CODEWITHSUNDEEP
androidandroid-layoutandroid-constraintlayout
eight
eight

Reputation: 351

ConstraintLayout Guideline expanding together with view

I got this setup:

<ScrollView 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"
    android:fillViewport="true">

    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <ImageView
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:adjustViewBounds="true"
            android:scaleType="centerCrop"
            app:layout_constraintBottom_toTopOf="@+id/guideline"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <android.support.constraint.Guideline
            android:id="@+id/guideline"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.35" />

        ...
    </android.support.constraint.ConstraintLayout>
</ScrollView>

Now when the view is not full and has no need for a scroll bar - everything works as expected - the image is 35% in relation to the screen size. But as more content appears under the image, a need for scroll bar appears and the guideline's constraintGuide of 0.35 percent seems to be calculated off whole length of the screen (not physical), so the ImageView also becomes bigger as the view becomes "longer". Is there a way to avoid this and always have x percent of physical screen size?

Upvotes: 2

Views: 5413

Answers (1)

Cheticamp
Cheticamp

Reputation: 62841

The guideline you have specified is placed at a percentage distance from the top of the ConstraintLayout. Unfortunately, for your application, the guideline is tied to the overall height of the view and not a percentage of the screen. So, if the ConstraintLayout is taller than the screen size allocated to it, you will see the shift. See documentation for Guideline.

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)

You can specify a static offset from the top of the layout in terms of dp, but this will not accommodate different screen sizes. I don't believe there is a solution just using XML.

You can, however, calculate the number of pixels in code and set the distance on a run-time basis. You would need to change the Guideline to one that is a fixed distance from the top of the layout, calculate the distance from the top, and call setGuidelineBegin to place the guideline.

setGuidelineBegin

void setGuidelineBegin (int guidelineID, int margin)

Set the guideline's distance form the top or left edge.

Upvotes: 5

Related Questions