mutter/pango/cogl-pango-render.c

/*
 * Clutter.
 *
 * An OpenGL based 'interactive canvas' library.
 *
 * Authored By Matthew Allum  <mallum@openedhand.com>
 *
 * Copyright (C) 2008 OpenedHand
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifndef PANGO_ENABLE_BACKEND
#define PANGO_ENABLE_BACKEND 1
#endif

#include <pango/pango-fontmap.h>
#include <pango/pangocairo.h>
#include <pango/pango-renderer.h>
#include <cairo.h>

#include "cogl/cogl-debug.h"
#include "cogl-pango-private.h"
#include "cogl-pango-glyph-cache.h"
#include "cogl-pango-display-list.h"

struct _CoglPangoRenderer
{
  PangoRenderer parent_instance;

  /* The material used to texture from the glyph cache with */
  CoglMaterial *glyph_material;
  /* The material used for solid fills. (boxes, rectangles + trapezoids) */
  CoglMaterial *solid_material;

  /* Caches of glyphs as textures */
  CoglPangoGlyphCache *glyph_cache;

  /* The current display list that is being built */
  CoglPangoDisplayList *display_list;
};

struct _CoglPangoRendererClass
{
  PangoRendererClass class_instance;
};

typedef struct _CoglPangoRendererQdata CoglPangoRendererQdata;

/* An instance of this struct gets attached to each PangoLayout to
   cache the VBO and to detect changes to the layout */
struct _CoglPangoRendererQdata
{
  CoglPangoRenderer *renderer;
  /* The cache of the geometry for the layout */
  CoglPangoDisplayList *display_list;
  /* A reference to the first line of the layout. This is just used to
     detect changes */
  PangoLayoutLine *first_line;
};

static void
_cogl_pango_ensure_glyph_cache_for_layout_line (PangoLayoutLine *line);

static void
cogl_pango_renderer_draw_glyph (CoglPangoRenderer        *priv,
                                CoglPangoGlyphCacheValue *cache_value,
                                float                     x1,
                                float                     y1)
{
  float x2, y2;

  g_return_if_fail (priv->display_list != NULL);

  x2 = x1 + (float) cache_value->draw_width;
  y2 = y1 + (float) cache_value->draw_height;

  _cogl_pango_display_list_add_texture (priv->display_list,
                                        cache_value->texture,
                                        x1, y1, x2, y2,
                                        cache_value->tx1,
                                        cache_value->ty1,
                                        cache_value->tx2,
                                        cache_value->ty2);
}

static void cogl_pango_renderer_finalize (GObject *object);
static void cogl_pango_renderer_draw_glyphs (PangoRenderer    *renderer,
                                             PangoFont        *font,
                                             PangoGlyphString *glyphs,
                                             int               x,
                                             int               y);
static void cogl_pango_renderer_draw_rectangle (PangoRenderer    *renderer,
                                                PangoRenderPart   part,
                                                int               x,
                                                int               y,
                                                int               width,
                                                int               height);
static void cogl_pango_renderer_draw_trapezoid (PangoRenderer    *renderer,
                                                PangoRenderPart   part,
                                                double            y1,
                                                double            x11,
                                                double            x21,
                                                double            y2,
                                                double            x12,
                                                double            x22);

G_DEFINE_TYPE (CoglPangoRenderer, cogl_pango_renderer, PANGO_TYPE_RENDERER);

static void
cogl_pango_renderer_init (CoglPangoRenderer *priv)
{
  priv->glyph_material = cogl_material_new ();

