C++ cairo_create函数代码示例

static gboolean dt_iop_zonesystem_preview_draw(GtkWidget *widget, cairo_t *crf, dt_iop_module_t *self)
{
  const int inset = DT_PIXEL_APPLY_DPI(2);
  GtkAllocation allocation;
  gtk_widget_get_allocation(widget, &allocation);
  int width = allocation.width, height = allocation.height;

  dt_iop_zonesystem_gui_data_t *g = (dt_iop_zonesystem_gui_data_t *)self->gui_data;
  dt_iop_zonesystem_params_t *p = (dt_iop_zonesystem_params_t *)self->params;

  cairo_surface_t *cst = dt_cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
  cairo_t *cr = cairo_create(cst);

  /* clear background */
  GtkStyleContext *context = gtk_widget_get_style_context(self->expander);
  gtk_render_background(context, cr, 0, 0, allocation.width, allocation.height);

  width -= 2 * inset;
  height -= 2 * inset;
  cairo_translate(cr, inset, inset);

  dt_pthread_mutex_lock(&g->lock);
  if(g->in_preview_buffer && g->out_preview_buffer && self->enabled)
  {
    /* calculate the zonemap */
    float zonemap[MAX_ZONE_SYSTEM_SIZE] = { -1 };
    _iop_zonesystem_calculate_zonemap(p, zonemap);

    /* let's generate a pixbuf from pixel zone buffer */
    guchar *image = g_malloc_n((size_t)4 * g->preview_width * g->preview_height, sizeof(guchar));
    guchar *buffer = g->mouse_over_output_zones ? g->out_preview_buffer : g->in_preview_buffer;
    for(int k = 0; k < g->preview_width * g->preview_height; k++)
    {
      int zone = 255 * CLIP(((1.0 / (p->size - 1)) * buffer[k]));
      image[4 * k + 2] = (g->hilite_zone && buffer[k] == g->zone_under_mouse) ? 255 : zone;
      image[4 * k + 1] = (g->hilite_zone && buffer[k] == g->zone_under_mouse) ? 255 : zone;
      image[4 * k + 0] = (g->hilite_zone && buffer[k] == g->zone_under_mouse) ? 0 : zone;
    }
    dt_pthread_mutex_unlock(&g->lock);

    const int wd = g->preview_width, ht = g->preview_height;
    const float scale = fminf(width / (float)wd, height / (float)ht);
    const int stride = cairo_format_stride_for_width(CAIRO_FORMAT_RGB24, wd);
    cairo_surface_t *surface = cairo_image_surface_create_for_data(image, CAIRO_FORMAT_RGB24, wd, ht, stride);
    cairo_translate(cr, width / 2.0, height / 2.0f);
    cairo_scale(cr, scale, scale);
    cairo_translate(cr, -.5f * wd, -.5f * ht);

    cairo_rectangle(cr, DT_PIXEL_APPLY_DPI(1), DT_PIXEL_APPLY_DPI(1), wd - DT_PIXEL_APPLY_DPI(2),
                    ht - DT_PIXEL_APPLY_DPI(2));
    cairo_set_source_surface(cr, surface, 0, 0);
    cairo_pattern_set_filter(cairo_get_source(cr), CAIRO_FILTER_GOOD);
    cairo_fill_preserve(cr);
    cairo_surface_destroy(surface);

    cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(1.0));
    cairo_set_source_rgb(cr, .1, .1, .1);
    cairo_stroke(cr);

    g_free(image);
  }
  else
  {
    dt_pthread_mutex_unlock(&g->lock);
    // draw a big, subdued dt logo
    if(g->image)
    {
      GdkRGBA *color;
      gtk_style_context_get(context, gtk_widget_get_state_flags(self->expander), "background-color", &color,
                            NULL);

      cairo_set_source_surface(cr, g->image, (width - g->image_width) * 0.5, (height - g->image_height) * 0.5);
      cairo_rectangle(cr, 0, 0, width, height);
      cairo_set_operator(cr, CAIRO_OPERATOR_HSL_LUMINOSITY);
      cairo_fill_preserve(cr);
      cairo_set_operator(cr, CAIRO_OPERATOR_DARKEN);
      cairo_set_source_rgb(cr, color->red + 0.02, color->green + 0.02, color->blue + 0.02);
      cairo_fill_preserve(cr);
      cairo_set_operator(cr, CAIRO_OPERATOR_LIGHTEN);
      cairo_set_source_rgb(cr, color->red - 0.02, color->green - 0.02, color->blue - 0.02);
      cairo_fill(cr);

