Question

这是我到目前为止所做的。我一直在搜索代码并尝试将其应用到我的程序中。但它根本不起作用。

    public Form1()
    {
        InitializeComponent();
        this.KeyDown += new System.Windows.Forms.KeyEventHandler(this.Form1_KeyDown);
    }
    int originalX, originalY;
    int startX, startY, endX, endY;
    int pointX1, pointY1;
    int pointX2, pointY2;
    Graphics g;
    int i = 0, j = 0;
    Bitmap image;


    private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
    {
        if (e.Button == System.Windows.Forms.MouseButtons.Left)
        {
            if (i == 0)
            {
                image = (Bitmap)pictureBox1.Image;
                pictureBox1.Invalidate();
                originalX = startX = e.X;
                originalY = startY = e.Y;
                 g = Graphics.FromImage(image);
            }

        }

    }

    private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
    {
        if (e.Button == System.Windows.Forms.MouseButtons.Left)
        {
            pictureBox1.Refresh();
            g = pictureBox1.CreateGraphics();
            if (j < 10000000)
            {
                if (i != 0  )
                {
                    startX = pointX1;
                    startY = pointY1;
                }

                pointX2 = e.X;
                pointY2 = e.Y;
                g.DrawLine(Pens.Black, new Point(startX, startY), new Point(pointX2, pointY2));
                j++;
            }

        }

    }

    private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
    {
        if (e.Button == System.Windows.Forms.MouseButtons.Left)
        {
            g = Graphics.FromImage(image);
            if (i <100000000 )
            {
                if (i != 0)
                {
                    startX = pointX1;
                    startY = pointY1;
                }
                pointX1 = e.X;
                pointY1 = e.Y;
                g.DrawLine(Pens.Black, new Point(startX, startY), new Point(pointX1, pointY1));
            }

          }
            i++;
        }

    private void button2_Click(object sender, EventArgs e)
    {
        pictureBox1.Image = Image.FromFile(@"C:\Users\student03\Documents\image\Sky2.jpg");
    }

    private void pictureBox1_MouseDoubleClick(object sender, MouseEventArgs e)
    {
        if (e.Button == System.Windows.Forms.MouseButtons.Right)
        {
            g = Graphics.FromImage(image);
            g.DrawLine(Pens.Black, new Point(pointX1, pointY1), new Point(originalX, originalY));
            pictureBox1.Image = image;
            i = 0;
        }
    }
   private void Form1_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Back)
        { 
                pictureBox1.Invalidate();
        }

Answer 1

在您的表单中，在this.KeyPreview = true;电话：

下添加InitializeComponent();

public Form1()
{
    InitializeComponent();
    this.KeyPreview = true;
    this.KeyDown += new System.Windows.Forms.KeyEventHandler(this.Form1_KeyDown);
}

Form.KeyPreview是一个布尔字段/属性，表示您的Form对象能够在进入焦点Control元素之前预览该按键。

修改

为了能够删除您正在绘制的行，您必须修改代码中的所有内容。但从头开始。您应该创建一种名为Line的结构来存储有关绘图项的信息：

public struct Line { public Point StartingPoint; public Point EndingPoint; }

然后在您的Form1代码中删除这些字段：

int originalX, originalY; int startX, startY, endX, endY; int pointX1, pointY1; int pointX2, pointY2; Graphics g;

并用以下内容替换它们：

List<Line> lines; Line current;

现在您应该在构造函数中实例化lines：

public Form1() { InitializeComponent(); this.KeyPreview = true; this.KeyDown += new System.Windows.Forms.KeyEventHandler(this.Form1_KeyDown); lines = new List<Line>(); }

这样做可以引用您将要创建的行，并且您有一个对象将保持当前正在生成的行。

接下来就是你直接在图像上绘图。我建议将原始图像存储为参考，并修改图像的副本，以便在Form1中添加新字段时需要：

Image originalImage;

在button2_Click：
内
originalImage = Image.FromFile(@"C:\Users\student03\Documents\image\Sky2.jpg"); pictureBox1.Image = originalImage.Clone();

进入绘图部分。将pictureBox1_MouseDown的内容修改为：

if (e.Button == System.Windows.Forms.MouseButtons.Left) { if (i == 0) { current = new Line(); current.StartingPoint = new Point(e.X, e.Y); } }

现在您的当前行已填充了起始位置，您可以继续修改pictureBox1_MouseUp：

if (e.Button == System.Windows.Forms.MouseButtons.Left) { current.EndingPoint = new Point(e.X, e.Y); lines.Add(current) pictureBox1.Image = originalImage.Clone(); Graphics g = Graphics.FromImage(pictureBox1.Image); if (i <100000000 ) { foreach(Line l in lines) { g.DrawLine(Pens.Black, l.StartingPoint, l.EndingPoint); } } } i++;

几乎相同的逻辑适用于pictureBox1_MouseMove，但不是将current行添加到lines列表，而是必须在最后绘制它：

if (e.Button == System.Windows.Forms.MouseButtons.Left) { pictureBox1.Image = originalImage.Clone(); Graphics g = Graphics.FromImage(pictureBox1.Image); if (i <100000000 ) { foreach(Line l in lines) { g.DrawLine(Pens.Black, l.StartingPoint, l.EndingPoint); } } current.EndingPoint = new Point(e.X, e.Y); g.DrawLine(Pens.Black, current.StartingPoint, current.EndingPoint); } i++;

然后要删除该行，您只需删除行集合中的最后一项并重绘图像：

if (e.KeyCode == Keys.Back) { if ( lines.RemoveAt(lines.Count - 1) ) { pictureBox1.Image = originalImage.Clone(); Graphics g = Graphics.FromImage(pictureBox1.Image); foreach(Line l in lines) { g.DrawLine(Pens.Black, l.StartingPoint, l.EndingPoint); } } }

即使它会起作用也是非常不合理的，因为你正在绘制图像本身，而不是pictureBox1控件。我建议您使用pictureBox1.Paint事件在图像上方进行绘画。

无法使用图片框上的退格键删除我在C＃中绘制的行

1 个答案: