pango-renderer.c

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

/* Pango
 * pango-renderer.h: Base class for rendering
 *
 * Copyright (C) 2004 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <config.h>
#include <stdlib.h>

#include "pango-renderer.h"
#include "pango-impl-utils.h"

#define N_RENDER_PARTS 4

#define PANGO_IS_RENDERER_FAST(renderer) (renderer != NULL)
#define IS_VALID_PART(part) ((guint)part < N_RENDER_PARTS)

typedef struct _LineState LineState;
typedef struct _Point Point;

struct _Point
{
  double x, y;
};

struct _LineState
{
  PangoUnderline underline;
  PangoRectangle underline_rect;

  gboolean strikethrough;
  PangoRectangle strikethrough_rect;

  int logical_rect_end;
};

struct _PangoRendererPrivate
{
  PangoColor color[N_RENDER_PARTS];
  gboolean color_set[N_RENDER_PARTS];

  PangoLayoutLine *line;
  LineState *line_state;
};

static void pango_renderer_finalize                     (GObject          *gobject);
static void pango_renderer_default_draw_glyphs          (PangoRenderer    *renderer,
							 PangoFont        *font,
							 PangoGlyphString *glyphs,
							 int               x,
							 int               y);
static void pango_renderer_default_draw_rectangle       (PangoRenderer    *renderer,
							 PangoRenderPart   part,
							 int               x,
							 int               y,
							 int               width,
							 int               height);
static void pango_renderer_default_draw_error_underline (PangoRenderer    *renderer,
							 int               x,
							 int               y,
							 int               width,
							 int               height);
static void pango_renderer_default_prepare_run          (PangoRenderer    *renderer,
							 PangoLayoutRun   *run);

static void pango_renderer_prepare_run (PangoRenderer  *renderer,
					PangoLayoutRun *run);

static void
to_device (PangoMatrix *matrix,
	   double       x,
	   double       y,
	   Point       *result)
{
  if (matrix)
    {
      result->x = (x * matrix->xx + y * matrix->xy) / PANGO_SCALE + matrix->x0;
      result->y = (x * matrix->yx + y * matrix->yy) / PANGO_SCALE + matrix->y0;
    }
  else
    {
      result->x = x / PANGO_SCALE;
      result->y = y / PANGO_SCALE;
    }
}

G_DEFINE_ABSTRACT_TYPE (PangoRenderer, pango_renderer, G_TYPE_OBJECT)

static void
pango_renderer_class_init (PangoRendererClass *klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);

  klass->draw_glyphs = pango_renderer_default_draw_glyphs;
  klass->draw_rectangle = pango_renderer_default_draw_rectangle;
  klass->draw_error_underline = pango_renderer_default_draw_error_underline;
  klass->prepare_run = pango_renderer_default_prepare_run;

  gobject_class->finalize = pango_renderer_finalize;

  g_type_class_add_private (gobject_class, sizeof (PangoRendererPrivate));
}

static void
pango_renderer_init (PangoRenderer *renderer)
{
  renderer->priv = G_TYPE_INSTANCE_GET_PRIVATE (renderer,
						PANGO_TYPE_RENDERER,
						PangoRendererPrivate);
  renderer->matrix = NULL;
}

static void
pango_renderer_finalize (GObject *gobject)
{
  PangoRenderer *renderer = PANGO_RENDERER (gobject);

  if (renderer->matrix)
    pango_matrix_free (renderer->matrix);
}

/**
 * pango_renderer_draw_layout:
 * @renderer: a #PangoRenderer
 * @layout: a #PangoLayout
 * @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 @layout with the specified #PangoRenderer.
 *
 * Since: 1.8
 **/
void
pango_renderer_draw_layout (PangoRenderer    *renderer,
			    PangoLayout      *layout,
			    int               x,
			    int               y)
{
  PangoLayoutIter *iter;

  g_return_if_fail (PANGO_IS_RENDERER (renderer));
  g_return_if_fail (PANGO_IS_LAYOUT (layout));

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

  pango_renderer_activate (renderer);

  iter = pango_layout_get_iter (layout);

  do
    {
      PangoRectangle   logical_rect;
      PangoLayoutLine *line;
      int              baseline;

      line = pango_layout_iter_get_line_readonly (iter);

      pango_layout_iter_get_line_extents (iter, NULL, &logical_rect);
      baseline = pango_layout_iter_get_baseline (iter);

      pango_renderer_draw_layout_line (renderer,
				       line,
				       x + logical_rect.x,
				       y + baseline);
    }
  while (pango_layout_iter_next_line (iter));

  pango_layout_iter_free (iter);

  pango_renderer_deactivate (renderer);
}

static void
draw_underline (PangoRenderer *renderer,
		LineState     *state)
{
  PangoRectangle *rect = &state->underline_rect;
  PangoUnderline underline = state->underline;

  state->underline = PANGO_UNDERLINE_NONE;

  switch (underline)
    {
    case PANGO_UNDERLINE_NONE:
      break;
    case PANGO_UNDERLINE_DOUBLE:
      pango_renderer_draw_rectangle (renderer,
				     PANGO_RENDER_PART_UNDERLINE,
				     rect->x,
				     rect->y + 2 * rect->height,
				     rect->width,
				     rect->height);
      /* Fall through */
    case PANGO_UNDERLINE_SINGLE:
    case PANGO_UNDERLINE_LOW:
      pango_renderer_draw_rectangle (renderer,
				     PANGO_RENDER_PART_UNDERLINE,
				     rect->x,
				     rect->y,
				     rect->width,
				     rect->height);
      break;
    case PANGO_UNDERLINE_ERROR:
      pango_renderer_draw_error_underline (renderer,
					   rect->x,
					   rect->y,
					   rect->width,
					   3 * rect->height);
      break;
    }
}