      gdk_rgba_free(color);
    }
  }

  cairo_destroy(cr);
  cairo_set_source_surface(crf, cst, 0, 0);
  cairo_paint(crf);
  cairo_surface_destroy(cst);

  return TRUE;
}

static gboolean
path_test_convert_to_cairo_path (CallbackData *data)
{
  cairo_surface_t *surface;
  cairo_t *cr;
  cairo_path_t *cpath;
  guint i, j;
  ClutterKnot path_start = { 0, 0 }, last_point = { 0, 0 };

  /* Create a temporary image surface and context to hold the cairo
     path */
  surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 10, 10);
  cr = cairo_create (surface);

  /* Convert to a cairo path */
  clutter_path_to_cairo_path (data->path, cr);

  /* Get a copy of the cairo path data */
  cpath = cairo_copy_path (cr);

  /* Convert back to a clutter path */
  clutter_path_clear (data->path);
  clutter_path_add_cairo_path (data->path, cpath);

  /* The relative nodes will have been converted to absolute so we
     need to reflect this in the node array for comparison */
  for (i = 0; i < data->n_nodes; i++)
    {
      switch (data->nodes[i].type)
        {
        case CLUTTER_PATH_MOVE_TO:
          path_start = last_point = data->nodes[i].points[0];
          break;

        case CLUTTER_PATH_LINE_TO:
          last_point = data->nodes[i].points[0];
          break;

        case CLUTTER_PATH_CURVE_TO:
          last_point = data->nodes[i].points[2];
          break;

        case CLUTTER_PATH_REL_MOVE_TO:
          last_point.x += data->nodes[i].points[0].x;
          last_point.y += data->nodes[i].points[0].y;
          data->nodes[i].points[0] = last_point;
          data->nodes[i].type = CLUTTER_PATH_MOVE_TO;
          path_start = last_point;
          break;

        case CLUTTER_PATH_REL_LINE_TO:
          last_point.x += data->nodes[i].points[0].x;
          last_point.y += data->nodes[i].points[0].y;
          data->nodes[i].points[0] = last_point;
          data->nodes[i].type = CLUTTER_PATH_LINE_TO;
          break;

        case CLUTTER_PATH_REL_CURVE_TO:
          for (j = 0; j < 3; j++)
            {
              data->nodes[i].points[j].x += last_point.x;
              data->nodes[i].points[j].y += last_point.y;
            }
          last_point = data->nodes[i].points[2];
          data->nodes[i].type = CLUTTER_PATH_CURVE_TO;
          break;

        case CLUTTER_PATH_CLOSE:
          last_point = path_start;

          /* Cairo always adds a move to after every close so we need
             to insert one here */
          memmove (data->nodes + i + 2, data->nodes + i + 1,
                   (data->n_nodes - i - 1) * sizeof (ClutterPathNode));
          data->nodes[i + 1].type = CLUTTER_PATH_MOVE_TO;
          data->nodes[i + 1].points[0] = last_point;
          data->n_nodes++;
          break;
        }
    }

  /* Free the cairo resources */
  cairo_path_destroy (cpath);
  cairo_destroy (cr);
  cairo_surface_destroy (surface);

  return TRUE;
}

//.........这里部分代码省略.........
    /* Check that we created a surface of the expected content,
     * (ignore the artificial CAIRO_TEST_CONTENT_COLOR_ALPHA_FLATTENED value).
     */
    expected_content = cairo_boilerplate_content (target->content);

    if (cairo_surface_get_content (surface) != expected_content) {
	MF (MEMFAULT_PRINT_FAULTS ());
	cairo_test_log (ctx, "Error: Created surface has content %d (expected %d)\n",
			cairo_surface_get_content (surface), expected_content);
	ret = CAIRO_TEST_FAILURE;
	goto UNWIND_SURFACE;
    }

    if (cairo_surface_set_user_data (surface,
				     &cairo_boilerplate_output_basename_key,
				     base_path,
				     NULL))
    {
#if HAVE_MEMFAULT
	cairo_surface_destroy (surface);

