ID Number: Q75256
3.00
WINDOWS
Summary:
Print preview is a very useful feature in a Windows application. It
provides the ability to display on the screen an accurate, scaled image of
what the selected printer will produce on paper. Most implementations
of print preview either do not allow editing or restrict editing in
the preview mode.
Ideally, the best implementation of print preview is to eliminate it
entirely. The trend is toward modeless applications that allow the
user to edit the screen image at all times. An application that
implements WYSIWYG (what you see is what you get) editing is not
required to use a fixed relationship (scale factor) between the size
of the image on the screen and on the paper. For example, a scale
factor of 2 specifies that 1 inch on the screen is 0.5 inch on paper.
Instead, this ratio can be variable and be adjustable by the user
through a slider control. Changing the scale factor to a variable
involves no increase in complexity for a true WYSIWYG application.
In this scenario, if the user was using very small fonts, using
superscripts or subscripts, or had impaired eyesight, the scale factor
could be set to magnify the region being edited. Conversely, if the
user wanted to view the format of the entire page, the scale factor
could be set to reduce the image size to fit the entire page (or two
pages) on the screen. This view is also more appropriate for users
editing the composition of the page.
The application's editing functions would remain fully operative
regardless of the setting of the scale factor. This adjustable scaling
is more versatile than conventional page preview.
Though adjustable scaling is no more difficult to implement than
WYSIWYG using a fixed scale factor, there are a few practical
limitations that complicate the task. Unless a scalable screen font is
employed, GDI (Windows' Graphics Device Interface) will use bitmap
fonts. Because bitmap fonts are available only in a limited set of
sizes, the screen appearance may not be faithful to the printed output
at all scaling factors. Because scaling bitmap or outline fonts takes
time, screen updates will be more sluggish at some scaling factors.
To summarize, WYSIWYG applications that implement user-adjustable
scale factors rather than a conventional print preview mode should be
no more difficult to create, but may incur a performance penalty at
some values of the scale factor. With the impending widespread
availability of scalable fonts and the steady increase in screen
resolution and processor speed, these costs will be rapidly outweighed
by the increase in functionality.