如何在 C# 中使用带有 sender 和 e 参数的方法？ [复制]

Question

所以我有这段代码，我想在resize_Handler void 中调用set_background void。我该怎么做？我在resize_Handler 中尝试了set_background(null, PaintEventArgs());，但它显示的是non-invocable member cannot be used like a method。

我的代码：

private void set_background(Object sender, PaintEventArgs e) {
    Graphics graphics = e.Graphics;

    Rectangle gradient_rectangle = new Rectangle(0, 0, Width, Height);

    Brush b = new LinearGradientBrush(gradient_rectangle, Color.FromArgb(255, 255, 255), Color.FromArgb(255, 102, 54), 0f);
 
    graphics.FillRectangle(b, gradient_rectangle);
}

private void resize_Handler(object sender, System.EventArgs e) {
    // where I want to call set_background()
}

Answer 1

不要尝试直接调用事件处理程序，而是将事件处理程序中的代码重构为自己的方法，然后调用新方法。

private void SetBackground(Graphics graphics)
{        
    Rectangle gradient_rectangle = new Rectangle(0, 0, Width, Height);

    Brush b = new LinearGradientBrush(gradient_rectangle, Color.FromArgb(255, 255, 255), Color.FromArgb(255, 102, 54), 0f);
 
    graphics.FillRectangle(b, gradient_rectangle);
}

private void set_background(Object sender, PaintEventArgs e) {
   SetBackground(e.Graphics);
}

private void resize_Handler(object sender, System.EventArgs e) {
   Graphics graphics = new Graphics(); // or whatever applies here.
   SetBackground(graphics);
}