C# 打造 QQ/MSN 風格任務列通知視窗：皮膚、動畫、無焦點顯示

功能特色

• 不規則視窗造型（透過 Region + 位圖透明色）
• 皮膚機制：任意位圖作為視窗背景
• 從螢幕右下角滑入/滑出動畫（雙重緩衝繪圖無閃爍）
• 顯示期間不搶奪主視窗焦點 (SW_SHOWNOACTIVATE)
• 支援標題列拖曳移動（無標題列視窗模擬拖曳）
• 自動停留計時並淡出關閉
• 關閉按鈕、內容區域點擊可觸發自訂動作（如開啟網頁）

核心技術點

1. 不規則視窗與皮膚

public void SetBackgroundBitmap(Image image, Color transparentColor)
{
    BackgroundBitmap = new Bitmap(image);
    this.Width = BackgroundBitmap.Width;
    this.Height = BackgroundBitmap.Height;
    this.Region = BitmapToRegion(BackgroundBitmap, transparentColor);
    this.FormBorderStyle = FormBorderStyle.None; // 移除標題列與邊框
}

public Region BitmapToRegion(Bitmap bmp, Color transparentColor)
{
    var path = new GraphicsPath();
    for (int y = 0; y < bmp.Height; y++)
    {
        for (int x = 0; x < bmp.Width; x++)
        {
            if (bmp.GetPixel(x, y) == transparentColor) continue;
            int x0 = x;
            while (x < bmp.Width && bmp.GetPixel(x, y) != transparentColor) x++;
            path.AddRectangle(new Rectangle(x0, y, x - x0, 1));
        }
    }
    var region = new Region(path);
    path.Dispose();
    return region;
}

2. 雙重緩衝繪圖 (OnPaintBackground 覆寫)

protected override void OnPaintBackground(PaintEventArgs e)
{
    Graphics g = e.Graphics;
    g.PageUnit = GraphicsUnit.Pixel;

    // 記憶體離屏繪圖
    using (Bitmap offscreen = new Bitmap(BackgroundBitmap.Width, BackgroundBitmap.Height))
    using (Graphics offG = Graphics.FromImage(offscreen))
    {
        if (BackgroundBitmap != null)
            offG.DrawImage(BackgroundBitmap, 0, 0);

        DrawText(offG); // 繪製標題與內容文字

        g.DrawImage(offscreen, 0, 0); // 一次性貼上螢幕
    }
}

void DrawText(Graphics g)
{
    g.DrawString(TitleText, TitleFont, TitleBrush, TitleRect);
    g.DrawString(ContentText, ContentFont, ContentBrush, ContentRect);
}

3. 無焦點顯示視窗 (P/Invoke ShowWindow)

[DllImport("user32.dll")]
private static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);

private const int SW_SHOWNOACTIVATE = 4;

public void ShowForm(string title, string content, ...)
{
    // 計算初始位置 (螢幕右下角外)
    WorkArea = Screen.GetWorkingArea(WorkArea);
    this.Top = WorkArea.Height + this.Height;
    this.Left = WorkArea.Width - this.Width;

    // 設定各區域矩形 (標題、內容、關閉鈕、拖曳區)
    // ...

    CurrentState = State.SlidingIn;
    timer1.Enabled = true;
    ShowWindow(this.Handle, SW_SHOWNOACTIVATE); // 關鍵：不搶焦點
}

4. 滑入/滑出動畫 (Timer 控制)

void timer1_Tick(object sender, EventArgs e)
{
    switch (CurrentState)
    {
        case State.SlidingIn:
            this.Top -= SlideSpeed;
            if (this.Top <= WorkArea.Height - this.Height)
            {
                this.Top = WorkArea.Height - this.Height;
                CurrentState = State.Staying;
                stayTimer.Enabled = true;
            }
            break;

        case State.SlidingOut:
            this.Top += SlideSpeed;
            if (this.Top >= WorkArea.Height + this.Height)
            {
                this.Hide();
                CurrentState = State.Hidden;
            }
            break;
    }
    this.SetBounds(this.Left, this.Top, this.Width, this.Height);
}

5. 無標題列拖曳 (WM_NCLBUTTONDOWN)

[DllImport("user32.dll")]
static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);
[DllImport("user32.dll")]
static extern bool ReleaseCapture();

const int WM_NCLBUTTONDOWN = 0xA1;
const int HT_CAPTION = 0x2;

private void TaskbarForm_MouseDown(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        if (TitleBarRect.Contains(e.Location)) // 標題列區域
        {
            ReleaseCapture();
            SendMessage(Handle, WM_NCLBUTTONDOWN, HT_CAPTION, 0);
        }
        else if (CloseBtnRect.Contains(e.Location))
        {
            Hide(); // 關閉
        }
        else if (ContentRect.Contains(e.Location))
        {
            Process.Start("https://www.example.com"); // 自訂動作
        }
    }
}

執行畫面 (兩種皮膚)

專案結構

• Form1：主視窗，按鈕觸發通知視窗
• TaskbarForm：通知視窗核心邏輯 (繼承 Form)
• 資源：兩張位圖皮膚 (.bmp/.png)，背景色設為粉紅 (#FF00FF) 作為透明色

總結

結合 Region、GraphicsPath、雙重緩衝、ShowWindow(SW_SHOWNOACTIVATE)、SendMessage(WM_NCLBUTTONDOWN) 等技術，可在純 C# WinForms 中實作媲美 QQ/MSN 的專業級通知視窗，且具備換膚、動畫、無焦點干擾等優秀使用者體驗特性。