Magnifying Glass - demonstrates different ways to obtain or create proper DC and use BitBlt - StretchBlt functions


Generally the sample demonstrates different ways to obtain or create proper DC and use BitBlt - StretchBlt functions.

It is another ZoomIn demo application created with doc-view architecture. CView derived class experienced minimum changes from AppWizard generated one.

CImageWnd window covers CView derived class window. CImageWnd contains a copy (mirror) of CView derived class window bitmap to draw. CImageWnd window becomes transparent when magnifying glass is inactive and draws a "lens" over the bitmap when active. The "lens" is a small zoom window. Magnifying Glass doesn't depend on a view contents. It is easy to modify CMgnView::OnDraw or CMgnView::OnEraseBkgnd and Magnifying Glass still will work with another contents.

To activate or deactivate magnifying glass - press button on a toolbar.

To magnify a portion of a view - activate magnifying glass, press left mouse button and move "lens" around a view.

To change magnifying glass size, shape or zoom - activate magnifying and click a view with right mouse button. It is possible to create several views just use file - new command. Note that for each view magnify glass keeps its own properties.

It is easy enough to make a "lens" astigmatic (cylinder) or add another "optical effects".

I couldn't remove some "optical side effects". When magnifying glass is slowly moved from outside a frame inside it over a border you see a "diffraction grid".

Download source - 27 Kb


  • There are no comments yet. Be the first to comment!

Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • U.S. companies are desperately trying to recruit and hire skilled software engineers and developers, but there's simply not enough quality talent to go around. In response, companies often resort to inferior solutions -- hiring substandard developers and engineers, recruiting talent on a part-time or temporary basis, poaching people from competitors, or burdening an already stressed IT staff for more of their labor. Fortunately, there's a better solution. Read this white paper to learn the business value of …

  • Lenovo recommends Windows 8 Pro. "I dropped my laptop getting out of the taxi." This probably sounds familiar to most IT professionals. If your employees are traveling, you know their devices are in for a rough go. Whether it's a trip to the conference room or a convention out of town, any time equipment leaves a user's desk it is at risk of being put into harm's way. Stay connected at all times, whether at the office or on the go, with agile, durable, and flexible devices like the Lenovo® …

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date