xamarin - 如何在 Android 和 iOS (Xamarin Forms) 上获取键盘高度？

Question

我想得到 Keyboard 的高度在 Android和 iOS ( Xamarin Forms )。

当屏幕显示 Portrait模式和 Landscape模式，如何获得height值(value)？



我找到了 Swift 的引用文献在 iOS :

What is the height of iPhone's onscreen keyboard?

How to get height of Keyboard?

但是可以在Xamarin上给我提供源代码

以及如何在 Android 上获取键盘的高度?

请帮我!

Answer 1

对于 iOS
有两种方法可以做到这一点!
第一种方式 :为一个 UIViewController 实现它，如果你的应用程序很小，如下:
步骤 1:为显示和隐藏观察者添加字段:

private NSObject _keyboardObserverWillShow;
private NSObject _keyboardObserverWillHide;

第 2 步:更新 ViewDidLoad 和 ViewDidUnload 覆盖以在键盘显示或隐藏时添加/删除观察者:

public override void ViewDidLoad() {
    base.ViewDidLoad ();
    _keyboardObserverWillShow = NSNotificationCenter.DefaultCenter.AddObserver(UIKeyboard.DidShowNotification, KeyboardDidShowNotification);
    _keyboardObserverWillHide = NSNotificationCenter.DefaultCenter.AddObserver(UIKeyboard.WillHideNotification, KeyboardWillHideNotification);
}
    
public override void ViewDidUnload() {
    base.ViewDidUnload();
    NSNotificationCenter.DefaultCenter.RemoveObserver(_keyboardObserverWillShow);
    NSNotificationCenter.DefaultCenter.RemoveObserver(_keyboardObserverWillHide);
}

第 3 步:然后填充函数 KeyboardDidShowNotification & KeyboardWillHideNotification为每个观察者执行。它相当长，需要我花一些时间来解释每个部分，但你可以在评论中问我。它是这样的:

private void KeyboardWillHideNotification (NSNotification notification) 
{
    UIView activeView = View.FindFirstResponder();
    if (activeView == null)
        return;
    
    UIScrollView scrollView = activeView.FindSuperviewOfType (this.View, typeof(UIScrollView)) as UIScrollView;
    if (scrollView == null)
        return;
    
    // Reset the content inset of the scrollView and animate using the current keyboard animation duration
    double animationDuration = UIKeyboard.AnimationDurationFromNotification(notification);
    UIEdgeInsets contentInsets = new UIEdgeInsets(0.0f, 0.0f, 0.0f, 0.0f);
    UIView.Animate(animationDuration, delegate{
        scrollView.ContentInset = contentInsets;
        scrollView.ScrollIndicatorInsets = contentInsets;
    });
}   

private void KeyboardDidShowNotification (NSNotification notification) 
{
    UIView activeView = View.FindFirstResponder();
    if (activeView == null)
        return;

    ((UITextField)activeView).ShowDoneButtonOnKeyboard();

    UIScrollView scrollView = activeView.FindSuperviewOfType(this.View, typeof(UIScrollView)) as UIScrollView;
    if (scrollView == null)
        return;
    
    RectangleF keyboardBounds = UIKeyboard.BoundsFromNotification(notification);
    
    UIEdgeInsets contentInsets = new UIEdgeInsets(0.0f, 0.0f, keyboardBounds.Size.Height, 0.0f);
    scrollView.ContentInset = contentInsets;
    scrollView.ScrollIndicatorInsets = contentInsets;
    
    // If activeField is hidden by keyboard, scroll it so it's visible
    RectangleF viewRectAboveKeyboard = new RectangleF(this.View.Frame.Location, new SizeF(this.View.Frame.Width, this.View.Frame.Size.Height - keyboardBounds.Size.Height));
    
    RectangleF activeFieldAbsoluteFrame = activeView.Superview.ConvertRectToView(activeView.Frame, this.View);
    // activeFieldAbsoluteFrame is relative to this.View so does not include any scrollView.ContentOffset
    
    // Check if the activeField will be partially or entirely covered by the keyboard
    if (!viewRectAboveKeyboard.Contains(activeFieldAbsoluteFrame)) {
        // Scroll to the activeField Y position + activeField.Height + current scrollView.ContentOffset.Y - the keyboard Height
        PointF scrollPoint = new PointF(0.0f, activeFieldAbsoluteFrame.Location.Y + activeFieldAbsoluteFrame.Height + scrollView.ContentOffset.Y - viewRectAboveKeyboard.Height);
        scrollView.SetContentOffset(scrollPoint, true);
    }
}

第二种方式 : 创建 keyboard handler您可以通过您的 BaseViewController 用于每个页面
对于安卓:
您可以按照 stackOverflow Xamarin solution here 中提到的解决方案进行操作。 ((Activity)Forms.Context).Window.SetSoftInputMode(SoftInput.AdjustPan); .有时这不起作用，所以你可以 use this to fix it . PS:没有复制这些答案，因为重写答案没有意义。