在Monomac中打印

Question

如何在monomac中打印？这就是我所能得到的，但是我似乎不能在NSView中获得对图形上下文的引用。如果我将一个控件添加到PrintDoc中，这很好，但我想要绘制。

//Print Function
void Print(){
    PrintDoc NewDoc = new PrintDoc ();
    NewDoc.SetFrameSize(new SizeF(600,1000));
    NSPrintOperation P = NSPrintOperation.FromView (NewDoc);
    P.RunOperation ();
}

//NSView to be printed
class PrintDoc:NSView
{
    public PrintDoc ()
    {
    }
    public override void DrawRect (System.Drawing.RectangleF dirtyRect)
    {
        //NSPrintOperation.CurrentOperation.Context !! this is null
        //NSGraphicsContext.CurrentContext !! this hangs
    }
}

Answer 1

我已经设法通过手动获取上下文，而不是使用NSGraphicsContext.CurrentContext来让它工作：

https://github.com/picoe/Eto/blob/feature/printing/Source/Eto.Platform.Mac/Forms/Printing/PrintDocumentHandler.cs#L39

代码片段：

static IntPtr selCurrentContext = Selector.GetHandle ("currentContext");
static IntPtr classNSGraphicsContext = Class.GetHandle ("NSGraphicsContext");

public override void DrawRect (System.Drawing.RectangleF dirtyRect)
{
    var operation = NSPrintOperation.CurrentOperation;

    var context = new NSGraphicsContext(Messaging.IntPtr_objc_msgSend (classNSGraphicsContext, selCurrentContext));
    // this causes monomac to hang for some reason:
    //var context = NSGraphicsContext.CurrentContext;
}