c# - Xamarin.Forms iOS CursorPosition 没有被兑现
问题描述
在我的 Xamarin.Forms 应用程序中,我有一个设置光标位置的行为(该行为充当我们输入字段的掩码)。
CursorPosition 是通过调用来设置的:targetEntry.CursorPosition = newCursorPosition
。这在 Android 上运行得很好,但在 iOS 上,光标总是移到文本的末尾,它是 iOS 版本特定的错误,还是只是全面?
有关该行为的所有其他内容(确保正确屏蔽文本,正确删除作为用户输入数据的指南的下划线字符)按其应有的方式工作。如果需要,我可以发布更多代码
编辑:newCursorPosition 是一个静态 int 变量
编辑 2:包括我的代码
公共类 DurationViewMaskBehavior : 行为 { 公共静态 DurationViewMaskBehavior 实例 = 新 DurationViewMaskBehavior(); 私有静态 int cursorPosition = 0;
protected override void OnAttachedTo(BorderlessEntry entry) {
entry.TextChanged += OnInput;
base.OnAttachedTo(entry);
}
protected override void OnDetachingFrom(BorderlessEntry entry) {
entry.TextChanged -= OnInput;
base.OnDetachingFrom(entry);
}
/// <summary>
/// This method exists to ensure that if the user tried to shape the field to be something it shouldn't
/// that it will return the mask to the correct format; this is to ensure that we only have valid data and also that
/// </summary>
/// <param name="text"></param>
/// <returns></returns>
private bool PatternMatchCheck(string text) {
var regex = @"^(([0-9]\d{1}|__|[0-9]_|[0-9]|[0-9]*__|[0-9]\d{1}_| *) Min, ([0-9]\d{1}|__|[0-9]_|[0-9]|[0-9]__|[0-9]\d{1}_|) Sec|((Min, Sec)|[0-9]+ Min, Sec|Min, [0-9]+ Sec))$";
var match = Regex.Match(text, regex, RegexOptions.IgnoreCase);
return match.Success;
}
private void OnInput(object sender, TextChangedEventArgs args) {
//Only fire this behavior when the user actually inputs some type of value
if(!string.IsNullOrWhiteSpace(args.NewTextValue)) {
var text = args.NewTextValue;
//How this works so far:
//At first you get the input, so text.length == 1 is fine. Then
//it updates itself, so really for every input this event fires twice.
//After that we will have to look at the actual text itself so we can use
//the index instead
var targetObject = ((BorderlessEntry)sender);
if(!PatternMatchCheck(args.NewTextValue) && args.OldTextValue.Length > 2) {
targetObject.Text = args.OldTextValue;
return;
}
if (text.Length == 1) {
targetObject.Text = $"{text}_ Min, __ Sec";
cursorPosition = 1;
}
if(text.Contains("_")) {
if (text.Length > 1 && (text[2] != '_' || text[1] != '_')) {
if (text[2] == '_' && text[0] != '_') {
targetObject.Text = $"{text.Substring(0, 2)} Min, __ Sec";
cursorPosition = 8;
}
}
if (text.Length > 1 && text[8] != '_' && text[9] == '_' && text[8] != ' ') {
targetObject.Text = $"{text.Substring(0, 2)} Min, {text[8]}_ Sec";
cursorPosition = 9;
}
if (text.Length > 1 && text[8] != '_' && text[9] != '_') {
targetObject.Text = $"{text.Substring(0, 2)} Min, {text.Substring(8, 2)} Sec";
cursorPosition = text.Length-1;
}
}
targetObject.CursorPosition = cursorPosition;
}
}
}
解决方案
弄清楚为什么,看起来 iOS 需要我绑定另一个 .TextChanged 事件来处理光标的设置。它很奇怪而且很落后,但它确实有效。
private void SetCursor(object sender, TextChangedEventArgs args) {
((BorderlessEntry)sender).CursorPosition = cursorPosition;
}
if(isRegistered) {
targetObject.TextChanged -= SetCursor;
isRegistered = false;
}
else {
targetObject.TextChanged += SetCursor;
isRegistered = true;
}
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