<html> <head> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> </head> <body text="#000000" bgcolor="#FFFFFF"> I have modified my code to set the font after doing the transform (previously was setting before doing the transform) but doing this doesn't seem to make any difference. Here's an edited version of the code I've implemented outlining key points for cairo and font interactions... void draw_glyphs( cairo_t *cr, FT_Face face, unsigned int const x, unsigned int const y, paint_t paint ) { cairo_save( cr ); cairo_translate( cr, x, y ); cairo_rotate( cr, 1.5708 ); /* The freetype {x,y}_scale is a 16.16 value to convert from font units 26.6 pixels. The cairo scaling factor is the size of the em square in pixels. */ cairo_matrix_t font_scale; float units_per_EM_scaled = (float)face->units_per_EM / 64.0f; double sx = (double)( (float)face->size->metrics.x_scale / 65536.0f * units_per_EM_scaled ); double sy = (double)( (float)face->size->metrics.y_scale / 65536.0f * units_per_EM_scaled ); cairo_matrix_init_scale( &font_scale, sx, sy ); cairo_set_font_matrix( cr, &font_scale); cairo_font_face_t *font_face; font_face = cairo_ft_font_face_create_for_ft_face( face, 0 ); cairo_set_font_face( cr, font_face ); cairo_set_source_rgba( cr, paint->red, paint->green, paint->blue, paint->alpha ); cairo_show_glyphs( cr, glyphs, num_glyphs ); cairo_identity_matrix( cr ); cairo_set_font_face( cr, NULL); cairo_font_face_destroy( font_face ); cairo_restore( cr ); } I re-ran the code after commenting out the line: /* cairo_set_font_face( cr, font_face ); */ This resulted in a default font face being used (looks like a cursive font?), but the rotation worked perfectly. I never saw any mixed horizontal and vertical characters, which to me, indicates there's an issue somewhere in Cairo when drawing a "non-default" font face after being rotated. BTW, I also re-ran the code using a scaled font and locking / unlocking it, but doing that also shows the issue. Thanks, Matt. <div class="moz-cite-prefix">On 06/01/16 18:38, Bill Spitzak wrote: </div> <blockquote cite="mid:CAL-8oAhoePpaW2C=U6KA85BvNUoUf+6M3QDby2Oa2c1aadV=fw@mail.gmail.com" type="cite"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <div dir="ltr"> <div>You have to set the font after you do the transform. </div> However I did not expect this mess, I thought what Cairo did was draw the font as though the transform it was using before was still in effect (ie "font lock", similar to the proposed "line width lock"). </div> <div class="gmail_extra"> <div class="gmail_quote">On Wed, Jan 6, 2016 at 7:45 AM, Matthew Conway <<a moz-do-not-send="true" href="mailto:mconway@espial.com" target="_blank">mconway@espial.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I'm trying to rotate an array of glyphs (where each glyph represents a textual character). Consider the following: ---------------- | A TEXT LABEL | ---------------- Where the rectangle is a solid coloured background and the text is drawn (centered) on top of the rectangle (think subtitles being displayed on a TV screen). For some situations, I need to rotate the text label (rectangle and text) 90 degrees clockwise. I do not expect the text rotation to be vertical as shown here: |̄ ̄ ̄ | | A | | | | T | | E | | X | | T | | | | L | | A | | B | | E | | L | |___| Instead, I am expecting the text to be rotated (in position) with the label. Sometimes (about 25% of the time), Cairo seems to be rotating random text characters and drawing them over the top of other correctly rotated characters. /* Draw the labels background */ cairo_rectangle( cr, x, y, width, height ); cairo_set_source_rgba( cr, red, green, blue, alpha ); cairo_fill( vg->cairo_context ); /* Rotate 90 degrees clockwise and show the text */cairo_translate( cr, x, y ); cairo_rotate( cr, 1.5708 ); cairo_show_glyphs( cr, glyphs, num_glyphs ); Notes: 1. The glyphs are created by freetype libraries. 2. The system is using Wayland to draw the text labels. I've tried quite a few things, the most successful was to add a call to show_glyphs before translating, which reduces the issue to show approximatley 5% of the time: /* Rotate 90 degrees clockwise and show the text */ cairo_show_glyphs( cr, glyphs, num_glyphs ); cairo_translate( cr, x, y ); cairo_rotate( cr, 1.5708 ); cairo_show_glyphs( cr, glyphs, num_glyphs ); I've taken a photo of the screen to show what the issue looks like, it can be viewed here: <a moz-do-not-send="true" href="http://postimg.org/image/x4g4fne5h/" rel="noreferrer" target="_blank">http://postimg.org/image/x4g4fne5h/</a> I'm using: - latest cairo 1.14.6 - freetype to create the font glyphs - Wayland Thanks, Matt. -- cairo mailing list <a moz-do-not-send="true" href="mailto:cairo@cairographics.org" target="_blank">cairo@cairographics.org</a> <a moz-do-not-send="true" href="http://lists.cairographics.org/mailman/listinfo/cairo" rel="noreferrer" target="_blank">http://lists.cairographics.org/mailman/listinfo/cairo</a></blockquote> </div> </div> </blockquote> </body> </html>