android-relativelayout | 易学教程

How to get RelativeLayout working with merge and include?

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问题 I have been trying for a few days now to make my layouts more efficient by converting from using several levels of nested LinearLayouts to one RelativeLayout and have come across a few problems that I haven not been able to find a workaround for... I have searched the Android beginners group and this site and have not been able to find anything that would help me solve the problem. I read on one of the blogs that you can combine layouts with merge and include tags. So what I have is a main

How do I programmatically remove an existing rule that was defined in XML?

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问题 I have a linear layout that is contained inside a relative layout. It is set in the XML file to be to the right of another linear layout (this works fine). In some cases I want to change the relative position of the layout during the onCreate of the activity so I need to modify the "to the right of" param to relate to another layout. I tryed this: RelativeLayout.LayoutParams layoutParams; layoutParams = (RelativeLayout.LayoutParams) linearLayoutToMove .getLayoutParams(); layoutParams.addRule

How to set RelativeLayout layout params in code not in xml?

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For example I want to add 3 buttons on screen: one align left, one align center, last one align right. How can I set their layout in code, not in xml ? Just a basic example: RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT); params.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE); Button button1; button1.setLayoutParams(params); params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT); params.addRule

Is a RelativeLayout more expensive than a LinearLayout?

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I've always been using RelativeLayout everytime I needed a View container, because of it's flexibility, even if I just wanted to display something really simple. Is it ok to do so, or should I try using a LinearLayout when I can, from a performance/good practices standpoint? Thanks! In a talk at Google I/O 2013 (Writing Custom Views for Android), Romain Guy clarified the misunderstanding that caused everyone to start using RelativeLayouts for everything. A RelativeLayout always has to do two measure passes. Overall it is negligible as long as your view hierarchy is simple. But if your

Circular dependencies cannot exist in RelativeLayout, android?

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问题 I have the following layout: I need to keep the button at the bottom of screen and it should be visible to the user. The rest of the layout should scroll. <RelativeLayout xmlns:android=\"http://schemas.android.com/apk/res/android\" xmlns:tools=\"http://schemas.android.com/tools\" android:layout_width=\"match_parent\" android:layout_height=\"match_parent\" android:paddingBottom=\"@dimen/activity_vertical_margin\" android:paddingLeft=\"@dimen/activity_horizontal_margin\" android:paddingRight=\"

Extending RelativeLayout, and overriding dispatchDraw() to create a zoomable ViewGroup

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问题 I\'ve seen a few people ask how to zoom an entire ViewGroup (such as a RelativeLayout) in one go. At the moment this is something I need to achieve. The most obvious approach, to me, would be to hold the zoom scale factor as a single variable somewhere; and in each of the child Views\' onDraw() methods, that scale factor would be applied to the Canvas prior to graphics being drawn. However, before doing that, I have tried to be clever (ha - usually a bad idea) and extend RelativeLayout, into

What are the differences between LinearLayout, RelativeLayout, and AbsoluteLayout?

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问题 I am confused about the difference between LinearLayout, RelativeLayout, and AbsoluteLayout. Could someone please tell me the exact differences between them? 回答1: LinearLayout means you can align views one by one (vertically/ horizontally). RelativeLayout means based on relation of views from its parents and other views. ConstraintLayout is similar to a RelativeLayout in that it uses relations to position and size widgets, but has additional flexibility and is easier to use in the Layout

How to programmatically set the layout_align_parent_right attribute of a Button in Relative Layout?

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问题 I have a relative layout which I am creating programmatically: RelativeLayout layout = new RelativeLayout( this ); RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT); Now I have two buttons which I want to add in this relative layout. But the problem is both buttons are being shown on the left of the RelatiiveLayout overlapping on each other. buttonContainer.addView(btn1); buttonContainer.addView(btn2); Now I want to know

java.lang.ClassCastException: android.view.ViewGroup$LayoutParams cannot be cast to android.widget.Gallery$LayoutParams

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问题 I am trying to add Fancycoverflow in my app,It works fine with static image as given in this example. but i did some changes in Adapter, and i try to run my app and it crashes and shows following error FATAL EXCEPTION: main java.lang.ClassCastException: android.view.ViewGroup$LayoutParams cannot be cast to android.widget.Gallery$LayoutParams at android.widget.Gallery.setUpChild(Gallery.java:889) at android.widget.Gallery.makeAndAddView(Gallery.java:858) at android.widget.Gallery.layout

Overlapping Views in Android

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问题 Is it possible to have overlapping views in Android? I would like to have an ImageView with a transparent png in the front and another view in the background. edit: This is what I have at the moment, the problem is that the image in the imageView is not transparent, the parts that should be transparent are just black. <RelativeLayout xmlns:android=\"http://schemas.android.com/apk/res/android\" android:orientation=\"vertical\" android:layout_width=\"wrap_content\" android:layout_height=\"wrap