	if (target->cleanup)
	    target->cleanup (closure);

	goto REPEAT;
#else
	ret = CAIRO_TEST_FAILURE;
	goto UNWIND_SURFACE;
#endif
    }

    cairo_surface_set_device_offset (surface, dev_offset, dev_offset);

    cr = cairo_create (surface);
    if (cairo_set_user_data (cr, &_cairo_test_context_key, (void*) ctx, NULL)) {
#if HAVE_MEMFAULT
	cairo_destroy (cr);
	cairo_surface_destroy (surface);

	if (target->cleanup)
	    target->cleanup (closure);

	goto REPEAT;
#else
	ret = CAIRO_TEST_FAILURE;
	goto UNWIND_CAIRO;
#endif
    }

    if (similar)
	cairo_push_group_with_content (cr, expected_content);

    /* Clear to transparent (or black) depending on whether the target
     * surface supports alpha. */
    cairo_save (cr);
    cairo_set_operator (cr, CAIRO_OPERATOR_CLEAR);
    cairo_paint (cr);
    cairo_restore (cr);

    /* Set all components of font_options to avoid backend differences
     * and reduce number of needed reference images. */
    font_options = cairo_font_options_create ();
    cairo_font_options_set_hint_style (font_options, CAIRO_HINT_STYLE_NONE);
    cairo_font_options_set_hint_metrics (font_options, CAIRO_HINT_METRICS_ON);
    cairo_font_options_set_antialias (font_options, CAIRO_ANTIALIAS_GRAY);
    cairo_set_font_options (cr, font_options);

static gboolean _lib_navigation_expose_callback(GtkWidget *widget, GdkEventExpose *event, gpointer user_data)
{

  const int inset = DT_NAVIGATION_INSET;
  int width = widget->allocation.width, height = widget->allocation.height;

  dt_develop_t *dev = darktable.develop;

  if (dev->preview_dirty) return FALSE;

  /* get the current style */
  GtkStyle *style=gtk_rc_get_style_by_paths(gtk_settings_get_default(), NULL,"GtkWidget", GTK_TYPE_WIDGET);
  if(!style) style = gtk_rc_get_style(widget);
  cairo_surface_t *cst = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
  cairo_t *cr = cairo_create(cst);
  
  /* fill background */ 
  cairo_set_source_rgb(cr, style->bg[0].red/65535.0, style->bg[0].green/65535.0, style->bg[0].blue/65535.0);
  cairo_paint(cr);

  width -= 2*inset;
  height -= 2*inset;
  cairo_translate(cr, inset, inset);

  /* draw navigation image if available */
  if(dev->preview_pipe->backbuf && !dev->preview_dirty)
  {
    dt_pthread_mutex_t *mutex = &dev->preview_pipe->backbuf_mutex;
    dt_pthread_mutex_lock(mutex);
    const int wd = dev->preview_pipe->backbuf_width;
    const int ht = dev->preview_pipe->backbuf_height;
    const float scale = fminf(width/(float)wd, height/(float)ht);

    const int stride = cairo_format_stride_for_width (CAIRO_FORMAT_RGB24, wd);
    cairo_surface_t *surface = cairo_image_surface_create_for_data (dev->preview_pipe->backbuf, CAIRO_FORMAT_RGB24, wd, ht, stride);
    cairo_translate(cr, width/2.0, height/2.0f);
    cairo_scale(cr, scale, scale);
    cairo_translate(cr, -.5f*wd, -.5f*ht);

    // draw shadow around
    float alpha = 1.0f;
    for(int k=0; k<4; k++)
    {
      cairo_rectangle(cr, -k/scale, -k/scale, wd + 2*k/scale, ht + 2*k/scale);
      cairo_set_source_rgba(cr, 0, 0, 0, alpha);
      alpha *= 0.6f;
      cairo_fill(cr);
    }

    cairo_rectangle(cr, 0, 0, wd-2, ht-1);
    cairo_set_source_surface (cr, surface, 0, 0);
    cairo_pattern_set_filter(cairo_get_source(cr), CAIRO_FILTER_FAST);
    cairo_fill(cr);
    cairo_surface_destroy (surface);

    dt_pthread_mutex_unlock(mutex);

