Added files

README.md

@@ -1,2 +1,61 @@
 # cutiepi-rotation-scripts
-A set of scripts and services to manage screen rotation on the CutiePi
+
+A set of scripts and services to manage display rotation on the CutiePi tablet.
+
+It interacts with the CutiePi gyroscope over `iio-sensor-proxy` to detect the
+orientation of the device, and it manipulates the display rotation using some
+simple `xrandr` and `xinput` scripting.
+
+## Installation
+
+1. Ensure that the `iio-sensor-proxy` package is installed:
+
+```shell
+$ sudo apt install iio-sensor-proxy
+```
+
+2. Clone the repo:
+
+```shell
+$ git clone https://github.com/BlackLight/cutiepi-rotation-scripts
+$ cd cutiepi-rotation-scripts
+```
+
+3. Simply add the `bin` folder to your `PATH`, or copy/symlink its content
+   somewhere in your `PATH`
+
+4. If you want to run the `autorotate` script as a startup service:
+
+```shell
+$ mkdir -p ~/.config/systemd/user
+$ cp systemd/autorotate.service ~/.config/systemd/user
+$ systemctl --user daemon-reload
+# Start the service
+$ systemctl --user start autorotate
+# Enable the service at startup
+$ systemctl --user enable autorotate
+```
+
+## Usage
+
+As shown in the previous example, the `autorotate` script can be enabled as a
+startup service and it can automatically handle the rotation of the display by
+polling gyroscope sensor data.
+
+There are also two auxiliary scripts (`screen-rotate-left` and
+`screen-rotate-right`) that can be programmatically called in your scripts or
+launched from the panel to manually force display orientation.
+
+## Notes
+
+The `autorotate` script disables the HDMI input when started. The reason is
+that the calculation of the coordinate transformation matrices for the touchpad
+is much more complex when working with extended displays. If your tablet is
+physically connected to a screen, however, the chances that you may want to
+leverage auto-rotation are quite low anyway, so a workaround could be a simple
+script that turns on the HDMI input and stops the `autorotate` service when an
+HDMI input is plugged, and restarts it when it's unplugged.
+
+If a strong use case exists for handling auto-rotation on extended displays,
+feel free to open an issue.
+

bin/autorotate

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+script_dir="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+source "$script_dir/cutiepi-screen-common"
+
+# Turn off the HDMI interface. This actually shouldn't be required, but taking
+# the second display into account would make the xinput coordinate transformation
+# matrices more complex (TODO it can be tackled later if there's enough demand for
+# screen rotation features while the tablet is attached to another screen)
+xrandr --output HDMI-2 --off
+
+# Default rotation: standard horizontal
+screen_set_horizontal
+
+monitor-sensor | while read line; do
+    echo "$line" | egrep '^\s*Accelerometer orientation changed: ' >/dev/null || continue
+    orientation=$(echo "$line" | awk '{print $4}')
+    case "$orientation" in
+        left-up) screen_set_horizontal;;
+        normal) screen_set_vertical;;
+        right-up) screen_set_horizontal_inverted;;
+        bottom-up) screen_set_vertical_inverted;;
+    esac
+done
+

bin/cutiepi-screen-common

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+# Ensure that the display variable is set
+export DISPLAY=:0
+
+screen_rotation() {
+    cur_rotation=$(xrandr --query --verbose | grep DSI-1 | cut -d ' ' -f 5)
+    echo $cur_rotation
+}
+
+screen_set_horizontal() {
+    xrandr --output DSI-1 --rotate left
+    xinput set-prop 11 "Coordinate Transformation Matrix" 0 -1 1 1 0 0 0 0 1
+}
+
+screen_set_vertical() {
+    xrandr --output DSI-1 --rotate normal
+    xinput set-prop 11 "Coordinate Transformation Matrix" 1 0 0 0 1 0 0 0 1
+}
+
+screen_set_horizontal_inverted() {
+    xrandr --output DSI-1 --rotate right
+    xinput set-prop 11 "Coordinate Transformation Matrix" 0 1 0 -1 0 1 0 0 1
+}
+
+screen_set_vertical_inverted() {
+    xrandr --output DSI-1 --rotate inverted
+    xinput set-prop 11 "Coordinate Transformation Matrix" -1 0 1 0 -1 1 0 0 1
+}
+

bin/screen-rotate-left

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+script_dir="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+source "$script_dir/cutiepi-screen-common"
+
+cur_rotation=$(screen_rotation)
+
+case "$cur_rotation" in
+    left) screen_set_vertical_inverted;;
+    right) screen_set_vertical;;
+    normal) screen_set_horizontal;;
+    inverted) screen_set_horizontal_inverted;;
+esac
+

bin/screen-rotate-right

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+script_dir="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+source "$script_dir/cutiepi-screen-common"
+
+cur_rotation=$(screen_rotation)
+
+case "$cur_rotation" in
+    left) screen_set_vertical;;
+    right) screen_set_vertical_inverted;;
+    normal) screen_set_horizontal_inverted;;
+    inverted) screen_set_horizontal;;
+esac
+

systemd/autorotate.service

@@ -0,0 +1,19 @@
+# Copy or symlink this systemd service to ~/.config/systemd/user
+# (create the folder if it doesn't exist).
+# Start with: systemctl --user start autorotate
+# Stop with: systemctl --user stop autorotate
+# Enable at startup with: systemctl --user enable autorotate
+# Disable at startup with: systemctl --user disable autorotate
+
+[Unit]
+Description=Manage screen auto-rotation on a CutiePi tablet
+After=graphical.target
+
+[Service]
+ExecStart=/home/pi/bin/autorotate
+Restart=always
+RestartSec=5
+
+[Install]
+WantedBy=default.target
+