C#在面板中绘制并左移绘制的对象

Question

我正在从左侧开始在面板中绘制矩形。

当我到达面板的右侧时，我想将之前绘制的矩形向左移动，以便有空间绘制另一个矩形，依此类推。

哪种方法最简单？

我正在使用 System.Drawings.Graphics 绘图。

我正在使用 Winforms。代码是：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace FFViewer
{
    public partial class Form1 : Form
    {
        [DllImport("shlwapi.dll")]
        public static extern int ColorHLSToRGB(int H, int L, int S);

        int x=0;
        int y=300;
        int h = 0;


        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            panel_Paint();

            x = x + 40;
            h = h + 40;

            if (h >= 240)
                h = 0;
        }

        private void panel_Paint()
        {
            int val;
            Color color;

            val = ColorHLSToRGB(h, 128, 240);

            Graphics g = panel1.CreateGraphics();

            color = ColorTranslator.FromWin32(val);

            SolidBrush sb = new SolidBrush( color );

            g.FillRectangle(sb, x, y, 40, 100);

        }
    }

}

所以，当我在右侧绘制最新的矩形时，我想将所有矩形向左移动以留出空间在右侧绘制另一个。

附：我没有足够的声誉来发布图片:(

Answer 1

这是“老派”的做法。这基本上是当需要显示实时值的连续图并且您不想在任何地方存储任何值时所做的。这有严重的限制，因为它从屏幕复制，并且当窗口重新绘制自身时，绘图将被删除。第一个示例仅用于演示该过程，并且是您创建初始块的方式的扩展：

public partial class Form1 : Form
{

    public Form1()
    {
        InitializeComponent();
    }

    [DllImport("shlwapi.dll")]
    public static extern int ColorHLSToRGB(int H, int L, int S);

    int x = 0;
    int width = 40;
    int y = 300;
    int height = 100;
    int h = 0;

    private void button1_Click(object sender, EventArgs e)
    {
        if (x + width > panel1.ClientSize.Width) // if drawing the next block would exceed the panel width...
        {
            // capture what's currently on the screen
            Bitmap bmp = new Bitmap(x, height);
            using (Graphics g = Graphics.FromImage(bmp))
            {
                g.CopyFromScreen(panel1.PointToScreen(new Point(0, y)), new Point(0, 0), bmp.Size);
            }
            // draw it shifted to the left
            using (Graphics g = panel1.CreateGraphics())
            {
                g.DrawImage(bmp, new Point(-width, y));
            }
            // move x back so the new rectangle will draw where the last one was previously
            x = x - width;                
        }

        // draw the new block and increment values
        panel_Paint();
        x = x + width;
        h = h + width;
        if (h >= 240)
        { 
            h = 0;
        }
    }

    private void panel_Paint()
    {
        int val;
        Color color;
        val = ColorHLSToRGB(h, 128, 240);
        color = ColorTranslator.FromWin32(val);

        using (Graphics g = panel1.CreateGraphics())
        {
            using (SolidBrush sb = new SolidBrush(color))
            {
                g.FillRectangle(sb, x, y, width, height);
            }
        }
    }

}

这可以通过创建正确大小的位图并绘制到该位图来解决。然后你移动所有东西并在右侧绘制新块。最后，您将在 Paint() 事件中绘制该位图。所以这和上面做的一样，除了我们不是从屏幕复制，面板会在请求时正确地重绘自己：

public partial class Form1 : Form
{

    [DllImport("shlwapi.dll")]
    public static extern int ColorHLSToRGB(int H, int L, int S);

    int x = 0;
    int width = 40;
    int y = 300;
    int height = 100;
    int h = 0;

    Bitmap bmp;

    public Form1()
    {
        InitializeComponent();
        this.Load += Form1_Load;
        panel1.Paint += Panel1_Paint;
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        int numBlocks = (int)(panel1.Width / width);
        bmp = new Bitmap(numBlocks * width, height);
        using (Graphics g = Graphics.FromImage(bmp))
        {
            g.Clear(panel1.BackColor);
        }
    }

    private void Panel1_Paint(object sender, PaintEventArgs e)
    {
        if (bmp != null)
        {
            e.Graphics.DrawImage(bmp, new Point(0, y));
        }
    }

    private void button1_Click(object sender, EventArgs e)
    {
        using (Graphics g = Graphics.FromImage(bmp))
        {
            if (x + width > bmp.Width) // if drawing the next block would exceed the bmp width...
            {                
                g.DrawImage(bmp, new Point(-width, 0)); // draw ourself shifted to the left   
                x = x - width;
            }

            // draw the new block 
            int val;
            Color color;
            val = ColorHLSToRGB(h, 128, 240);
            color = ColorTranslator.FromWin32(val);
            using (SolidBrush sb = new SolidBrush(color))
            {
                g.FillRectangle(sb, x, 0, width, height);
            }
        }

        x = x + width;
        h = h + width;
        if (h >= 240)
        { 
            h = 0;
        }

        panel1.Invalidate(); // force panel1 to redraw itself
    }

}

Answer 2

您不应使用panel1.CreateGraphics()，而应处理面板的Paint 事件，否则矩形可能会消失，例如在您的表单前面出现一个弹出窗口后：

panel1.Paint += new PaintEventHandler(panel1_paint);

您需要在绘制处理程序中绘制所有（可见）矩形；您可以在表单中保留 List<Rectangle> 来存储您添加的矩形：

private List<Rectangle> rectangles = new List<Rectangle>();
...
private void button1_Click(object sender, EventArgs e)
{
    rectangles.Add(new Rectangle(x, y, width, height));
    panel1.Invalidate(); // cause the paint event to be called
    // todo increment x/y
}

然后，在panel1_Paint 处理程序中，您可以在调用Graphics.TranslateTransform() 移动整个绘图区域之后简单地绘制矩形：

private void panel1_Paint(object sender, PaintEventArgs e)
{
    e.Graphics.TranslateTransform(-x, 0);
    foreach (Rectangle rectangle in rectangles)
    {
        // paint em
    }

    e.Graphics.ResetTransform();
}