Android screenshot (Glass, Wear, mobile)

gcap.sh

#!/usr/bin/env bash

##
# Screencaps, pulls, and deletes the png from a device.
#
# gcap [w | a | device identifier]
#
# For debugging over Bluetooth (i.e., Android Wear), see
#  https://developer.android.com/training/wearables/apps/bt-debugging.html
#
# Instructions:
#  https://medium.com/@msanford/taking-android-screenshots-652d6794f679
##

set -o nounset  # Exit on unset variable
set -o errexit  # Exit on first error

TARGET_DEVICE=${1:-""}
ETIME=$(date +"%s")

# Options
TARGET_PATH=~/Desktop

capture() {
    local dev=${1}
    local file="screen-${dev}-${ETIME}.png"

    if [[ "${dev}" == *localhost* ]]; then
      file="screen-wear-${ETIME}.png"
    fi

    local dest=${TARGET_PATH}/${file}

    echo "Capping ${dev} to ${dest}..."

    adb -s "${dev}" shell /system/bin/screencap -p "/sdcard/${file}" || {

      # Cap failed, inform and break
      if [[ $? -eq 255 ]]; then
        echo "Could not communicate with specified device [${dev}]; exiting !"
      else
        echo "Unknown error occured for [${dev}]; exiting !"
      fi

      exit $?
    }

    # Pull cap and clean up the SD card (if dest pulled)
    adb -s "${dev}" pull "/sdcard/${file}" "${dest}" && \
    adb -s "${dev}" shell rm "/sdcard/${file}"
}

if [ "${TARGET_DEVICE}" = "" ]; then

  # If no device is provided, use the first one, which is adb's default
  # behaviour but we need to acquire the device identifier for the file name.

  DEVICE=$(adb devices | sed -n 2p | awk '{print $1}')
  capture "${DEVICE}"

elif [ "${TARGET_DEVICE}" = "w" ]; then

  # "w" represents an Android Wear device, teathered over bluetooth.
  # If not teathered, this section is irrelevant.

  DEVICE=$(adb devices | grep "localhost" | awk '{print $1}')
  capture "${DEVICE}"

elif [ "${TARGET_DEVICE}" = "a" ]; then

    # "a" loop over all connected devices and cap them
    DEVICE_ARRAY=$(adb devices | awk '{print $1}' | tail -n +2)

    for dev in "${DEVICE_ARRAY[@]}"; do
      capture "${dev}"
    done

else

  # We assume a device identifier has been passed, so use that directly
  capture "${TARGET_DEVICE}"

fi