Bottom sheet dialog 드래그 방지 방법

<bottom_sheet_sample.xml>

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@mipmap/ic_launcher_round"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toTopOf="@id/text"
        android:layout_marginBottom="50dp"/>
    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="this is bottom sheet"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"/>

    <Button
        android:id="@+id/close_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="CLOSE"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

 

<MainActivity.java>

package com.demo.testing;

import android.app.Dialog;
import android.os.Bundle;
import android.view.View;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import com.demo.testing.R;
import com.google.android.material.bottomsheet.BottomSheetBehavior;
import com.google.android.material.bottomsheet.BottomSheetDialog;
import com.google.android.material.bottomsheet.BottomSheetDialogFragment;

import java.lang.reflect.Field;

public class MainActivity extends AppCompatActivity {

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

        findViewById(R.id.start_button).setOnClickListener(v -> {
            new MyBottomSheetFragment().show(getSupportFragmentManager(), "tag");
        });
    }

    public static class MyBottomSheetFragment extends BottomSheetDialogFragment {

        @Override
        public void setupDialog(Dialog dialog, int style) {
            BottomSheetDialog bottomSheetDialog = (BottomSheetDialog) dialog;
            bottomSheetDialog.setContentView(R.layout.bottom_sheet_layout);

            try {
                Field behaviorField = bottomSheetDialog.getClass().getDeclaredField("behavior");
                behaviorField.setAccessible(true);
                final BottomSheetBehavior behavior = (BottomSheetBehavior) behaviorField.get(bottomSheetDialog);
                behavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {

                    @Override
                    public void onStateChanged(@NonNull View bottomSheet, int newState) {
                        if (newState == BottomSheetBehavior.STATE_DRAGGING) {
                            behavior.setState(BottomSheetBehavior.STATE_EXPANDED);
                        }
                    }

                    @Override
                    public void onSlide(@NonNull View bottomSheet, float slideOffset) {
                    }
                });
            } catch (NoSuchFieldException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
    }
}

 

드래그를 방지하는법은 아래와 같이 bottomSheet에 behavior을 얻어내어 onStateChanged에서 DRAGGING일떄 계속해서 EXPANDED로 유지시켜주면 된다.

try {
                Field behaviorField = bottomSheetDialog.getClass().getDeclaredField("behavior");
                behaviorField.setAccessible(true);
                final BottomSheetBehavior behavior = (BottomSheetBehavior) behaviorField.get(bottomSheetDialog);
                behavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {

                    @Override
                    public void onStateChanged(@NonNull View bottomSheet, int newState) {
                        if (newState == BottomSheetBehavior.STATE_DRAGGING) {
                            behavior.setState(BottomSheetBehavior.STATE_EXPANDED);
                        }
                    }

                    @Override
                    public void onSlide(@NonNull View bottomSheet, float slideOffset) {
                    }
                });
            } catch (NoSuchFieldException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }

 

혹은 아래와 같은 방법으로도 behavior을 얻을 수 있다.

 

    private void method(BottomSheetDialog bottomSheetDialog) {
        //id = com.google.android.material.R.id.design_bottom_sheet for Material Components
        //id = android.support.design.R.id.design_bottom_sheet for support librares
        FrameLayout bottomSheet = (FrameLayout)
                bottomSheetDialog.findViewById(R.id.design_bottom_sheet);
        BottomSheetBehavior behavior = BottomSheetBehavior.from(bottomSheet);
        ViewGroup.LayoutParams layoutParams = bottomSheet.getLayoutParams();
        layoutParams.width = getBottomSheetDialogDefaultWidth();
        layoutParams.height = getBottomSheetDialogDefaultHeight();
        bottomSheet.setLayoutParams(layoutParams);

        behavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
            @Override
            public void onStateChanged(@NonNull View view, int i) {
                if (i == BottomSheetBehavior.STATE_DRAGGING) {
                    behavior.setState(BottomSheetBehavior.STATE_EXPANDED);
                }
            }

            @Override
            public void onSlide(@NonNull View view, float v) {

            }
        });

        behavior.setState(BottomSheetBehavior.STATE_EXPANDED);
    }