  /* The default combine mode of materials is to modulate (A x B) the texture
   * RGBA channels with the RGBA channels of the previous layer (which in our
   * case is just the font color)
   *
   * Since the RGB for an alpha texture is defined as 0, this gives us:
   *
   *  result.rgb = color.rgb * 0
   *  result.a = color.a * texture.a
   *
   * What we want is premultiplied rgba values:
   *
   *  result.rgba = color.rgb * texture.a
   *  result.a = color.a * texture.a
   */
  cogl_material_set_layer_combine (priv->glyph_material, 0, /* layer */
                                   "RGBA = MODULATE (PREVIOUS, TEXTURE[A])",
                                   NULL);
  cogl_material_set_layer_wrap_mode (priv->glyph_material, 0,
                                     COGL_MATERIAL_WRAP_MODE_CLAMP_TO_EDGE);

  priv->solid_material = cogl_material_new ();

  priv->glyph_cache = cogl_pango_glyph_cache_new ();

  _cogl_pango_renderer_set_use_mipmapping (priv, FALSE);
}

static void
cogl_pango_renderer_class_init (CoglPangoRendererClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);
  PangoRendererClass *renderer_class = PANGO_RENDERER_CLASS (klass);

  object_class->finalize = cogl_pango_renderer_finalize;

  renderer_class->draw_glyphs = cogl_pango_renderer_draw_glyphs;
  renderer_class->draw_rectangle = cogl_pango_renderer_draw_rectangle;
  renderer_class->draw_trapezoid = cogl_pango_renderer_draw_trapezoid;
}

static void
cogl_pango_renderer_finalize (GObject *object)
{
  CoglPangoRenderer *priv = COGL_PANGO_RENDERER (object);

  cogl_pango_glyph_cache_free (priv->glyph_cache);

  G_OBJECT_CLASS (cogl_pango_renderer_parent_class)->finalize (object);
}

static CoglPangoRenderer *
cogl_pango_get_renderer_from_context (PangoContext *context)
{
  PangoFontMap      *font_map;
  PangoRenderer     *renderer;
  CoglPangoFontMap  *font_map_priv;

  font_map = pango_context_get_font_map (context);
  g_return_val_if_fail (COGL_PANGO_IS_FONT_MAP (font_map), NULL);

  font_map_priv = COGL_PANGO_FONT_MAP (font_map);
  renderer = cogl_pango_font_map_get_renderer (font_map_priv);
  g_return_val_if_fail (COGL_PANGO_IS_RENDERER (renderer), NULL);

  return COGL_PANGO_RENDERER (renderer);
}

static GQuark
cogl_pango_render_get_qdata_key (void)
{
  static GQuark key = 0;

  if (G_UNLIKELY (key == 0))
    key = g_quark_from_static_string ("CoglPangoDisplayList");

  return key;
}

static void
cogl_pango_render_qdata_forget_display_list (CoglPangoRendererQdata *qdata)
{
  if (qdata->display_list)
    {
      _cogl_pango_glyph_cache_remove_reorganize_callback
        (qdata->renderer->glyph_cache,
         (GHookFunc) cogl_pango_render_qdata_forget_display_list,
         qdata);

      _cogl_pango_display_list_free (qdata->display_list);

      qdata->display_list = NULL;
    }
}

static void
cogl_pango_render_qdata_destroy (CoglPangoRendererQdata *qdata)
{
  cogl_pango_render_qdata_forget_display_list (qdata);
  if (qdata->first_line)
    pango_layout_line_unref (qdata->first_line);
  g_slice_free (CoglPangoRendererQdata, qdata);
}

/**
 * cogl_pango_render_layout_subpixel:
 * @layout: a #PangoLayout
 * @x: FIXME
 * @y: FIXME
 * @color: color to use when rendering the layout
 * @flags: flags to pass to the renderer
 *
 * FIXME
 *
 * Since: 1.0
 */
void
cogl_pango_render_layout_subpixel (PangoLayout     *layout,
				   int              x,
				   int              y,
				   const CoglColor *color,
				   int              flags)
{
  PangoContext           *context;
  CoglPangoRenderer      *priv;
  CoglPangoRendererQdata *qdata;

  context = pango_layout_get_context (layout);
  priv = cogl_pango_get_renderer_from_context (context);
  if (G_UNLIKELY (!priv))
    return;

  qdata = g_object_get_qdata (G_OBJECT (layout),
                              cogl_pango_render_get_qdata_key ());

  if (qdata == NULL)
    {
      qdata = g_slice_new0 (CoglPangoRendererQdata);
      qdata->renderer = priv;
      g_object_set_qdata_full (G_OBJECT (layout),
                               cogl_pango_render_get_qdata_key (),
                               qdata,
                               (GDestroyNotify)
                               cogl_pango_render_qdata_destroy);
    }

