Evaluation of A Visual Programming Keyboard on Touchscreen Devices

Block-based programming languages are used by millions of people around the world. Blockly is a popular JavaScript library for creating visual block programming editors. To input a block, users employ a drag-and-drop input style. However, there are some limitations to this input style. We introduce a custom soft keyboard to input Blockly programs. This keyboard allows inputting, changing or editing blocks with a single touch. We evaluated the keyboard users' speed, number of touches, and errors while inputting a Blockly program and compared its performance with the drag-and-drop method. Our keyboard reduces the input errors by 68.37% and the keystrokes by 47.97 %. Moreover, it increases the input speed by 71.26% when compared to the drag-and-drop. The keyboard users perceived it to be physically less demanding with less effort than the drag-and-drop method. Moreover, participants rated the drag-and-drop method to have a higher frustration level. The Blockly keyboard was the preferred input method.