android ConstraintLayout does not allow negative margins

问题

I position lots of items relative to a layout guide, and would like to position a new item nearly relative to this layout guide.

I tried with a negative layout margin without success.

回答1:

Here is a blog posting that discusses negative margins in ConstraintLayout.

Using Spaces for negative margins

A view in a ConstraintLayout cannot have negative margins (it’s not supported). However, with an easy trick you can have similar functionality by inserting a Space (which is essentially an empty View) and setting its size to the margin you want.

回答2:

android:translationX="-10dp"
android:translationY="-10dp"

回答3:

It's a Bad practice to use NEGATIVE MARGIN .

A ConstraintLayout is a ViewGroup which allows you to position and size widgets in a flexible way.

Note that a margin can only be positive or equals to zero .ConstraintLayout cannot have negative margins.

You can use

android:layout_marginStart

android:layout_marginEnd

android:layout_marginLeft

android:layout_marginTop

android:layout_marginRight

android:layout_marginBottom

回答4:

You can use a View to hold a fixed value like 30dp like below:

 <com.mapbox.mapboxsdk.maps.MapView
    android:id="@+id/mapView"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:layout_marginTop="45dp"
    app:layout_constraintBottom_toBottomOf="@id/space"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:mapbox_uiRotateGestures="false" />

<View
    android:id="@+id/space"
    android:layout_width="match_parent"
    android:layout_height="30dp"
    app:layout_constraintTop_toBottomOf="parent" />

回答5:

Creating a view for position your siblings might not be the best call because the view will be drawn (even if it's invisible) it will still uses ressources.

You can try to use guidelines instead :

You can add a vertical or horizontal guideline to which you can constrain views, and the guideline will be invisible to app users. You can position the guideline within the layout based on either dp units or percent, relative to the layout's edge.

https://developer.android.com/training/constraint-layout#constrain-to-a-guideline

来源：https://stackoverflow.com/questions/45670999/android-constraintlayout-does-not-allow-negative-margins

标签

android

android-constraintlayout