I have found that hand written notes will be transformed into corresponding shapes by preview's shape detection. This seems handy. However, when those shapes are opened in other pdf applications, they behaves different.
Example 1
Originally, the annotations are an oval, a tilted rectangle, an arrow, and a freely written character:
If this is read by GoodReader on iPad, everything except the free form distort:
Similar behaviour will happen when it has been edited by Adobe Acrobat.
Example 2
Text annotations changes oddly:
Question
Why does this happens?
- Since PDF = Portable Document Format (PDF)
- = a file format used to present documents in a manner independent of application software, hardware, and operating systems. (wikipedia)
why should the annotations behave so differently?
Can we fix/avoid it?
Note
Preview Version 10.0 (High Sierra)