static void
draw_strikethrough (PangoRenderer *renderer,
		    LineState     *state)
{
  PangoRectangle *rect = &state->strikethrough_rect;
  gboolean strikethrough = state->strikethrough;

  state->strikethrough = FALSE;

  if (strikethrough)
    pango_renderer_draw_rectangle (renderer,
				   PANGO_RENDER_PART_STRIKETHROUGH,
				   rect->x,
				   rect->y,
				   rect->width,
				   rect->height);
}

static void
handle_line_state_change (PangoRenderer  *renderer,
			  PangoRenderPart part)
{
  LineState *state = renderer->priv->line_state;
  if (!state)
    return;

  if (part == PANGO_RENDER_PART_UNDERLINE &&
      state->underline != PANGO_UNDERLINE_NONE)
    {
      PangoRectangle *rect = &state->underline_rect;

      rect->width = state->logical_rect_end - rect->x;
      draw_underline (renderer, state);
      state->underline = renderer->underline;
      rect->x = state->logical_rect_end;
      rect->width = 0;
    }

  if (part == PANGO_RENDER_PART_STRIKETHROUGH &&
      state->strikethrough)
    {
      PangoRectangle *rect = &state->strikethrough_rect;

      rect->width = state->logical_rect_end - rect->x;
      draw_strikethrough (renderer, state);
      state->strikethrough = renderer->strikethrough;
      rect->x = state->logical_rect_end;
      rect->width = 0;
    }
}

static void
add_underline (PangoRenderer    *renderer,
	       LineState        *state,
	       PangoFontMetrics *metrics,
	       int               base_x,
	       int               base_y,
	       PangoRectangle   *ink_rect,
	       PangoRectangle   *logical_rect)
{
  PangoRectangle *current_rect = &state->underline_rect;
  PangoRectangle new_rect;

  int underline_thickness = pango_font_metrics_get_underline_thickness (metrics);
  int underline_position = pango_font_metrics_get_underline_position (metrics);

  new_rect.x = base_x + logical_rect->x;
  new_rect.width = logical_rect->width;
  new_rect.height = underline_thickness;
  new_rect.y = base_y;

  switch (renderer->underline)
    {
    case PANGO_UNDERLINE_NONE:
      g_assert_not_reached ();
      break;
    case PANGO_UNDERLINE_SINGLE:
    case PANGO_UNDERLINE_DOUBLE:
    case PANGO_UNDERLINE_ERROR:
      new_rect.y -= underline_position;
      break;
    case PANGO_UNDERLINE_LOW:
      new_rect.y += ink_rect->y + ink_rect->height + underline_thickness;
      break;
    }

  if (renderer->underline == state->underline &&
      new_rect.y == current_rect->y &&
      new_rect.height == current_rect->height)
    {
      current_rect->width = new_rect.x + new_rect.width - current_rect->x;
    }
  else
    {
      draw_underline (renderer, state);

      *current_rect = new_rect;
      state->underline = renderer->underline;
    }
}

static void
add_strikethrough (PangoRenderer    *renderer,
		   LineState        *state,
		   PangoFontMetrics *metrics,
		   int               base_x,
		   int               base_y,
		   PangoRectangle   *ink_rect,
		   PangoRectangle   *logical_rect)
{
  PangoRectangle *current_rect = &state->strikethrough_rect;
  PangoRectangle new_rect;

  int strikethrough_thickness = pango_font_metrics_get_strikethrough_thickness (metrics);
  int strikethrough_position = pango_font_metrics_get_strikethrough_position (metrics);

  new_rect.x = base_x + logical_rect->x;
  new_rect.width = logical_rect->width;
  new_rect.y = base_y - strikethrough_position;
  new_rect.height = strikethrough_thickness;

  if (state->strikethrough &&
      new_rect.y == current_rect->y &&
      new_rect.height == current_rect->height)
    {
      current_rect->width = new_rect.x + new_rect.width - current_rect->x;
    }
  else
    {
      draw_strikethrough (renderer, state);

      *current_rect = new_rect;
      state->strikethrough = TRUE;
    }
}

static void
get_item_properties (PangoItem       *item,
		     gint            *rise,
		     PangoAttrShape **shape_attr)
{
  GSList *l;

  if (rise)
    *rise = 0;

  if (shape_attr)
    *shape_attr = NULL;

  for (l = item->analysis.extra_attrs; l; l = l->next)
    {
      PangoAttribute *attr = l->data;

      switch (attr->klass->type)
	{
	case PANGO_ATTR_SHAPE:
	  if (shape_attr)
	    *shape_attr = (PangoAttrShape *)attr;
	  break;

	case PANGO_ATTR_RISE:
	  if (rise)
	    *rise = ((PangoAttrInt *)attr)->value;
	  break;

	default:
	  break;
	}
    }
}

static void
draw_shaped_glyphs (PangoRenderer    *renderer,
		    PangoGlyphString *glyphs,
		    PangoAttrShape   *attr,
		    int               x,
		    int               y)
{
  PangoRendererClass *class = PANGO_RENDERER_GET_CLASS (renderer);
  int i;

  if (!class->draw_shape)
    return;

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

      class->draw_shape (renderer, attr, x, y);

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


/**
 * pango_renderer_draw_layout_line:
 * @renderer: a #PangoRenderer
 * @line: a #PangoLayoutLine
 * @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 @line with the specified #PangoRenderer.
 *
 * Since: 1.8