c# - 为什么在 Visual C# 中将像素写入图片框时遇到问题？

Question

我正在编写一个模拟器程序，虚拟显示器应该能够接收 3 个字节的颜色数据并显示正确的颜色像素，类似于真实屏幕的工作方式。但是当我设置一些滚动条来测试像素的生成时，什么也没有发生。这是我的代码和表单的屏幕截图:

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 TSC_Multi_System_Emulator
{

    public partial class Form1 : Form
    {
        private PictureBox Display = new PictureBox();
        string @emulationfolderpath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
        Bitmap screen = new Bitmap(@Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + @"\Resource_Folder\" + @"FirstFrame.bmp");
        int x = 0;
        int y = 0;

        public Form1()
        {
            InitializeComponent();

        }
        private void Form1_Load(object sender, System.EventArgs e) {
            // Dock the PictureBox to the form and set its background to black.
            Display.BackColor = Color.Black;
            // Connect the Paint event of the PictureBox to the event handler method.

            // Add the PictureBox control to the Form. 
            this.Controls.Add(Display);


        }
        public void DigitalGraphicsDisplay(int red, int green, int blue) {
            Graphics g = Display.CreateGraphics(); 
            screen.SetPixel(x, y, Color.FromArgb(red, green, blue));
            g.DrawImage(screen, 0, 0, screen.Width, screen.Height);
            g.Save();
            if (x < screen.Width)
            {
                x = x + 1;
            }
            else if (x == screen.Width)
            {
                x = 0;
                if (y < screen.Height)
                {
                    y = y + 1;
                }
                else if (y == screen.Height)
                {
                    y = 0;
                }
            }
        }



        private void button1_Click(object sender, EventArgs e){
            int rchannel = redControl.Value;
            int gchannel = greenControl.Value;
            int bchannel = blueControl.Value;             
            DigitalGraphicsDisplay(rchannel, gchannel, bchannel);
        }




    }
}

更新:

代码现在可以正常工作，但我无法仅使用测试按钮来测试代码。我必须使用第一个答案中给我的确切代码，它只显示渐变，我想知道我做错了什么......:(

public partial class Form1 : Form
{

    string @emulationfolderpath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
    Bitmap screen = new Bitmap(@Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + @"\Resource_Folder\" + @"FirstFrame.bmp");
    int x = 0;
    int y = 0;

    public Form1()
    {
        InitializeComponent();

    }
    private void Form1_Load(object sender, System.EventArgs e) {
        // Dock the PictureBox to the form and set its background to black.
        Display.BackColor = Color.Black;
        // Connect the Paint event of the PictureBox to the event handler method.

        // Add the PictureBox control to the Form. 
        this.Controls.Add(Display);


    }

    public void DigitalGraphicsDisplay(int red, int green, int blue)
    {
        if (Display.Image == null)
        {
            Bitmap NewBMP = new Bitmap(Display.ClientRectangle.Width, Display.ClientRectangle.Height);
            using (Graphics g = Graphics.FromImage(NewBMP))
            {
                g.Clear(Color.White);
            }
            Display.Image = NewBMP;
        }

        (Display.Image as Bitmap).SetPixel(x, y, Color.FromArgb(red, green, blue));

        Display.Invalidate();

        x++;

        if (x >= Display.Image.Width)
        {
            x = 0;
            y++;

            if (y >= Display.Image.Height)
            {
                y = 0;
            }
        }
    }


    private void button1_Click(object sender, EventArgs e){
        Boolean a = false;
        int b = 0;
        do
        {
            DigitalGraphicsDisplay(51, 153, 102);
            if (b == 10000)
            {
                a = true;
            }
            b = b + 1;
        } while (a);

    }





}

}

我得到的只是一个白色的图片盒，里面没有其他东西......(渐变代码确实有效)

Answer 1

看起来您正在尝试直接在 PictureBox 控件本身上绘图。

相反，您应该将图像分配给 PictureBox，然后在该图像上绘图。

尝试更改您的代码，如下所示。 (包括测试用的点击事件。)
请注意，PictureBox 直接保留对图像的引用，因此您不需要在类中使用单独的屏幕图像，除非您有不同的目的。

此外，这还使用了Bitmap.SetPixel()，这是一种非常慢的设置像素的方法。在这些其他链接中，有一种更快但稍微复杂的方法:

• SetPixel is too slow. Is there a faster way to draw to bitmap?
• Work with bitmaps faster in C#

请记住，单击按钮一次只会绘制一个像素。
所以一定要仔细看:

在点击事件中运行我的测试代码将产生以下结果:

int x = 0;
int y = 0;
public void DigitalGraphicsDisplay(int red, int green, int blue)
{
    if (Display.Image == null)
    {
        Bitmap NewBMP = new Bitmap(Display.ClientRectangle.Width, Display.ClientRectangle.Height);
        using (Graphics g = Graphics.FromImage(NewBMP))
        {
            g.Clear(Color.White);
        }
        Display.Image = NewBMP;
    }

    (Display.Image as Bitmap).SetPixel(x, y, Color.FromArgb(red, green, blue));

    Display.Invalidate();

    x++;

    if (x >= Display.Image.Width)
    {
        x = 0;
        y++;

        if (y >= Display.Image.Height)
        {
            y = 0;
        }
    }
}

private void button1_Click(object sender, EventArgs e)
{
    // Temporary code to show that it works (Due to Bitmap.SetPixel() it will be slow)
    for (int I = 1; I < Display.ClientRectangle.Width * Display.ClientRectangle.Height; I++)
        DigitalGraphicsDisplay((I/255)%255, (I % Display.ClientRectangle.Width) % 255, 127);
}

---

更新:根据您的评论，请尝试以下示例代码:

private void button1_Click(object sender, EventArgs e)
{ 
    Boolean a = true; 
    int b = 0; 
    do
    { 
        DigitalGraphicsDisplay(51, 153, 102); 

        if (b == 10000) 
        {
            a = false;
        } 

        b = b + 1; 
    } while (a); 
}