IT英语翻译!谢谢!（请不要用翻译工具翻译）

IT英语翻译!谢谢!（请不要用翻译工具翻译）
The top and right handles affect only themselves, which means that they do not use the
m_handles list. The center point of the shape is not affected; the horizontal direction is not
affected by the top handler nor is the vertical direction affected by the right handle.
Listings 7-30 and 7-31 show how the roles are handled. The listings look very similar; the
only difference is the direction in which they act.
Let’s look at the details of Listing 7-30; that is, the top handle. The listing starts with an if
clause that ensures that the shape will not be too small. If that’s the case, pass the current
position as the next position to the QGraphicsItem itemChange method.
If the handled shape is big enough, continue by limiting the movement to the direction
of the handle (you don’t allow horizontal movement for the top handle). Then you translate
the shape being handled so the center of the shape is the origo of the coordinate system. This
is a preparation for the scaling, in which you scale the shape according to the movement.
The shape is translated back into its original location, the switch statement is left, and the
QGraphicsItem itemChange method is given the event, but with the direction of limited
movement.
Printing
Qt handles printers with the QPrinter class, which represents a print job to a specific printer
and can be used as a paint device. This means that you can create a QPainter for painting onto
a page represented through QPrinter. The printer object is then used to create new pages and
tell the printer when the job is ready to be printed.
Take a look at some of the properties available from the class:
• colorMode: The printer prints in color or grayscale. Can be set to either QPrinter::Color
or QPrinter::GrayScale.
• orientation: The page can either be positioned as a landscape (QPrinter::Landscape)
or as a portrait (QPrinter::Portrait).
• outputFormat: The printer can print to the platform’s native printing system
(QPrinter::Native), a PDF document (QPrinter::PdfFormat), or a PostScript document
(QPrinter::PostScriptFormat). When printing to a file, which is necessary when creating
PDF and PostScript documents, you must set the file name for the document using
setOutputFileName.
• pageSize: The size of the paper according to different standards. Includes the paper
sizes A4 (QPrinter::A4) and Letter (QPrinter::Letter), but supports many more. Refer
to the Qt documentation for details.
Let’s continue with some actual printing.