    // draw box where we are
    dt_dev_zoom_t zoom;
    int closeup;
    float zoom_x, zoom_y;
    DT_CTL_GET_GLOBAL(zoom, dev_zoom);
    DT_CTL_GET_GLOBAL(closeup, dev_closeup);
    DT_CTL_GET_GLOBAL(zoom_x, dev_zoom_x);
    DT_CTL_GET_GLOBAL(zoom_y, dev_zoom_y);
    const float min_scale = dt_dev_get_zoom_scale(dev, DT_ZOOM_FIT, closeup ? 2.0 : 1.0, 0);
    const float cur_scale = dt_dev_get_zoom_scale(dev, zoom,        closeup ? 2.0 : 1.0, 0);
    // avoid numerical instability for small resolutions:
    if(cur_scale > min_scale+0.001)
    {
      float boxw = 1, boxh = 1;
      dt_dev_check_zoom_bounds(darktable.develop, &zoom_x, &zoom_y, zoom, closeup, &boxw, &boxh);

      cairo_translate(cr, wd*(.5f+zoom_x), ht*(.5f+zoom_y));
      cairo_set_source_rgb(cr, 0., 0., 0.);
      cairo_set_line_width(cr, 1.f/scale);
      boxw *= wd;
      boxh *= ht;
      cairo_rectangle(cr, -boxw/2-1, -boxh/2-1, boxw+2, boxh+2);
      cairo_stroke(cr);
      cairo_set_source_rgb(cr, 1., 1., 1.);
      cairo_rectangle(cr, -boxw/2, -boxh/2, boxw, boxh);
      cairo_stroke(cr);
    }
  }

  /* blit memsurface into widget */
  cairo_destroy(cr);
  cairo_t *cr_pixmap = gdk_cairo_create(gtk_widget_get_window(widget));
  cairo_set_source_surface (cr_pixmap, cst, 0, 0);
  cairo_paint(cr_pixmap);
  cairo_destroy(cr_pixmap);
  cairo_surface_destroy(cst);
  
  return TRUE;
}

int main(int argc, char **argv)
{
  cairo_surface_t *surface;
  cairo_t *context;
  int x, y, i,
      width, height, depth,
      screen, pressed_key,
      png;
  double r, b, v;
  QTnode *tree;
  bool rendering;
  struct XWin **xwin;

  /* Get the arguments */
  if(argc != 3) {
    printf("Usage: nbody rendering resultsdir\n");
    exit(1);
  }
  if(*argv[1] == '0') {
    rendering = false;
  } else {
    rendering = true;
  }
  char buf[strlen(argv[2]) + 10];

  /* Set window size */
  width = 1024;
  height = 1024;
  depth = 32;

  tree = init_tree(10, NULL);
  for (i = 0; i < 100000; i++) {
    tree->insert(phys_gen_particle());
    if (i % 10000 == 0)
      printf("%d\n", i);
  }

  /* Create the drawing surface */
  if(rendering) {
    /* Create the X11 window */
    xwin = (struct XWin **)calloc(sizeof(struct XWin *), 1);
    xwindow_init(width, height, depth, xwin);
    surface = cairo_xlib_surface_create((*xwin)->dsp, (*xwin)->win, DefaultVisual((*xwin)->dsp, screen), width, height);
    cairo_xlib_surface_set_size(surface, width, height);
  } else {
    surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, width, height); 
  }
  context = cairo_create(surface);
  cairo_scale(context, width, height);

  png = 0;
  while(1) {
    if(rendering) {
      if((*xwin)->should_close) {
        break;
      }
      /* Wait on the input (also sync up to disable flickering) */
      if(input_ready(xwin)) {
        pressed_key = get_key(xwin);
      }
    }

