text: /*
   * vim:ts=4:sw=4:expandtab
   *
   * i3 - an improved dynamic tiling window manager
   * © 2009 Michael Stapelberg and contributors (see also: LICENSE)
   *
   */
  #include <assert.h>
  #include <stdint.h>
  #include <stdlib.h>
  #include <string.h>
  #include <stdbool.h>
  #include <err.h>
  
  #if PANGO_SUPPORT
  #include <cairo/cairo-xcb.h>
  #include <pango/pangocairo.h>
  #endif
  
  #include "libi3.h"
  
  extern xcb_connection_t *conn;
  extern xcb_screen_t *root_screen;
  
  static const i3Font *savedFont = NULL;
  
  #if PANGO_SUPPORT
  static xcb_visualtype_t *root_visual_type;
  static double pango_font_red;
  static double pango_font_green;
  static double pango_font_blue;
  
  /* Necessary to track whether the dpi changes and trigger a LOG() message,
   * which is more easily visible to users. */
  static double logged_dpi = 0.0;
  
  static PangoLayout *create_layout_with_dpi(cairo_t *cr) {
      PangoLayout *layout;
      PangoContext *context;
  
      context = pango_cairo_create_context(cr);
      const double dpi = (double)root_screen->height_in_pixels * 25.4 /
                         (double)root_screen->height_in_millimeters;
      if (logged_dpi != dpi) {
          logged_dpi = dpi;
          LOG("X11 root window dictates %f DPI\n", dpi);
      } else {
          DLOG("X11 root window dictates %f DPI\n", dpi);
      }
      pango_cairo_context_set_resolution(context, dpi);
      layout = pango_layout_new(context);
      g_object_unref(context);
  
      return layout;
  }
  
  /*
   * Loads a Pango font description into an i3Font structure. Returns true
   * on success, false otherwise.
   *
   */
  static bool load_pango_font(i3Font *font, const char *desc) {
      /* Load the font description */
      font->specific.pango_desc = pango_font_description_from_string(desc);
      if (!font->specific.pango_desc) {
          ELOG("Could not open font %s with Pango, fallback to X font.\n", desc);
          return false;
      }
  
      LOG("Using Pango font %s, size %d\n",
          pango_font_description_get_family(font->specific.pango_desc),
          pango_font_description_get_size(font->specific.pango_desc) / PANGO_SCALE);
  
      /* We cache root_visual_type here, since you must call
       * load_pango_font before any other pango function
       * that would need root_visual_type */
      root_visual_type = get_visualtype(root_screen);
  
      /* Create a dummy Pango layout to compute the font height */
      cairo_surface_t *surface = cairo_xcb_surface_create(conn, root_screen->root, root_visual_type, 1, 1);
      cairo_t *cr = cairo_create(surface);
      PangoLayout *layout = create_layout_with_dpi(cr);
      pango_layout_set_font_description(layout, font->specific.pango_desc);
  
      /* Get the font height */
      gint height;
      pango_layout_get_pixel_size(layout, NULL, &height);
      font->height = height;
  
      /* Free resources */
      g_object_unref(layout);
      cairo_destroy(cr);
      cairo_surface_destroy(surface);
  
      /* Set the font type and return successfully */
      font->type = FONT_TYPE_PANGO;
      return true;
  }
  
  /*
   * Draws text using Pango rendering.
   *
   */
  static void draw_text_pango(const char *text, size_t text_len,
                              xcb_drawable_t drawable, int x, int y,
                              int max_width, bool is_markup) {
      /* Create the Pango layout */
      /* root_visual_type is cached in load_pango_font */
      cairo_surface_t *surface = cairo_xcb_surface_create(conn, drawable,
                                                          root_visual_type, x + max_width, y + savedFont->height);
      cairo_t *cr = cairo_create(surface);
      PangoLayout *layout = create_layout_with_dpi(cr);
      gint height;
  
      pango_layout_set_font_description(layout, savedFont->specific.pango_desc);
      pango_layout_set_width(layout, max_width * PANGO_SCALE);
      pango_layout_set_wrap(layout, PANGO_WRAP_CHAR);
      pango_layout_set_ellipsize(layout, PANGO_ELLIPSIZE_END);
  
      if (is_markup)
          pango_layout_set_markup(layout, text, text_len);
      else
          pango_layout_set_text(layout, text, text_len);
  
      /* Do the drawing */
      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);
      /* Center the piece of text vertically if its height is smaller than the
       * cached font height, and just let "high" symbols fall out otherwise. */
      int yoffset = (height < savedFont->height ? 0.5 : 1) * (height - savedFont->height);
      cairo_move_to(cr, x, y - yoffset);
      pango_cairo_show_layout(cr, layout);
  
