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 ?

score 50 · Answer 1 · edited May 11 '18 at 10:39

50

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 '18 at 10:39

Edric

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answered Jan 09 '18 at 10:03

Re'em

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Thanks a lot man. You just helped a lot. I was having issue settings toptotop of a view. You method worked flawlessly. – Hashir Baig Jan 15 '18 at 07:52
2

Note: It is completely necessary to call `setLayoutParams()`. Some times, it works even if you don't call it, but not this one. – Juan José Melero Gómez Sep 19 '19 at 14:17
Awesome, you saved me – Hamdy Abd El Fattah Oct 11 '20 at 12:57
That is the best answer. for some reason calling requestLayout not working – CmTiger Feb 07 '21 at 10:46

score 39 · Answer 2 · answered Oct 29 '20 at 10:39

39

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 '20 at 10:39

Ashley Figueira

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This was easy and quick. Thanks! – Saurabh Padwekar Nov 24 '20 at 14:44
tnx sir ... very quick and useful – reza laki Oct 12 '22 at 12:58
this is the answer, so glad I found. – SilverTech Mar 20 '23 at 13:18

Amir Ziarati · Accepted Answer · 2022-06-13T15:13:54.570

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));

score 0 · Answer 4 · answered Aug 28 '17 at 13:41

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 '17 at 13:41

Xavier Rubio Jansana

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this is not what i want; i just want to change bias only. actually its toggling between two state !!! not my answer. – Amir Ziarati Aug 28 '17 at 13:43
`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. – Xavier Rubio Jansana Aug 28 '17 at 13:45
1

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. – Amir Ziarati Aug 28 '17 at 13:49

how to MODIFY a constraint layout programmatically?

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