i have to draw a ball inside a view (or anything else that is good for this task).
I have followed some tutorial about the matter, but every tutorial that i have found
uses only one view (that is shown on the screen without the use of a layout).
But in my Activity i use a layout, that is composed by many views, and i want to draw
only on one of them.
here a little mockup!
Anybody knows a way to do it?
Is the view the wrong container to do it?
Thanks is advance!
Bye
...
You should extend a view that inherits from ViewGroup. this kind of view lets you handle a view that contains other views. with that, you can control the drawing, measures and layout of each of it's children separately
Your mockup can be made with a LinearLayout, which will contain some TextView's and you own View (the one which is containing the ball).
I'm surprised by this question, because there are many examples over the net explaining how to build a layout containing multiple views.
Related
I have been working with Android for about 4 months. I need some guidance on how to implement something like this:
In that picture I've used three of the custom viewGroups (calling it ArcScrollView) stacked on top of on another which is what I am trying to achieve.
The questions that I have are:
Do I need to extend ViewGroup, frameLayout or what?
How can I make it scrollable?
I took a look at LinearLayout source code and it was extending frameLayout but again LinearLayout is not scrollable and need to be hosted by a scrollView.
I need to have complete control over scrolling because these arcScrollView are rectangles and I need onTouchIntercept of the viewGroup to return false (not consuming) at certain positions.
Is scrolling actually just changing the starting position of the first child view and putting them after one another or something magical that Android does?
I think I need to override the onDraw method also for drawing the partial circle. Does that effect anything that I need to worry about?
Should I override the ScrollView and LinearLayout instead? because I think there is a lot that have been implemented in them.
I'm trying to achieve something similar to this:
So, this is a container which can hold an arbitrary number of children. Each child is a simple text with border. Children may differ by their width. I assume this part can be implemented by extending the TextView widget (since it isn't clickable). Much more interesting thing here is the container for these bordered text views. It should support a regular addView(child) operation which automatically aligns the child according to the simple rule: if there is enough room within a current row - place child to the right of the last item in row. If there is no space - move child to the next row. So the basic logic seems quite similar to TextView or EditText: if text is too long, we display it in several lines. My idea is too extend RelativeLayout, but I still hope to find something easier.
The scheme I've described above (custom container + custom TextView) is not a mandatory, I'm just looking for ways to achieve this. Any thoughts guys?
Seems that pattern I was looking for is called FlowLayout (thanks to nitzanj). There are several of implementations of it:
FlowLayout by blazsolar
FlowLayout by ApmeM
If you decide to write your own version, here are helpful guides about writing custom views:
Official docs
Dive into Android (video)
Custom views (video, Google I/O 2013)
I'm developing an App with lot's of custom views and ran into performance issues with a quite complex one of them. The time they take for measuring and drawing is to high (>= 30ms typical). To give some more details: It's a custom ViewGroup (extending RelativeLayout) with custom Views (extending RelativeLayout although) as it's children.
So I'm it came across my mind what might be the better/quicker approach for getting rid of this performance problems: Optimize the children and layouts or switch to a completely custom drawn view (lines, rectangles and stuff like these)?
Do any of you have experience in one or another? Or even some done some benchmarks and is willing to share them?
The simple approach would be to work on simplifying and flattening the current view hierarchy and maybe you'll be able to make the measuring and drawing process much cheaper(or decent at least). You didn't posted a layout so there isn't something specific to say, I've seen you mentioned RelativeLayouts in RelativeLayouts, maybe you could remove one and move the views up one level(even with the expense of adding other helper views), every level counts(especially with nesting RelativeLayouts). You probably know already but the merge and include tags in layouts could prove quite useful.
RelativeLayout being in the standard SDK was built as a general widget so it most likely can't achieve the performance of a custom designed layout. It would make much more sense to make your current layouts extending RelativeLayout to extend ViewGroup and implement the measuring and layout of children manually especially as you probably know the use case scenarios in your apps(for example a RelativeLayout always needs to handle all the size constraint cases it could be in, your custom layout on the other hand could handle this much faster if you know that the custom view will have a certain size).
Related to a completely custom drawn view, it's an option but it depends on the complexity of your layout.
Or even some done some benchmarks and is willing to share them?
I don't see how various view benchmarks(which most likely will not apply to your specific situation) will help.
I am going to start one app where my activity page will contain "n" grouped views. Grouped view means "collections of views (i.e. One group can have TextView+Button+ImageView)". So the page will have "n" number of such grouped views.
I need suggestions like what would be the best practice to implement this. I could think of below ones:
1) Should a ScrollView be used (Then I will have to create groups in runtime and place one under another)?
2) Or a ListView be used (Then how can I accommodate the height of each row as grouped views height may differ from each other?)
Or is there any other way I can go along with?
Appreciate the suggestions and any sample examples if have. Advance Thanks.
Both options would work, it really depends on your use case.
Place a vertical LinearLayout inside of a ScrollView and add your grouped-views to the LinearLayout. I would recommend this if you have a relatively small number of such views (not necessarily a fixed number, but small enough that you wouldn't have to scroll many "pages" to see them all). Make sure the ScrollView has android:layout_height="match_parent" and the LinearLayout has android:layout_height="wrap_content".
If the number of grouped-views is not small, you could use a ListView and make an Adapter for it. This lets you take advantage of ListView's automatic view recycling when items get scrolled off screen.
For either case, make an XML file for just the grouped-views. In code, you would get a LayoutInflater object (usually by calling Activity.getLayoutInflater()) and call inflate(R.layout.your_grouped_views, null). If using the LinearLayout, you would add it in code with one of the LinearLayout.addView(..) methods; if using the ListView, your adapter would return the whole thing from getView(...).
create one xml layout containing the constant elements of your group view.
in you main xml layout which will be the contentView of your application, put a ScrollView and a single LinearLayout.
then in the program inflate as many views of your group view as you want.
For your answer i want to give you referance of this website, on this website you can learn create dynamic view in android...
What purpose does FrameLayout serve in Android? Is there any specific scenario for which it is designed for?
In my Android application, I have a scenario where I have to show two ImageViews, one over the other. This is a .png image file with a 9-patch drawable over this image.
Which ViewGroup should I use for this purpose: RelativeLayout or FrameLayout?
I also want to know the different scenarios that each of the ViewGroups should be used for.
I don't recall how i got to this question but here is my answer that could help anyone:
As you can see here
FrameLayout is designed to block out an area on the screen to display a single item. Generally, FrameLayout should be used to hold a single child view, because it can be difficult to organize child views in a way that's scalable to different screen sizes without the children overlapping each other.
In general is not useful to have 2 views one over the other because you're going to have overdraw effect (an area of the screen that is getting drawn by the gpu more than once which is really useless).
If you really have to, then you need to use the onDraw method (you can see an example here) and Canvas API (have a look here) and the clipRect method (you can see an example here)
Regarding FrameLayout or RelativeLayout, if you want to keep things simple or your activity has already enough nested layouts, better use FrameLayout. In 2017, there is the constraint layout which could be of some help as well.
Yes, you can use a FrameLayout in your scenario.