From eea280b1f1d9d66c903014fd6703f401eb119a87 Mon Sep 17 00:00:00 2001 Message-Id: From: "Jan Alexander Steffens (heftig)" Date: Sat, 9 Sep 2017 00:22:13 +0200 Subject: [PATCH] Use OVER operator for drawing text For opaque text, SOURCE is not any different from OVER. However, when drawing color glyphs (which consist of RGBA pixels instead of strokes) SOURCE's handling of alpha is not what we want. I stumbled across this because cairo 1.15.8 seems to clear the surface before drawing color emoji if the operator is SOURCE, deleting every- thing drawn before. Arguably, the area outside the glyph bounds should not be touched, but even if this is a cairo bug the problem of alpha within the glyph remains. --- libi3/font.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- ./libi3/font.c +++ ./libi3/font.c @@ -103,7 +103,7 @@ static void draw_text_pango(const char *text, size_t text_len, pango_layout_set_text(layout, text, text_len); /* Do the drawing */ - cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE); + cairo_set_operator(cr, CAIRO_OPERATOR_OVER); cairo_set_source_rgb(cr, pango_font_red, pango_font_green, pango_font_blue); pango_cairo_update_layout(cr, layout); pango_layout_get_pixel_size(layout, NULL, &height); -- 2.14.1