  /* Check if the layout has changed since the last build of the
     display list. This trick was suggested by Behdad Esfahbod here:
     http://mail.gnome.org/archives/gtk-i18n-list/2009-May/msg00019.html */
  if (qdata->display_list && qdata->first_line
      && qdata->first_line->layout != layout)
    cogl_pango_render_qdata_forget_display_list (qdata);

  if (qdata->display_list == NULL)
    {
      cogl_pango_ensure_glyph_cache_for_layout (layout);

      qdata->display_list = _cogl_pango_display_list_new ();

      /* Register for notification of when the glyph cache changes so
         we can rebuild the display list */
      _cogl_pango_glyph_cache_add_reorganize_callback
        (priv->glyph_cache,
         (GHookFunc) cogl_pango_render_qdata_forget_display_list,
         qdata);

      priv->display_list = qdata->display_list;
      pango_renderer_draw_layout (PANGO_RENDERER (priv), layout, 0, 0);
      priv->display_list = NULL;
    }

  cogl_push_matrix ();
  cogl_translate (x / (gfloat) PANGO_SCALE, y / (gfloat) PANGO_SCALE, 0);
  _cogl_pango_display_list_render (qdata->display_list,
                                   color,
                                   priv->glyph_material,
                                   priv->solid_material);
  cogl_pop_matrix ();

  /* Keep a reference to the first line of the layout so we can detect
     changes */
  if (qdata->first_line)
    {
      pango_layout_line_unref (qdata->first_line);
      qdata->first_line = NULL;
    }
  if (pango_layout_get_line_count (layout) > 0)
    {
      qdata->first_line = pango_layout_get_line (layout, 0);
      pango_layout_line_ref (qdata->first_line);
    }
}

/**
 * cogl_pango_render_layout:
 * @layout: a #PangoLayout
 * @x: X coordinate to render the layout at
 * @y: Y coordinate to render the layout at
 * @color: color to use when rendering the layout
 * @flags: flags to pass to the renderer
 *
 * Renders @layout.
 *
 * Since: 1.0
 */
void
cogl_pango_render_layout (PangoLayout     *layout,
                          int              x,
                          int              y,
                          const CoglColor *color,
                          int              flags)
{
  cogl_pango_render_layout_subpixel (layout,
                                     x * PANGO_SCALE,
                                     y * PANGO_SCALE,
                                     color,
                                     flags);
}

/**
 * cogl_pango_render_layout_line:
 * @line: a #PangoLayoutLine
 * @x: X coordinate to render the line at
 * @y: Y coordinate to render the line at
 * @color: color to use when rendering the line
 *
 * Renders @line at the given coordinates using the given color.
 *
 * Since: 1.0
 */
void
cogl_pango_render_layout_line (PangoLayoutLine *line,
                               int              x,
                               int              y,
                               const CoglColor *color)
{
  PangoContext      *context;
  CoglPangoRenderer *priv;

  context = pango_layout_get_context (line->layout);
  priv = cogl_pango_get_renderer_from_context (context);
  if (G_UNLIKELY (!priv))
    return;

  priv->display_list = _cogl_pango_display_list_new ();

  _cogl_pango_ensure_glyph_cache_for_layout_line (line);

  pango_renderer_draw_layout_line (PANGO_RENDERER (priv), line, x, y);

  _cogl_pango_display_list_render (priv->display_list,
                                   color,
                                   priv->glyph_material,
                                   priv->solid_material);

