使用 ConstraintLayout 进行绝对定位

Question

I am trying to bring an older app back to life. I used a library to position locations of stores on a floor plan, but it seems deprecated.

My attempt with ConstraintLayout: I positioned all items in the editor and pushed the "Infer Constraints" button, as suggested somewhere on StackOverflow. It worked great... until I ran my app on my device, and noticed all poi's all over the place.

There is a deprecated view which supports layout_marginLeftPercent etc, but I can't seem to find the ConstraintLayout alternative? Any suggestions?

Answer 1

This can be accomplished with ConstraintLayout using Guidelines. So if you want a dot to be placed 24% from the top of the screen and 14% from the left, your code might look something like this:

<android.support.constraint.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.constraint.Guideline
        android:id="@+id/guideline"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.14" />

    <android.support.constraint.Guideline
        android:id="@+id/guideline2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.24" />

    <ImageView
        android:id="@+id/dot"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toTopOf="@+id/guideline2"
        app:layout_constraintEnd_toStartOf="@+id/guideline"
        app:layout_constraintStart_toStartOf="@+id/guideline"
        app:layout_constraintTop_toTopOf="@+id/guideline2"
        app:srcCompat="@android:color/background_dark" />
</android.support.constraint.ConstraintLayout>

More documentation and information about this can be found here