1, canvas draw pictures if there is a network path to a local now need to obtain a temporary path to use
2, measureText ios phone only recognizes the character string width not recognized digit width
3, rounded drawing image because color is transparent in a vacuum dryer above it is necessary to fillStyle = '#fff' disposed over and then plotted
4 fillets process is, first draw a rounded area before cutting saved, and then draw a rounded want to generate content, the content will automatically generate the fillet to the previous section, the section does not show beyond it presents a rounded state