Is there any way I can get around having to add the layout_width and layout_height parameters to my custom views? I know there are a few built in android views that you don't have to supply those attributes for.
5 Answers
It's not a View's responsibility to decide whether or not it can/should provide these attributes. The parent ViewGroup dictates whether these attributes are mandatory or not. TableRow for instance makes them optional. Other layouts (LinearLayout, FrameLayout, etc.) require these params.
1 Comment
Nicholas Roge
I hadn't thought about about it like that. That being the case, how do I make the parent ViewGroup let the XML that "Hey, this guy doesn't need to show me these things."?
When would you want to not use the height and width parameters? I'm not sure but I think that would cause them to not even show up on the layout?
Look here for reference http://developer.android.com/guide/topics/ui/declaring-layout.html#layout-params
1 Comment
Nicholas Roge
Much like the table, I don't need them because the parent view controls the children's layout parameters. So the attributes I specify in the XML don't do anything at all.
From the same Reference Dave has suggested.
All view groups include a width and height (layout_width and layout_height), and each view is required to define them. Many LayoutParams also include optional margins and borders.
So it looks like, you have to.
4 Comments
Nicholas Roge
How does the TableRow ViewGroup get around this?
Orkun
@NicholasRoge I didnT know about the
ViewGroup but it says it s an abstract class (developer.android.com/reference/android/view/ViewGroup.html) The classes that extend it, however, they implement layout_height and layout_widthOrkun
@NicholasRoge But as i said, I didnT know about it. Can you define a ViewGroup and use it as a layout in an xml, for example ? I doubt it..
Orkun
@NicholasRoge If you want the parent to arrange your CustomControl's width and height, why not use "match_parent"?
If reducing common and redundant attributes is what you want, then you should try styling.
Developer guide here.
1 Comment
Nicholas Roge
It's not reduction I'm going for though. It's removal. There's no need at all for them to be there.
The problem is that ViewGroup.LayoutParams.setBaseAttributes() uses the strict getLayoutDimension(int, String). You need to extend whichever LayoutParams you need and override setBaseAttributes. Inside you can either manually set width and height or use the more lenient getLayoutDimension(int, int). Finally, you'll have to override in your layout class that you are using your own LayoutParams.
@Override public LayoutParams generateLayoutParams(AttributeSet attrs) { return new LayoutParams(getContext(), attrs); } public static class LayoutParams extends FrameLayout.LayoutParams { public LayoutParams(Context context, AttributeSet attrs) { super(context, attrs); } @Override protected void setBaseAttributes(TypedArray a, int widthAttr, int heightAttr) { width = a.getLayoutDimension(widthAttr, WRAP_CONTENT); height = a.getLayoutDimension(heightAttr, WRAP_CONTENT); } } 