How to dynamically change the text size in Android

Question

I want to implement a function,

EditText user when entering text, you can make changes in accordance with the set font size,

Such as Google Docs of Office,

Now I found a way to SpannableString, but read some examples seem unable to reach my needs

int index = input.getSelectionEnd();
SpannableString  spann = new SpannableString(show_input);
AbsoluteSizeSpan word_size = new AbsoluteSizeSpan(18,true);
spann.setSpan(word_size, 0, 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
input.getText().insert(index, spann);

So is there any way to provide it?

Answer 1

Looks like you want to change size of selected text:

int start = editText.getSelectionStart();
int end = editText.getSelectionEnd();
Spannable text=(Spannable)editText.getText();
text.setSpan(new AbsoluteSizeSpan(NEW_TEXT_SIZE, true), start, end, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
editText.setText(text);

Use AbsoluteSizeSpan to change for actual size or RelativeSizeSpan for proportional size.