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Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
@allObjects
Drawing things over each other with updates is quite a nice challenge: Merge individual layers in the final, display buffer layer, and this every time in a layer something changes. Two layers would be good enough: layer one holds face and hour and minute hand. Layer two includes second hand. second hand. Every second, new second hand layer is created w/ second hand for current second. Layers are merged for the part where second hand layer has changed from previous layer. Knowing origin and extend of previous and current second hand layer allows to update the display buffer only where something has changed. Shortest - in time - and smallest - in number of pixels - update is at seconds 1, 15+16, 30+31 and 45+46... and longest/largest is at seconds 7+8, 22+23, 37+38 and 52+53 (assuming it is all done with rectangles. The additional code and additional meta data transmission to the display to achieve higher optimization may outweigh its gain).