how to MODIFY a constraint layout programmatically?

Question

Ive got a view like below :

 <org.rayanmehr.atlas.shared.customview.CustomTextView
    android:id="@+id/tvDownVoteCount"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginLeft="6dp"
    app:layout_constraintVertical_bias="0"
    app:layout_constraintTop_toBottomOf="@+id/anchorHelper"
    app:layout_constraintLeft_toRightOf="@+id/tvDownVoteIcon"
    app:layout_constraintBottom_toBottomOf="@+id/imgComment"
    />

how can i modify the value of app:layout_constraintVertical_bias or any other constraint property programmatically without having top set the whole set of the properties again in my activity ?

Edric · Accepted Answer · 2018-05-11 10:39:27Z

55

Here is what I did (no need for ConstraintSet, we can work directly on the constraints themselves):

ConstraintLayout.LayoutParams params = (ConstraintLayout.LayoutParams) myView.getLayoutParams();
params.horizontalBias = 0.2f; // here is one modification for example. modify anything else you want :)
myView.setLayoutParams(params); // request the view to use the new modified params

it worked like a charm when I had a SeekBar and a TextView below it (aligned to it both left+right), and I wanted to update the TextView position to be under the SeekBar's cursor, so I had to update the horizontal bias params on the SeekBar's OnSeekBarChangeListener

edited May 11, 2018 at 10:39

Edric

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answered Jan 9, 2018 at 10:03

Re'em

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4 Comments

Hashir Baig Over a year ago

Thanks a lot man. You just helped a lot. I was having issue settings toptotop of a view. You method worked flawlessly.

Juan José Melero Gómez Over a year ago

Note: It is completely necessary to call setLayoutParams(). Some times, it works even if you don't call it, but not this one.

Hamdy Abd El Fattah Over a year ago

Awesome, you saved me

CmTiger Over a year ago

That is the best answer. for some reason calling requestLayout not working

Ashley Figueira · Accepted Answer · 2020-10-29 10:39:23Z

48

If you are using Kotlin and you have androidx-core-ktx lib you can simply do:

someView.updateLayoutParams<ConstraintLayout.LayoutParams> { horizontalBias = 0.5f }

answered Oct 29, 2020 at 10:39

Ashley Figueira

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2 Comments

reza laki Over a year ago

tnx sir ... very quick and useful 👌👌👌👌

SilverTech Over a year ago

this is the answer, so glad I found.

Amir Ziarati · Accepted Answer · 2022-06-13 15:13:54Z

14

I just found the answer in here and you can use ConstraintSet to achieve this like below:

ConstraintSet constraintSet = new ConstraintSet();
constraintSet.clone(context, R.id.activity_constraint);

//for example lets change the vertical bias of tvDownVoteIcon
float biasedValue = 0.2f;
constraintSet.setVerticalBias(R.id.tvDownVoteIcon, biasedValue);

//or change the anchor
constraintSet.connect
(R.id.tvDownVoteIcon,ConstraintSet.RIGHT,R.id.txt,ConstraintSet.RIGHT,0);

//then apply
constraintSet.applyTo( (ConstraintLayout) findViewById(R.id.activity_constraint));

edited Jun 13, 2022 at 15:13

answered Aug 28, 2017 at 13:44

Amir Ziarati

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Comments

Xavier Rubio Jansana · Accepted Answer · 2017-08-28 13:41:51Z

0

Disclaimer: I haven't used this specific functionality. This is just my interpretation on how I would try to do it.

I think that what you need is ConstraintSet. After obtaining it, you could modify it and apply it again. This is a relevant example from this article.

override fun onCreate(savedInstanceState: Bundle?) {
    ...
    val constraintSet1 = ConstraintSet()
    constraintSet1.clone(constraintLayout)
    val constraintSet2 = ConstraintSet()
    constraintSet2.clone(constraintLayout)
    constraintSet2.centerVertically(R.id.image, 0)

    var changed = false
    findViewById(R.id.button).setOnClickListener {
        TransitionManager.beginDelayedTransition(constraintLayout)
        val constraint = if (changed) constraintSet1 else constraintSet2
        constraint.applyTo(constraintLayout)
        changed = !changed
    }
}

answered Aug 28, 2017 at 13:41

Xavier Rubio Jansana

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3 Comments

Amir Ziarati Over a year ago

this is not what i want; i just want to change bias only. actually its toggling between two state !!! not my answer.

Xavier Rubio Jansana Over a year ago

ConstraintLayout bases the layout in constraints, which are stored in a ConstraintSet. So, you need to alter a ConstraintSet in order to modify the bias, you cannot modify the bias directly. Of course, the example that I copied is not modifying specifically the bias, but that's the structure you should follow.

Amir Ziarati Over a year ago

yes you are true but thats not good to answer questions like this which will make the person who asks more confused. i found the answer myself. anyway thanks a lot to help.

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