Question QU-013:

On Windows, why does the AUI display circles as ellipses, or squares as rectangles?

Answer:

The AUI relies on information provided by Windows in order to determine the number of pixels per cm in the horizontal and vertical directions. If these "pixel/cm" factors are incorrectly set, then circles will be displayed as ellipses, squares will be displayed as rectangles, etc.

In order to determine the pixel/cm factors actually used by the AUI, in the AUI, choose Display > Graphics System Info. The AUI will display a window with information such as

...
Window width = 1058 pixels = 26.45 cm using 40.00 pixels/cm.
Window height = 697 pixels = 16.34 cm using 42.67 pixels/cm.

For this example, the horizontal pixel/cm factor is 40.00 and the vertical pixel/cm factor is 42.67.

There are several possible reasons why the pixel/cm factors might be incorrectly set:

  1. You might not have specified to Windows the monitor actually in use. Make sure that the monitor is properly specified to Windows, using, for example, the Control Panel.

  2. If you are using Windows Remote Desktop, there is a known issue in which Windows reports the wrong information. See the link

    http://support.microsoft.com/kb/2768741

    for more information.

If, after checking the above, the wrong pixel factors are still being used, it is possible to set the pixel factors within the AUI. In the Command Window of the AUI, you can type the commands

PLCONTROL GDI  XPIXFC=45 YPIXFC=45
PLCONTROL OPENGL  XPIXFC=45 YPIXFC=45

This tells the AUI to assume 45 pixels/cm in both the horizontal and vertical directions.

(Remember to hit Enter twice after typing in these commands.)

Of course you can enter any values for XPIXFC, YPIXFC.

You can verify that the AUI is using these numbers using the Display > Graphics System Info dialog box.

You will need to click the Clear icon before these numbers take effect.

Unfortunately you need to type in this command each time you invoke the AUI: the AUI does not remember these values.

You can however create an AUI initialization file, see the AUI Online Help, selection Help > Index and choose Initialization File. You can insert the above commands into the initialization file. In this way you don't need to type in the commands each time you invoke the AUI.


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