Hi all,
The images above are taken from the "Nike Boom" App. I am wondering how to do a magnified effect on the number list as shown in the images. I also want to point out that it is very very smooth animation, so screen capturing certain part of a screen and projected it back on UIView may not work (I tried that)
Thankz in advance,
Pondd
Update:
Hey,
Just so for anyone who might comes across this topic, I've made a simple sample based on Nielsbot's suggestion and posted up on github here
Please feel free to fork it, improve it and pass it on :)
Best,
Pondd
It's done with 2 scroll views, one in front of the other. One scroll view (A) contains the small numbers. The second scroll view (B) contains the zoomed numbers. The frame of (B) is the transparent window. When you scroll (A), you scroll (B) programmatically, but you move it farther than (A). (I.e. if (A) scrolls 10 pixels, you might scroll (B) 20 pixels.)
Make sense?
If you've ever used Convert.app from TapTapTap they use a similar effect.
Related
I have an infinite scrollview in which I add images as the user scrolls. Those images have varying heights and I've been trying to come up with the best way of finding a clear space inside the current bounds of the view that would allow me to add the image view.
Is there anything built-in that would make my search more efficient?
The problem is I want the images to be sort of glued to one another with no blank space between them. Making the search through 320x480 pixels tends to be quite a CPU hog. Does anyone know an efficient method to do it?
Thanks!
It seems that you're scrolling this thing vertically (you mentioned varying image heights).
There's nothing built in to UIScrollView that will do this for you. You'll have to track your UIImageView subviews manually. You could simply maintain the max y coordinate occupied by you images as you add them.
You might consider using UITableView instead, and implementing a very customized tableView:heightForRowAtIndexPath: in your delegate. You would probably need to do something special with the actual cells as well, but it would seem to make your job a little easier.
Also, for what it's worth, you might find a way to avoid making your solution infinite. Be careful about your memory footprint! iOS will shut your app off if things get out of hand.
UPDATE
Ok, now I understand what you're going for. I had imagined that you were presenting photographs or something rectangular like that. If I were trying to cover a scroll view with UILeafs (wah wah) I would take a statistical approach. I would 'paint' leaves randomly along horizontal/vertical strips as the user scrolls. Perhaps that's what you're doing already? Whatever you're doing I think it looks good.
Now I guess that the reason you're asking is to prevent the little random white spots that show through - is that right? If I may suggest a different solution: try to color the background of your scroll view to something earthy that looks good if it shows through here and there.
Also, it occurred to me that you could use a larger template image -- something that already has a nice distribution of leaves -- with transparency all along the outside outline of the leaves but nowhere else. Then you could tile these, but with overlap, so that the alpha just shows through to the leaves below. You could have a number of these images so that it doesn't look obvious. This would take away all of the uncertainty and make your retiling very efficient.
Also, consider learning about CoreAnimation (CALayer in particular) and CoreGraphics/Quartz 2D ). Proper use of these libraries will probably yield great improvements in rendering speed.
UPDATE 2:
If your images are all 150px wide, then split your scrollview into columns and add/remove based on those (as discussed in chat).
Good luck!
I have a UITableView within a UIView that has a PNG of a rubber rope attached to the top of the tableview. It stays on top though when the table slides down, it's not a part of the table, just a part of the view.
Desired behavior:
when the user pulls the tableview down, I'd like somehow for this rope to extend realistically like a rubber band
when they let go of the table, the table cells extend back up with the same speed as the attached rubber band.
This is not for scrolling through the table view, but when you only have say 2 or 3 cells and you pull it down, and it extends a rope, and when you let go, it goes back up.
It's the same behavior as a default table view, but now there's just a rope attached to the top.
I'm not looking for any specific answers since I know that can be difficult, but if you have any idea what direction I should be heading in to accomplish this, please share.
I came up with two different ideas:
Using Images as transitions and stretching
My first idea is to create a bunch of images for each transition. Of course, not the entire animation, just 5 different states for the rubberband, something like this:
Each transition is then fit to the next one by stretching the image, and then swap to the next state until the last one is reached. This wouldn't look entirely realistic, but convincing enough, and enough to capture the attention of the user.
Using CGPathAddEllipseInRect
On the other hand, if stretching & swapping images doesn't work, you could draw an oval using CALayer methods, something like a CGPathAddEllipseInRect (sample code here), and drawing a close loop. This is more handy as it draws the entire transition.
I hardly know how to explain my case other than to point to the excellent Absolute vodka app, Drink Spiration.
I am trying to make a carousel like image browsing with a little spice. I would really like to find a simple core animation explanation on how to accomplish something like the above app.
I hope someone can help with this. The solution doesn't have to be exactly the same, but just explain what is happening and it would be best if it was simple and no opengl. Just something to point me in the right direction. I don't think using just a scrollview with uiimageviews is enough.
I wrote something similar and its quite easy once you figure it out in your mind. All done justing using regular old views and animating transforms on them.
