SAMPLE of using rocket chat API from Google Apps Script
https://rocket.chat/docs/developer-guides/rest-api/
rocketchat_api.gs
login_rocketchat()- login to rocketchat
get_channel_id(channel)- get channnel ID
post_message(channel, text)- send message to specified channel
post_file(channel, file)- send file to specified channel
get_channel_history(channel)- get specified channel history
delete_message(channel, message_id)- delete message
delete_latest_message(channel)- delete latest message
Please see the code for details!
get sheet pdf -> png function
https://www.convertapi.com/pdf-to-png
send_images.gs
pdf2png(pdf)- convert pdf to png using convertapi
get_sheet_image()- get specified sheet image
send_sheet_image()- send sheet image