Question

我正在制作一个自定义颜色选择器，我有一个hsv色轮作为图片框中的图像。我正试图这样做，而我的鼠标按住它就在圆圈内。我累了Cursor.Clip但它只使用矩形。

enter image description here

在这张照片中，我在车轮周围画了一个薄的黑色椭圆。

        Size mySize = new Size(348, 348);
        Point myloc = new Point(26, 26);
        Rectangle rec = new Rectangle();
        rec.Size = mySize;
        rec.Location = myloc;


        Graphics.FromImage(pictureBox1.Image).DrawEllipse(Pens.Black, rec);
        this.pictureBox1.Refresh();

Answer 1

示例解决方案，不是最好的，但有效。当然，MouseMove事件不适合您的目的，您应该将WinAPI附加到全局鼠标移动处理，但这是另一项任务。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WinForm
{
    public partial class frmMain : Form
    {
        private Point centerPoint;              // circle center point
        private double radius;                  // circle radius (R)
        private double radius2;                 // R^2

        /// <summary>
        /// form constructor
        /// </summary>
        public frmMain()
        {
            InitializeComponent();

            this.Size = new Size(640, 480);
            this.Load += delegate
            {
                PictureBox pb = new PictureBox();

                int size = Math.Min(this.ClientSize.Width, this.ClientSize.Height) - 20;

                pb.Location = new Point((this.ClientSize.Width - size) / 2, (this.ClientSize.Height - size) / 2);
                pb.Size = new Size(size, size);
                pb.Paint += (s, e) =>
                {
                    var g = e.Graphics;
                    var rect = new Rectangle(Point.Empty, pb.Size);

                    g.FillEllipse(Brushes.ForestGreen, rect);
                    g.DrawEllipse(Pens.Navy, rect);

                    // base cursor clip
                    this.Cursor = new Cursor(Cursor.Current.Handle);
                    Cursor.Position = new Point(Cursor.Position.X - 50, Cursor.Position.Y - 50);
                    Cursor.Clip = pb.RectangleToScreen(rect);
                };

                this.Controls.Add(pb);

                // setup circle parameters
                centerPoint = new Point(pb.Left + pb.Width / 2, pb.Top + pb.Height / 2);
                radius = (double)size * 0.5;
                radius2 = radius * radius;


                // bind to events
                pb.MouseMove += Mouse_Move;
                this.MouseMove += Mouse_Move;
            };
        }

        private void Mouse_Move(object sender, MouseEventArgs e)
        {
            // client mouse point
            var point = this.PointToClient(((Control)sender).PointToScreen(e.Location));

            // circle center point
            double cx = centerPoint.X;
            double cy = centerPoint.Y;

            // circle center offset
            double sx = point.X - cx;
            double sy = point.Y - cy;

            // direction angle
            double alpha = Math.Atan2(-sy, sx);
            this.Text = string.Format("{0} {1} {2:0.00} rad, {3:0} degrees", sx, sy, alpha, 180.0 * alpha / Math.PI);

            // range to center
            double range = sx * sx + sy * sy;
            if (range > radius2)
            {
                int px = (int)Math.Round(cx + Math.Cos(alpha) * radius);
                int py = (int)Math.Round(cy - Math.Sin(alpha) * radius);
                Cursor.Position = this.PointToScreen(new Point(px, py));
            }
        }
    }
}

将鼠标光标锁定在图片框中的椭圆内

1 个答案: