You can create your own span by extending ReplacementSpan. In draw
method, you can take into account the fontSpacing
which you can get from Paint
parameter.
Like this:
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.FontMetricsInt;
import android.graphics.RectF;
import android.text.style.ReplacementSpan;
public class BetterHighlightSpan extends ReplacementSpan {
private int backgroundColor;
public BetterHighlightSpan(int backgroundColor) {
super();
this.backgroundColor = backgroundColor;
}
@Override
public int getSize(Paint paint, CharSequence text, int start, int end, FontMetricsInt fm) {
return Math.round(paint.measureText(text, start, end));
}
@Override
public void draw(Canvas canvas, CharSequence text, int start, int end, float x, int top, int y, int bottom,
Paint paint) {
// save current color
int oldColor = paint.getColor();
// calculate new bottom position considering the fontSpacing
float fontSpacing = paint.getFontSpacing();
float newBottom = bottom - fontSpacing;
// change color and draw background highlight
RectF rect = new RectF(x, top, x + paint.measureText(text, start, end), newBottom);
paint.setColor(backgroundColor);
canvas.drawRect(rect, paint);
// revert color and draw text
paint.setColor(oldColor);
canvas.drawText(text, start, end, x, y, paint);
}
}
You can use it like this:
TextView textView = (TextView) findViewById(R.id.textView);
SpannableStringBuilder builder = new SpannableStringBuilder("here some text and more of it");
builder.setSpan(new BetterHighlightSpan(Color.CYAN), 4, 8, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
textView.setText(builder);
I couldn't much test it but you can improve it.