When jSignature signature WeChat is applied to refresh the web page, the canvas cannot be written

[zhangxue61]

hi：
Problem description: WeChat visited H5 web page A, after the first load of page A, the signature function was normally used, no problem. When A page to jump to page B, B to A page after page back, and in A page if the cache is used to monitor “pageshow” time forced to reload A page, to ensure normal use A page logic, but in the back after reloading A page signature functions appear asked, handwriting signature does not appear, get signed, that content is displayed,.