C# 在C中读取打印机设备上下文#

我能够显示屏幕设备并将其保存到DIB位图，我希望在打印机设备上下文中也能这样做。我可以得到一个非空位图，但它总是纯黑色

下面是允许我处理屏幕设备上下文的代码

        //In size variable we shall keep the size of the window.
        SIZE size;

        //Win32 API functions are imported in classes
        //PlatformInvokeGDI32
        //PlatformInvokeUSER32

        //Get handle of calc.exe window.
        IntPtr hwnd = PlatformInvokeUSER32.FindWindow("SciCalc", "Calculator");

        //Get window dimensions
        PlatformInvokeUSER32.RECT rect;
        PlatformInvokeUSER32.GetWindowRect(hwnd, out rect);
        size.cx = rect._Right - rect._Left;
        size.cy = rect._Bottom - rect._Top;

        //Get the device context of Calculator.
        IntPtr hDC = PlatformInvokeUSER32.GetDC(hwnd);

        //Draw on the Calculator surface.
        Graphics CalculatorGraphics = Graphics.FromHdc(hDC);
        Color colorRed = Color.FromName("Red");
        Pen penRed = new Pen(colorRed);
        CalculatorGraphics.DrawEllipse(penRed, 50, 50, 50, 50);
        CalculatorGraphics.Save();

        //Here we make a compatible device context in memory for screen device context.
        IntPtr hMemDC = PlatformInvokeGDI32.CreateCompatibleDC(hDC);

        //Create a compatible bitmap of window size and using screen device context.
        m_HBitmap = PlatformInvokeGDI32.CreateCompatibleBitmap(hDC, size.cx, size.cy);

        //As m_HBitmap is IntPtr we can not check it against null. For this purspose IntPtr.Zero is used.
        if (m_HBitmap != IntPtr.Zero)
        {
            //Here we select the compatible bitmap in memeory device context and keeps the refrence to Old bitmap.
            IntPtr hOld = (IntPtr)PlatformInvokeGDI32.SelectObject(hMemDC, m_HBitmap);
            //We copy the Bitmap to the memory device context.
            PlatformInvokeGDI32.BitBlt(hMemDC, 0, 0, size.cx, size.cy, hDC, 0, 0, PlatformInvokeGDI32.SRCCOPY);
            //We select the old bitmap back to the memory device context.
            PlatformInvokeGDI32.SelectObject(hMemDC, hOld);
            //We delete the memory device context.
            PlatformInvokeGDI32.DeleteDC(hMemDC);
            //We release the screen device context.
            PlatformInvokeUSER32.ReleaseDC(hwnd, hDC);
            //Image is created by Image bitmap handle and returned.
            return System.Drawing.Image.FromHbitmap(m_HBitmap);
        }
        //If m_HBitmap is null retunrn null.
        return null;

以下是获取打印机设备上下文的方法：

        //In size variable we shall keep the size of the window.
        SIZE size;
        size.cx = 1000;
        size.cy = 1000;

        //Get Printer Handle
        IntPtr PrinterHandle;
        PlatformInvokeGDI32.PRINTER_DEFAULTSW defaults = new PlatformInvokeGDI32.PRINTER_DEFAULTSW();
        PlatformInvokeGDI32.OpenPrinterW("Bullzip PDF Printer", out PrinterHandle, defaults);

        //Get Printer Device context
        IntPtr PrinterHDC = PlatformInvokeGDI32.CreateDCW("", "Bullzip PDF Printer", "", IntPtr.Zero);

        //Initialize DocInfo structure.
        PlatformInvokeGDI32.DOCINFOW docInfo = new PlatformInvokeGDI32.DOCINFOW();

        //Start printing.
        PlatformInvokeGDI32.StartDocW(PrinterHDC, ref docInfo);
        PlatformInvokeGDI32.StartPage(PrinterHDC);
        Graphics graphics = Graphics.FromHdc(PrinterHDC, PrinterHandle);

        Color theColor = Color.FromName("Red");
        Pen pen = new Pen(theColor);
        graphics.DrawRectangle(pen, 50, 50, 50, 50);
        graphics.DrawEllipse(pen, 50, 50, 50, 50);
        graphics.Save();

        //Here we make a compatible device context in memory for screen device context.
        IntPtr hMemDC = PlatformInvokeGDI32.CreateCompatibleDC(PrinterHDC);

