OS X Yosemite: About entering Chinese handwritten characters
If you have a trackpad, you can use the Trackpad Handwriting input source to enter Chinese characters and punctuation with your finger. When Trackpad Handwriting is on, OS X recognizes character strokes as you draw them in the Trackpad Handwriting window, and shows matching characters in a list, with the closest match at the top.
When the Trackpad Handwriting window is open, you can’t see or move the pointer on the screen. To use the pointer without closing the window, tap the trackpad in the bottom left corner (the location corresponds to the 暂停手写, or Pause, button), or press the Escape key. To close the Trackpad Handwriting window, press Control–Shift–Space bar.