    /* Clear the surface with black */
    cairo_set_source_rgb(context, 0.0, 0.0, 0.0);
    cairo_paint(context);

    std::queue <QTnode *> nodes;
    QTnode *t;

    nodes.push(tree);

    while (!nodes.empty()) {
      t = nodes.front();
      nodes.pop();

      if (!t->children.empty()) {
        for (i = 0; i < t->children.size(); i++) {
          nodes.push(t->children[i]);
        }
      } else {
        for (std::list <Particle>::iterator p = t->particles.begin(); p != t->particles.end(); p++) {

          v = f2_norm((*p).vel);
          if(v >= 0.4) {
            r = 1.0; b = 0.0;
          } else if(v < 0.5) {
            b = 1.0; r = 0.0;
          }
          cairo_set_source_rgba(context, (double)r, 0.0, (double)b, 1.0);
          cairo_rectangle(context, (*p).pos.x,
              (*p).pos.y, 2e-3, 2e-3);
          cairo_fill(context);
          cairo_set_source_rgba(context, (double)r, 0.0, (double)b, 0.2);
          cairo_rectangle(context, (*p).pos.x - 1e-3,
              (*p).pos.y - 1e-3, 4e-3, 4e-3);
          cairo_fill(context);
        }
      }
    }

//.........这里部分代码省略.........

wxRegion::wxRegion( size_t n, const wxPoint *points,
                    wxPolygonFillMode fillStyle )
{
#ifdef __WXGTK3__
    // Make a cairo path from the points, draw it onto an image surface, use
    // gdk_cairo_region_create_from_surface() to get a cairo region

    // need at least 3 points to make a useful polygon
    if (n < 3)
        return;
    // get bounding rect
    int min_x = points[0].x;
    int max_x = min_x;
    int min_y = points[0].y;
    int max_y = min_y;
    size_t i;
    for (i = 1; i < n; i++)
    {
        const int x = points[i].x;
        if (min_x > x)
            min_x = x;
        else if (max_x < x)
            max_x = x;
        const int y = points[i].y;
        if (min_y > y)
            min_y = y;
        else if (max_y < y)
            max_y = y;
    }
    const int w = max_x - min_x + 1;
    const int h = max_y - min_y + 1;
    // make surface just big enough to contain polygon (A1 is native format
    //   for gdk_cairo_region_create_from_surface)
    cairo_surface_t* surface = cairo_image_surface_create(CAIRO_FORMAT_A1, w, h);
    memset(cairo_image_surface_get_data(surface), 0, cairo_image_surface_get_stride(surface) * h);
    cairo_surface_mark_dirty(surface);
    cairo_surface_set_device_offset(surface, -min_x, -min_y);
    cairo_t* cr = cairo_create(surface);
    cairo_set_antialias(cr, CAIRO_ANTIALIAS_NONE);
    if (fillStyle == wxODDEVEN_RULE)
        cairo_set_fill_rule(cr, CAIRO_FILL_RULE_EVEN_ODD);
    // make path
    cairo_move_to(cr, points[0].x, points[0].y);
    for (i = 1; i < n; i++)
        cairo_line_to(cr, points[i].x, points[i].y);
    cairo_close_path(cr);
    cairo_fill(cr);
    cairo_destroy(cr);
    cairo_surface_flush(surface);
    m_refData = new wxRegionRefData;
    M_REGIONDATA->m_region = gdk_cairo_region_create_from_surface(surface);
    cairo_surface_destroy(surface);
#else
    GdkPoint *gdkpoints = new GdkPoint[n];
    for ( size_t i = 0 ; i < n ; i++ )
    {
        gdkpoints[i].x = points[i].x;
        gdkpoints[i].y = points[i].y;
    }

    m_refData = new wxRegionRefData();

    GdkRegion* reg = gdk_region_polygon
                     (
                        gdkpoints,
                        n,
                        fillStyle == wxWINDING_RULE ? GDK_WINDING_RULE
                                                    : GDK_EVEN_ODD_RULE
                     );

    M_REGIONDATA->m_region = reg;

    delete [] gdkpoints;
#endif
}

void
draw_shadow (cairo_t* cr,
	     gdouble  width,
	     gdouble  height,
	     gint     shadow_radius,
	     gint     corner_radius)
{
	cairo_surface_t* tmp_surface = NULL;
	cairo_surface_t* new_surface = NULL;
	cairo_pattern_t* pattern     = NULL;
	cairo_t*         cr_surf     = NULL;
	cairo_matrix_t   matrix;
	raico_blur_t*    blur        = NULL;

	tmp_surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
						  4 * shadow_radius,
						  4 * shadow_radius);
	if (cairo_surface_status (tmp_surface) != CAIRO_STATUS_SUCCESS)
		return;

