When saving a canvas using the toDataUrl method, and then converting it to an image on the server, an empty image is sometimes saved. This happens on iphone 6,7, and also recently noticed that the same problem on Meizu MX4 PRO. On ios, I read that there is a pixel limit. (3 MP)
My canvas is 950*950. How to bypass this problem? If you make the canvas smaller and then enlarge it on the server, the quality will be significantly lost.
Try using several instead of one canvas. Put them in such a way that they visually form a single picture, and on the server glue the complete image from the parts, arranging them according to the desired coordinates.