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After
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canvas inserts a picture, operations such as rotation and magnification need to be carried out, and the track will be recorded by hand on the basis of the operation. The problem is that the rotation and magnification operation will change the original coordinates, and the hand drawing also needs to record the coordinates to draw the track. These two coordinates do not overlap, resulting in the contact position cannot be drawn by hand after magnification or rotation. I do not know how to solve the problem
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- is it because the screen coordinates are always obtained by the touchmove event when drawing, and whether there is a method to obtain the origin coordinates of the upper-left corner of canvas
- do you have to use the method of zooming and rotating to get the corresponding conversion relationship, and hand-drawing the touch event with the converted value? But in this case, the rotation is based on the center point rotation coordinate system touch to obtain the coordinate system with the upper left corner as the origin
and zooming, isn"t it very troublesome to convert