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

Flow

This package is part of the Android support library which is no longer maintained. The Constraint Layout support library has been superseded by the AndroidX Constraint Layout library, which is part of Jetpack. The Flow class has been superseded by androidx.constraintlayout.helper.widget.Flow.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

public class Flow
extends View

java.lang.Object
↳	View
	↳	android.support.constraint.helper.Flow

Flow virtual layout. Added in 2.0 Allows positioning of referenced widgets horizontally or vertically, similar to a Chain. The elements referenced are indicated via constraint_referenced_ids, as with other ContraintHelper implementations. Those referenced widgets are then laid out by the Flow virtual layout in three possible ways:

wrap none : simply create a chain out of the referenced elements
wrap chain : create multiple chains (one after the other) if the referenced elements do not fit
wrap aligned : similar to wrap chain, but will align the elements by creating rows and columns

As VirtualLayout are ConstraintHelper, they are normal views; you can thus treat them as such, and setting up constraints on them (position, dimension) or some view attributes (background, padding) will work. The main difference between VirtualLayouts and ViewGroups is that:

VirtualLayout keep the hierarchy flat
Other views can thus reference / constrain to not only the VirtualLayout, but also the views laid out by the VirtualLayout
VirtualLayout allow on the fly behavior modifications (e.g. for Flow, chaing the orientation)

flow_wrapMode = "none"

This will simply create an horizontal or vertical chain out of the referenced widgets. This is the default behavior of Flow. XML attributes that are allowed in this mode:

flow_horizontalStyle = "spread|spread_inside|packed"
flow_verticalStyle = "spread|spread_inside|packed"
flow_horizontalBias = "float"
flow_verticalBias = "float"
flow_horizontalGap = "dimension"
flow_verticalGap = "dimension"
flow_horizontalAlign = "start|end|center"
flow_verticalAlign = "top|bottom|center|baseline

While the elements are laid out as a chain in the orientation defined, the way they are laid out in the other dimension is controlled by flow_horizontalAlign and flow_verticalAlign attributes.

flow_wrapMode = "chain"

Similar to wrap none in terms of creating chains, but if the referenced widgets do not fit the horizontal or vertical dimension (depending on the orientation picked), they will wrap around to the next line / column. XML attributes are the same same as in wrap_none, with the addition of attributes specifying chain style and chain bias applied to the first chain. This way, it is possible to specify different chain behavior between the first chain and the rest of the chains eventually created.

flow_firstHorizontalStyle = "spread|spread_inside|packed"
flow_firstVerticalStyle = "spread|spread_inside|packed"
flow_firstHorizontalBias = "float"
flow_firstVerticalBias = "float"

One last important attribute is flow_maxElementsWrap, which specify the number of elements before wrapping, regardless if they fit or not in the available space.

flow_wrapMode = "aligned"

Same XML attributes as for WRAP_CHAIN, with the difference that the elements are going to be laid out in a set of rows and columns instead of chains. The attribute specifying chains style and bias are thus not going to be applied.

Summary

Fields
`public static final int`	`CHAIN_PACKED`
`public static final int`	`CHAIN_SPREAD`
`public static final int`	`CHAIN_SPREAD_INSIDE`
`public static final int`	`HORIZONTAL`
`public static final int`	`HORIZONTAL_ALIGN_CENTER`
`public static final int`	`HORIZONTAL_ALIGN_END`
`public static final int`	`HORIZONTAL_ALIGN_START`
`public static final int`	`VERTICAL`
`public static final int`	`VERTICAL_ALIGN_BASELINE`
`public static final int`	`VERTICAL_ALIGN_BOTTOM`
`public static final int`	`VERTICAL_ALIGN_CENTER`
`public static final int`	`VERTICAL_ALIGN_TOP`
`public static final int`	`WRAP_ALIGNED`
`public static final int`	`WRAP_CHAIN`
`public static final int`	`WRAP_NONE`

