Clone & max out resolution on both screen-projector in Linux

Summary: Use

sudo xrandr --output VGA --pos 0x0

If your projector is called VGA. Read on for more detailed info

How to clone your screen with a projector, when they have different  resolutions

I have a Dell vostro 1015  laptop with a resolution of 1366x768 pixels, and an Epson Emp-tw420 projector with a resolution of 1280x720 pixels. I run Ubuntu 9.04. Problem is when I hold a presentation I want to clone the screen of the laptop to the projector, and a negotiation starts and I end up with a measly 1024x768 on both screens. This is the highest resolution that both screens support. It is a waste of pixels especially on the projector's side.

The solution is to tell Ubuntu to have both screens active side by side (or one above the other), and set the maximum resolution of each and then use the xrandr utility to set both screen to start at the the top left (0x0).

If you type xrandr in a terminal you will get information on both screens and one will have an offset, expressed something like:

VGA connected 1280x720+1366x0

In this case VGA is the name it has given to my projector, 1280x720 is the resolution and 1366x0 is the offset of the screen. the trick is to move the offset to 0x0 so that the screens show the same thing. You do this if your projector is called VGA with:

sudo xrandr --output VGA --pos 0x0

So now I have the same output on both screens at full resolution. The projector does not show the rightmost 86 pixels and the lowermost 48 pixels of the laptop's screen. But that is quite OK as long as I do not need to run in 1024x768.

You could probably achieve this in xorg. conf but the above command is convenient as is. I had to manually set the aspect ratio to wide on the Epson projector afterwards.