[英]C# - Passing custom arguments to events
因此,我試圖向事件發送自定義參數,但是它從未起作用,我嘗試了許多不同的方法,但是我卻從未使其起作用,所以基本上!
public void CreateEmojiList()
{
CreateAllEmojis();
int btnCount = 0;
foreach(Emoji emoji in emojiList)
{
Button btnEmoji = new Button();
btnEmoji.Size = new Size(40, 36);
btnEmoji.FlatStyle = FlatStyle.Flat;
btnEmoji.FlatAppearance.MouseDownBackColor = Color.Cyan;
btnEmoji.Cursor = Cursors.Hand;
btnEmoji.Font = new Font("Bahnschrift", 6.75f);
btnEmoji.Text = emoji.EmojiText;
btnEmoji.Top = (panel_main.Controls.OfType<Button>().Count<Button>() / 4) * (1 + btnEmoji.Height) + 6;
btnEmoji.Left = (btnEmoji.Width + 1) * btnCount + 6;
panel_main.Controls.Add(btnEmoji);
btnEmoji.Click += //What do I do here?
; btnCount++;
if (btnCount == 4)
btnCount = 0;
}
}
protected virtual void OnEmojiClick(EmojiClickEventArgs e)
{
if (this.EmojiClick != null)
EmojiClick(e);
}
這是我想用來傳遞參數的類:
public class EmojiClickEventArgs : EventArgs
{
private string emojiText;
private string emojiName;
public EmojiClickEventArgs(string EmojiText, string EmojiName)
{
this.EmojiText = EmojiText;
this.EmojiName = EmojiName;
}
public string EmojiText { get { return emojiText; } set { emojiText = value; } }
public string EmojiName { get { return emojiName; } set { emojiName = value; } }
}
我想從emoji.EmojiText和emoji.EmojiName中獲得這兩個值
一種方法是從Button
繼承並創建一個名為EmojiButton
的類。 然后,您聲明一個與您的事件處理程序的簽名匹配的委托。 之后,使用EmojiButton
類中的委托聲明一個事件,並將EmojiText
和EmojiName
之類的屬性也添加到按鈕子類中。 最后,您需要將按鈕單擊事件與自定義事件鏈接。 每當單擊按鈕時,引發事件並傳遞參數,即this.EmojiText, this.EmojiName
。
另一種方法是將Emoji
對象分配給Tag
屬性。 然后,您可以使用普通的EventHandler
簽名( object sender, EventArgs e
)編寫事件處理程序,並查看sender
的Tag
是什么。 然后,您可以將Tag
投放到Emoji
並訪問其屬性。
您可以利用閉包為每個按鈕的事件處理程序“打包”其他事件數據。 只要確保不要關閉循環變量即可。
public void CreateEmojiList()
{
CreateAllEmojis();
int btnCount = 0;
foreach(Emoji emoji in emojiList)
{
Button btnEmoji = new Button();
btnEmoji.Size = new Size(40, 36);
btnEmoji.FlatStyle = FlatStyle.Flat;
btnEmoji.FlatAppearance.MouseDownBackColor = Color.Cyan;
btnEmoji.Cursor = Cursors.Hand;
btnEmoji.Font = new Font("Bahnschrift", 6.75f);
btnEmoji.Text = emoji.EmojiText;
btnEmoji.Top = (panel_main.Controls.OfType<Button>().Count<Button>() / 4) * (1 + btnEmoji.Height) + 6;
btnEmoji.Left = (btnEmoji.Width + 1) * btnCount + 6;
panel_main.Controls.Add(btnEmoji);
var emojiCopy = emoji; //don't close on the loop variable!
btnEmoji.Click += (sender,args) => OnEmojiClick(emojiCopy);
btnCount++;
if (btnCount == 4)
btnCount = 0;
}
}
protected virtual void OnEmojiClick(Emoji emoji)
{
//do something
}
我想到的最快的解決方案是,它不暗示自定義UserControl
類的定義, Button
的子類和其他類似的做法是:
btnEmoji.Click += (sender, e) =>
{
Button b = (Button)sender;
// let's suppose that the button name corresponds to the emoji name
String emojiName = b.Name;
// let's suppose that the button tag contains the emoji text
String emojiText = (String)b.Tag;
Emoji_Clicked(sender, e, (new EmojiClickEventArgs(emojiText, emojiName)));
};
private void Emoji_Clicked(Object sender, EventArgs e, EmojiClickEventArgs ee)
{
// Your code...
}
首先需要定義委托,然后創建一個實例。
class Emojis
{
// public delegate void EmojiClickEventHandler(object sender,EventArgs args);
//public event EmojiEventHandler EmojiClicked;
//you can use above two lines or replace them instead below code.
public event EventHandler<EmojiClickEventArgs> EmojiClicked;
public void CreateEmojiList()
{
CreateAllEmojis();
int btnCount = 0;
//rest of the code
panel_main.Controls.Add(btnEmoji);
btnEmoji.Click += OnEmojiClick(btnEmoji);
btnCount++;
}
protected virtual void OnEmojiClick(Button emoji)
{
//Here null check to handle if no subscribers for the event
if(EmojiClicked!=null)
{
//there is no name property define for emoji but only text hence passing only text.
EmojiClicked(this ,new EmojiClickEventArgs(emoji.Text,emoji.Text){ });
}
}
private void Emoji_Clicked(Object sender, EmojiClickEventArgs args)
{
Button mybutton = sender as Button;
Console.WriteLine("emoji text "+ args.Text);
}
}
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