GNAySolution

適用範圍：微軟的WPF框架

好處：只針對指定視窗或UI元件截圖，不像Print Screen全螢幕可能會截到客戶的隱私，也比Alt+Print Screen使用上更有彈性

原始碼參考出處：
https://stackoverflow.com/questions/5124825/generating-a-screenshot-of-a-wpf-window

稍微調整，增加支援的圖檔格式：
BMP (System.Windows.Media.Imaging.BmpBitmapEncoder)
Gif (System.Windows.Media.Imaging.GifBitmapEncoder)
Jpeg (System.Windows.Media.Imaging.JpegBitmapEncoder)
PNG (System.Windows.Media.Imaging.PngBitmapEncoder)
Tiff (System.Windows.Media.Imaging.TiffBitmapEncoder)
WMP (System.Windows.Media.Imaging.WmpBitmapEncoder)

調整後原始碼：
ButtonLoginUser.ScreenshotToFile<PngBitmapEncoder>($"{DateTime.Now:yyMMdd_HHmmss}_{nameof(ButtonLoginUser)}.png");

public static void ScreenshotToFile<T>(this Visual obj, string fileName) where T : BitmapEncoder, new ()
{
    DrawingVisual visual = new DrawingVisual();
    Rect bounds = VisualTreeHelper.GetDescendantBounds(obj);

    using (DrawingContext context = visual.RenderOpen())
    {
        context.DrawRectangle(new VisualBrush(obj), null, new Rect(new Point(), bounds.Size));
    }

    RenderTargetBitmap renderTarget = new RenderTargetBitmap((int)bounds.Width, (int)bounds.Height, 96, 96, PixelFormats.Pbgra32);
    renderTarget.Render(visual);

    T bitmapEncoder = new T();
    bitmapEncoder.Frames.Add(BitmapFrame.Create(renderTarget));

    FileInfo fInfo = new FileInfo(fileName);
    fInfo.Directory.Create();

    using (Stream stm = File.Create(fInfo.FullName))
    {
        bitmapEncoder.Save(stm);
    }
}