Better Print Preview

One of the biggest advantages to using the MFC document/view architecture is
the Print Preview feature. However, this feature is sometimes far less than
easy to understand and utilize to its fullest capacity. Therefore, in this
article, I’m presenting some improvements to Print Preview
that I developed while working on a recent project.

The first thing I did was to eliminate flicker from the preview dialog by
utilizing the BitBlt function. You can see an outline of the ExtPreviewView
class definition below. This class is derived from the MFC
CPreviewView class (described in detail in the MFC Technical Note 30).

The three protected members are used to hold the virtual viewport data.
These values are initialized when the InitVxPrintOffset function is called.
Therefore, you are able to create a bitmap on a memory DC which is compatible
with the Preview DC in MFC for high-speed drawing now that you can get the
maximum size of virtual paper.

// override MFC class
class ExtPreviewView : public CPreviewView
{
…
protected:
 // Original viewport point of memory DC
 CSize m_VxPrintOffset;
 CSize m_sizeVxVpExt, m_sizeVxWinExt;
public:
 void InitVxPrintOffset(CDC* pDC);
 …
 friend class CAdvancedPreviewView;
};

The second improvement I made was to add three additional zoom-in
levels.

#define ZOOM_IN_150     3
#define ZOOM_IN_200     4
#define ZOOM_IN_400     5

Caution!

You need to include the gafximpl.h
in order to incorporate into your project the source code supplied with this article.

This is how to configure Visual Studio so that it can locate this needed header file.

1. On the Project menu, click Settings.
2. In the Settings dialog box, select the C/C++ tab.
3. Select Preprocessor from the Category drop-down list.
4. The project-specific include paths are located in the Additional include
   directories edit box.

Downloads

Download demo project – 28 Kb
Download demo application – 15 Kb