I have an app that show the tv guide for a list of channels. My UI is made from a a lot of custom views with different widths that show the tv programs, all these custom views are added into a horizontal scrollview that is added into a scrollview so my views can be scroll in 2 dimensions left-right and top-down. It all works good until i add add a lot of views and it starts to slow down very much. So i need a way to recycle views like listiew does in a scrollview maybe there is a custom made scrollview that does this, or someone has an idea how to do this, its strange that scrollview isnt backed up by an adapter like gridview and listview.
I did something similar only my Views were not connected as yours but they were all different sizes.
First you need to define if your entire area (not just viewing screen) has definitive or dynamical number of your custom views.
If you have definitive number of views and their positions you should create their position map with list of Rect's (Rect has a good function whether the xy point belongs). Then you define maximum of Views which are visible on your screen. For this to work without constant loading you should have maximum visible views + at least one line of border views of total objects. After all this you should easily have your own positioning system where you load views which are in bounds of your screen + some overhead (purpose of this is that you want your users to have smooth transition while scrolling at least for some length), if you need to load some in same time you unload (read reuse/ do not dispose objects and create them onScroll events) and place them according to your needs.
And if you want to determine which views should be visible you just go through list and ask whether Views Rect intersects with your Rect of area to be loaded.
Hope this image helps a little bit more
I know it sounds a little bit confusing and difficult to implement but you did not asked a simple question :)
Hope this helps and enjoy your work.
A ScrollView that is backed up by an adapter and recycles views is a ListView, with a couple of extra optional features on top.
Maybe you want a HorizontalScrollView that is backed by an adapter? Searching for HorizontalListView will give you a few results, ex: https://github.com/dinocore1/DevsmartLib-Android.
Related
I'm looking for a way to display views (like buttons, checkboxes, images etc) in a container, which might be bigger than the actual screen size.
A ScrollView within a HorizontalScrollView is no option, since you're only able to scroll one direction at once, not diagonal.
I have yet to find a simple solution to this problem. A zoom function would be nice to have, but that's not as important as the ability to scroll diagonal.
Are there any components out there able to do things like these? Doesn't even have to be for free.
I am trying to build a row of images. I want the number of images to increase based on screen width. For example, in portrait mode there may be 3 images present, but in landscape there would be five.
I have tried using a GridView, but I am having trouble stopping it from being populated after the first row has been filled (it goes to the next row). Is there an alternative view I should be using or is a GridView the right approach?
If you only want 1 row, then use a LinearLayout. If it needs to scroll, embed it in a HorizontalScrollView.
If you aren't scrolling you can then inflate and add each image, depending on available space.
You could make it more complex by creating custom classes, etc.
You can also try the Two-Way GridView (I've used it - it works great)
How to make grid-view horizontally scrollable in android
I have found a suggestion based off of this. Once a max width has been exceeded on the LinearLayout, simply stop adding to it!
I'm trying to build a point-and-click adventure for Android without using any pre-written engine, but I'm stuck in a really crucial point!
I have a HorizontalScrollView bigger than the screen, so the user can scroll left and right in portrait mode to search around rooms, now what I need is to insert items that the player can use inside this View.
I'm trying to use static ImageView, but I'm really confused on how to insert Views in an absolute position inside the HorizontalScrollView. All I know is that Android manages Views location relative to other views (align on top, next to, bottom of), but what I use if I need to position a View in a specified position using specific coordinates without worrying that the image will be misplaced in a different screen size for other Android devices?
I really am confused on how position views in Android :/
Consider creating your own view instead of abusing HSV.
Custom views, doDraw() method, canvas and even gesture detection is not that hard.
Here is a link that will help you with basics, simple viewport implementation for android with scrolling via key events: http://sonnygill.net/android/android-viewport/
what I use if I need to position a View in a specified position using specific coordinates without worrying that the image will be misplaced in a different screen size for other Android devices
Actually, that's exactly the reason ViewGroup (layouts) were created.
You should choose the right layout based on your requirements.
If you do want to position the views by yourself, you can create your own custom ViewGroup by extending one of the view group classes and override the onLayout(...) and onMeasure(...) methods which are used to position and measure child views (in you case, probably the ImageViews) respectively.
You can use this example of FlowLayout as a reference on how you can write your own custom ViewGroup.
Please note that if your content is bigger than the screen as you mentioned, the HorizontalScrollView should be a parent of a single child (which should be the ViewGroup containing your images).
hi i've some problems with listview. My list do have very different cell heights, some of them are even bigger then the height of the screen. What I found out, that listview scrolling intepolator has problems with calculating the inertia. each time when there is big height difference between two cells currently switching in the visible area, the scrolling junks..I've looked into traceview and there actually is not that much of a delay. (there is no line tallet then the 16ms treshold, though there is visible difference), that means it actually does not junk and it is rather only quickly accelerating and deccelerating the scrolling speed. (it occurs in exactly the same time as the scrollbar height changes)
Does anybody know how to solve this? I've read an article from facebook and they apparently had the same issue..There is written they needed to write their own item recycler. I'm kind of aware of that and would like to see some simpler solution..
Sorry for this question being so abstract, but I guess any code is not necessary..
thank you for your help..
ListViews recycle, the views that have been already inflated. Since in your case the Listview has items which vary in height, it is better to write your own recycler.
If you have specific categories as in X, Y and Z then you can check the layout type by adding an attribute to the layout as a tag, and inflating conditionally. But the best way to do this is write your own recycler.
I am starting a new application and I am willing to use the Dashboard pattern.
For example: The Google IO app uses it:
My issue is that the amount of buttons will be more than six.
I'm not sure if I should use vertical or horizontal scrolling.
Vertical scrolling could be done with a ScrollView or a GridView but I am not sure which would be the easier way to implement the horizontal version.
I was thinking of using an HorizontalScrollView but it doesn't have pagination. It should feel similar to the tweetdeck app.
How would you implement it?
My issue is that the amount of buttons will be more than six. I'm not sure if I should use vertical or horizontal scrolling.
IMHO, do neither. Reduce the number of buttons. Watch the 2010 Google I|O presentation on this design pattern -- the point behind the dashboard is to only surface a few items.
I would go with a vertical scroll. It is way more natural to scroll down to view more content of the same view.
A horizontal scroll kind of feels like you switch to another part of the application.
I have an app that uses a gridview with vertical scrolling but I dynamically adjust the number of rows in the gridview based on the width of the actual screen so that it in landscape or in a bigger display it uses more columns and avoid scrolling alltogether in most cases.
However in my case it is more of a search results display of categories and not a dashboard. I believe the whole point of a dashboard is to have only a small number of button (e.g. max six or so).
What you could do is dynamically interrogate the screen real estate and if there is not enough room just show e.g. 6 buttons of which one is a more/utils or whatever button. Sort of like the options menu does it.. but on a bigger screen display them all.
It would be interesting to scroll based on the orientation of the device, so you would scroll horizontally or vertically if the device is oriented that way. This would let you maximize the screen real estate.