如何打印OpenTK（OpenGL）或更改设备上下文？

Question

有了OpenTK/OpenGL，我可以将Winforms全部用于绘制。 但是，如何在打印机上绘图？

我曾在ganttchart上使用这段代码进行打印，但我不确定如何获取设备上下文以进入GLControl。

private void print_click(object sender, EventArgs e) 
{ 
    dialog.Document = new PrintDocument(); 
    using (var dialog = new PrintDialog()) 
    { 
     if (dialog.ShowDialog() == System.Windows.Forms.DialogResult.OK) 
     { 
      dialog.Document.BeginPrint += new System.Drawing.Printing.PrintEventHandler(Document_BeginPrint); 
      dialog.Document.EndPrint += new System.Drawing.Printing.PrintEventHandler(Document_EndPrint); 
      dialog.Document.PrintPage += new System.Drawing.Printing.PrintPageEventHandler(Document_PrintPage); 
      dialog.Document.Print(); 
     } 
    } 
} 

void Document_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e) 
{ 
    // This code does not work! 
    // something to do with e.Graphics.GetHdc() ??? 
    var nullWindow = OpenTK.Platform.Utilities.CreateWindowsWindowInfo(IntPtr.Zero); 
    // Exception of type 'OpenTK.Graphics.GraphicsContextException' was thrown. 
    var printcontext = new OpenTK.Graphics.GraphicsContext(new ContextHandle(e.Graphics.GetHdc()), nullWindow); 
    printcontext.MakeCurrent(nullWindow); 
    // GL.Begin(...) 
    // ... 
    // GL.End() 
    // printcontext.SwapBuffers()? Should be single-buffered? 
} 

void Document_EndPrint(object sender, System.Drawing.Printing.PrintEventArgs e) 
{ 

} 

void Document_BeginPrint(object sender, System.Drawing.Printing.PrintEventArgs e) 
{ 

} 

我也注意到了OpenTK.Graphics.GraphicsContext (ContextHandle handle, IWindowInfo window)构造函数，但我不知道要放什么东西了IWindowInfo。

Answer 1

我只是认为一个解决办法是采取渲染图像的位图快照，喜欢这里http://www.opentk.com/doc/graphics/save-opengl-rendering-to-disk