ConstraintLayout is a
ViewGroup which allows you to position and size widgets in a flexible way. It is compatible with Android 2.3 (API level 9) and higher.
It allows you to create large and complex layouts with a flat view hierarchy. It is similar to
RelativeLayout in that all views are laid out according to relationships between sibling views and the parent layout, but it's more flexible than
RelativeLayout and easier to use with Android Studio's Layout Editor.
public void addView(View child, int index, ViewGroup.LayoutParams params)
public ConstraintLayout.LayoutParams generateLayoutParams(AttributeSet attrs)
public void onViewAdded(View view)
public void onViewRemoved(View view)
public void removeView(View view)
public void requestLayout()
protected boolean checkLayoutParams(ViewGroup.LayoutParams params)
protected ConstraintLayout.LayoutParams generateDefaultLayoutParams()
protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams params)
protected void onLayout(boolean changed, int left, int top, int right, int bottom)
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
public void resolveLayoutDirection(int layoutDirection)
public void validate()
protected void setBaseAttributes(TypedArray a, int widthAttr, int heightAttr)
|index||The index of the |
|changed||Indicates if this |
|left||The left position, relative to the parent |
|top||The top position, relative to the parent |
|right||The right position, relative to the parent |
|bottom||The bottom position, relative to the parent |
|widthMeasureSpec||The horizontal space requirements imposed by the parent |
|heightMeasureSpec||The vertical space requirements imposed by the parent |
At Google IO 2016 Google announced a new Android layout named ConstraintLayout.
Pay attention because currently, this layout is a Beta release.
Fore More About Constraint Layout:
Adding ConstraintLayout to your project
To work with ConstraintLayout, you need Android Studio Version 2.2 or newer and have at least version 32 (or higher) of Android Support Repository.
- Add the Constraint Layout library as a dependency in your
- Sync project
To add a new constraint layout to your project:
- Right-click on your module's layout directory, then click
New > XML > Layout XML.
- Enter a name for the layout and enter
"android.support.constraint.ConstraintLayout"for the Root Tag.
- Click Finish.
Otherwise just add in a layout file:
ConstraintLayout alpha 9, Chains are available. A Chain is a set of views inside a
ConstraintLayout that are connected in a bi-directional way between them, i.e A connected to B with a constraint, and B connected to A with another constraint.
In this example, the two views are positioned one under another and both of them are centered vertically. You may change the vertical position of these views by adjusting the chain's bias. Add the following code to the first element of a chain:
In a vertical chain, the first element is a top-most view, and in a horizontal chain it is the left-most view. The first element defines the whole chain's behavior.
Chains are a new feature and are updated frequently. Here is an official Android Documentation on Chains.