绘制已绘制的多边形

Question

我正在尝试制作一个卷用户控件（仅 UI）。我一切正常，除了当条形图低于 picturebox.Width 的 50%（即 100）时，我希望三角形颜色发生变化，例如从红色变为绿色。 mouseMove 事件中注释的三行是我想要完成的，但这行不通。提前谢谢你。

这是我的控件示例：

到目前为止我的代码：

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

namespace ControlAudio
{
    public partial class volumen: UserControl
    {
        Bitmap im_soundOn = Properties.Resources.sound_on;
        Bitmap im_soundOff = Properties.Resources.sound_off;
        int coordenadaX;
        bool barClicked = false;
        bool muted = false;

        public volumen()
        {
            InitializeComponent();

        }
        //Dibujar triangulo
        private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            var g = e.Graphics;
            var points = new PointF[] { new PointF(0, 0), new PointF(1, 0), new PointF(0, 1) };

            var mx = g.Transform.Clone();

            g.TranslateTransform(100f, 100f);
            g.ScaleTransform(-135f, -70f);
            g.FillPolygon(Brushes.Olive, points);
            g.Transform = mx;
        }

        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            barClicked = true;
        }

        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            barClicked = false;
        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            MouseEventArgs me = (MouseEventArgs)e;
            Point coordenadasNuevas = me.Location;
            coordenadaX = coordenadasNuevas.X;

            if(barClicked && pictureBox1.Width <= 100)
            {
                if (coordenadaX > 100)
                {
                    coordenadaX = 100;
                }
                pictureBox1.Width = coordenadaX;
            }

            //When it reaches 0
            if (pictureBox1.Width == 0) {
                pictureBox1.Width = 0;
                muted = true;
                pb_imagen.Image = im_soundOff;
            }
            else //When it goes over 0
            {
                muted = false;
                pb_imagen.Image = im_soundOn;
            }

            //if(pictureBox1.Width <= 50) g.FillPolygon(Brushes.Olive, points);
            //if(pictureBox1.Width >50 && pictureBox1.Width <= 90) g.FillPolygon(Brushes.Yellow, points);
            //if (pictureBox1.Width > 90) g.FillPolygon(Brushes.Red, points);

        }    
    }
}

Answer 1

为了解决这个问题，感谢@LarsTech，我做了以下事情：

创建了默认颜色的画笔：Brush brush = Brushes.Red;
在pictureBox1_Paint事件中我把之前的g.FillPolygon(Brushes.Olive, points);改成了g.FillPolygon(brush, points);

在MouseMove事件中，我添加了以下内容：

if (pictureBox1.Width <= 50)
{
    brush = Brushes.LightGreen;
    pictureBox1.Invalidate();
}
else if (pictureBox1.Width > 50 && pictureBox1.Width <= 90)
{
    brush = Brushes.Yellow;
    pictureBox1.Invalidate();
}
else
{
    brush = Brushes.Red;
    pictureBox1.Invalidate();
}

绘制已绘制的多边形

Paint polygon already drawn

c#

user-controls

winforms