I'm creating a Kakuro game for Android and it mainly consists of a large grid which contains only black and white squares according to a pattern. I have decided to use a custom class extended from Button to represent black and white squares.
But the problem is, I can't figure out what to use and/or extend to represent the square-containing (Button-containing) grid. It should have the following behavior:
Should be able to house Buttons along both x- and y-axes.
Should be scrollable in both ways as the grid will most definitely exceed the device's screen size.
Should not be too hard on the memory footprint.
So after some thinking, I have decided to create a custom class that extends View. But I don't know exactly which methods to override to obtain the behavior I want.
So can anyone please tell me which methods I should override to obtain the behavior I need? (The behavior is somewhat similar to that of Minesweeper).
Or is there any other easier/faster method I can use?
Thanks in advance!
if it is a grid you want, I recommend the GridView.
A view that shows items in two-dimensional scrolling grid. The items
in the grid come from the ListAdapter associated with this view.
GridView tutorial: http://developer.android.com/resources/tutorials/views/hello-gridview.html
Extending the GridView seems more suitable for your need: http://developer.android.com/resources/tutorials/views/hello-gridview.html
Related
I want to implement a graph as below for each item of a listview.
The cell will turn green or red based upon the input.
The number of coloured cells will increase based upon the input.
Could you please tell me what would be the best approach in attaining the same. Right now I have used table view to achieve this. But the list view is very slow. Tried searching for some third party graph libraries but had no luck.
Thank You.
If there's a fixed number of cells, you could define a custom view.
Inside the custom view, you can then define a canvas, where you can draw colored rectangles. Just provide some kind of update method for your custom view, to keep the canvas refreshing whenever there's a data change.
The advantage of this solution:
+ It's faster than hiding / showing and inflating views
+ You can custimze it much faster
+ You have all functions you need in one class
And it's relatively easy to accomplish, have a look at the android developer page for this topic: https://developer.android.com/training/custom-views/index.html
I am dynamically adding around 150 linearlayouts to a scrollview in a grid-like layout. If I set the background resource to a drawable for each of them using setBackgroundResource(R.drawable.x), the scrollview shows extremely noticeable lag and choppiness, even though the drawable is a simple colour and border.
If I remove the call to setBackgroundResource, the scrollview is smooth again.
Is this expected to happen with so many views containing backgrounds? If so, how would I go about making a grid with custom backgrounds for each cell?
You're going to want to use a list view in your scroll, and you're going to want to use a ListAdapater:
http://developer.android.com/guide/topics/ui/layout/listview.html
http://developer.android.com/reference/android/widget/Adapter.html
Basically what's going on is you're loading a large number of images into memory, and the scroll view by default doesn't do a very good job of managing releasing and inflating these resources.
Using methods similar to the above, with some custom image management, I've managed to get thousands of views running smoothly on a scroll.
It seems like you're trying to create your own list view implementation so that you can set your own layouts for each row. I don't recommend doing this. Instead, use the default list view implementation provided by Android and instead of setting a default ArrayAdapter instance on the list view, subclass ArrayAdapter, override the getView method, and return your custom layout.
I highly recommend you check out this tutorial for a more thorough explanation:
http://www.ezzylearning.com/tutorial.aspx?tid=1763429
Everyone knows that GridView does not supports headers and footers like a ListView.
There is a few ways to implementing this:
Use a ListView and form columnt manually via ViewGroups. It not works for me, because it's require a lot of layout operations like measuring and layouting, and it's difficult to implement draw selector on top.
Use special adapter. It works fine with a footer: we should fill last cells with a Space and manually insert after them out footer with width that equals GridView width. But this not works with headers: although header is stretched, next cells float on it.
Use a GridLayout. GridLayout is good, but what about performance with 500-1000 cells? AdapterView supports caching and reusing Views, as far as I know, this is not possible with GridLayout.
Extend GridView and write custom class, that allows to draw a header before the grid content. It's difficult, but it's should work very fast. Let's try to figure out how to do this:
Measure the header. It's very simple, I have not questions about this.
Layout header in the top of the grid. We also should consider with scrolling position to allow move header with whole grid content, so my first question is: how to know where bottom border should be located while scrolling?
Layout whole grid content after the header. How to do that? I've newer do this before.
Dispatch draw to the header view too and resolve overscrolling effect if it's not work well.
Handle the scroll event and refresh header position.
So what you can suggest me? How to do header offset? Is it right to invoke relayouting with every scroll event?
I searched an answer on a same situation with a GridView (but for a FooterView).
I've read attentively your suggestions and some from other websites. I had the same reflexion. I found a simple way as your tip: "Use special adapter. It works fine with a footer..." and this answer by #RaulSoto helped me a lot. But when I tried to update my gridview, I had a NPE, because my footer was not like the layout of my items and I had a custom filter which recalculated the getCount() method, but without understand that another view was added.
Finally, I found only solution which works: a custom class.
Create your own class as you said: "Extend GridView and write custom class" but don't extend GridView. You should extend with ListView and measure the entire width, the column width and the number of columns. I think, it's less difficult that to extend GridView, calculate the height of the header view and move it as you move your gridview or refresh the header each time you handle a scroll event..
I searched to do it in this way and I took this little project on GitHub: HFGridView by Sergey Burish. It was exactly what I need, no more.
I only added a custom attrs file in my app and customize a bit his project to have the expected result (especially, it was to have one column in portrait, two in landscape mode, refering to the numColumns attribute in my layout).
And when I try, just for test, to add a HeaderView and refresh the content with adding new items, the header view stays at the top of my gridview list, without refreshing himself.
So, I think you should search to create your class as GridView extends ListView. Refer you to the HFGridView by SBurish, it is very simple to understand how it does.
Hope this helps you with your purpose.
I would like to create a grid of dots very much like in this game: https://play.google.com/store/apps/details?id=com.nerdyoctopus.gamedots&hl=en
The aim is for each dot to be touchable, so I can recognise where that particular dot is and other information about it.
I don't really know where to start. Do I want to create a custom View for a dot with all the information I want, and then create multiple versions of it? And then do I arrange them in a grid with the setTranslation() method, or would it be better to use LayoutParams with offsets?
If I created my own "Dot" that extended "View", then I could add a lot of different information/methods to it - I could theoretically have a changeColor() method. Is this the best way?
A GridView is not what I am thinking of (as far as I know) as it is basically a different style of ListView.
There are lots of questions here! I have looked at a number of questions here on StackOverflow and elsewhere, but none show/ explain how I should start.
I would use a TableLayout for this. A GridView is the equivalent of a ListView in a 'grid' form, with scrolling, view recycling and whatnot, and that is not what you need. A GridLayout, as Dalmas suggested, would be a much better option if you want to build a static grid, but in my experience it is not easy to distribute the available space equally between columns, and if you are going to need to alter the grid distribution during the game, a TableLayout is much easier to use.
For the dots, yes, a custom view with a configurable color would be the best way to go around it.
You should use a GridLayout. It will do exactly what you need. It is available through the android support library v7 : http://developer.android.com/tools/support-library/features.html#v7-gridlayout
It allows you to arrange views using a grid of rectangular cells.
For the dots, I would go with a custom dot view as you suggest, with a simple method to set the color. Don't store any data in the views if possible, it will make things much easier and flexible.
How do i create this kind of views in my application?
(The screenshot is actually of an android application available in android market).
I am confused as i assume that we can create the same kind of layout either by using Gridview or by using ListView.
Problems:
In Gridview, can we give separator between two rows? can we give background to each row in gridview?
In Listview, i think we can customize the listview with 3 books in a row with background, and we can give a separator as well.
From your expert side, please suggest me a possible solution to design and create the same kind of layouts for the android application.
Look at the code of Shelves, written by Romain Guy (one of the ListView's creator).
He used a GridView:
no separator
background is a bitmap drawable
< bitmap
xmlns:android="http://schemas.android.com/apk/res/android"
android:src="#drawable/shelf_panel"
android:tileMode="repeat" />
background image is like this:
The code is worth a look because it contains other interesting solutions, too.
Stated problems:
In Gridview, can we give separator between two rows? can we give background to each row in gridview?
Well, you can always make up a separator by adding something on the bottom of your view. Make it so that it 'connects' on the sides, and you won't know the difference. It will cost you an extra view per grid-item, so probably not the best option.
In Listview, i think we can customize the listview with 3 books in a row with background, and we can give a separator as well.
Eeuhm, yes, although I don't see what the problem is?
With a ListView, each row is counted as an element, so there will be extra work in logic that keeps each item within the row separate. I would suggest you use a gridview. For each grid element, keep an empty shelf space (for one book) as the background image. This image will include the shelf-base. So there is no need for additional rows. The image should look like this:
I would instead suggest to have grid view and view flipper if the number of books are limited.
View flipper will give a better effect than scrolling.