[英]C# - Passing custom arguments to events
因此,我试图向事件发送自定义参数,但是它从未起作用,我尝试了许多不同的方法,但是我却从未使其起作用,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);
}
这是我想用来传递参数的类:
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; } }
}
我想从emoji.EmojiText和emoji.EmojiName中获得这两个值
一种方法是从Button
继承并创建一个名为EmojiButton
的类。 然后,您声明一个与您的事件处理程序的签名匹配的委托。 之后,使用EmojiButton
类中的委托声明一个事件,并将EmojiText
和EmojiName
之类的属性也添加到按钮子类中。 最后,您需要将按钮单击事件与自定义事件链接。 每当单击按钮时,引发事件并传递参数,即this.EmojiText, this.EmojiName
。
另一种方法是将Emoji
对象分配给Tag
属性。 然后,您可以使用普通的EventHandler
签名( object sender, EventArgs e
)编写事件处理程序,并查看sender
的Tag
是什么。 然后,您可以将Tag
投放到Emoji
并访问其属性。
您可以利用闭包为每个按钮的事件处理程序“打包”其他事件数据。 只要确保不要关闭循环变量即可。
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
}
我想到的最快的解决方案是,它不暗示自定义UserControl
类的定义, Button
的子类和其他类似的做法是:
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...
}
首先需要定义委托,然后创建一个实例。
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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