PercentLayoutHelper

public class PercentLayoutHelper
extends Object

This class is deprecated.
consider using ConstraintLayout and associated layouts instead. The following shows how to replicate the functionality of percentage layouts with a ConstraintLayout. The Guidelines are used to define each percentage break point, and then a Button view is stretched to fill the gap:

 <androidx.constraintlayout.widget.ConstraintLayout
         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">

     <androidx.constraintlayout.widget.Guideline
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:id="@+id/left_guideline"
         app:layout_constraintGuide_percent=".15"
         android:orientation="vertical"/>

     <androidx.constraintlayout.widget.Guideline
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:id="@+id/right_guideline"
         app:layout_constraintGuide_percent=".85"
         android:orientation="vertical"/>

     <androidx.constraintlayout.widget.Guideline
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:id="@+id/top_guideline"
         app:layout_constraintGuide_percent=".15"
         android:orientation="horizontal"/>

     <androidx.constraintlayout.widget.Guideline
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:id="@+id/bottom_guideline"
         app:layout_constraintGuide_percent=".85"
         android:orientation="horizontal"/>

     <Button
         android:text="Button"
         android:layout_width="0dp"
         android:layout_height="0dp"
         android:id="@+id/button"
         app:layout_constraintLeft_toLeftOf="@+id/left_guideline"
         app:layout_constraintRight_toRightOf="@+id/right_guideline"
         app:layout_constraintTop_toTopOf="@+id/top_guideline"
         app:layout_constraintBottom_toBottomOf="@+id/bottom_guideline" />

 </androidx.constraintlayout.widget.ConstraintLayout>

  



  
Helper for layouts that want to support percentage based dimensions.

 
This class collects utility methods that are involved in extracting percentage based dimension
 attributes and applying them to ViewGroup's children. If you would like to implement a layout
 that supports percentage based dimensions, you need to take several steps:

 

 
 You need a ViewGroup.LayoutParams subclass in your ViewGroup that implements
 PercentLayoutHelper.PercentLayoutParams.
 
 In your LayoutParams(Context c, AttributeSet attrs) constructor create an instance
 of PercentLayoutHelper.PercentLayoutInfo by calling
 getPercentLayoutInfo(Context, AttributeSet). Return this
 object from public PercentLayoutHelper.PercentLayoutInfo getPercentLayoutInfo()
 method that you implemented for PercentLayoutHelper.PercentLayoutParams interface.
 
 Override
 ViewGroup.LayoutParams.setBaseAttributes(TypedArray, int, int)
 with a single line implementation PercentLayoutHelper.fetchWidthAndHeight(this, a,
 widthAttr, heightAttr);
 
 In your ViewGroup override ViewGroup.generateLayoutParams(AttributeSet) to return
 your LayoutParams.
 
 In your View.onMeasure(int, int) override, you need to implement following
 pattern:
 
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     mHelper.adjustChildren(widthMeasureSpec, heightMeasureSpec);
     super.onMeasure(widthMeasureSpec, heightMeasureSpec);
     if (mHelper.handleMeasuredStateTooSmall()) {
         super.onMeasure(widthMeasureSpec, heightMeasureSpec);
     }
 }
 
 
In your ViewGroup.onLayout(boolean, int, int, int, int) override, you need to
 implement following pattern:
 
 protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
     super.onLayout(changed, left, top, right, bottom);
     mHelper.restoreOriginalParams();
 }
 
 










Summary





Nested classes


  
    

      

        
        
        
        
        class
      

        PercentLayoutHelper.PercentLayoutInfo
        

      This class is deprecated.
    use ConstraintLayout and Guidelines for layout support.
 
        
    

      
    
    
    
    

      

        
        
        
        
        interface
      

        PercentLayoutHelper.PercentLayoutParams
        

      This interface is deprecated.
    this class is deprecated along with its parent class.
 
        
    

      
    
    
    

























Public constructors



  

  
  
    

      
      PercentLayoutHelper(ViewGroup host)
      
      
    
  
  











Public methods



  

  
  
    

        
        
        
        
        
        void
    
  
    

      
      adjustChildren(int widthMeasureSpec, int heightMeasureSpec)
      
      
        
Iterates over children and changes their width and height to one calculated from percentage
 values.
        
    

      
    
  
  

  

  
  
    

        
        
        static
        
        
        void
    
  
    

      
      fetchWidthAndHeight(ViewGroup.LayoutParams params, TypedArray array, int widthAttr, int heightAttr)
      
      
        
Helper method to be called from ViewGroup.LayoutParams.setBaseAttributes(TypedArray, int, int) override
 that reads layout_width and layout_height attribute values without throwing an exception if
 they aren't present.
        
    

      
    
  
  

  

  
  
    

        
        
        static
        
        
        PercentLayoutHelper.PercentLayoutInfo
    
  
    

      
      getPercentLayoutInfo(Context context, AttributeSet attrs)
      
      
        
Constructs a PercentLayoutInfo from attributes associated with a View.
        
