C# 允许用户通过 mouse/screen 次点击在 winform 上绘图

Question

我正在处理一个个人项目，我需要允许客户在新的弹出窗体上绘制一个 "signature"，这是通过处理事件（可能是单击和鼠标悬停）事件实现的。

此签名必须存储在图像对象上，以便将其保存到数据库的 varbinary(max) 字段中。

谷歌搜索无效，知道如何实现吗？

Answer 1

我检查了我的触摸屏笔记本电脑，touchdown 事件可以通过 MouseDown 事件处理，touchup 通过 MouseUp 和 touchmove 通过 MouseMove 窗体事件.

注意：我的机器同时支持触摸和鼠标。我不确定仅触摸设备或机器。

以下代码允许您通过 touch/mouse 交互在表单上绘图。

public partial class Form1 : Form
{
    Image signature;
    bool clicked = false;
    Point previousPoint;

    public Form1()
    {
        this.SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint | ControlStyles.DoubleBuffer, true);
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        this.Paint += Form1_Paint;
        this.MouseDown += Form1_MouseDown;
        this.MouseUp += Form1_MouseUp;
        this.MouseMove += Form1_MouseMove;
        this.MouseLeave += Form1_MouseLeave;

        this.FormClosing += Form1_FormClosing;
    }

    void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        //Dispose signature after closing the form to avoid memory leak
        signature.Dispose();
    }

    void Form1_Paint(object sender, PaintEventArgs e)
    {
        if (signature != null)
            e.Graphics.DrawImage(signature, 0, 0);
    }

    void Form1_MouseDown(object sender, MouseEventArgs e)
    {
        clicked = true;
        previousPoint = e.Location;
    }

    void Form1_MouseLeave(object sender, EventArgs e)
    {
        clicked = false;
    }

    void Form1_MouseUp(object sender, MouseEventArgs e)
    {
        clicked = false;
    }

    void Form1_MouseMove(object sender, MouseEventArgs e)
    {
        if (clicked)
        {
            if (signature == null)
                signature = new Bitmap(this.Width, this.Height);
            using (Graphics g = Graphics.FromImage(signature))
            {
                g.DrawLine(Pens.Black, previousPoint, e.Location);
                previousPoint = e.Location;
                this.Invalidate();
            }
        }
    }
}

签名绘制在图像上。所以您可以根据需要将图像保存在您的数据库中。

C# 允许用户通过 mouse/screen 次点击在 winform 上绘图

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