关于打印管理的理解

当前对于打印的基本流程的理解，如下：

      

1. When an application calls the CreateDC function to create a printer device context, GDI checks to see if the appropriate printer graphics DLL is loaded. If it is not, GDI loads the DLL and calls the DrvEnableDriver function in the DLL. The function is not called again unless the driver is reloaded.

2. Next, GDI calls the printer graphics DLL's DrvEnablePDEV function so the driver can create a physical device instance and return device characteristics. GDI uses the returned information to create an internal description of the device instance.

3. GDI then calls the graphics DLL's DrvCompletePDEV function to supply a GDI handle to the device instance. The graphics DLL must use this handle as input to some of the Eng-prefixed callbacks provided by the GDI drawing engine (see GDI Support Services).

4. After GDI receives the device instance handle, it then makes a call to the graphics DLL's DrvEnableSurface function, which sets up the surface for drawing, and associates it with the physical device instance.

5. The driver can create a drawing surface for the device instance by calling EngCreateBitmap. Alternatively, if the drawing surface is device-managed, the driver can call EngCreateDeviceSurface.

6. If EngCreateBitmap cannot supply a bitmap large enough to contain an entire physical page, and if the driver supports page banding, EngMarkBandingSurface can be called to inform GDI that banding will be employed.

7. Finally, the EngAssociateSurface must be called to allow GDI to associate the created surface with a specified device instance, and to let GDI know which driver-supplied graphics DDI drawing functions (if any) it should call when it draws on this particular surface.

   Banding in use

   For each document to be rendered when banding is used, GDI calls the following functions in the printer graphics DLL:

   DrvStartDoc

   For each physical page {

   DrvStartPage

   DrvStartBanding

   For each banding pass on a physical page{ // 特别要注意每次都在查找，每个band的大小。而且是一个循环的过程。

   DrvQueryPerBandInfo

   Rendering operations

   DrvNextBand // Send raster data for this band, then clear surface to reuse with next band

       }

   }

   DrvEndDoc

   Banding not in use

   For each document to be rendered when banding is not used, GDI calls the following functions in the printer graphics DLL:

   DrvStartDoc

   For each physical page

   DrvStartPage

   Rendering operations

   DrvSendPage // Send raster data for the page

   }

   DrvEndDoc

   With the exception of DrvQueryPerBandInfo, these functions are intended to allow the printer graphics DLL to send control sequences to the printer hardware (by calling EngWritePrinter), and to perform any internal operations needed to initialize or complete processing of a document, page, or band.