Pfthb

This is driving me crazy! measured layout is always 0 when i try to build layout programmatically using constraint layout and constraint set.

I tried requestLayout, forceLayout, invalidate on all child and parents. but width and height is 0 rendering whole view invisible.

here is my layout builder. my problem is that views are rendering invisible when i apply constraints.

public final class FormBuilder 

 private Context context;
 private ArrayList<ArrayList<TextInputLayout>> fields;

 private FormBuilder(Context context) 
 this.context = context;
 fields = new ArrayList<>();
 fields.add(new ArrayList<TextInputLayout>());
 

 private ArrayList<TextInputLayout> getLastRow() 
 return fields.get(fields.size() - 1);
 

 public static FormBuilder newForm(Context context) 
 return new FormBuilder(context);
 

 public FormBuilder addField(@NonNull String hint) 
 TextInputLayout field = newTextField(context, hint);
 getLastRow().add(field);
 return this;
 

 public FormBuilder nextRow() 
 if (getLastRow().size() > 0) fields.add(new ArrayList<TextInputLayout>());
 return this;
 

 public FormView build() 
 FormView formView = new FormView(context);
 ConstraintSet constraints = new ConstraintSet();

 int topId = ConstraintSet.PARENT_ID;
 for (ArrayList<TextInputLayout> row : fields) 
 if (row.size() == 0) continue;

 int rowIds = new int[row.size()];
 for (int i = 0; i < row.size(); i++) // constraint top
 TextInputLayout field = row.get(i);
 rowIds[i] = field.getId();
 ConstraintLayout.LayoutParams params = new ConstraintLayout.LayoutParams(
 ConstraintLayout.LayoutParams.WRAP_CONTENT,
 ConstraintLayout.LayoutParams.WRAP_CONTENT
 );
 formView.addView(field, params);

 if (topId == ConstraintSet.PARENT_ID) 
 constraints.connect(rowIds[i], ConstraintSet.TOP, ConstraintSet.PARENT_ID, ConstraintSet.TOP);
 else 
 constraints.connect(rowIds[i], ConstraintSet.TOP, topId, ConstraintSet.BOTTOM);
 
 
 if (row.size() >= 2) // constraint start and end
 constraints.createHorizontalChainRtl(
 ConstraintSet.PARENT_ID, ConstraintSet.START,
 ConstraintSet.PARENT_ID, ConstraintSet.END,
 rowIds, null, ConstraintSet.CHAIN_SPREAD);
 else // row.size = 1
 constraints.connect(rowIds[0], ConstraintSet.START, ConstraintSet.PARENT_ID, ConstraintSet.START);
 constraints.connect(rowIds[0], ConstraintSet.END, ConstraintSet.PARENT_ID, ConstraintSet.END);
 

 topId = rowIds[0];
 
 constraints.applyTo(formView); // this turns layout size to zero
 return formView;
 

 private static TextInputLayout newTextField(Context context, String hint) 
 TextInputLayout.LayoutParams layoutParams = new TextInputLayout.LayoutParams(
 TextInputLayout.LayoutParams.MATCH_PARENT,
 TextInputLayout.LayoutParams.WRAP_CONTENT
 );
 TextInputLayout inputLayout = new TextInputLayout(context);
 TextInputEditText editText = new TextInputEditText(context);
 inputLayout.addView(editText, layoutParams);
 inputLayout.setHint(hint);
 inputLayout.setId(ViewCompat.generateViewId());
 return inputLayout;
 

MainActivity.java

public class MainActivity extends AppCompatActivity 

 @Override
 protected void onCreate(Bundle savedInstanceState) 
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);

 FormView form = FormBuilder.newForm(this)
 .addField("First name").addField("Last name")
 .nextRow()
 .addField("Phone numnber")
 .build();

 FrameLayout layout = findViewById(R.id.main_content);
 FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(
 FrameLayout.LayoutParams.MATCH_PARENT,
 FrameLayout.LayoutParams.WRAP_CONTENT
 );
 layout.addView(form, params);
 

FormView.java

public class FormView extends ConstraintLayout 

 public FormView(Context context) 
 super(context);
 

main_activity.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:id="@+id/main_content"
 android:layout_width="match_parent"
 android:layout_height="match_parent" />

I had to clone ConstraintSet. not only that, cloning must be done after views are added. after adding views and cloning ConstraintSet, it knows size of the views and can set constraints accordingly.

private FormViewBuilder(Context context) 
 this.context = context;
 formView = new FormView(context); // initialize
 // ...


// ...

public FormViewBuilder addField(int id, @NonNull String key, @NonNull String hint, String requiredMessage) 
 TextInputLayout field = newTextField(context, id, key, hint, requiredMessage);
 getLastRow().add(field);

 // add views before build <<================ important
 ConstraintLayout.LayoutParams params = new ConstraintLayout.LayoutParams(
 ConstraintLayout.LayoutParams.CHAIN_SPREAD,
 ConstraintLayout.LayoutParams.WRAP_CONTENT
 );
 formView.addView(field, params);

 return this;



public FormView build() 
 ConstraintSet constraints = new ConstraintSet();
 constraints.clone(formView); // clone after views are added <<================ important

 // only set constraints. do not add or remove views

 constraints.applyTo(formView);
 return formView;