/// <summary>
/// Adjusts the size of the view when the user pans (if <see cref="AllowsManualResize"/> is <value>true</value>).
/// </summary>
/// <param name="recognizer">Gesture recognizer that is handling user interaction.</param>
private void HandleMoveView(UIPanGestureRecognizer recognizer)
{
// Do nothing if user resize isn't enabled
if (!AllowsManualResize)
{
return;
}
// Get the distance moved
var translation = recognizer.TranslationInView(View);
// In compact width scrolling up (negative translation) increases height as the card moves up
if (TraitCollection.HorizontalSizeClass == UIUserInterfaceSizeClass.Regular)
{
// translate height constraint
_heightConstraint.Constant += translation.Y;
}
else
{
// translate height constraint
_heightConstraint.Constant -= translation.Y;
}
// Prevent making the view too large
if (_heightConstraint.Constant > MaxHeightConstraint)
{
_heightConstraint.Constant = MaxHeightConstraint;
}
// Prevent making the view too small
if (_heightConstraint.Constant < MinimumHeight)
{
_heightConstraint.Constant = MinimumHeight;
}
// Enables 'flick' gesture to switch between states
if (recognizer.State == UIGestureRecognizerState.Ended)
{
if (Math.Abs(recognizer.VelocityInView(View).Y) > 0)
{
HandleFlick(recognizer);
}
if (_heightConstraint.Constant == MinimumHeight && AllowsMinimizedState)
{
_currentState = BottomSheetState.Minimized;
}
else if (_heightConstraint.Constant == MaxHeightConstraint)
{
_currentState = BottomSheetState.Full;
}
else
{
_currentState = BottomSheetState.Partial;
}
}
recognizer.SetTranslation(new CoreGraphics.CGPoint(0, 0), View);
}
/// <summary>
/// Layout the bottom sheet to its collapsed state, with animation.
/// </summary>
/// <returns>The task.</returns>
private async Task CollapseBottomSheet()
{
var bottomSheetRect = new Rectangle
{
Left = 0,
Top = Height - bottomSheetSize,
Size = new Size(Width, bottomSheetSize)
};
var buttonRect = new Rectangle
{
Top = bottomSheetRect.Top - Button.Height / 2,
Size = new Size(Button.Width, Button.Height),
X = Button.X
};
await Task.WhenAll(BottomSheetContentView.LayoutTo(bottomSheetRect), Button.LayoutTo(buttonRect), Button.RotateXTo(0));
bottomSheetState = BottomSheetState.Collapsed;
}
/// <summary>
/// Layout the bottom sheet to its extended state, with animation.
/// </summary>
/// <returns>The task.</returns>
private async Task ExtendBottomSheet()
{
var bottomSheetRect = new Rectangle
{
Left = 0,
Top = Height * (1 - bottomSheetExtensionFraction),
Size = new Size(Width, Height * bottomSheetExtensionFraction)
};
var buttonRect = new Rectangle
{
Top = bottomSheetRect.Top - Button.Height / 2,
Size = new Size(Button.Width, Button.Height),
X = Button.X
};
await Task.WhenAll(BottomSheetContentView.LayoutTo(bottomSheetRect), Button.LayoutTo(buttonRect), Button.RotateXTo(180));
bottomSheetState = BottomSheetState.Extended;
}
/// <summary>
/// Sets the bottom sheet state and updates the height of the sheet as needed.
/// </summary>
/// <param name="state"></param>
public void SetState(BottomSheetState state)
{
_currentState = state;
if (_heightConstraint == null)
{
return;
}
switch (state)
{
case BottomSheetState.Partial:
_heightConstraint.Constant = GetPartialHeight();
break;
case BottomSheetState.Minimized:
_heightConstraint.Constant = MinimumHeight;
break;
case BottomSheetState.Full:
_heightConstraint.Constant = MaxHeightConstraint;
break;
}
}
