JavaScript: Handling Large Files in the Browser. Part 1/2: Reading Large Files

The DGRM.net online whiteboard stores data in PNG images. With attachments, the files become large. I’ll explain how data is stored in PNG files. Fig. 1. DGRM.net opens diagrams from PNG images PNG file format A PNG file consists of blocks. These blocks contain various information. For example, the tIME block contains the editing date. At the end comes the required IEND block. After the IEND, you can append your own data to the file without breaking the image. This is what DGRM uses: it appends