      /* Free resources */
      g_object_unref(layout);
      cairo_destroy(cr);
      cairo_surface_destroy(surface);
  }
  
  /*
   * Calculate the text width using Pango rendering.
   *
   */
  static int predict_text_width_pango(const char *text, size_t text_len, bool is_markup) {
      /* Create a dummy Pango layout */
      /* root_visual_type is cached in load_pango_font */
      cairo_surface_t *surface = cairo_xcb_surface_create(conn, root_screen->root, root_visual_type, 1, 1);
      cairo_t *cr = cairo_create(surface);
      PangoLayout *layout = create_layout_with_dpi(cr);
  
      /* Get the font width */
      gint width;
      pango_layout_set_font_description(layout, savedFont->specific.pango_desc);
  
      if (is_markup)
          pango_layout_set_markup(layout, text, text_len);
      else
          pango_layout_set_text(layout, text, text_len);
  
      pango_cairo_update_layout(cr, layout);
      pango_layout_get_pixel_size(layout, &width, NULL);
  
      /* Free resources */
      g_object_unref(layout);
      cairo_destroy(cr);
      cairo_surface_destroy(surface);
  
      return width;
  }
  #endif
  
  /*
   * Loads a font for usage, also getting its metrics. If fallback is true,
   * the fonts 'fixed' or '-misc-*' will be loaded instead of exiting. If any
   * font was previously loaded, it will be freed.
   *
   */
  i3Font load_font(const char *pattern, const bool fallback) {
      /* if any font was previously loaded, free it now */
      free_font();
  
      i3Font font;
      font.type = FONT_TYPE_NONE;
  
      /* No XCB connction, return early because we're just validating the
       * configuration file. */
      if (conn == NULL) {
          return font;
      }
  
  #if PANGO_SUPPORT
      /* Try to load a pango font if specified */
      if (strlen(pattern) > strlen("pango:") && !strncmp(pattern, "pango:", strlen("pango:"))) {
          const char *font_pattern = pattern + strlen("pango:");
          if (load_pango_font(&font, font_pattern)) {
              font.pattern = sstrdup(pattern);
              return font;
          }
      } else if (strlen(pattern) > strlen("xft:") && !strncmp(pattern, "xft:", strlen("xft:"))) {
          const char *font_pattern = pattern + strlen("xft:");
          if (load_pango_font(&font, font_pattern)) {
              font.pattern = sstrdup(pattern);
              return font;
          }
      }
  #endif
  
      /* Send all our requests first */
      font.specific.xcb.id = xcb_generate_id(conn);
      xcb_void_cookie_t font_cookie = xcb_open_font_checked(conn, font.specific.xcb.id,
                                                            strlen(pattern), pattern);
      xcb_query_font_cookie_t info_cookie = xcb_query_font(conn, font.specific.xcb.id);
  
      /* Check for errors. If errors, fall back to default font. */
      xcb_generic_error_t *error;
      error = xcb_request_check(conn, font_cookie);
  
      /* If we fail to open font, fall back to 'fixed' */
      if (fallback && error != NULL) {
          ELOG("Could not open font %s (X error %d). Trying fallback to 'fixed'.\n",
               pattern, error->error_code);
          pattern = "fixed";
          font_cookie = xcb_open_font_checked(conn, font.specific.xcb.id,
                                              strlen(pattern), pattern);
          info_cookie = xcb_query_font(conn, font.specific.xcb.id);
  
          /* Check if we managed to open 'fixed' */
          error = xcb_request_check(conn, font_cookie);
  
          /* Fall back to '-misc-*' if opening 'fixed' fails. */
          if (error != NULL) {
              ELOG("Could not open fallback font 'fixed', trying with '-misc-*'.\n");
              pattern = "-misc-*";
              font_cookie = xcb_open_font_checked(conn, font.specific.xcb.id,
                                                  strlen(pattern), pattern);
              info_cookie = xcb_query_font(conn, font.specific.xcb.id);
  
              if ((error = xcb_request_check(conn, font_cookie)) != NULL)
                  errx(EXIT_FAILURE, "Could open neither requested font nor fallbacks "
                                     "(fixed or -misc-*): X11 error %d",
                       error->error_code);
          }
      }
  
      font.pattern = sstrdup(pattern);
      LOG("Using X font %s\n", pattern);
  
      /* Get information (height/name) for this font */
      if (!(font.specific.xcb.info = xcb_query_font_reply(conn, info_cookie, NULL)))
          errx(EXIT_FAILURE, "Could not load font \"%s\"", pattern);
  
