Summary: Fields | Ctors | Methods | Protected Methods | Inherited Methods

Barrier

This package is part of the Android support library which is no longer maintained. The Constraint Layout support library has been superseded by the AndroidX Constraint Layout library, which is part of Jetpack. The Barrier class has been superseded by androidx.constraintlayout.widget.Barrier. We recommend using the AndroidX libraries in all new projects. You should also consider migrating existing projects to AndroidX.

public class Barrier
extends View

java.lang.Object
↳	View
	↳	android.support.constraint.Barrier

Added in 1.1

A Barrier references multiple widgets as input, and creates a virtual guideline based on the most extreme widget on the specified side. For example, a left barrier will align to the left of all the referenced views.

Example

Let's have two buttons, @id/button1 and @id/button2. The constraint_referenced_ids field will reference them by simply having them as comma-separated list:

     <android.support.constraint.Barrier
              android:id="@+id/barrier"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              app:barrierDirection="start"
              app:constraint_referenced_ids="button1,button2" />

With the barrier direction set to start, we will have the following result:

Reversely, with the direction set to end, we will have:

If the widgets dimensions change, the barrier will automatically move according to its direction to get the most extreme widget:

Other widgets can then be constrained to the barrier itself, instead of the individual widget. This allows a layout to automatically adapt on widget dimension changes (e.g. different languages will end up with different length for similar worlds).

GONE widgets handling

If the barrier references GONE widgets, the default behavior is to create a barrier on the resolved position of the GONE widget. If you do not want to have the barrier take GONE widgets into account, you can change this by setting the attribute barrierAllowsGoneWidgets to false (default being true).

Summary

Fields
`public static final int`	`BOTTOM` Bottom direction constant
`public static final int`	`END` End Barrier constant
`public static final int`	`LEFT` Left direction constant
`public static final int`	`RIGHT` Right direction constant
`public static final int`	`START` Start direction constant
`public static final int`	`TOP` Top direction constant

Public constructors
`Barrier(Context context)`
`Barrier(Context context, AttributeSet attrs)`
`Barrier(Context context, AttributeSet attrs, int defStyleAttr)`

Public methods
`boolean`	`allowsGoneWidget()`
`int`	`getMargin()` Returns the barrier margin
`int[]`	`getReferencedIds()` Helpers typically reference a collection of ids
`int`	`getType()` Get the barrier type (`Barrier.LEFT`, `Barrier.TOP`, `Barrier.RIGHT`, `Barrier.BOTTOM`, `Barrier.END`, `Barrier.START`)
`void`	`loadParameters(ConstraintSet.Constraint constraint, HelperWidget child, ConstraintLayout.LayoutParams layoutParams, mapIdToWidget)`
`void`	`resolveRtl(ConstraintWidget widget, boolean isRtl)`
`void`	`setAllowsGoneWidget(boolean supportGone)`
`void`	`setDpMargin(int margin)` Set a margin on the barrier
`void`	`setMargin(int margin)` Set the barrier margin
`void`	`setReferencedIds(int[] ids)` Helpers typically reference a collection of ids
`void`	`setType(int type)` Set the barrier type (`Barrier.LEFT`, `Barrier.TOP`, `Barrier.RIGHT`, `Barrier.BOTTOM`, `Barrier.END`, `Barrier.START`)
`void`	`updatePostConstraints(ConstraintLayout constainer)`
`void`	`updatePreLayout(ConstraintWidgetContainer container, Helper helper, map)`

Protected methods
`View[]`	`getViews(ConstraintLayout layout)`

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()`

Fields

BOTTOM

public static final int BOTTOM

Bottom direction constant

END

public static final int END

End Barrier constant

LEFT

public static final int LEFT

Left direction constant

RIGHT

public static final int RIGHT

Right direction constant

START

public static final int START

Start direction constant

TOP

public static final int TOP

Top direction constant

Public constructors

Barrier

public Barrier (Context context)

Parameters
`context`	`Context`

Barrier

public Barrier (Context context, 
                AttributeSet attrs)

Parameters
`context`	`Context`
`attrs`	`AttributeSet`

Barrier

public Barrier (Context context, 
                AttributeSet attrs, 
                int defStyleAttr)

Parameters
`context`	`Context`
`attrs`	`AttributeSet`
`defStyleAttr`	`int`

Public methods

allowsGoneWidget

public boolean allowsGoneWidget ()

Returns
`boolean`

getMargin

public int getMargin ()

Returns the barrier margin

Returns
`int`	the barrier margin (in pixels)

getReferencedIds

public int[] getReferencedIds ()

Helpers typically reference a collection of ids

Returns
`int[]`	ids referenced

getType

public int getType ()

Get the barrier type (Barrier.LEFT, Barrier.TOP, Barrier.RIGHT, Barrier.BOTTOM, Barrier.END, Barrier.START)

Returns
`int`

loadParameters

public void loadParameters (ConstraintSet.Constraint constraint, 
                HelperWidget child,
                ConstraintLayout.LayoutParams layoutParams,
                 mapIdToWidget)

Parameters
`constraint`	`ConstraintSet.Constraint`
`child`	`HelperWidget`
`layoutParams`	`ConstraintLayout.LayoutParams`
`mapIdToWidget`

resolveRtl

public void resolveRtl (ConstraintWidget widget, 
                boolean isRtl)

Parameters
`widget`	`ConstraintWidget`
`isRtl`	`boolean`

setAllowsGoneWidget

public void setAllowsGoneWidget (boolean supportGone)

Parameters
`supportGone`	`boolean`

setDpMargin

public void setDpMargin (int margin)

Set a margin on the barrier

Parameters
`margin`	`int`: in dp

setMargin

public void setMargin (int margin)

Set the barrier margin

Parameters
`margin`	`int`: in pixels

setReferencedIds

public void setReferencedIds (int[] ids)

Helpers typically reference a collection of ids

Parameters
`ids`	`int`

Returns
`void`	ids referenced

setType

public void setType (int type)

Set the barrier type (Barrier.LEFT, Barrier.TOP, Barrier.RIGHT, Barrier.BOTTOM, Barrier.END, Barrier.START)

Parameters
`type`	`int`

updatePostConstraints

public void updatePostConstraints (ConstraintLayout constainer)

Parameters
`constainer`	`ConstraintLayout`

updatePreLayout

public void updatePreLayout (ConstraintWidgetContainer container,
                Helper helper,
                 map)

Parameters
`container`	`ConstraintWidgetContainer`
`helper`	`Helper`
`map`

Protected methods

getViews

protected View[] getViews (ConstraintLayout layout)

Parameters
`layout`	`ConstraintLayout`

Returns
`View[]`