pango-renderer.c

Pango is a library for layout and rendering of text, with an emphasis on internationalization. Pang

 **/
void
pango_renderer_draw_layout_line (PangoRenderer    *renderer,
				 PangoLayoutLine  *line,
				 int               x,
				 int               y)
{
  int x_off = 0;
  int glyph_string_width;
  LineState state;
  GSList *l;
  gboolean got_overall = FALSE;
  PangoRectangle overall_rect;

  g_return_if_fail (PANGO_IS_RENDERER_FAST (renderer));

  /* We only change the matrix if the renderer isn't already
   * active.
   */
  if (!renderer->active_count)
    {
      PangoContext *context = pango_layout_get_context (line->layout);
      pango_renderer_set_matrix (renderer,
				 pango_context_get_matrix (context));
    }

  pango_renderer_activate (renderer);

  renderer->priv->line = line;
  renderer->priv->line_state = &state;

  state.underline = PANGO_UNDERLINE_NONE;
  state.strikethrough = FALSE;

  for (l = line->runs; l; l = l->next)
    {
      PangoFontMetrics *metrics;
      gint rise;
      PangoLayoutRun *run = l->data;
      PangoAttrShape *shape_attr;
      PangoRectangle ink_rect, *ink = NULL;
      PangoRectangle logical_rect, *logical = NULL;

      if (run->item->analysis.flags & PANGO_ANALYSIS_FLAG_CENTERED_BASELINE)
	logical = &logical_rect;

      pango_renderer_prepare_run (renderer, run);

      get_item_properties (run->item, &rise, &shape_attr);

      if (shape_attr)
	{
	  ink = &ink_rect;
	  logical = &logical_rect;
          _pango_shape_get_extents (run->glyphs->num_glyphs,
				    &shape_attr->ink_rect,
				    &shape_attr->logical_rect,
				    ink,
				    logical);
	  glyph_string_width = logical->width;
	}
      else
	{
	  if (renderer->underline != PANGO_UNDERLINE_NONE ||
	      renderer->strikethrough)
	    {
	      ink = &ink_rect;
	      logical = &logical_rect;
	    }
	  if (G_UNLIKELY (ink || logical))
	    pango_glyph_string_extents (run->glyphs, run->item->analysis.font,
					ink, logical);
	  if (logical)
	    glyph_string_width = logical_rect.width;
	  else
	    glyph_string_width = pango_glyph_string_get_width (run->glyphs);
	}

      state.logical_rect_end = x + x_off + glyph_string_width;

      if (run->item->analysis.flags & PANGO_ANALYSIS_FLAG_CENTERED_BASELINE)
	{
	  gboolean is_hinted = ((logical_rect.y | logical_rect.height) & (PANGO_SCALE - 1)) == 0;
	  int adjustment = logical_rect.y + logical_rect.height / 2;

	  if (is_hinted)
	    adjustment = PANGO_UNITS_ROUND (adjustment);

	  rise += adjustment;
	}


      if (renderer->priv->color_set[PANGO_RENDER_PART_BACKGROUND])
	{
	  if (!got_overall)
	    {
	      pango_layout_line_get_extents (line, NULL, &overall_rect);
	      got_overall = TRUE;
	    }

	  pango_renderer_draw_rectangle (renderer,
					 PANGO_RENDER_PART_BACKGROUND,
					 x + x_off,
					 y + overall_rect.y,
					 glyph_string_width,
					 overall_rect.height);
	}

      if (shape_attr)
	{
	  draw_shaped_glyphs (renderer, run->glyphs, shape_attr, x + x_off, y - rise);
	}
      else
	{
	  pango_renderer_draw_glyphs (renderer,
				      run->item->analysis.font, run->glyphs,
				      x + x_off, y - rise);
	}

      if (renderer->underline != PANGO_UNDERLINE_NONE ||
	  renderer->strikethrough)
	{
	  metrics = pango_font_get_metrics (run->item->analysis.font,
					    run->item->analysis.language);

	  if (renderer->underline != PANGO_UNDERLINE_NONE)
	    add_underline (renderer, &state,metrics,
			   x + x_off, y - rise,
			   ink, logical);

	  if (renderer->strikethrough)
	    add_strikethrough (renderer, &state, metrics,
			       x + x_off, y - rise,
			       ink, logical);

	  pango_font_metrics_unref (metrics);
	}

      if (renderer->underline == PANGO_UNDERLINE_NONE &&
	  state.underline != PANGO_UNDERLINE_NONE)
	draw_underline (renderer, &state);

      if (!renderer->strikethrough && state.strikethrough)
	draw_strikethrough (renderer, &state);

      x_off += glyph_string_width;
    }

  /* Finish off any remaining underlines
   */
  draw_underline (renderer, &state);
  draw_strikethrough (renderer, &state);

  renderer->priv->line_state = NULL;
  renderer->priv->line = NULL;

