在Windows窗体中创建带有圆角的自定义ComboBox [英] Create custom ComboBox with rounded corners in Windows Forms

问题描述

我想创建一个带有圆角和渐变颜色的自定义组合框.我通过覆盖OnPaint方法在Button中实现了相同的功能.但是它不适用于ComboBox.任何帮助将不胜感激.

I want to create a custom combo-box with rounded corners and gradient color. I have implemented the same feature in Button by overriding the OnPaint method. But it is not working for ComboBox. Any help will be appreciated.

我用于覆盖OnPaint的代码如下:

The code I am using for overriding OnPaint is given below:

protected override void OnPaint(PaintEventArgs paintEvent)
{
     Graphics graphics = paintEvent.Graphics;

     SolidBrush backgroundBrush = new SolidBrush(this.BackColor);
     graphics.FillRectangle(backgroundBrush, ClientRectangle);

     graphics.SmoothingMode = SmoothingMode.AntiAlias;

     Rectangle rectangle = new Rectangle(ClientRectangle.X, ClientRectangle.Y, ClientRectangle.Width - 1, ClientRectangle.Height - 1);
     GraphicsPath graphicsPath = RoundedRectangle(rectangle, cornerRadius, 0);
     Brush brush = new LinearGradientBrush(rectangle, gradientTop, gradientBottom, LinearGradientMode.Horizontal);
     graphics.FillPath(brush, graphicsPath);

     rectangle = new Rectangle(ClientRectangle.X, ClientRectangle.Y, ClientRectangle.Width - 1, ClientRectangle.Height - 100);
     graphicsPath = RoundedRectangle(rectangle, cornerRadius, 2);
     brush = new LinearGradientBrush(rectangle, gradientTop, gradientBottom, LinearGradientMode.Horizontal);
     graphics.FillPath(brush, graphicsPath);
}

private GraphicsPath RoundedRectangle(Rectangle rectangle, int cornerRadius, int margin)
{
    GraphicsPath roundedRectangle = new GraphicsPath();
    roundedRectangle.AddArc(rectangle.X + margin, rectangle.Y + margin, cornerRadius * 2, cornerRadius * 2, 180, 90);
    roundedRectangle.AddArc(rectangle.X + rectangle.Width - margin - cornerRadius * 2, rectangle.Y + margin, cornerRadius * 2, cornerRadius * 2, 270, 90);
    roundedRectangle.AddArc(rectangle.X + rectangle.Width - margin - cornerRadius * 2, rectangle.Y + rectangle.Height - margin - cornerRadius * 2, cornerRadius * 2, cornerRadius * 2, 0, 90);
    roundedRectangle.AddArc(rectangle.X + margin, rectangle.Y + rectangle.Height - margin - cornerRadius * 2, cornerRadius * 2, cornerRadius * 2, 90, 90);
    roundedRectangle.CloseFigure();
    return roundedRectangle;
}

推荐答案

我能够找到此问题的解决方案.实际上，问题在于OnPaint事件没有被Combobox调用.因此，我必须进行以下更改.

I was able to find a solution to this problem. Actually, the problem was that OnPaint event was not getting called for Combobox. So I had to do the following changes.

public CustomComboBox()
{
    InitializeComponent();
    SetStyle(ControlStyles.UserPaint, true);
}

我必须在构造函数内部调用SetStyle()方法，以便调用OnPaint()事件.

I had to call SetStyle() method inside the constructor so that OnPaint() event will get called.

我发现这篇文章很有趣:从不调用OnPaint覆盖

I found this post as helful : OnPaint override is never called

相同的解决方案可用于自定义文本框.

The same solution can be used for Custom TextBoxes.

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