setImg: we make sure the globalCompositeOperation is good so that the image is shown correctly
setImg: we make sure the globalCompositeOperation is good
so that the image is shown correctly

Leimi/drawingboard.js,mattjmattj/drawingboard.js,zartata/drawingboard.js,Leimi/drawingboard.js,zartata/drawingboard.js,zartata/drawingboard.js,Leimi/drawingboard.js,mattjmattj/drawingboard.js