      /* Get the font table, if possible */
      if (xcb_query_font_char_infos_length(font.specific.xcb.info) == 0)
          font.specific.xcb.table = NULL;
      else
          font.specific.xcb.table = xcb_query_font_char_infos(font.specific.xcb.info);
  
      /* Calculate the font height */
      font.height = font.specific.xcb.info->font_ascent + font.specific.xcb.info->font_descent;
  
      /* Set the font type and return successfully */
      font.type = FONT_TYPE_XCB;
      return font;
  }
  
  /*
   * Defines the font to be used for the forthcoming calls.
   *
   */
  void set_font(i3Font *font) {
      savedFont = font;
  }
  
  /*
   * Frees the resources taken by the current font. If no font was previously
   * loaded, it simply returns.
   *
   */
  void free_font(void) {
      /* if there is no saved font, simply return */
      if (savedFont == NULL)
          return;
  
      free(savedFont->pattern);
      switch (savedFont->type) {
          case FONT_TYPE_NONE:
              /* Nothing to do */
              break;
          case FONT_TYPE_XCB: {
              /* Close the font and free the info */
              xcb_close_font(conn, savedFont->specific.xcb.id);
              if (savedFont->specific.xcb.info)
                  free(savedFont->specific.xcb.info);
              break;
          }
  #if PANGO_SUPPORT
          case FONT_TYPE_PANGO:
              /* Free the font description */
              pango_font_description_free(savedFont->specific.pango_desc);
              break;
  #endif
          default:
              assert(false);
              break;
      }
  
      savedFont = NULL;
  }
  
  /*
   * Defines the colors to be used for the forthcoming draw_text calls.
   *
   */
  void set_font_colors(xcb_gcontext_t gc, uint32_t foreground, uint32_t background) {
      assert(savedFont != NULL);
  
      switch (savedFont->type) {
          case FONT_TYPE_NONE:
              /* Nothing to do */
              break;
          case FONT_TYPE_XCB: {
              /* Change the font and colors in the GC */
              uint32_t mask = XCB_GC_FOREGROUND | XCB_GC_BACKGROUND | XCB_GC_FONT;
              uint32_t values[] = {foreground, background, savedFont->specific.xcb.id};
              xcb_change_gc(conn, gc, mask, values);
              break;
          }
  #if PANGO_SUPPORT
          case FONT_TYPE_PANGO:
              /* Save the foreground font */
              pango_font_red = ((foreground >> 16) & 0xff) / 255.0;
              pango_font_green = ((foreground >> 8) & 0xff) / 255.0;
              pango_font_blue = (foreground & 0xff) / 255.0;
              break;
  #endif
          default:
              assert(false);
              break;
      }
  }
  
  static int predict_text_width_xcb(const xcb_char2b_t *text, size_t text_len);
  
  static void draw_text_xcb(const xcb_char2b_t *text, size_t text_len, xcb_drawable_t drawable,
                            xcb_gcontext_t gc, int x, int y, int max_width) {
      /* X11 coordinates for fonts start at the baseline */
      int pos_y = y + savedFont->specific.xcb.info->font_ascent;
  
      /* The X11 protocol limits text drawing to 255 chars, so we may need
       * multiple calls */
      int offset = 0;
      for (;;) {
          /* Calculate the size of this chunk */
          int chunk_size = (text_len > 255 ? 255 : text_len);
          const xcb_char2b_t *chunk = text + offset;
  
          /* Draw it */
          xcb_image_text_16(conn, chunk_size, drawable, gc, x, pos_y, chunk);
  
          /* Advance the offset and length of the text to draw */
          offset += chunk_size;
          text_len -= chunk_size;
  
          /* Check if we're done */
          if (text_len == 0)
              break;
  
          /* Advance pos_x based on the predicted text width */
          x += predict_text_width_xcb(chunk, chunk_size);
      }
  }
  
  /*
   * Draws text onto the specified X drawable (normally a pixmap) at the
   * specified coordinates (from the top left corner of the leftmost, uppermost
   * glyph) and using the provided gc.
   *
   * Text must be specified as an i3String.
   *
   */
  void draw_text(i3String *text, xcb_drawable_t drawable,
                 xcb_gcontext_t gc, int x, int y, int max_width) {
      assert(savedFont != NULL);
  
      switch (savedFont->type) {
          case FONT_TYPE_NONE:
              /* Nothing to do */
              return;
          case FONT_TYPE_XCB:
              draw_text_xcb(i3string_as_ucs2(text), i3string_get_num_glyphs(text),
                            drawable, gc, x, y, max_width);
              break;
  #if PANGO_SUPPORT
          case FONT_TYPE_PANGO:
              /* Render the text using Pango */
              draw_text_pango(i3string_as_utf8(text), i3string_get_num_bytes(text),
                              drawable, x, y, max_width, i3string_is_markup(text));
              return;
  #endif
          default:
              assert(false);
      }
  }
  
