<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">The following program reproduces the bug. Tested on Ubuntu 12. I am attaching the snapshot too.<div> </div><div>I am sure that the bug depends on the combination of FT_Set_Char_Size and cairo_scale. Moving the call to FT_Set_Char_Size to another point or calling it again inside the loop produces different results (different bugs, unfortunately).</div><div> </div><div>#include <stdlib.h> #include <stdio.h> #include <assert.h> #include <ft2build.h> #include FT_FREETYPE_H #include <ftadvanc.h> #include <ftsnames.h> #include <tttables.h> #include <harfbuzz/hb.h> #include <harfbuzz/hb-ft.h> #include <harfbuzz/hb-glib.h> #include <cairo/cairo.h> #include <cairo/cairo-ft.h> const char *texts[3] = { "File", "Edit", "http://" }; int main () { double ptSize = 13.0; int device_dpi = 72; double dpi_scale = device_dpi / 72.; FT_Library ft_library; assert(!FT_Init_FreeType(&ft_library)); FT_Face ft_face; assert(!FT_New_Face(ft_library, "/usr/share/fonts/truetype/freefont/FreeSans.ttf", 0, &ft_face)); assert(!FT_Set_Char_Size(ft_face, 0, ptSize*64, device_dpi, device_dpi )); cairo_font_face_t *cairo_ft_face; cairo_ft_face = cairo_ft_font_face_create_for_ft_face(ft_face, 0); hb_font_t *hb_ft_font; hb_face_t *hb_ft_face; hb_ft_font = hb_ft_font_create(ft_face, NULL); hb_ft_face = hb_ft_face_create(ft_face, NULL); int width = 800; int height = 300; cairo_surface_t *surface = cairo_image_surface_create(CAIRO_FORMAT_RGB24, width, height); cairo_t *cr = cairo_create(surface); cairo_scale(cr, 2, 2); cairo_font_options_t *fontOptions = cairo_font_options_create(); cairo_font_options_set_antialias(fontOptions, CAIRO_ANTIALIAS_GRAY); cairo_font_options_set_hint_style(fontOptions, CAIRO_HINT_STYLE_SLIGHT); cairo_set_font_options(cr, fontOptions); cairo_set_source_rgb(cr, 1.0, 1.0, 1.0); cairo_paint(cr); double x = 10; double y = 20; int k; for (k = 0; k < 3; ++k) { x = 10; hb_buffer_t *buf = hb_buffer_create(); hb_buffer_set_unicode_funcs(buf, hb_glib_get_unicode_funcs()); hb_buffer_set_direction(buf, HB_DIRECTION_LTR); hb_buffer_set_script(buf, HB_SCRIPT_LATIN); FT_Set_Char_Size(ft_face, 0, ptSize*64, device_dpi, device_dpi ); hb_buffer_add_utf8(buf, texts[k], strlen(texts[k]), 0, strlen(texts[k])); hb_shape(hb_ft_font, buf, NULL, 0); unsigned int glyph_count; hb_glyph_info_t *glyph_info = hb_buffer_get_glyph_infos(buf, &glyph_count); hb_glyph_position_t *glyph_pos = hb_buffer_get_glyph_positions(buf, &glyph_count); cairo_glyph_t *cairo_glyphs = malloc(sizeof(cairo_glyph_t) * glyph_count); int j; for (j=0; j < glyph_count; ++j) { cairo_glyphs[j].index = glyph_info[j].codepoint; cairo_glyphs[j].x = (int)(x + (glyph_pos[j].x_offset/64)); cairo_glyphs[j].y = (int)(y - (glyph_pos[j].y_offset/64)); x += glyph_pos[j].x_advance/64; y -= glyph_pos[j].y_advance/64; } cairo_set_source_rgba (cr, 0.2, 0.2, 0.2, 1.0); cairo_set_font_face(cr, cairo_ft_face); cairo_set_font_size(cr, ptSize * dpi_scale); cairo_show_glyphs(cr, cairo_glyphs, glyph_count); free(cairo_glyphs); hb_buffer_destroy(buf); y += 36; } cairo_surface_write_to_png(surface, "./out.png"); cairo_surface_destroy(surface); cairo_destroy(cr); cairo_font_face_destroy(cairo_ft_face); hb_font_destroy(hb_ft_font); hb_face_destroy(hb_ft_face); FT_Done_FreeType(ft_library); return 0; } </div><div><img apple-inline="yes" id="941C85AB-0F00-406D-810A-6B2B533DBF4E" height="205" width="203" apple-width="yes" apple-height="yes" src="cid:E549AA06-B8F3-4AC3-8539-A28A5BF7CEDC@fastwebnet.it"></div><div> </div></body></html>