviews] objectAtIndex:0]];
	
	//calculate dragging distance
	double dy = touchUp.y - touchDown.y;
	double dx = touchUp.x - touchDown.x;
	
	NSLog(@"touchDown x: %d, y: %d", touchDown.x, touchDown.y);
	NSLog(@"touchUp x: %d, y:%d", touchUp.x, touchUp.y);
	NSLog(@"distance between touches: %d", dy);

	if(abs(dy) > SCROLLOFFSET)
	{
		if(dy < 0)
			[self scrollForward];
		else
			[self scrollBackward];
	}
}

touchUp and touchDown are both CGPoints, the scrollForward and scrollBackward are used to call the scrollRectToVisible method with a calculated offset.

hope that helps
 
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