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

Public methods
`int[]`	`getReferencedIds()` Helpers typically reference a collection of ids
`void`	`loadParameters(ConstraintSet.Constraint constraint, HelperWidget child, ConstraintLayout.LayoutParams layoutParams, mapIdToWidget)`
`void`	`onMeasure(android.support.constraint.solver.widgets.VirtualLayout layout, int widthMeasureSpec, int heightMeasureSpec)`
`void`	`resolveRtl(ConstraintWidget widget, boolean isRtl)`
`void`	`setFirstHorizontalBias(float bias)` Similar to setHorizontalBias(), but only applied to the first chain.
`void`	`setFirstHorizontalStyle(int style)` Similar to setHorizontalStyle(), but only applies to the first chain.
`void`	`setFirstVerticalBias(float bias)` Similar to setVerticalBias(), but only applied to the first chain.
`void`	`setFirstVerticalStyle(int style)` Similar to setVerticalStyle(), but only applies to the first chain.
`void`	`setHorizontalAlign(int align)` Set up the horizontal alignment of the elements in the layout, if the layout orientation is set to Flow.VERTICAL Can be either: Flow.HORIZONTAL_ALIGN_START Flow.HORIZONTAL_ALIGN_END Flow.HORIZONTAL_ALIGN_CENTER
`void`	`setHorizontalBias(float bias)` Set the horizontal bias applied to the chain
`void`	`setHorizontalGap(int gap)` Set up the horizontal gap between elements
`void`	`setHorizontalStyle(int style)` Set horizontal chain style.
`void`	`setMaxElementsWrap(int max)` Set up the maximum number of elements before wrapping.
`void`	`setOrientation(int orientation)` Set the orientation of the layout
`void`	`setPadding(int padding)` Set padding around the content
`void`	`setPaddingBottom(int paddingBottom)` Set padding bottom around the content
`void`	`setPaddingLeft(int paddingLeft)` Set padding left around the content
`void`	`setPaddingRight(int paddingRight)` Set padding right around the content
`void`	`setPaddingTop(int paddingTop)` Set padding top around the content
`void`	`setReferencedIds(int[] ids)` Helpers typically reference a collection of ids
`void`	`setVerticalAlign(int align)` Set up the vertical alignment of the elements in the layout, if the layout orientation is set to Flow.HORIZONTAL Can be either: Flow.VERTICAL_ALIGN_TOP Flow.VERTICAL_ALIGN_BOTTOM Flow.VERTICAL_ALIGN_CENTER Flow.VERTICAL_ALIGN_BASELINE
`void`	`setVerticalBias(float bias)` Set the vertical bias applied to the chain
`void`	`setVerticalGap(int gap)` Set up the vertical gap between elements
`void`	`setVerticalStyle(int style)` Set vertical chain style.
`void`	`setWrapMode(int mode)` Set wrap mode for the layout.
`void`	`updatePostConstraints(ConstraintLayout constainer)`
`void`	`updatePreLayout(ConstraintWidgetContainer container, Helper helper, map)`

Protected methods
`View[]`	`getViews(ConstraintLayout layout)`
`void`	`onMeasure(int widthMeasureSpec, int heightMeasureSpec)`

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

CHAIN_PACKED

public static final int CHAIN_PACKED

CHAIN_SPREAD

public static final int CHAIN_SPREAD

CHAIN_SPREAD_INSIDE

public static final int CHAIN_SPREAD_INSIDE

HORIZONTAL

public static final int HORIZONTAL

HORIZONTAL_ALIGN_CENTER

public static final int HORIZONTAL_ALIGN_CENTER

HORIZONTAL_ALIGN_END

public static final int HORIZONTAL_ALIGN_END

HORIZONTAL_ALIGN_START

public static final int HORIZONTAL_ALIGN_START

VERTICAL

public static final int VERTICAL

VERTICAL_ALIGN_BASELINE

public static final int VERTICAL_ALIGN_BASELINE

VERTICAL_ALIGN_BOTTOM

public static final int VERTICAL_ALIGN_BOTTOM

VERTICAL_ALIGN_CENTER

public static final int VERTICAL_ALIGN_CENTER

VERTICAL_ALIGN_TOP

public static final int VERTICAL_ALIGN_TOP

WRAP_ALIGNED

public static final int WRAP_ALIGNED

WRAP_CHAIN

public static final int WRAP_CHAIN

WRAP_NONE

public static final int WRAP_NONE

Public constructors

Flow

public Flow (Context context)

Parameters
`context`	`Context`

Flow

public Flow (Context context, 
                AttributeSet attrs)

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

Flow

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

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

Public methods

getReferencedIds

public int[] getReferencedIds ()

