First, EventIDE estimates how many DVA is in 1 cm of the screen surface given the monitor distance:

double DVAInOneCM = 2 * Atan(1.0 / (2.0 * MonitorDistance)) * 180.0 / PI

Second, it estimates the diagonal length of the monitor area in pixels, given the selected screen resolution in pixels:

double MonitorDiagonalInPixels = Math.Sqrt(Math.Pow(ScreenPixelWidth, 2) + Math.Pow(ScreenPixelHeight, 2))

Finally, the conversion ratio, as a number of pixels in 1 DVA, is derived from the above values and the monitor diagonal:

Ratio = (MonitorDiagonalInPixels / MonitorDiagonalInCM) / DVAInOneCM;

The ratio is then used in all pixel<->DVA conversions for X and Y, for instance in conversion from the centered dva coordinates to the centered pixels coordinates:

Ypix = Ydva * Ratio + ScreenPixelHeight / 2.0;