	cr_surf = cairo_create (tmp_surface);
	if (cairo_status (cr_surf) != CAIRO_STATUS_SUCCESS)
	{
		cairo_surface_destroy (tmp_surface);
		return;
	}

	cairo_scale (cr_surf, 1.0f, 1.0f);
	cairo_set_operator (cr_surf, CAIRO_OPERATOR_CLEAR);
	cairo_paint (cr_surf);
	cairo_set_operator (cr_surf, CAIRO_OPERATOR_OVER);
	cairo_set_source_rgba (cr_surf, 0.0f, 0.0f, 0.0f, 0.75f);
	cairo_arc (cr_surf,
		   2 * shadow_radius,
		   2 * shadow_radius,
		   2.0f * corner_radius,
		   0.0f,
		   360.0f * (G_PI / 180.f));
	cairo_fill (cr_surf);
	cairo_destroy (cr_surf);

	// create and setup blur
	blur = raico_blur_create (RAICO_BLUR_QUALITY_LOW);
	raico_blur_set_radius (blur, shadow_radius);

	// now blur it
	raico_blur_apply (blur, tmp_surface);

	// blur no longer needed
	raico_blur_destroy (blur);

	new_surface = cairo_image_surface_create_for_data (
			cairo_image_surface_get_data (tmp_surface),
			cairo_image_surface_get_format (tmp_surface),
			cairo_image_surface_get_width (tmp_surface) / 2,
			cairo_image_surface_get_height (tmp_surface) / 2,
			cairo_image_surface_get_stride (tmp_surface));
	pattern = cairo_pattern_create_for_surface (new_surface);
	if (cairo_pattern_status (pattern) != CAIRO_STATUS_SUCCESS)
	{
		cairo_surface_destroy (tmp_surface);
		cairo_surface_destroy (new_surface);
		return;
	}

	// top left
	cairo_pattern_set_extend (pattern, CAIRO_EXTEND_PAD);
	cairo_set_source (cr, pattern);
	cairo_rectangle (cr,
			 0.0f,
			 0.0f,
			 width - 2 * shadow_radius,
			 2 * shadow_radius);
	cairo_fill (cr);

	// bottom left
	cairo_matrix_init_scale (&matrix, 1.0f, -1.0f);
	cairo_matrix_translate (&matrix, 0.0f, -height);
	cairo_pattern_set_matrix (pattern, &matrix);
	cairo_rectangle (cr,
			 0.0f,
			 2 * shadow_radius,
			 2 * shadow_radius,
			 height - 2 * shadow_radius);
	cairo_fill (cr);

	// top right
	cairo_matrix_init_scale (&matrix, -1.0f, 1.0f);
	cairo_matrix_translate (&matrix, -width, 0.0f);
	cairo_pattern_set_matrix (pattern, &matrix);
	cairo_rectangle (cr,
			 width - 2 * shadow_radius,
			 0.0f,
			 2 * shadow_radius,
			 height - 2 * shadow_radius);
	cairo_fill (cr);

	// bottom right
	cairo_matrix_init_scale (&matrix, -1.0f, -1.0f);
	cairo_matrix_translate (&matrix, -width, -height);
//.........这里部分代码省略.........

void
setup_tile (gint w, gint h)
{
	cairo_status_t   status;
	cairo_t*         cr          = NULL;
	cairo_surface_t* cr_surf     = NULL;
	cairo_surface_t* tmp         = NULL;
	cairo_surface_t* dummy_surf  = NULL;
	cairo_surface_t* norm_surf   = NULL;
	cairo_surface_t* blur_surf   = NULL;
	gdouble          width       = (gdouble) w;
	gdouble          height      = (gdouble) h;
	raico_blur_t*    blur        = NULL;

	cr_surf = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
					      3 * BUBBLE_SHADOW_SIZE,
					      3 * BUBBLE_SHADOW_SIZE);
	status = cairo_surface_status (cr_surf);
	if (status != CAIRO_STATUS_SUCCESS)
		g_print ("Error: \"%s\"\n", cairo_status_to_string (status));

	cr = cairo_create (cr_surf);
	status = cairo_status (cr);
	if (status != CAIRO_STATUS_SUCCESS)
	{
		cairo_surface_destroy (cr_surf);
		g_print ("Error: \"%s\"\n", cairo_status_to_string (status));
	}