Helpers typically reference a collection of ids

Returns
`int[]`	ids referenced

loadParameters

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

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

onMeasure

public void onMeasure (android.support.constraint.solver.widgets.VirtualLayout layout, 
                int widthMeasureSpec, 
                int heightMeasureSpec)

Parameters
`layout`	`android.support.constraint.solver.widgets.VirtualLayout`
`widthMeasureSpec`	`int`
`heightMeasureSpec`	`int`

resolveRtl

public void resolveRtl (ConstraintWidget widget, 
                boolean isRtl)

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

setFirstHorizontalBias

public void setFirstHorizontalBias (float bias)

Similar to setHorizontalBias(), but only applied to the first chain.

setFirstHorizontalStyle

public void setFirstHorizontalStyle (int style)

Similar to setHorizontalStyle(), but only applies to the first chain.

setFirstVerticalBias

public void setFirstVerticalBias (float bias)

Similar to setVerticalBias(), but only applied to the first chain.

setFirstVerticalStyle

public void setFirstVerticalStyle (int style)

Similar to setVerticalStyle(), but only applies to the first chain.

setHorizontalAlign

public void setHorizontalAlign (int align)

Set up the horizontal alignment of the elements in the layout, if the layout orientation is set to Flow.VERTICAL Can be either: Flow.HORIZONTAL_ALIGN_START Flow.HORIZONTAL_ALIGN_END Flow.HORIZONTAL_ALIGN_CENTER

setHorizontalBias

public void setHorizontalBias (float bias)

Set the horizontal bias applied to the chain

Parameters
`bias`	`float`: from 0 to 1

setHorizontalGap

public void setHorizontalGap (int gap)

Set up the horizontal gap between elements

setHorizontalStyle

public void setHorizontalStyle (int style)

Set horizontal chain style. Can be: Flow.CHAIN_SPREAD Flow.CHAIN_SPREAD_INSIDE Flow.CHAIN_PACKED

setMaxElementsWrap

public void setMaxElementsWrap (int max)

Set up the maximum number of elements before wrapping.

setOrientation

public void setOrientation (int orientation)

Set the orientation of the layout

Parameters
`orientation`	`int`: either Flow.HORIZONTAL or FLow.VERTICAL

setPadding

public void setPadding (int padding)

Set padding around the content

setPaddingBottom

public void setPaddingBottom (int paddingBottom)

Set padding bottom around the content

setPaddingLeft

public void setPaddingLeft (int paddingLeft)

Set padding left around the content

setPaddingRight

public void setPaddingRight (int paddingRight)

Set padding right around the content

setPaddingTop

public void setPaddingTop (int paddingTop)

Set padding top around the content

setReferencedIds

public void setReferencedIds (int[] ids)

Helpers typically reference a collection of ids

Parameters
`ids`	`int`

Returns
`void`	ids referenced

setVerticalAlign

public void setVerticalAlign (int align)

Set up the vertical alignment of the elements in the layout, if the layout orientation is set to Flow.HORIZONTAL Can be either: Flow.VERTICAL_ALIGN_TOP Flow.VERTICAL_ALIGN_BOTTOM Flow.VERTICAL_ALIGN_CENTER Flow.VERTICAL_ALIGN_BASELINE

setVerticalBias

public void setVerticalBias (float bias)

Set the vertical bias applied to the chain

Parameters
`bias`	`float`: from 0 to 1

setVerticalGap

public void setVerticalGap (int gap)

Set up the vertical gap between elements

setVerticalStyle

public void setVerticalStyle (int style)

Set vertical chain style. Can be: Flow.CHAIN_SPREAD Flow.CHAIN_SPREAD_INSIDE Flow.CHAIN_PACKED

setWrapMode

public void setWrapMode (int mode)

Set wrap mode for the layout. Can be: Flow.WRAP_NONE (default) -- no wrap behavior, create a single chain Flow.WRAP_CHAIN -- if not enough space to fit the referenced elements, will create additional chains after the first one Flow.WRAP_ALIGNED -- if not enough space to fit the referenced elements, will wrap the elements, keeping them aligned (like a table)

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[]`

onMeasure

protected void onMeasure (int widthMeasureSpec, 
                int heightMeasureSpec)

Parameters
`widthMeasureSpec`	`int`
`heightMeasureSpec`	`int`