【Android】如何改变TextView字体间距

Typeface myfOnt= Typeface.createFromAsset(getAssets(),
          "fonts/Blocks2.ttf");

myeditText.setTypeface(myfont);

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             String c = ""+ originalText.charAt(i);
            builder.append(c.toLowerCase());
            if(i+1                 builder.append("\u00A0");
            }
        }
        SpannableString finalText = new SpannableString(builder.toString());
        if(builder.toString().length() > 1) {
            for(int i = 1; i                 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;
    }
}