	// clear and render drop-shadow and bubble-background
	cairo_scale (cr, 1.0f, 1.0f);
	cairo_set_operator (cr, CAIRO_OPERATOR_CLEAR);
	cairo_paint (cr);
	cairo_set_operator (cr, CAIRO_OPERATOR_OVER);

	if (g_composited)
	{
		draw_shadow (cr,
			     width,
			     height,
			     BUBBLE_SHADOW_SIZE,
			     CORNER_RADIUS);
		cairo_set_operator (cr, CAIRO_OPERATOR_CLEAR);
		draw_round_rect (cr,
				 1.0f,
				 (gdouble) BUBBLE_SHADOW_SIZE,
				 (gdouble) BUBBLE_SHADOW_SIZE,
				 (gdouble) CORNER_RADIUS,
				 (gdouble) (width - 2.0f * BUBBLE_SHADOW_SIZE),
				 (gdouble) (height - 2.0f* BUBBLE_SHADOW_SIZE));
		cairo_fill (cr);
		cairo_set_operator (cr, CAIRO_OPERATOR_OVER);
		cairo_set_source_rgba (cr,
				       BUBBLE_BG_COLOR_R,
				       BUBBLE_BG_COLOR_G,
				       BUBBLE_BG_COLOR_B,
				       0.95f);
	}
	else
		cairo_set_source_rgb (cr,
				      BUBBLE_BG_COLOR_R,
				      BUBBLE_BG_COLOR_G,
				      BUBBLE_BG_COLOR_B);
	draw_round_rect (cr,
			 1.0f,
			 BUBBLE_SHADOW_SIZE,
			 BUBBLE_SHADOW_SIZE,
			 CORNER_RADIUS,
			 (gdouble) (width - 2.0f * BUBBLE_SHADOW_SIZE),
			 (gdouble) (height - 2.0f * BUBBLE_SHADOW_SIZE));
	cairo_fill (cr);

	tmp = cairo_image_surface_create_for_data (
			cairo_image_surface_get_data (cr_surf),
			cairo_image_surface_get_format (cr_surf),
			3 * BUBBLE_SHADOW_SIZE,
			3 * BUBBLE_SHADOW_SIZE,
			cairo_image_surface_get_stride (cr_surf));
	dummy_surf = copy_surface (tmp);
	cairo_surface_destroy (tmp);

	tmp = cairo_image_surface_create_for_data (
			cairo_image_surface_get_data (dummy_surf),
			cairo_image_surface_get_format (dummy_surf),
			2 * BUBBLE_SHADOW_SIZE,
			2 * BUBBLE_SHADOW_SIZE,
			cairo_image_surface_get_stride (dummy_surf));
	norm_surf = copy_surface (tmp);
	cairo_surface_destroy (tmp);

	blur = raico_blur_create (RAICO_BLUR_QUALITY_LOW);
	raico_blur_set_radius (blur, 6);
	raico_blur_apply (blur, dummy_surf);
	raico_blur_destroy (blur);

	tmp = cairo_image_surface_create_for_data (
			cairo_image_surface_get_data (dummy_surf),
			cairo_image_surface_get_format (dummy_surf),
			2 * BUBBLE_SHADOW_SIZE,
			2 * BUBBLE_SHADOW_SIZE,
//.........这里部分代码省略.........

/* estimate_textsize:
 * Estimate width of text, for given face and size, in points.
 * Value is stored textline->width.
 * NOTE: Tables are based on a font of size 1. Need to multiply by
 * fontsize to get appropriate value.
 */
static void
estimate_textsize(textline_t * textline, char *fontname, double fontsz,
		  char **fontpath)
{
    double *Fontwidth;
    char c, *p;