  _cogl_pango_display_list_free (priv->display_list);
  priv->display_list = NULL;
}

void
_cogl_pango_renderer_clear_glyph_cache (CoglPangoRenderer *renderer)
{
  cogl_pango_glyph_cache_clear (renderer->glyph_cache);
}

void
_cogl_pango_renderer_set_use_mipmapping (CoglPangoRenderer *renderer,
                                         gboolean value)
{
  if (value)
    cogl_material_set_layer_filters (renderer->glyph_material, 0,
                                     COGL_MATERIAL_FILTER_LINEAR_MIPMAP_LINEAR,
                                     COGL_MATERIAL_FILTER_LINEAR);
  else
    cogl_material_set_layer_filters (renderer->glyph_material, 0,
                                     COGL_MATERIAL_FILTER_LINEAR,
                                     COGL_MATERIAL_FILTER_LINEAR);
}

gboolean
_cogl_pango_renderer_get_use_mipmapping (CoglPangoRenderer *renderer)
{
  const GList *layers = cogl_material_get_layers (renderer->glyph_material);

  g_return_val_if_fail (layers != NULL, FALSE);

  return (cogl_material_layer_get_min_filter (layers->data)
          == COGL_MATERIAL_FILTER_LINEAR_MIPMAP_LINEAR);
}

static CoglPangoGlyphCacheValue *
cogl_pango_renderer_get_cached_glyph (PangoRenderer *renderer,
                                      gboolean       create,
                                      PangoFont     *font,
                                      PangoGlyph     glyph)
{
  CoglPangoRenderer *priv = COGL_PANGO_RENDERER (renderer);

  return cogl_pango_glyph_cache_lookup (priv->glyph_cache, create, font, glyph);
}

static void
cogl_pango_renderer_set_dirty_glyph (PangoFont *font,
                                     PangoGlyph glyph,
                                     CoglPangoGlyphCacheValue *value)
{
  cairo_surface_t *surface;
  cairo_t *cr;
  cairo_scaled_font_t *scaled_font;
  cairo_glyph_t cairo_glyph;

  COGL_NOTE (PANGO, "redrawing glyph %i", glyph);

  surface = cairo_image_surface_create (CAIRO_FORMAT_A8,
                                        value->draw_width,
                                        value->draw_height);
  cr = cairo_create (surface);

  scaled_font = pango_cairo_font_get_scaled_font (PANGO_CAIRO_FONT (font));
  cairo_set_scaled_font (cr, scaled_font);

  cairo_glyph.x = -value->draw_x;
  cairo_glyph.y = -value->draw_y;
  /* The PangoCairo glyph numbers directly map to Cairo glyph
     numbers */
  cairo_glyph.index = glyph;
  cairo_show_glyphs (cr, &cairo_glyph, 1);

  cairo_destroy (cr);
  cairo_surface_flush (surface);

  /* Copy the glyph to the texture */
  cogl_texture_set_region (value->texture,
                           0, /* src_x */
                           0, /* src_y */
                           value->tx_pixel, /* dst_x */
                           value->ty_pixel, /* dst_y */
                           value->draw_width, /* dst_width */
                           value->draw_height, /* dst_height */
                           value->draw_width, /* width */
                           value->draw_height, /* height */
                           COGL_PIXEL_FORMAT_A_8,
                           cairo_image_surface_get_stride (surface),
                           cairo_image_surface_get_data (surface));

  cairo_surface_destroy (surface);
}

static void
_cogl_pango_ensure_glyph_cache_for_layout_line_internal (PangoLayoutLine *line)
{
  PangoContext *context;
  PangoRenderer *renderer;
  GSList *l;

  context = pango_layout_get_context (line->layout);
  renderer =
    PANGO_RENDERER (cogl_pango_get_renderer_from_context (context));

  for (l = line->runs; l; l = l->next)
    {
      PangoLayoutRun *run = l->data;
      PangoGlyphString *glyphs = run->glyphs;
      int i;

