c#在picturebox画点

在C#中，在PictureBox上画点有多种方法。
第一种方法是利用GDI，首先需要在窗体上插入PictureBox控件和一个Button按钮。当点击按钮后，鼠标进入PictureBox控件中，每左击一次画一个点。具体代码如下：

private string sType; // 用来记录button的Name

private void btnDrawPoint_Click(object sender, EventArgs e)
{
    sType = "btnDrawPoint"; // 获取button的Name
}

private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
    Graphics g = pictureBox1.CreateGraphics(); // 创建一个画板

    if (sType == "btnDrawPoint")
    {
        if (e.Button == MouseButtons.Left)
        {
            g.FillEllipse(Brushes.Red, e.X, e.Y, 4, 4); // 画一个半径为4的圆点
        }
    }
}

第二种方法是调用gdi32.dll库中的SetPixel方法。具体代码如下：

[DllImport("gdi32.dll")]
private static extern int SetPixel(IntPtr hdc, int x1, int y1, int color);

private string sType; // 用来记录button的Name

private void btnDrawPoint_Click(object sender, EventArgs e)
{
    sType = "btnDrawPoint"; // 获取button的Name
}

private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
    Graphics g = pictureBox1.CreateGraphics(); // 创建一个画板
    PointF p = new PointF(e.X, e.Y); // 实例化一个点，这个点的坐标就是鼠标的x,y

    if (sType == "btnDrawPoint")
    {
        if (e.Button == MouseButtons.Left)
        {
            DrawPoint(g, p); // 调用画点的方法，把相应参数传入
        }
    }
}

public void DrawPoint(Graphics g, PointF p)
{
    IntPtr hdc = g.GetHdc();
    int color = 255; // 这里定义了一个整型的颜色变量，255为红色
    SetPixel(hdc, (int)p.X, (int)p.Y, color);
    g.ReleaseHdc();
}

以上是两种常用的方法，在PictureBox控件上实现鼠标每左击一次就会画一个点的效果。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
#### 引用[.reference_title]
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