如何判断 BottomSheetDialogFragment 何时展开以填满屏幕？

Question

我正在尝试按照 Material 设计 specification 使用 Android 设计支持库向模态底部 sheet 添加关闭可供性工具栏。

When full-screen, bottom sheets can be internally scrolled to reveal additional content. A toolbar should be used to provide a collapse or close affordance to exit this view.

我使用 BottomSheetBehavior.BottomSheetCallback 根据 BottomSheetBehavior 的 expanded/collapsed 状态切换工具栏的可见性。问题是当我尝试向上拖动时工具栏出现，即使 BottomSheetDialogFragment 内容无法填满整个屏幕。我如何判断底部 sheet 何时全屏显示而底部 sheet 正在展开？

public class BottomSheetToolbarToggleCallback : BottomSheetBehavior.BottomSheetCallback
{
    public BottomSheetToolbarToggleCallback(BottomSheetDialogFragment bottomSheetDialogFragment)
    {
        this.bottomSheetDialogFragment = bottomSheetDialogFragment ?? throw new System.ArgumentNullException(nameof(bottomSheetDialogFragment));
    }

    public override void OnSlide(View bottomSheet, float slideOffset)
    {
    }

    public override void OnStateChanged(View bottomSheet, int newState)
    {
        switch (newState)
        {
            case BottomSheetBehavior.StateCollapsed:
                ShowToolbar(bottomSheet, ViewStates.Gone);
                break;
            case BottomSheetBehavior.StateExpanded:
                ShowToolbar(bottomSheet, ViewStates.Visible);
                break;
            case BottomSheetBehavior.StateHidden:
                bottomSheetDialogFragment.Dismiss();
                break;
        }
    }

    private void ShowToolbar(View bottomSheet, ViewStates viewState)
    {
        var toolbar = bottomSheet.FindViewById<Toolbar>(Resource.Id.toolbar);
        if (toolbar != null)
        {
            toolbar.Visibility = viewState;
        }
    }

    private readonly BottomSheetDialogFragment bottomSheetDialogFragment;
}

public abstract class BaseBottomSheetDialogFragment<TViewModel> : MvxBottomSheetDialogFragment<TViewModel> where TViewModel : BaseViewModel
{
    protected BaseBottomSheetDialogFragment()
    {
    }

    protected BaseBottomSheetDialogFragment(IntPtr javaReference, JniHandleOwnership transfer) : base(javaReference, transfer)
    {
    }

    public override void SetupDialog(Dialog dialog, int style)
    {
        base.SetupDialog(dialog, style);

        this.EnsureBindingContextIsSet(); // This is required to use this.BindingInflate()
        var view = this.BindingInflate(LayoutResourceId, null);
        dialog.SetContentView(view);

        // Add support to handle material design specification to dynamically show a toolbar with an 'X' button.
        var layoutParams = (CoordinatorLayout.LayoutParams)((View)view.Parent).LayoutParameters;
        var behavior = layoutParams.Behavior;
        if (behavior != null && behavior is BottomSheetBehavior)
        {
            var toolbar = view.FindViewById<Toolbar>(Droid.Resource.Id.toolbar);
            if (toolbar != null)
            {
                toolbar.SetNavigationIcon(Droid.Resource.Drawable.clear);
                ((BottomSheetBehavior)behavior).SetBottomSheetCallback(new BottomSheetToolbarToggleCallback(this));
                if (CloseCommand != null)
                {
                    toolbar.SetNavigationOnClickListener(new MvxAsyncCommandOnClickListener(CloseCommand));
                }
            }
        }
    }

    /// <summary>
    /// The Android layout resource id of the layout to show in the modal bottom sheet.
    /// </summary>
    protected abstract int LayoutResourceId { get; }

    /// <summary>
    /// Optional <see cref="MvxAsyncCommand"/> to call when the optional toolbar navigation button is clicked.
    /// </summary>
    protected abstract IMvxAsyncCommand CloseCommand { get; }
}

Answer 1

由于我不知道你的具体代码，这里是我试过的一个简单例子的片段：

public View mView;

public override void SetupDialog(Dialog dialog, int style)
{
    base.SetupDialog(dialog, style);

    this.EnsureBindingContextIsSet(); // This is required to use this.BindingInflate()
    mView = this.BindingInflate(LayoutResourceId, null);
    dialog.SetContentView(view);
        ...        
}

在BottomSheetCallback中：

public override void OnStateChanged(View bottomSheet, int newState)
        {
            switch (newState)
            {          
                case BottomSheetBehavior.StateExpanded:
                   var height = bottomSheetDialogFragment.mView.Height;//need you convert to your BottomSheetDialogFragment
                    break;              
            }
        }

Answer 2

这是我最终使用的解决方案。如果 BottomSheetDialogFragment 占据了 window 的整个高度，它只会显示接近的可供性。它已经在 multi-window 模式、cutouts/insets、横向和纵向方向上进行了测试。

public class BottomSheetDialogFragmentCloseAffordanceCallback : BottomSheetBehavior.BottomSheetCallback
{
    public BottomSheetDialogFragmentCloseAffordanceCallback(BottomSheetDialogFragment bottomSheetDialogFragment)
    {
        this.bottomSheetDialogFragment = bottomSheetDialogFragment ?? throw new System.ArgumentNullException(nameof(bottomSheetDialogFragment));
    }

    public override void OnSlide(View bottomSheet, float slideOffset)
    {
    }

    public override void OnStateChanged(View bottomSheet, int newState)
    {
        switch (newState)
        {
            case BottomSheetBehavior.StateCollapsed:
                ShowToolbar(bottomSheet, ViewStates.Gone);
                break;
            case BottomSheetBehavior.StateExpanded:
                if (IsViewSameHeightAsWindow(bottomSheet))
                {
                    ShowToolbar(bottomSheet, ViewStates.Visible);
                }
                break;
            case BottomSheetBehavior.StateHalfExpanded:
                break;
            case BottomSheetBehavior.StateHidden:
                bottomSheetDialogFragment.Dismiss();
                break;
        }
    }

    private void ShowToolbar(View bottomSheet, ViewStates viewState)
    {
        var toolbar = bottomSheet.FindViewById<Toolbar>(Resource.Id.toolbar);
        if (toolbar != null)
        {
            toolbar.Visibility = viewState;
        }
    }

    private bool IsViewSameHeightAsWindow(View view)
    {
        int[] locationInWindow = new int[2];
        view.GetLocationInWindow(locationInWindow);
        return locationInWindow[1] == view.RootWindowInsets.StableInsetTop;
    }

    private readonly BottomSheetDialogFragment bottomSheetDialogFragment;
}

如何判断 BottomSheetDialogFragment 何时展开以填满屏幕？

How to tell when BottomSheetDialogFragment expanded to fill the screen?

c#

android

xamarin.android

androiddesignsupport