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

          /* If the glyph isn't cached then this will reserve
             space for it now. We won't actually draw the glyph
             yet because reserving space could cause all of the
             other glyphs to be moved so we might as well redraw
             them all later once we know that the position is
             settled */
          cogl_pango_renderer_get_cached_glyph (renderer, TRUE,
                                                run->item->analysis.font,
                                                gi->glyph);
        }
    }
}

static void
_cogl_pango_ensure_glyph_cache_for_layout_line (PangoLayoutLine *line)
{
  PangoContext *context;
  CoglPangoRenderer *priv;

  context = pango_layout_get_context (line->layout);
  priv = cogl_pango_get_renderer_from_context (context);

  _cogl_pango_ensure_glyph_cache_for_layout_line_internal (line);

  /* Now that we know all of the positions are settled we'll fill in
     any dirty glyphs */
  _cogl_pango_glyph_cache_set_dirty_glyphs
    (priv->glyph_cache, cogl_pango_renderer_set_dirty_glyph);
}

void
cogl_pango_ensure_glyph_cache_for_layout (PangoLayout *layout)
{
  PangoContext *context;
  CoglPangoRenderer *priv;
  PangoLayoutIter *iter;

  context = pango_layout_get_context (layout);
  priv = cogl_pango_get_renderer_from_context (context);

  g_return_if_fail (PANGO_IS_LAYOUT (layout));

  if ((iter = pango_layout_get_iter (layout)) == NULL)
    return;

  do
    {
      PangoLayoutLine *line;

      line = pango_layout_iter_get_line_readonly (iter);

      _cogl_pango_ensure_glyph_cache_for_layout_line_internal (line);
    }
  while (pango_layout_iter_next_line (iter));

  pango_layout_iter_free (iter);

  /* Now that we know all of the positions are settled we'll fill in
     any dirty glyphs */
  _cogl_pango_glyph_cache_set_dirty_glyphs
    (priv->glyph_cache, cogl_pango_renderer_set_dirty_glyph);
}

static void
cogl_pango_renderer_set_color_for_part (PangoRenderer   *renderer,
                                        PangoRenderPart  part)
{
  PangoColor *pango_color = pango_renderer_get_color (renderer, part);
  CoglPangoRenderer *priv = COGL_PANGO_RENDERER (renderer);

  if (pango_color)
    {
      CoglColor color;

      cogl_color_init_from_4ub (&color,
                                pango_color->red >> 8,
                                pango_color->green >> 8,
                                pango_color->blue >> 8,
                                0xff);

      _cogl_pango_display_list_set_color_override (priv->display_list, &color);
    }
  else
    _cogl_pango_display_list_remove_color_override (priv->display_list);
}

static void
cogl_pango_renderer_draw_box (PangoRenderer *renderer,
                              int            x,
                              int            y,
                              int            width,
                              int            height)
{
  CoglPangoRenderer *priv = COGL_PANGO_RENDERER (renderer);

  g_return_if_fail (priv->display_list != NULL);

  _cogl_pango_display_list_add_rectangle (priv->display_list,
                                          x,
                                          y - height,
                                          x + width,
                                          y);
}

static void
cogl_pango_renderer_get_device_units (PangoRenderer *renderer,
                                      int            xin,
                                      int            yin,
                                      float     *xout,
                                      float     *yout)
{
  const PangoMatrix *matrix;

  if ((matrix = pango_renderer_get_matrix (renderer)))
    {
      /* Convert user-space coords to device coords */
      *xout =  ((xin * matrix->xx + yin * matrix->xy)
				     / PANGO_SCALE + matrix->x0);
      *yout =  ((yin * matrix->yy + xin * matrix->yx)
				     / PANGO_SCALE + matrix->y0);
    }
  else
    {
      *xout = PANGO_PIXELS (xin);
      *yout = PANGO_PIXELS (yin);
    }
}

static void
cogl_pango_renderer_draw_rectangle (PangoRenderer   *renderer,
                                    PangoRenderPart  part,
                                    int              x,
                                    int              y,
                                    int              width,
                                    int              height)
{
  CoglPangoRenderer *priv = COGL_PANGO_RENDERER (renderer);
  float x1, x2, y1, y2;

  g_return_if_fail (priv->display_list != NULL);

  cogl_pango_renderer_set_color_for_part (renderer, part);

  cogl_pango_renderer_get_device_units (renderer,
                                        x, y,
                                        &x1, &y1);
  cogl_pango_renderer_get_device_units (renderer,
                                        x + width, y + height,
                                        &x2, &y2);

