Flow2Code: from Hand-Drawn Flowcharts to Code Execution.

Flowcharts play an important role when learning to program by conveying algorithms graphically and making them easy to read and understand. Computer-based flowchart design requires the user to learn the software first, which often results in a steep learning curve. Paper-drawn flowcharts don't provide feedback. We propose a system that allows users to draw their flowcharts directly on paper combined with a mobile phone app that takes a photo of the flowchart, interprets it, and generates and executes the resulting code. Flow2Code uses off-line sketch recognition and computer vision algorithms to recognize flowcharts drawn on paper. To gain practice and feedback with flowcharts, the user needs only a pencil, white paper, and a mobile device. The paper describes a tested system and algorithmic model for recognizing and interpreting offline flowcharts as well as a novel geometric feature, Axis Aligned Score (AAS), that enables fast accurate recognition of various quadrilaterals.