Say its 3 images on screen, and you can rotate new ones on and off ... then you will need 5 views set up (most simply just a UIImageView with a relevant image set). They are the currently selected image, the two either side of it and the ones that are, or will be animating on or off when the user flicks left or right.
Each of these 5 images has a position, an angle and an image. When the user flicks left or right each gets animated to the next position and angle, views that are about to come onscreen have their image updated to the next image in the set. If the user keeps on flicking in the same direction you simply reposition views on one side as they come off the other.
With this setup you can do lots of cool carousel like things very simply.
I'm trying to make a level-of-detail line chart, where the user can zoom in/out horizontally by using two fingers, and grow the contentSize attribute of the the UIScrollView field. They can also scroll horizontally to shift left or right and see more of the chart (check any stock on Google Finance charts to get an idea of what I'm talking about). Potentially, the scroll view could grow to up to 100x its original size, as the user is zooming in.
My questions are:
- Has anyone had any experience with UIScrollViews that have such large contentSize restrictions? Will it work?
- The view for the scroll view could potentially be really huge, since the user is zooming in. How is this handled in memory?
- Just a thought, but would it be possible to use UITableViewCells, oriented to scroll horizontally, to page in/out the data?
This is kind of an open ended question right now - I'm still brainstorming myself. If anyone has any ideas or has implemented such a thing before, please respond with your experience. Thanks!
This is quite an old topic, but still I want to share some my experiences.
Using such a large UIView (100x than its origin size) in UIScrollView could cause Memory Warning. You should avoid render the entire UIView at once.
A better way to implement this is to render the only area which you can see and the area just around it. So, UIViewScroll can scroll within this area smoothly. But what if user scrolled out of the area that has been rendered? Use delegate to get notified when user scroll out of the pre-rendered area and try to render the new area which is going to be showed.
The basic idea under this implementation is to use 9 UIViews (or more) to tile a bigger area, when user scrolled (or moved) from old position to new position. Just move some UIViews to new place to make sure that one of UIView is the main view which you can see mostly, and other 8 UIViews are just around it.
Hope it is useful.
I have something similar, although probably not to the size your talking about. The UIScrollView isn't a problem. The problem is that if you're drawing UIViews on it (rather than drawing lines yourself) UIViews that are well, well off the screen continue to exist in memory. If you're actually drawing the lines by creating your own UIView and responding to drawRect, it's fine.
Assuming that you're a reasonably experienced programmer, getting a big scroll view working that draws pars of the chart is only a days work, so my recommendation would be to create a prototype for it, and run the prototype under the object allocations tool and see if that indicates any problems.
Sorry for the vagueness of my answer; it's a brainstorming question
But still, this approach (in the example above) is not good enough in some cases. Cause we only rendered a limited area in the UIScrollView.
User can use different gestures in UIScrollView: drag or fling. With drag, the pre-rendered 8 small UIViews is enough for covering the scrolling area in most of the case. But with flinging, UIScrollView could scroll over a very large area when user made a quick movement, and this area is totally blank (cause we didn't render it) while scrolling. Even we can display the right content after the UIScrollView stops scrolling, the blank during scrolling isn't very UI friendly to user.
For some apps, this is Ok, for example Google map. Since the data couldn't be downloaded immediately. Waiting before downloading is reasonable.
But if the data is local, we should eliminate this blank area as possible as we can. So, pre-render the area that is going to be scrolled is crucial. Unlike UITableView, UIScrollView doesn't have the ability to tell us which cell is going to be displayed and which cell is going to be recycled. So, we have to do it ourselves. Method [UIScrollViewDelegate scrollViewWillEndDragging:withVelocity:targetContentOffset:] will be called when UIScrollView starts to decelerating (actually, scrollViewWillBeginDecelerating is the method been called before decelerating, but in this method we don't know the information about what content will be displayed or scrolled). So based on the UIScrollView.contentOffset.x and parameter targetContentOffset, we can know exactly where the UIScrollView starts and where the UIScrollView will stop, then pre-render this area to makes the scrolling more smoothly.
i am quit new at iphone development and trying to make a photo collage software while learning it. Right now i have a lil problem and hope you can help me out.
I have an UiviewController with a view in it, in this view i have 7 scrollviews with uiimagevies in them for zooming and scollign images within these scrollviews.
All that works well but now i want to make these 7 scrollviews dragable and maybe if possible zoomable (so that the image within the given scroolview zoom together with the scrollview).
It should be possible to drag them all around the screen and if possible even overlap them
and by the way rotating would be great ;-) hope that is not to much asked for.
Would be great if someone can help me out with this..
Well you've got to decide on some other choice here because the functionality you are asking for overlaps, and you can't ask the app to magically know which the user wants to do. What I mean by this is that when you touch and drag within a scroll view, it's going to try to scroll itself, rather than drag the entire scroll view around.
As for rotation and zooming - that gets more complicated, because you start dealing with vector math and the like. You can check out my question on rotation here. The link I gave you has the code to get both rotation and zooming to work.