  _cogl_pango_display_list_add_rectangle (priv->display_list,
                                          x1, y1, x2, y2);
}

static void
cogl_pango_renderer_draw_trapezoid (PangoRenderer   *renderer,
				    PangoRenderPart  part,
				    double           y1,
				    double           x11,
				    double           x21,
				    double           y2,
				    double           x12,
				    double           x22)
{
  CoglPangoRenderer *priv = COGL_PANGO_RENDERER (renderer);
  float points[8];

  g_return_if_fail (priv->display_list != NULL);

  points[0] =  (x11);
  points[1] =  (y1);
  points[2] =  (x12);
  points[3] =  (y2);
  points[4] =  (x22);
  points[5] = points[3];
  points[6] =  (x21);
  points[7] = points[1];

  cogl_pango_renderer_set_color_for_part (renderer, part);

  _cogl_pango_display_list_add_trapezoid (priv->display_list,
                                          y1,
                                          x11,
                                          x21,
                                          y2,
                                          x12,
                                          x22);
}

static void
cogl_pango_renderer_draw_glyphs (PangoRenderer    *renderer,
				 PangoFont        *font,
				 PangoGlyphString *glyphs,
				 int               xi,
				 int               yi)
{
  CoglPangoRenderer *priv = (CoglPangoRenderer *) renderer;
  CoglPangoGlyphCacheValue *cache_value;
  int i;

  cogl_pango_renderer_set_color_for_part (renderer,
					  PANGO_RENDER_PART_FOREGROUND);

  for (i = 0; i < glyphs->num_glyphs; i++)
    {
      PangoGlyphInfo *gi = glyphs->glyphs + i;
      float x, y;

      cogl_pango_renderer_get_device_units (renderer,
					    xi + gi->geometry.x_offset,
					    yi + gi->geometry.y_offset,
					    &x, &y);

      if ((gi->glyph & PANGO_GLYPH_UNKNOWN_FLAG))
	{
	  PangoFontMetrics *metrics;

	  if (font == NULL ||
              (metrics = pango_font_get_metrics (font, NULL)) == NULL)
            {
	      cogl_pango_renderer_draw_box (renderer,
                                            x,
                                            y,
                                            PANGO_UNKNOWN_GLYPH_WIDTH,
                                            PANGO_UNKNOWN_GLYPH_HEIGHT);
            }
	  else
	    {
	      cogl_pango_renderer_draw_box (renderer,
                                            x,
					    y,
					    metrics->approximate_char_width
					    / PANGO_SCALE,
					    metrics->ascent / PANGO_SCALE);

	      pango_font_metrics_unref (metrics);
	    }
	}
      else
	{
	  /* Get the texture containing the glyph */
	  cache_value =
            cogl_pango_renderer_get_cached_glyph (renderer,
                                                  FALSE,
                                                  font,
                                                  gi->glyph);

          /* cogl_pango_ensure_glyph_cache_for_layout should always be
             called before rendering a layout so we should never have
             a dirty glyph here */
          g_assert (cache_value == NULL || !cache_value->dirty);

	  if (cache_value == NULL)
            {
              cogl_pango_renderer_draw_box (renderer,
                                            x,
                                            y,
                                            PANGO_UNKNOWN_GLYPH_WIDTH,
                                            PANGO_UNKNOWN_GLYPH_HEIGHT);
            }
	  else
	    {
	      x += (float)(cache_value->draw_x);
	      y += (float)(cache_value->draw_y);

              cogl_pango_renderer_draw_glyph (priv, cache_value, x, y);
	    }
	}

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