Attach my result here:
There's no way to do this in an application.
Because the TextView draws the text at the top of a line in framework.
If u want the visual effect that the text shown center vertically in a line, the framework code must be modified.
The file location is:
frameworks/base/core/java/android/text/StaticLayout.java
The change:
- lines[off + DESCENT] = below + extra;
+ lines[off + DESCENT] = below + extra/2;//Show the text center vertically in the line.
Please correct me if something is wrong or there's a better way to do this.