My answer tweaks the first answer. Actually I have tried both two methods above, and I don't think they are really center vertical. It would make the drawable more center if it's placed in between ascent
and descent
, rather than top
and bottom
. So as to the second answer, it aligns the center of the drawable to the baseline of the text, rather than the center of that text. Here's my solution:
public class CenteredImageSpan extends ImageSpan {
private WeakReference<Drawable> mDrawableRef;
public CenteredImageSpan(Context context, final int drawableRes) {
super(context, drawableRes);
}
@Override
public int getSize(Paint paint, CharSequence text,
int start, int end,
Paint.FontMetricsInt fm) {
Drawable d = getCachedDrawable();
Rect rect = d.getBounds();
if (fm != null) {
Paint.FontMetricsInt pfm = paint.getFontMetricsInt();
// keep it the same as paint's fm
fm.ascent = pfm.ascent;
fm.descent = pfm.descent;
fm.top = pfm.top;
fm.bottom = pfm.bottom;
}
return rect.right;
}
@Override
public void draw(@NonNull Canvas canvas, CharSequence text,
int start, int end, float x,
int top, int y, int bottom, @NonNull Paint paint) {
Drawable b = getCachedDrawable();
canvas.save();
int drawableHeight = b.getIntrinsicHeight();
int fontAscent = paint.getFontMetricsInt().ascent;
int fontDescent = paint.getFontMetricsInt().descent;
int transY = bottom - b.getBounds().bottom + // align bottom to bottom
(drawableHeight - fontDescent + fontAscent) / 2; // align center to center
canvas.translate(x, transY);
b.draw(canvas);
canvas.restore();
}
// Redefined locally because it is a private member from DynamicDrawableSpan
private Drawable getCachedDrawable() {
WeakReference<Drawable> wr = mDrawableRef;
Drawable d = null;
if (wr != null)
d = wr.get();
if (d == null) {
d = getDrawable();
mDrawableRef = new WeakReference<>(d);
}
return d;
}
}
I also rewrite getSize
to keep the FontMetrics of drawable the same as other text, otherwise the parent view won't wrap the content correctly.
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