この回答はPedroの回答に基づいていますが、テキスト属性がすべて設定されている場合にも機能するように編集されています。
package nl.raakict.android.spc.widget;
import android.content.Context;
import android.text.Spannable;
import android.text.SpannableString;
import android.text.style.ScaleXSpan;
import android.util.AttributeSet;
import android.widget.TextView;
public class LetterSpacingTextView extends TextView {
private float letterSpacing = LetterSpacing.BIGGEST;
private CharSequence originalText = "";
public LetterSpacingTextView(Context context) {
super(context);
}
public LetterSpacingTextView(Context context, AttributeSet attrs){
super(context, attrs);
originalText = super.getText();
applyLetterSpacing();
this.invalidate();
}
public LetterSpacingTextView(Context context, AttributeSet attrs, int defStyle){
super(context, attrs, defStyle);
}
public float getLetterSpacing() {
return letterSpacing;
}
public void setLetterSpacing(float letterSpacing) {
this.letterSpacing = letterSpacing;
applyLetterSpacing();
}
@Override
public void setText(CharSequence text, BufferType type) {
originalText = text;
applyLetterSpacing();
}
@Override
public CharSequence getText() {
return originalText;
}
private void applyLetterSpacing() {
StringBuilder builder = new StringBuilder();
for(int i = 0; i < originalText.length(); i++) {
String c = ""+ originalText.charAt(i);
builder.append(c.toLowerCase());
if(i+1 < originalText.length()) {
builder.append("\u00A0");
}
}
SpannableString finalText = new SpannableString(builder.toString());
if(builder.toString().length() > 1) {
for(int i = 1; i < builder.toString().length(); i+=2) {
finalText.setSpan(new ScaleXSpan((letterSpacing+1)/10), i, i+1, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
super.setText(finalText, BufferType.SPANNABLE);
}
public class LetterSpacing {
public final static float NORMAL = 0;
public final static float NORMALBIG = (float)0.025;
public final static float BIG = (float)0.05;
public final static float BIGGEST = (float)0.2;
}
}