重写Button控件实现渐变背景 - (第十一讲)

视频讲解如下：

网盘下载，提取码：pt2b

https://pan.baidu.com/s/1C2ri-X89szdMtxfgc-feGg

这里给大家讲解一下如何重写Button控件实现渐变背景

重写Button控件后的效果如下：

using System;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Collections.Generic;

namespace WindowsFormsApp
{
    /// <summary>
    /// 椭圆形按钮
    /// </summary>
    public partial class MyButton : Button
    {
        enum MODE { leave, enter, down, up }
        MODE pModel = MODE.leave;

        /// <summary>
        /// 倒圆角值
        /// </summary>
        public int Radius { get; set; }

        /// <summary>
        /// 默认颜色
        /// </summary>
        public Color DefaultShowColor { get; set; }

        /// <summary>
        /// 点击后的颜色
        /// </summary>
        public Color DefaultDownColor { get; set; }

        public MyButton()
        {
            //这些得带上，不然会有黑边
            FlatStyle = FlatStyle.Flat;
            FlatAppearance.BorderSize = 0;
            FlatAppearance.BorderColor = Color.FromArgb(0, 0, 0, 0);
            FlatAppearance.MouseDownBackColor = Color.Transparent;
            FlatAppearance.MouseOverBackColor = Color.Transparent;

            // 设置默认值
            Radius = 10;
            DefaultShowColor = Color.FromArgb(48, 176, 253);
            DefaultDownColor = Color.FromArgb(255, 165, 53);
        }
        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);
            List<Color> cols = new List<Color>() { Color.White, DefaultShowColor, DefaultDownColor };
            Color begin = cols[0];
            Color end = cols[1];
            if (pModel == MODE.down) { begin = cols[2]; end = cols[0]; }  // 点击后的颜色
            if (pModel == MODE.up) { begin = cols[0]; end = cols[2]; }    // 弹起后的颜色
            if (pModel == MODE.enter) { begin = cols[0]; end = cols[2]; } // 鼠标移动时的颜色
            Draw(e.ClipRectangle, e.Graphics, false, begin, end); // 设置颜色
            RectangleF rect = DrawText(e.ClipRectangle, e.Graphics, this.ForeColor);   // 重新绘制文字
            // 重新绘制图片
            if (this.Image != null)
            {
                int X = (int)(rect.Location.X - this.Image.Width);
                int Y = (int)(rect.Location.Y);
                Point p = new Point(X, Y);
                Size s = new Size(this.Image.Width, this.Image.Height);
                e.Graphics.DrawImage(this.Image, new Rectangle(p, s), 0, 0, this.Image.Width, this.Image.Height, GraphicsUnit.Pixel);
            }
        }
        // 按下
        protected override void OnMouseDown(MouseEventArgs mevent)
        {
            pModel = MODE.down;
            base.OnMouseDown(mevent);
        }
        // 弹起
        protected override void OnMouseUp(MouseEventArgs mevent)
        {
            pModel = MODE.up;
            base.OnMouseUp(mevent);
        }
        // 移动进入
        protected override void OnMouseEnter(EventArgs e)
        {
            pModel = MODE.enter;
            base.OnMouseEnter(e);
        }
        // 移动离开
        protected override void OnMouseLeave(EventArgs e)
        {
            pModel = MODE.leave;
            base.OnMouseLeave(e);
        }
        // 绘图
        void Draw(Rectangle rectangle, Graphics g, bool cusp, Color begin_color, Color? end_colorex = null)
        {
            Color end_color = end_colorex == null ? begin_color : (Color)end_colorex;
            int span = 2;
            //抗锯齿
            g.SmoothingMode = SmoothingMode.AntiAlias;
            //渐变填充
            LinearGradientBrush myLinearGradientBrush = new LinearGradientBrush(rectangle, begin_color, end_color, LinearGradientMode.Vertical);
            //画尖角
            if (cusp)
            {
                span = 10;
                PointF p1 = new PointF(rectangle.Width - 12, rectangle.Y + 10);
                PointF p2 = new PointF(rectangle.Width - 12, rectangle.Y + 30);
                PointF p3 = new PointF(rectangle.Width, rectangle.Y + 20);
                PointF[] ptsArray = { p1, p2, p3 };
                g.FillPolygon(myLinearGradientBrush, ptsArray);
            }
            // 填充圆角18
            g.FillPath(myLinearGradientBrush, DrawRoundRect(rectangle.X, rectangle.Y, rectangle.Width - span, rectangle.Height - 1, Radius));
        }
        // 绘制文字
        RectangleF DrawText(Rectangle rectangle, Graphics g, Color color)
        {
            Rectangle NewRec = new Rectangle(rectangle.X, rectangle.Y + 1, rectangle.Width, rectangle.Height);
            SolidBrush sbr = new SolidBrush(color);
            RectangleF rect = new RectangleF();
            switch (TextAlign)
            {
                case ContentAlignment.MiddleCenter:
                    rect = getTextRec(NewRec, g);
                    break;
                default:
                    rect = getTextRec(NewRec, g);
                    break;
            }
            g.DrawString(Text, Font, sbr, rect);
            return rect;
        }
        RectangleF getTextRec(Rectangle rectangle, Graphics g)
        {
            var rect = new RectangleF();
            var size = g.MeasureString(Text, Font);
            if (size.Width > rectangle.Width || size.Height > rectangle.Height)
            {
                rect = rectangle;
            }
            else
            {
                rect.Size = size;
                int X = rectangle.X;
                if (this.Image != null) X += this.Image.Width;
                rect.Location = new PointF(X + (rectangle.Width - size.Width) / 2, rectangle.Y + (rectangle.Height - size.Height) / 2);
            }
            return rect;
        }
        // 四边圆角
        GraphicsPath DrawRoundRect(int x, int y, int width, int height, int radius)
        {
            GraphicsPath gp = new GraphicsPath();
            gp.AddArc(x, y, radius, radius, 180, 90);
            gp.AddArc(width - radius, y, radius, radius, 270, 90);
            gp.AddArc(width - radius, height - radius, radius, radius, 0, 90);
            gp.AddArc(x, height - radius, radius, radius, 90, 90);
            gp.CloseAllFigures();
            return gp;
        }
    }
}