  pango_renderer_deactivate (renderer);
}

/**
 * pango_renderer_draw_glyphs:
 * @renderer: a #PangoRenderer
 * @font: a #PangoFont
 * @glyphs: a #PangoGlyphString
 * @x: X position of left edge of baseline, in user space coordinates
 *   in Pango units.
 * @y: Y position of left edge of baseline, in user space coordinates
 *    in Pango units.
 *
 * Draws the glyphs in @glyphs with the specified #PangoRenderer.
 *
 * Since: 1.8
 **/
void
pango_renderer_draw_glyphs (PangoRenderer    *renderer,
			    PangoFont        *font,
			    PangoGlyphString *glyphs,
			    int               x,
			    int               y)
{
  g_return_if_fail (PANGO_IS_RENDERER_FAST (renderer));

  pango_renderer_activate (renderer);

  PANGO_RENDERER_GET_CLASS (renderer)->draw_glyphs (renderer, font, glyphs, x, y);

  pango_renderer_deactivate (renderer);
}

static void
pango_renderer_default_draw_glyphs (PangoRenderer    *renderer,
				    PangoFont        *font,
				    PangoGlyphString *glyphs,
				    int               x,
				    int               y)
{
  int i;
  int x_position = 0;

  for (i = 0; i < glyphs->num_glyphs; i++)
    {
      PangoGlyphInfo *gi = &glyphs->glyphs[i];
      Point p;

      to_device (renderer->matrix,
		 x + x_position + gi->geometry.x_offset,
		 y +              gi->geometry.y_offset,
		 &p);

      pango_renderer_draw_glyph (renderer, font, gi->glyph, p.x, p.y);

      x_position += gi->geometry.width;
    }
}

/**
 * pango_renderer_draw_rectangle:
 * @renderer: a #PangoRenderer
 * @part: type of object this rectangle is part of
 * @x: X position at which to draw rectangle, in user space coordinates in Pango units
 * @y: Y position at which to draw rectangle, in user space coordinates in Pango units
 * @width: width of rectangle in Pango units in user space coordinates
 * @height: height of rectangle in Pango units in user space coordinates
 *
 * Draws an axis-aligned rectangle in user space coordinates with the
 * specified #PangoRenderer.
 *
 * This should be called while @renderer is already active.  Use
 * pango_renderer_activate() to activate a renderer.
 *
 * Since: 1.8
 **/
void
pango_renderer_draw_rectangle (PangoRenderer   *renderer,
			       PangoRenderPart  part,
			       int              x,
			       int              y,
			       int              width,
			       int              height)
{
  g_return_if_fail (PANGO_IS_RENDERER_FAST (renderer));
  g_return_if_fail (IS_VALID_PART (part));
  g_return_if_fail (renderer->active_count > 0);

  PANGO_RENDERER_GET_CLASS (renderer)->draw_rectangle (renderer, part, x, y, width, height);
}

static int
compare_points (const void *a,
		const void *b)
{
  const Point *pa = a;
  const Point *pb = b;

  if (pa->y < pb->y)
    return -1;
  else if (pa->y > pb->y)
    return 1;
  else if (pa->x < pb->x)
    return -1;
  else if (pa->x > pb->x)
    return 1;
  else
    return 0;
}

static void
draw_rectangle (PangoRenderer   *renderer,
		PangoMatrix     *matrix,
		PangoRenderPart  part,
		int              x,
		int              y,
		int              width,
		int              height)
{
  Point points[4];

  /* Convert the points to device coordinates, and sort
   * in ascending Y order. (Ordering by X for ties)
   */
  to_device (matrix, x, y, &points[0]);
  to_device (matrix, x + width, y, &points[1]);
  to_device (matrix, x, y + height, &points[2]);
  to_device (matrix, x + width, y + height, &points[3]);

  qsort (points, 4, sizeof (Point), compare_points);

  /* There are essentially three cases. (There is a fourth
   * case where trapezoid B is degenerate and we just have
   * two triangles, but we don't need to handle it separately.)
   *
   *     1            2             3
   *
   *     ______       /\           /\
   *    /     /      /A \         /A \
   *   /  B  /      /____\       /____\
   *  /_____/      /  B  /       \  B  \
   *              /_____/         \_____\
   *              \ C  /           \ C  /
   *               \  /             \  /
   *                \/               \/
   */
  if (points[0].y == points[1].y)
    {
     /* Case 1 (pure shear) */
      pango_renderer_draw_trapezoid (renderer, part,                                      /* B */
				     points[0].y, points[0].x, points[1].x,
				     points[2].y, points[2].x, points[3].x);
    }
  else if (points[1].x < points[2].x)
    {
      /* Case 2 */
      double tmp_width = ((points[2].x - points[0].x) * (points[1].y - points[0].y)) / (points[2].y - points[0].y);
      double base_width = tmp_width + points[0].x - points[1].x;

      pango_renderer_draw_trapezoid (renderer, part,                                      /* A */
				     points[0].y, points[0].x, points[0].x,
				     points[1].y, points[1].x, points[1].x + base_width);
      pango_renderer_draw_trapezoid (renderer, part,                                      /* B */
				     points[1].y, points[1].x, points[1].x + base_width,
				     points[2].y, points[2].x - base_width, points[2].x);
      pango_renderer_draw_trapezoid (renderer, part,                                      /* C */
				     points[2].y, points[2].x - base_width, points[2].x,
				     points[3].y, points[3].x, points[3].x);
    }
  else
    {
      /* case 3 */
      double tmp_width = ((points[0].x - points[2].x) * (points[1].y - points[0].y)) / (points[2].y - points[0].y);
      double base_width = tmp_width + points[1].x - points[0].x;

      pango_renderer_draw_trapezoid (renderer, part,                                     /* A */
				     points[0].y, points[0].x, points[0].x,
				     points[1].y,  points[1].x - base_width, points[1].x);
      pango_renderer_draw_trapezoid (renderer, part,                                     /* B */
				     points[1].y, points[1].x - base_width, points[1].x,
				     points[2].y, points[2].x, points[2].x + base_width);
      pango_renderer_draw_trapezoid (renderer, part,                                     /* C */
				     points[2].y, points[2].x, points[2].x + base_width,
				     points[3].y, points[3].x, points[3].x);
    }
}

static void
pango_renderer_default_draw_rectangle (PangoRenderer  *renderer,
				       PangoRenderPart part,
				       int             x,
				       int             y,
				       int             width,
				       int             height)
{
  draw_rectangle (renderer, renderer->matrix, part, x, y, width, height);
}

/**
 * pango_renderer_draw_error_underline:
 * @renderer: a #PangoRenderer
 * @x: X coordinate of underline, in Pango units in user coordinate system
 * @y: Y coordinate of underline, in Pango units in user coordinate system
 * @width: width of underline, in Pango units in user coordinate system
 * @height: height of underline, in Pango units in user coordinate system
 *
 * Draw a squiggly line that approximately covers the given rectangle
 * in the style of an underline used to indicate a spelling error.
 * (The width of the underline is rounded to an integer number
 * of up/down segments and the resulting rectangle is centered
 * in the original rectangle)
 *
 * This should be called while @renderer is already active.  Use
 * pango_renderer_activate() to activate a renderer.
 *
 * Since: 1.8
 **/
void
pango_renderer_draw_error_underline (PangoRenderer *renderer,
				     int            x,
				     int            y,
				     int            width,
				     int            height)
{
  g_return_if_fail (PANGO_IS_RENDERER_FAST (renderer));
  g_return_if_fail (renderer->active_count > 0);

  PANGO_RENDERER_GET_CLASS (renderer)->draw_error_underline (renderer, x, y, width, height);
}

/* We are drawing an error underline that looks like one of:
 *
 *  /\      /\      /\        /\      /\               -
 * /  \    /  \    /  \      /  \    /  \              |
 * \   \  /\   \  /   /      \   \  /\   \             |
 *  \   \/B \   \/ C /        \   \/B \   \            | height = HEIGHT_SQUARES * square
 *   \ A \  /\ A \  /          \ A \  /\ A \           |
 *    \   \/  \   \/            \   \/  \   \          |
 *     \  /    \  /              \  /    \  /          |
 *      \/      \/                \/      \/           -
 *      |---|
 *    unit_width = (HEIGHT_SQUARES - 1) * square
 *
 * To do this conveniently, we work in a coordinate system where A,B,C
 * are axis aligned rectangles. (If fonts were square, the diagrams
 * would be clearer)
 *
 *             (0,0)
 *              /\      /\
 *             /  \    /  \
 *            /\  /\  /\  /
 *           /  \/  \/  \/
 *          /    \  /\  /
 *      Y axis    \/  \/
 *                 \  /\
 *                  \/  \
 *                       \ X axis
 *
 * Note that the long side in this coordinate system is HEIGHT_SQUARES + 1
 * units long
 *
 * The diagrams above are shown with HEIGHT_SQUARES an integer, but
 * that is actually incidental; the value 2.5 below seems better than
 * either HEIGHT_SQUARES=3 (a little long and skinny) or
 * HEIGHT_SQUARES=2 (a bit short and stubby)
 */

#define HEIGHT_SQUARES 2.5

static void
get_total_matrix (PangoMatrix       *total,
		  const PangoMatrix *global,
		  int                x,
		  int                y,
		  int                square)
{
  PangoMatrix local;
  gdouble scale = 0.5 * square;

  /* The local matrix translates from the axis aligned coordinate system
   * to the original user space coordinate system.
   */
  local.xx = scale;
  local.xy = - scale;
  local.yx = scale;
  local.yy = scale;
  local.x0 = 0;
  local.y0 = 0;