.net - Winforms - 单击/拖动表单中的任意位置以移动它，就像在表单标题中单击一样

Question

我正在创建一个用于 Winforms 应用程序的小型模态表单。它基本上是一个进度条。但我希望用户能够单击表单中的任意位置并拖动它以在桌面上移动它，同时它仍在显示。

我该如何实现这种行为？

Answer 1

Microsoft 知识库文章 320687对此问题有详细解答。

基本上，当被测试的点位于表单的客户区域时，您重写 WndProc 方法以将 HTCAPTION 返回到 WM_NCHITTEST 消息——实际上，这告诉 Windows 将点击视为发生在表格的标题。

private const int WM_NCHITTEST = 0x84;
private const int HTCLIENT     = 0x1;
private const int HTCAPTION    = 0x2;

protected override void WndProc(ref Message m)
{
    switch(m.Msg)
    {
        case WM_NCHITTEST:
        base.WndProc(ref m);

        if ((int)m.Result == HTCLIENT)
            m.Result = (IntPtr)HTCAPTION;
        return;
    }

    base.WndProc(ref m);
}

Answer 2

这是一种使用 P/Invoke 的方法。

public const int WM_NCLBUTTONDOWN = 0xA1;
public const int HTCAPTION = 0x2;
[DllImport("User32.dll")]
public static extern bool ReleaseCapture();
[DllImport("User32.dll")]
public static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);

void Form_Load(object sender, EventArgs e)
{
   this.MouseDown += new MouseEventHandler(Form_MouseDown);  
}

void Form_MouseDown(object sender, MouseEventArgs e)
{                        
    if (e.Button == MouseButtons.Left)
    {
        ReleaseCapture();
        SendMessage(Handle, WM_NCLBUTTONDOWN, HTCAPTION, 0);
    }
}

Answer 3

下面的代码假定 ProgressBarForm 表单有一个 ProgressBar 控件，其Dock属性设置为Fill

public partial class ProgressBarForm : Form
{
    private bool mouseDown;
    private Point lastPos;

    public ProgressBarForm()
    {
        InitializeComponent();
    }

    private void progressBar1_MouseMove(object sender, MouseEventArgs e)
    {
        if (mouseDown)
        {
            int xoffset = MousePosition.X - lastPos.X;
            int yoffset = MousePosition.Y - lastPos.Y;
            Left += xoffset;
            Top += yoffset;
            lastPos = MousePosition;
        }
    }

    private void progressBar1_MouseDown(object sender, MouseEventArgs e)
    {
        mouseDown = true;
        lastPos = MousePosition;
    }

    private void progressBar1_MouseUp(object sender, MouseEventArgs e)
    {
        mouseDown = false;
    }
}

Answer 4

公认的答案是一个很酷的技巧，但如果 Form 被诸如 Panel（或派生类）之类的 Fill-docking 子控件覆盖，它并不总是有效，因为此控件将吃掉所有大多数 Windows 消息。

这是一种在这种情况下也适用的简单方法：派生有问题的控件（使用此类而不是标准类）处理鼠标消息，如下所示：

    private class MyTableLayoutPanel : Panel // or TableLayoutPanel, etc.
    {
        private Point _mouseDown;
        private Point _formLocation;
        private bool _capture;

        // NOTE: we cannot use the WM_NCHITTEST / HTCAPTION trick because the table is in control, not the owning form...
        protected override void OnMouseDown(MouseEventArgs e)
        {
            _capture = true;
            _mouseDown = e.Location;
            _formLocation = ((Form)TopLevelControl).Location;
        }

        protected override void OnMouseUp(MouseEventArgs e)
        {
            _capture = false;
        }

        protected override void OnMouseMove(MouseEventArgs e)
        {
            if (_capture)
            {
                int dx = e.Location.X - _mouseDown.X;
                int dy = e.Location.Y - _mouseDown.Y;
                Point newLocation = new Point(_formLocation.X + dx, _formLocation.Y + dy);
                ((Form)TopLevelControl).Location = newLocation;
                _formLocation = newLocation;
            }
        }
    }

Answer 5

VC++ 2010 版本（FlySwat 的）：

#include <Windows.h>

namespace DragWithoutTitleBar {

    using namespace System;
    using namespace System::Windows::Forms;
    using namespace System::ComponentModel;
    using namespace System::Collections;
    using namespace System::Data;
    using namespace System::Drawing;

    public ref class Form1 : public System::Windows::Forms::Form
    {
    public:
        Form1(void) { InitializeComponent(); }

    protected:
        ~Form1() { if (components) { delete components; } }

    private:
        System::ComponentModel::Container ^components;
        HWND hWnd;

#pragma region Windows Form Designer generated code
        void InitializeComponent(void)
        {
            this->SuspendLayout();
            this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
            this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
            this->ClientSize = System::Drawing::Size(640, 480);
            this->FormBorderStyle = System::Windows::Forms::FormBorderStyle::None;
            this->Name = L"Form1";
            this->Text = L"Form1";
            this->Load += gcnew EventHandler(this, &Form1::Form1_Load);
            this->MouseDown += gcnew System::Windows::Forms::MouseEventHandler(this, &Form1::Form1_MouseDown);
            this->ResumeLayout(false);

        }
#pragma endregion
    private: System::Void Form1_Load(Object^ sender, EventArgs^  e) {
                    hWnd = static_cast<HWND>(Handle.ToPointer());
                }

    private: System::Void Form1_MouseDown(Object^ sender, System::Windows::Forms::MouseEventArgs^ e) {
                    if (e->Button == System::Windows::Forms::MouseButtons::Left) {
                        ::ReleaseCapture();
                        ::SendMessage(hWnd, /*WM_NCLBUTTONDOWN*/ 0xA1, /*HT_CAPTION*/ 0x2, 0);
                    }
                }

    };
}