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Displaying properly on a high-DPI display

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Although Direct2D addresses many high-DPI issues for you, there are two steps you should take to ensure that your application works properly on high-DPI displays.

Step 1: Use the window's own DPI after creating it

The GetDpiForWindow function retrieves the dots per inch (dpi) value for a specified window. To use that value to set the width of a window, use the following formula:

<DPI> * <width, in pixels> / <default DPI>

...where DPI is the value retrived by GetDpiForWindow, and default DPI is 96 (defined as USER_DEFAULT_SCREEN_DPI in winuser.h header). The formula is similar for the vertical axis:

<DPI> * <height, in pixels> / <default vertical DPI>

The code example in step 2.3 of Create a simple Direct2D application retrieves a window's DPI, and then sets its size to 640 × 480, scaled to the DPI.

Note

For a Universal Windows Platform (UWP) app, you can use the DisplayInformation::LogicalDpi property.

Step 2: Declare That the application is DPI-aware

When an application declares itself to be DPI-aware, it is a statement specifying that the application behaves well at DPI settings up to 200 DPI. In Windows Vista and Windows 7, when DPI virtualization is enabled, applications that are not DPI-aware are scaled, and applications receive virtualized data from the system APIs, such as the GetSystemMetric function. To declare that your application is DPI-aware, complete the following steps.

  1. Create a file called DeclareDPIAware.manifest.

  2. Copy the following xml into the file and save it:

    <assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" xmlns:asmv3="urn:schemas-microsoft-com:asm.v3" >
  <asmv3:application>
    <asmv3:windowsSettings xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">
      <dpiAware>true</dpiAware>
    </asmv3:windowsSettings>
  </asmv3:application>
</assembly>

  3. In the project's .vcproj file, add the following entry inside each Configuration element under VisualStudioProject/Configurations:

    <Tool
    Name="VCManifestTool"
    AdditionalManifestFiles="DeclareDPIAware.manifest"
/>