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PercentRelativeLayout

public class PercentRelativeLayout
extends RelativeLayout

java.lang.Object
   ↳ android.view.View
     ↳ android.view.ViewGroup
       ↳ android.widget.RelativeLayout
         ↳ android.support.percent.PercentRelativeLayout


Subclass of RelativeLayout that supports percentage based dimensions and margins. You can specify dimension or a margin of child by using attributes with "Percent" suffix. Follow this example:

 <android.support.percent.PercentRelativeLayout
         xmlns:android="http://schemas.android.com/apk/res/android"
         xmlns:app="http://schemas.android.com/apk/res-auto"
         android:layout_width="match_parent"
         android:layout_height="match_parent">
     <ImageView
         app:layout_widthPercent="50%"
         app:layout_heightPercent="50%"
         app:layout_marginTopPercent="25%"
         app:layout_marginLeftPercent="25%"/>
 </android.support.percent.PercentFrameLayout>
 
The attributes that you can use are: It is not necessary to specify layout_width/height if you specify layout_widthPercent. However, if you want the view to be able to take up more space than what percentage value permits, you can add layout_width/height="wrap_content". In that case if the percentage size is too small for the View's content, it will be resized using wrap_content rule.

You can also make one dimension be a fraction of the other by setting only width or height and using layout_aspectRatio for the second one to be calculated automatically. For example, if you would like to achieve 16:9 aspect ratio, you can write:

     android:layout_width="300dp"
     app:layout_aspectRatio="178%"
 
This will make the aspect ratio 16:9 (1.78:1) with the width fixed at 300dp and height adjusted accordingly.

Summary

Nested classes

class PercentRelativeLayout.LayoutParams

 

Inherited XML attributes

From class android.widget.RelativeLayout
From class android.view.ViewGroup
From class android.view.View

Inherited constants

From class android.widget.RelativeLayout
From class android.view.ViewGroup
From class android.view.View

Inherited fields

From class android.view.View

Public constructors

PercentRelativeLayout(Context context)
PercentRelativeLayout(Context context, AttributeSet attrs)
PercentRelativeLayout(Context context, AttributeSet attrs, int defStyle)

Public methods

PercentRelativeLayout.LayoutParams generateLayoutParams(AttributeSet attrs)

Returns a new set of layout parameters based on the supplied attributes set.

Protected methods

PercentRelativeLayout.LayoutParams generateDefaultLayoutParams()

Returns a set of layout parameters with a width of WRAP_CONTENT, a height of WRAP_CONTENT and no spanning.

void onLayout(boolean changed, int left, int top, int right, int bottom)

Called from layout when this view should assign a size and position to each of its children.

void onMeasure(int widthMeasureSpec, int heightMeasureSpec)

Measure the view and its content to determine the measured width and the measured height.

Inherited methods

From class android.widget.RelativeLayout
From class android.view.ViewGroup
From class android.view.View
From class java.lang.Object
From interface android.view.ViewParent
From interface android.view.ViewManager
From interface android.graphics.drawable.Drawable.Callback
From interface android.view.KeyEvent.Callback
From interface android.view.accessibility.AccessibilityEventSource

Public constructors

PercentRelativeLayout

PercentRelativeLayout (Context context)

Parameters
context Context

PercentRelativeLayout

PercentRelativeLayout (Context context, 
                AttributeSet attrs)

Parameters
context Context
attrs AttributeSet

PercentRelativeLayout

PercentRelativeLayout (Context context, 
                AttributeSet attrs, 
                int defStyle)

Parameters
context Context
attrs AttributeSet
defStyle int

Public methods

generateLayoutParams

PercentRelativeLayout.LayoutParams generateLayoutParams (AttributeSet attrs)

Returns a new set of layout parameters based on the supplied attributes set.

Parameters
attrs AttributeSet: the attributes to build the layout parameters from
Returns
PercentRelativeLayout.LayoutParams an instance of ViewGroup.LayoutParams or one of its descendants

Protected methods

generateDefaultLayoutParams

PercentRelativeLayout.LayoutParams generateDefaultLayoutParams ()

Returns a set of layout parameters with a width of WRAP_CONTENT, a height of WRAP_CONTENT and no spanning.

Returns
PercentRelativeLayout.LayoutParams a set of default layout parameters or null

onLayout

void onLayout (boolean changed, 
                int left, 
                int top, 
                int right, 
                int bottom)

Called from layout when this view should assign a size and position to each of its children. Derived classes with children should override this method and call layout on each of their children.

Parameters
changed boolean: This is a new size or position for this view
left int: Left position, relative to parent
top int: Top position, relative to parent
right int: Right position, relative to parent
bottom int: Bottom position, relative to parent

onMeasure

void onMeasure (int widthMeasureSpec, 
                int heightMeasureSpec)

Measure the view and its content to determine the measured width and the measured height. This method is invoked by measure(int, int) and should be overridden by subclasses to provide accurate and efficient measurement of their contents.

CONTRACT: When overriding this method, you must call setMeasuredDimension(int, int) to store the measured width and height of this view. Failure to do so will trigger an IllegalStateException, thrown by measure(int, int). Calling the superclass' onMeasure(int, int) is a valid use.

The base class implementation of measure defaults to the background size, unless a larger size is allowed by the MeasureSpec. Subclasses should override onMeasure(int, int) to provide better measurements of their content.

If this method is overridden, it is the subclass's responsibility to make sure the measured height and width are at least the view's minimum height and width (getSuggestedMinimumHeight() and getSuggestedMinimumWidth()).

Parameters
widthMeasureSpec int: horizontal space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.
heightMeasureSpec int: vertical space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.

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