gistfile1.txt

static float getDisplayDensity_init()
{
	const char* current_display = getenv("DISPLAY");

	if (current_display != NULL) {
			Display * x11display = XOpenDisplay(current_display);

			if (x11display != NULL) {
				/* try x direct */
				float dpi_height =
						floor(DisplayHeight(x11display, 0) /
								(DisplayHeightMM(x11display, 0) * 0.039370) + 0.5);
				float dpi_width =
						floor(DisplayWidth(x11display, 0) /
								(DisplayWidthMM(x11display, 0) * 0.039370) +0.5);

				XCloseDisplay(x11display);

				return std::max(dpi_height,dpi_width) / 96.0;
			}
		}

	/* return manually specified dpi */
	return g_settings->getFloat("screen_dpi")/96.0;
}

static float cached_display_density = getDisplayDensity_init();

float getDisplayDensity()
{
	return cached_display_density;
}