Question

我试图通过扩展System.Windows.Forms.button类在c＃中添加渐变。我遇到的问题是它在设计或运行时都没有为按钮添加渐变，尽管设计师确实选择了color1，color2和angle字段，所以它绝对是正确覆盖和实例化。我错过了什么吗？

class ps_button : System.Windows.Forms.Button
{
    private Color _Color1 = Color.FromArgb(255, 224, 138, 25);
    private Color _Color2 = Color.FromArgb(255, 245, 202, 134);
    private float _ColorAngle = 45f;

    public Color Color1
    {
        get { return _Color1; }
        set
        {
            _Color1 = value;
            this.Invalidate(); // Tell the Form to repaint itself
        }
    }

    public Color Color2
    {
        get { return _Color2; }
        set
        {
            _Color2 = value;
            this.Invalidate(); // Tell the Form to repaint itself
        }
    }

    public float ColorAngle
    {
        get { return _ColorAngle; }
        set
        {
            _ColorAngle = value;
            this.Invalidate(); // Tell the Form to repaint itself
        }

    }
    protected override void OnPaintBackground(PaintEventArgs pevent)
    {
        // Getting the graphics object
        Graphics g = pevent.Graphics;

        // Creating the rectangle for the gradient
        Rectangle rBackground = new Rectangle(0, 0,
                                  this.Width, this.Height);

        // Creating the lineargradient
        System.Drawing.Drawing2D.LinearGradientBrush bBackground
            = new System.Drawing.Drawing2D.LinearGradientBrush(rBackground,
                                              _Color1, _Color2, _ColorAngle);

        // Draw the gradient onto the form
        g.FillRectangle(bBackground, rBackground);

        // Disposing of the resources held by the brush
        bBackground.Dispose();
    }
}

Answer 1

您需要覆盖OnPaint()函数并使用GDI +绘制渐变。

以下几行：

protected override void OnPaint(PaintEventArgs pevent)
{
  base.OnPaint(pevent);

  pevent.Graphics.FillRectangle(new System.Drawing.Drawing2D.LinearGradientBrush(
    new PointF(0, this.Height / 2), new PointF(this.Width, this.Height / 2),
    Color.Red, Color.White), this.ClientRectangle);
}

这将从按钮的左边缘到右边缘绘制水平线性渐变（红色到白色）。请注意，我在上面的代码中使用了常量颜色。您应该用您的属性替换它们。同样，如果要支持渐变角度，请使用简单的数学计算渐变的起点和终点。

无法在c＃中创建按钮渐变

1 个答案: