So you would draw it after everything else. You could use writePixel, drawPixel, drawLine, drawRect... etc..

For maximum framerate, you could 'draw it yourself' in the offscreen buffer before it gets copied to the screen.

I made a tiny thermal camera with a Tinyscreen+ and an AMG Grideye sensor from Adafruit. Three of the buttons are used: to control the colormap, the interpolation mode, and emphasis. It has a pretty good framerate. It needs a 3d printed case, but I haven't got that far. Here is a picture and some code.

Since i'm not happy with the thermostat on on my rv, I decided to build a new one. Basic Components are.
TinyScreen+
Custom Interface Board.
Major components on the i/o board are
2 NO switches
Opto Isolator with transistor output Or smt SSR
Connectors for power, output of Opto-Isolator and connection for DS18B20 temp sensor.

Program allows for setting Temp set point. Has predefined sleep mode, OFF/ON hysterisis, Attached is a pic.

Cool. what kind of heater is it?

Hi, yeah the solution for that specific problem is in my post above... 

What kind of problem are you having exactly?

Another issue I had, just FYI:

I had alot of trouble uploading code to tinyscreen+ on Linux. Half the time it would fail or tell me the port was busy. This is due to ModemManager scoping out any serial ports to see if they are GSM modems. You can fix this by putting a udev rule something like this in /etc/udev/rules.d/77-arduino.rules

# stop modemmanager from checking every serial port for a modem.. it locks up the port
# for a few seconds and interferes with uploading.
#
# arduino
ATTRS{idVendor}=="2a03", ENV{ID_MM_DEVICE_IGNORE}="1"
# tinyscreen / atmel
ATTRS{idVendor}=="03eb", ENV{ID_MM_DEVICE_IGNORE}="1"

...as described here:
http://starter-kit.nettigo.eu/2015/serial-port-busy-for-avrdude-on-ubuntu-with-arduino-leonardo-eth/

bump

me too

just FYI, I was about to ask for help becuase my tinyscreen+ wasn't showing up at all when I plugged it in. I had tried two different USB micro cables on 2 different computers. Then I tried a 3rd cable, and now it is working fine. Touchy cables or touchy connector, I wonder.