    

      
    
  
  

  

  
  
    

        
        
        
        
        
        boolean
    
  
    

      
      handleMeasuredStateTooSmall()
      
      
        
Iterates over children and checks if any of them would like to get more space than it
 received through the percentage dimension.
        
    

      
    
  
  

  

  
  
    

        
        
        
        
        
        void
    
  
    

      
      restoreOriginalParams()
      
      
        
Iterates over children and restores their original dimensions that were changed for
 percentage values.
        
    

      
    
  
  












Inherited methods




  

    From class
      
        
          java.lang.Object
        
      
    
    

      


  

  
  
    

        
        
        
        
        
        Object
    
  
    

      
      clone()
      
      
    
  
  

  

  
  
    

        
        
        
        
        
        boolean
    
  
    

      
      equals(Object arg0)
      
      
    
  
  

  

  
  
    

        
        
        
        
        
        void
    
  
    

      
      finalize()
      
      
    
  
  

  

  
  
    

        
        
        
        final
        
        Class<?>
    
  
    

      
      getClass()
      
      
    
  
  

  

  
  
    

        
        
        
        
        
        int
    
  
    

      
      hashCode()
      
      
    
  
  

  

  
  
    

        
        
        
        final
        
        void
    
  
    

      
      notify()
      
      
    
  
  

  

  
  
    

        
        
        
        final
        
        void
    
  
    

      
      notifyAll()
      
      
    
  
  

  

  
  
    

        
        
        
        
        
        String
    
  
    

      
      toString()
      
      
    
  
  

  

  
  
    

        
        
        
        final
        
        void
    
  
    

      
      wait(long arg0, int arg1)
      
      
    
  
  

  

  
  
    

        
        
        
        final
        
        void
    
  
    

      
      wait(long arg0)
      
      
    
  
  

  

  
  
    

        
        
        
        final
        
        void
    
  
    

      
      wait()
      
      
    
  
  


    
  























Public constructors



    
PercentLayoutHelper
    

      

  
      
  

    
public PercentLayoutHelper (ViewGroup host)
    
    

    
  

    

    
Parameters
      

        
host
        

          ViewGroup 

      
    















Public methods



    
adjustChildren
    

      

  
      
  

    
public void adjustChildren (int widthMeasureSpec, 
                int heightMeasureSpec)
    
    

    
  
Iterates over children and changes their width and height to one calculated from percentage
 values.

    

    
Parameters
      

        
widthMeasureSpec
        

          int: Width MeasureSpec of the parent ViewGroup.

      
      

        
heightMeasureSpec
        

          int: Height MeasureSpec of the parent ViewGroup.

      
    




    
fetchWidthAndHeight
    

      

  
      
  

    
public static void fetchWidthAndHeight (ViewGroup.LayoutParams params, 
                TypedArray array, 
                int widthAttr, 
                int heightAttr)
    
    

    
  
Helper method to be called from ViewGroup.LayoutParams.setBaseAttributes(TypedArray, int, int) override
 that reads layout_width and layout_height attribute values without throwing an exception if
 they aren't present.

    

    
Parameters
      

        
params
        

          ViewGroup.LayoutParams 

      
      

        
array
        

          TypedArray 

      
      

        
widthAttr
        

          int 

      
      

        
heightAttr
        

          int 

      
    




    
getPercentLayoutInfo
    

      

  
      
  

    
public static PercentLayoutHelper.PercentLayoutInfo getPercentLayoutInfo (Context context, 
                AttributeSet attrs)
    
    

    
  
Constructs a PercentLayoutInfo from attributes associated with a View. Call this method from
 LayoutParams(Context c, AttributeSet attrs) constructor.

    

    
Parameters
      

        
context
        

          Context 

      
      

        
attrs
        

          AttributeSet 

      
    
    

      
Returns
      

        
PercentLayoutHelper.PercentLayoutInfo
        

      
    




    
handleMeasuredStateTooSmall
    

      

  
      
  

    
public boolean handleMeasuredStateTooSmall ()
    
    

    
  
Iterates over children and checks if any of them would like to get more space than it
 received through the percentage dimension.

 If you are building a layout that supports percentage dimensions you are encouraged to take
 advantage of this method. The developer should be able to specify that a child should be
 remeasured by adding normal dimension attribute with wrap_content value. For example
 he might specify child's attributes as app:layout_widthPercent="60%p" and
 android:layout_width="wrap_content". In this case if the child receives too little
 space, it will be remeasured with width set to WRAP_CONTENT.

    

      
Returns
      

        
boolean
        
True if the measure phase needs to be rerun because one of the children would like
 to receive more space.

      
    




    
restoreOriginalParams
    

      

  
      
  

    
public void restoreOriginalParams ()
    
    

    
  
Iterates over children and restores their original dimensions that were changed for
 percentage values. Calling this method only makes sense if you previously called
 adjustChildren(int, int).