Guideline

public class Guideline extends View

Utility class representing a Guideline helper object for ConstraintLayout. Helper objects are not displayed on device (they are marked as View.GONE) and are only used for layout purposes. They only work within a ConstraintLayout.

A Guideline can be either horizontal or vertical:

• Vertical Guidelines have a width of zero and the height of their ConstraintLayout parent
• Horizontal Guidelines have a height of zero and the width of their ConstraintLayout parent

Positioning a Guideline is possible in three different ways:

• specifying a fixed distance from the left or the top of a layout (layout_constraintGuide_begin)
• specifying a fixed distance from the right or the bottom of a layout (layout_constraintGuide_end)
• specifying a percentage of the width or the height of a layout (layout_constraintGuide_percent)

Widgets can then be constrained to a Guideline, allowing multiple widgets to be positioned easily from one Guideline, or allowing reactive layout behavior by using percent positioning.

See the list of attributes in androidx.constraintlayout.widget.ConstraintLayout.LayoutParams to set a Guideline in XML, as well as the corresponding setGuidelineBegin, setGuidelineEnd and setGuidelinePercent functions in ConstraintSet.

Example of a Button constrained to a vertical Guideline:

         <androidx.constraintlayout.widget.ConstraintLayout
             xmlns:android="http://schemas.android.com/apk/res/android"
             xmlns:app="http://schemas.android.com/apk/res-auto"
             xmlns:tools="http://schemas.android.com/tools"
             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/guideline"
                 app:layout_constraintGuide_begin="100dp"
                 android:orientation="vertical"/>
             <Button
                 android:text="Button"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:id="@+id/button"
                 app:layout_constraintLeft_toLeftOf="@+id/guideline"
                 android:layout_marginTop="16dp"
                 app:layout_constraintTop_toTopOf="parent" />
         </androidx.constraintlayout.widget.ConstraintLayout>
       

Summary

public Guideline(Context context)

public Guideline(Context context, AttributeSet attrs)

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

public Guideline(
    Context context,
    AttributeSet attrs,
    int defStyleAttr,
    int defStyleRes
)

public void draw(@NonNull Canvas canvas)

public void setFilterRedundantCalls(boolean filter)

public void setGuidelineBegin(int margin)

public void setGuidelineEnd(int margin)

public void setGuidelinePercent(float ratio)

public void setVisibility(int visibility)

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)