The scaling algorithm that Windows Vista uses is a fairly good one??”it respects pixel boundaries to
avoid blurry edges and uses the video card hardware where possible to increase speed??”but it inevitably
leads to a fuzzier display. It also has a serious limitation in that Windows can??™t recognize older applications
that do support high DPI settings. That??™s because applications need to include a manifest or call SetProcess-
DPIAware (in User32) to advertise their high DPI support. Although WPF applications handle this step
correctly, applications prior to Windows Vista won??™t use either approach and will be stuck with the less than
ideal bitmap scaling.
CHAPTER 1 n INTRODUCING WPF 10
There are two possible solutions. If you have a few specific applications that support high DPI settings,
but don??™t indicate it, you can configure that detail manually. To do so, right-click the shortcut that starts the
application (in the Start menu) and choose Properties. In the Compatibility tab, switch on the option named
Disable Display Scaling on High DPI Settings. If you have a lot of applications to configure, this gets tiring
fast.
The other possible solution is to disable bitmap scaling altogether. To do so, choose the Use Windows XP
Style DPI Scaling option in the Custom DPI Setting dialog box shown in Figure 1-1.
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