Material Design 2 BottomSheetDialog that doesn't draw over the bottom navigation bar.

FiskBottomSheetDialog.java

package online.fisk.kroki.views;

import android.app.Activity;
import android.app.Dialog;
import android.content.DialogInterface;
import android.graphics.Color;
import android.graphics.Point;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.GradientDrawable;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomSheetBehavior;
import android.support.design.widget.CoordinatorLayout;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;

import timber.log.Timber;

/*
    FiskBottomSheetDialog dialog = new FiskBottomSheetDialog(activity, R.layout.some_layout, R.style.AppTheme);
    View view = dialog.getContentView();
 */
public class FiskBottomsheetDialog {

  private final Dialog dialog;
  private View contentView;
  private boolean cancelable = true;

  private CoordinatorLayout coordinatorLayout;

  private Dialog.OnDismissListener onDismissListener = null;

  private BottomSheetBehavior bottomSheetBehavior;

  public FiskBottomsheetDialog(Activity context, int layout, int theme) {

    dialog = new Dialog(context, theme);

    Window window = dialog.getWindow();

    if (window != null) {
      window.setDimAmount(0);
      window.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
      window.setLayout(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
    }

    contentView = context.getLayoutInflater().inflate(layout, null);

    //Curved top corners:
    GradientDrawable curvedBackground = new GradientDrawable();
    curvedBackground.setColor(Color.WHITE);

    float cornerRadius = 8 * ((float) context.getResources().getDisplayMetrics().densityDpi / DisplayMetrics.DENSITY_DEFAULT);

    curvedBackground.setCornerRadii(new float[]{cornerRadius, cornerRadius, cornerRadius, cornerRadius, 0, 0, 0, 0});
    contentView.setBackground(curvedBackground);

    //Full screen coordinator to hold the bottomsheet
    coordinatorLayout = new CoordinatorLayout(context);

    WindowManager.LayoutParams layoutParams = new WindowManager.LayoutParams(WindowManager.LayoutParams.MATCH_PARENT, WindowManager.LayoutParams.MATCH_PARENT);
    layoutParams.gravity = Gravity.CENTER;
    coordinatorLayout.setLayoutParams(layoutParams);
    coordinatorLayout.setBackgroundColor(Color.parseColor("#00000000"));

    bottomSheetBehavior = new BottomSheetBehavior();
    bottomSheetBehavior.setSkipCollapsed(true);
    bottomSheetBehavior.setHideable(true);
    bottomSheetBehavior.setState(BottomSheetBehavior.STATE_HIDDEN);

    CoordinatorLayout.LayoutParams params = new CoordinatorLayout.LayoutParams(CoordinatorLayout.LayoutParams.MATCH_PARENT, CoordinatorLayout.LayoutParams.WRAP_CONTENT);
    params.setBehavior(bottomSheetBehavior);

    contentView.setLayoutParams(params);

    coordinatorLayout.addView(contentView);

    //Any click on the dimmed coordinator in the background should dismiss the dialog (unless setCanceleable(false); has been called):
    coordinatorLayout.setOnClickListener(_view -> {
      if (cancelable) BottomSheetBehavior.from(contentView).setState(BottomSheetBehavior.STATE_HIDDEN);
    });

    bottomSheetBehavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {

      @Override
      public void onStateChanged(@NonNull View bottomSheet, int newState) {
        switch (newState) {
          case BottomSheetBehavior.STATE_HIDDEN:
            dialog.dismiss();
            if (onDismissListener != null) onDismissListener.onDismiss(dialog);
            break;
        }
      }

      //slideOffset is float in range 0 to 1 - remapped to 0 to 153 (0x99000000)
      @Override
      public void onSlide(@NonNull View bottomSheet, float slideOffset) {
        int alpha = (int) map(slideOffset, 0f, 1f, 0f, 153f);
        int overlayColor = Color.argb(alpha, Color.red(Color.BLACK), Color.green(Color.BLACK), Color.blue(Color.BLACK));

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP && window != null) {
          window.setStatusBarColor(overlayColor);
        }

        coordinatorLayout.setBackgroundColor(overlayColor);
      }
    });


    dialog.setContentView(coordinatorLayout);

    //Without this the bottom sheet doesn't animate, despite the default state being hidden
    BottomSheetBehavior.from(contentView).setState(BottomSheetBehavior.STATE_HIDDEN);

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) dialog.create();
  }

  public void show() {
    dialog.show();
    contentView.post(() -> BottomSheetBehavior.from(contentView).setState(BottomSheetBehavior.STATE_EXPANDED));
  }

  public void dismiss() {
    BottomSheetBehavior.from(contentView).setState(BottomSheetBehavior.STATE_HIDDEN);
  }

  public void setOnShowListener(DialogInterface.OnShowListener onShowListener) {
    dialog.setOnShowListener(onShowListener);
  }

  public void setCancelable(boolean cancelable) {
    this.cancelable = cancelable;
    dialog.setCancelable(cancelable);
  }

  public View getContentView() {
    return contentView;
  }

  public CoordinatorLayout getCoordinatorLayout() {
    return coordinatorLayout;
  }

  public void setOnDismissListener(Dialog.OnDismissListener onDismissListener) {
    this.onDismissListener = onDismissListener;
  }

  private float map(float value, float start1, float stop1, float start2, float stop2) {
    return start2 + (stop2 - start2) * ((value - start1) / (stop1 - start1));
  }

  public Dialog getDialog() {
    return dialog;
  }

  public void setMaxWidth(float dp){
    int maxWidth = Math.round(contentView.getContext().getResources().getDisplayMetrics().density * dp);

    Display display = dialog.getWindow().getWindowManager().getDefaultDisplay();
    Point size = new Point();
    display.getSize(size);

    if(size.x > maxWidth){
      contentView.getLayoutParams().width = maxWidth;
      ((CoordinatorLayout.LayoutParams)contentView.getLayoutParams()).gravity = Gravity.CENTER_HORIZONTAL;
    }
  }

  public void setMaxWidth(int dimenRes){
    float dp = contentView.getContext().getResources().getDimension(dimenRes);
    setMaxWidth(dp);
  }

}

how to expand this bottom sheet?

hideable not working