Android TextView setTextSize incorrectly increases

问题:

This question already has an answer here:

• TextView.setTextSize behaves abnormally - How to set text size of textview dynamically for different screens 6 answers

This is in an extension of TextView. getTextSize() and setTextSize() are not overridden, I do not extend those methods. Programming in 1.6, API level 4.

The loop in this code causes size to be multiplied by 1.5 every time it iterates, e.g. if size initially reads 200 from getTextSize, then setTextSize(size) is called, getTextSize called again reads back 300.

public void shrinkTest() {
    float size = this.getTextSize(); 
    while (size > 8) {
        this.setTextSize(size);
        size = this.getTextSize();
    }
}

Why is this?

回答1:

Heh, mixed units problem. Seems a little counterintuitive, but it's an easy fix. The default method setTextSize(float) assumes you're inputting sp units (scaled pixels), while the getTextSize() method returns an exact pixel size.

You can fix this by using the alternate setTextSize(TypedValue, float), like so:

this.setTextSize(TypedValue.COMPLEX_UNIT_PX, size);

This will make sure you're working with the same units.

回答2:

setTextSize() and getTextSize() work with different units. The parameter to set() is density-independent "scaled pixels", whereas get() returns plain old pixels.

回答3:

pass units with size using TypedValue like below:

TypedValue.COMPLEX_UNIT_PX //Pixels

TypedValue.COMPLEX_UNIT_SP //Scaled Pixels

TypedValue.COMPLEX_UNIT_DIP //Device Independent Pixels

setTextSize(TypedValue.COMPLEX_UNIT_SP, 18)