        //Create a compatible bitmap of window size and using screen device context.
        m_HBitmap = PlatformInvokeGDI32.CreateCompatibleBitmap(PrinterHDC, size.cx, size.cy);

        //As m_HBitmap is IntPtr we can not check it against null. For this purspose IntPtr.Zero is used.
        if (m_HBitmap != IntPtr.Zero)
        {
            //Here we select the compatible bitmap in memeory device context and keeps the refrence to Old bitmap.
            IntPtr hOld = (IntPtr)PlatformInvokeGDI32.SelectObject(hMemDC, m_HBitmap);
            //We copy the Bitmap to the memory device context.
            PlatformInvokeGDI32.BitBlt(hMemDC, 0, 0, size.cx, size.cy, PrinterHDC, 0, 0, PlatformInvokeGDI32.SRCCOPY);
            //We select the old bitmap back to the memory device context.
            PlatformInvokeGDI32.SelectObject(hMemDC, hOld);
            //We delete the memory device context.
            PlatformInvokeGDI32.DeleteDC(hMemDC);
            //We release the screen device context.
            //PlatformInvokeUSER32.ReleaseDC(hwnd, PrinterHDC);
            //Image is created by Image bitmap handle and returned.

            PlatformInvokeGDI32.EndPage(PrinterHDC);
            PlatformInvokeGDI32.EndDoc(PrinterHDC);
            PlatformInvokeGDI32.ClosePrinter(PrinterHandle);
            pen.Dispose();
            graphics.Dispose();


            return System.Drawing.Image.FromHbitmap(m_HBitmap);
        }
        //If m_HBitmap is null retunrn null.
        return null;

如何在打印机设备上下文上绘图？ 如何将打印机设备上下文保存到DIB

谢谢,

---

Jacob

打印机设备上下文是只写的

例如，假设您正在打印到PostScript打印机。创建打印机设备上下文并在其上绘制一些文本。打印机设备驱动程序不会呈现包含文本的位图。相反，它创建一系列PostScript命令来绘制文本，并将命令发送到打印机。换句话说，没有要复制的位图

---

你想实现什么？

这是一件非常不寻常的事情。一个名为“Bullzip PDF printer”的假打印机驱动程序无疑不支持它。工作原理类似于光栅设备，而不是位图设备。我现在在其他物理和软件打印机上尝试了相同的代码，得到了相同的结果：图形打印成功，但DC没有像我希望的那样转换为位图。打印机：HP LaserJet 4100系列PCL、Apple Color LaserWriter 12/600、Bullzip PDF打印机、DOXPrinter801和LaserWriter Personal NT v51.8。打印机Ricoh Aficio MP C4000 PCL6在PlatformInvokeGDI32.StartPage（PrinterHDC）上给出了一个AccessViolationException；。我以编程方式将大量文档打印到TIFF。有时，文档是基于HTML的电子邮件，包含的表格太宽，无法在页面上打印，这意味着某些内容没有打印出来。我希望保存一个位图，然后确定该区域以外是否有任何非白色像素可以打印到页面上。能否将电子邮件加载到HTML渲染器中，并询问其文档宽度？电子邮件存储在Outlook PST中。提交电子邮件进行打印的应用程序是一个名为DiscoveryCracker的现成应用程序，它将电子邮件提交到Outlook 2007进行打印。我不知道在这个过程中，我可以将文档发送到HTML渲染器的哪个位置。我之所以想使用设备上下文，是因为我可以将DLL注入DiscoveryCracker或Outlook and hook StartPage，后者使用hDC。我不是Outlook专家，但似乎可以编写一个宏在加载消息时运行。然而，如果只打印正在打开的消息的一个子集，这将没有多大用处。与Excel不同，打印文档时似乎不可能运行宏。或者，如果要挂接GDI，可以挂接文本和线条绘制函数并检查它们的边界。尽管如果需要考虑映射模式，这可能会变得复杂。或者可能有一种更干净的方式连接到打印管道中。获取ExtTextOut和其他文本方法的坐标是我想到的另一种方式。我同意必须考虑映射模式会使事情变得具有挑战性。如果有一种更干净的方法连接到打印管道，我还没有找到。你有什么想法吗？宏观的想法不是我想到的。我会考虑一下。