  /*
   * ASCII version of draw_text to print static strings.
   *
   */
  void draw_text_ascii(const char *text, xcb_drawable_t drawable,
                       xcb_gcontext_t gc, int x, int y, int max_width) {
      assert(savedFont != NULL);
  
      switch (savedFont->type) {
          case FONT_TYPE_NONE:
              /* Nothing to do */
              return;
          case FONT_TYPE_XCB: {
              size_t text_len = strlen(text);
              if (text_len > 255) {
                  /* The text is too long to draw it directly to X */
                  i3String *str = i3string_from_utf8(text);
                  draw_text(str, drawable, gc, x, y, max_width);
                  i3string_free(str);
              } else {
                  /* X11 coordinates for fonts start at the baseline */
                  int pos_y = y + savedFont->specific.xcb.info->font_ascent;
  
                  xcb_image_text_8(conn, text_len, drawable, gc, x, pos_y, text);
              }
              break;
          }
  #if PANGO_SUPPORT
          case FONT_TYPE_PANGO:
              /* Render the text using Pango */
              draw_text_pango(text, strlen(text),
                              drawable, x, y, max_width, false);
              return;
  #endif
          default:
              assert(false);
      }
  }
  
  static int xcb_query_text_width(const xcb_char2b_t *text, size_t text_len) {
      /* Make the user know we’re using the slow path, but only once. */
      static bool first_invocation = true;
      if (first_invocation) {
          fprintf(stderr, "Using slow code path for text extents\n");
          first_invocation = false;
      }
  
      /* Query the text width */
      xcb_generic_error_t *error;
      xcb_query_text_extents_cookie_t cookie = xcb_query_text_extents(conn,
                                                                      savedFont->specific.xcb.id, text_len, (xcb_char2b_t *)text);
      xcb_query_text_extents_reply_t *reply = xcb_query_text_extents_reply(conn,
                                                                           cookie, &error);
      if (reply == NULL) {
          /* We return a safe estimate because a rendering error is better than
           * a crash. Plus, the user will see the error in their log. */
          fprintf(stderr, "Could not get text extents (X error code %d)\n",
                  error->error_code);
          return savedFont->specific.xcb.info->max_bounds.character_width * text_len;
      }
  
      int width = reply->overall_width;
      free(reply);
      return width;
  }
  
  static int predict_text_width_xcb(const xcb_char2b_t *input, size_t text_len) {
      if (text_len == 0)
          return 0;
  
      int width;
      if (savedFont->specific.xcb.table == NULL) {
          /* If we don't have a font table, fall back to querying the server */
          width = xcb_query_text_width(input, text_len);
      } else {
          /* Save some pointers for convenience */
          xcb_query_font_reply_t *font_info = savedFont->specific.xcb.info;
          xcb_charinfo_t *font_table = savedFont->specific.xcb.table;
  
          /* Calculate the width using the font table */
          width = 0;
          for (size_t i = 0; i < text_len; i++) {
              xcb_charinfo_t *info;
              int row = input[i].byte1;
              int col = input[i].byte2;
  
              if (row < font_info->min_byte1 ||
                  row > font_info->max_byte1 ||
                  col < font_info->min_char_or_byte2 ||
                  col > font_info->max_char_or_byte2)
                  continue;
  
              /* Don't you ask me, how this one works… (Merovius) */
              info = &font_table[((row - font_info->min_byte1) *
                                  (font_info->max_char_or_byte2 - font_info->min_char_or_byte2 + 1)) +
                                 (col - font_info->min_char_or_byte2)];
  
              if (info->character_width != 0 ||
                  (info->right_side_bearing |
                   info->left_side_bearing |
                   info->ascent |
                   info->descent) != 0) {
                  width += info->character_width;
              }
          }
      }
  
      return width;
  }
  
  /*
   * Predict the text width in pixels for the given text. Text must be
   * specified as an i3String.
   *
   */
  int predict_text_width(i3String *text) {
      assert(savedFont != NULL);
  
      switch (savedFont->type) {
          case FONT_TYPE_NONE:
              /* Nothing to do */
              return 0;
          case FONT_TYPE_XCB:
              return predict_text_width_xcb(i3string_as_ucs2(text), i3string_get_num_glyphs(text));
  #if PANGO_SUPPORT
          case FONT_TYPE_PANGO:
              /* Calculate extents using Pango */
              return predict_text_width_pango(i3string_as_utf8(text), i3string_get_num_bytes(text),
                                              i3string_is_markup(text));
  #endif
          default:
              assert(false);
              return 0;
      }
  }
  