Is there a way to add some margin/padding above a line?

Question

For example I have this text in a buffer:

aaa
bbb
ccc

and I want it displayed with some spacing above the bbb line:

aaa

bbb
ccc

Is there a face or something which I could add to the bbb line, so it has some margin above it (without modyfing the buffer contents, so not with a newline like here, which I added only for demonstration purposes).

Answer 1

I found a solution which is bit hackish, but not too much. I find the first space in the line and set it to a larger height. The line in my case always have a space somewhere (and it's generally true usually), the bigger height space forces the line height to be bigger which is effectively a top margin:

(let ((pos (1- (save-excursion (beginning-of-line) (search-forward " ")))))
    (put-text-property pos (1+ pos) 'display '(height 1.5)))

In the comments @rpluim suggested an even simpler alternative: putting the text property on the newline, but note that this method does not work well if the line is long and spans multiple visual lines.

(put-text-property (line-end-position) (1+ (line-end-position)) 'display '(height 1.5))