    textline->width = 0.0;
    textline->xshow = NULL;
#if !defined(DISABLE_CODEGENS) && !defined(HAVE_GD_FREETYPE) && !defined(ONLY_PLAIN_GEN) //maks
    if (Output_codegen == &GD_CodeGen) {
	int cwidth;
	double fsize = (fontsz * _dpi) / POINTS_PER_INCH;	/* in pixels */
	*fontpath = "[internal gd]";
	cwidth = builtinFontWd(fsize);
	if ((p = textline->str)) {
	    textline->width = strlen(p) * cwidth * POINTS_PER_INCH / _dpi;
	}
	return;
    } else if (!strncasecmp(fontname, "cour", 4)) {
#else
    if (!strncasecmp(fontname, "cour", 4)) {
#endif
	*fontpath = "[internal courier]";
	Fontwidth = courFontWidth;
    } else if (!strncasecmp(fontname, "arial", 5)
	       || !strncasecmp(fontname, "helvetica", 9)) {
	*fontpath = "[internal arial]";
	Fontwidth = arialFontWidth;
    } else {
	*fontpath = "[internal times]";
	Fontwidth = timesFontWidth;
    }
    if ((p = textline->str)) {
	while ((c = *p++))
	    textline->width += Fontwidth[(unsigned char) c];
	textline->width *= fontsz;
    }
}
#endif

double textwidth(textline_t * textline, char *fontname, double fontsize)
{
    char *fontpath = NULL;
    int freeFontpath = 0;

#ifdef CAIRO_HAS_FT_FONT
    cairo_t *cr;
    cairo_text_extents_t extents;

    cr = cairo_create();
    cairo_select_font(cr, fontname, 0, 0);
    cairo_scale_font(cr, fontsize);
    cairo_text_extents(cr, textline->str, &extents);
    cairo_destroy(cr);

    textline->width = extents.width;
    textline->xshow = NULL;
    fontpath = "[cairo]";
#else
    if (gd_textsize(textline, fontname, fontsize, &fontpath))
	estimate_textsize(textline, fontname, fontsize, &fontpath);
    else
	freeFontpath = 1; /* libgd mallocs space for fontpath */
#endif

    if (Verbose) {
	if (emit_once(fontname)) {
	    fprintf(stderr, "%s: fontname=%s fontpath=%s\n", CmdName,
		    fontname, fontpath);
	}
    }
    if (freeFontpath) free (fontpath);
    return textline->width;
}

TemporaryRef<Path>
ScaledFontBase::GetPathForGlyphs(const GlyphBuffer &aBuffer, const DrawTarget *aTarget)
{
#ifdef USE_SKIA
  if (aTarget->GetType() == BACKEND_SKIA) {
    SkPaint paint;
    paint.setTypeface(GetSkTypeface());
    paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
    paint.setTextSize(SkFloatToScalar(mSize));

    std::vector<uint16_t> indices;
    std::vector<SkPoint> offsets;
    indices.resize(aBuffer.mNumGlyphs);
    offsets.resize(aBuffer.mNumGlyphs);

    for (unsigned int i = 0; i < aBuffer.mNumGlyphs; i++) {
      indices[i] = aBuffer.mGlyphs[i].mIndex;
      offsets[i].fX = SkFloatToScalar(aBuffer.mGlyphs[i].mPosition.x);
      offsets[i].fY = SkFloatToScalar(aBuffer.mGlyphs[i].mPosition.y);
    }

    SkPath path;
    paint.getPosTextPath(&indices.front(), aBuffer.mNumGlyphs*2, &offsets.front(), &path);
    return new PathSkia(path, FILL_WINDING);
  }
#endif
#ifdef USE_CAIRO
  if (aTarget->GetType() == BACKEND_CAIRO) {
    MOZ_ASSERT(mScaledFont);

    DrawTarget *dt = const_cast<DrawTarget*>(aTarget);
    cairo_t *ctx = static_cast<cairo_t*>(dt->GetNativeSurface(NATIVE_SURFACE_CAIRO_CONTEXT));

    bool isNewContext = !ctx;
    if (!ctx) {
      ctx = cairo_create(DrawTargetCairo::GetDummySurface());
      cairo_matrix_t mat;
      GfxMatrixToCairoMatrix(aTarget->GetTransform(), mat);
      cairo_set_matrix(ctx, &mat);
    }

    cairo_set_scaled_font(ctx, mScaledFont);

    // Convert our GlyphBuffer into an array of Cairo glyphs.
    std::vector<cairo_glyph_t> glyphs(aBuffer.mNumGlyphs);
    for (uint32_t i = 0; i < aBuffer.mNumGlyphs; ++i) {
      glyphs[i].index = aBuffer.mGlyphs[i].mIndex;
      glyphs[i].x = aBuffer.mGlyphs[i].mPosition.x;
      glyphs[i].y = aBuffer.mGlyphs[i].mPosition.y;
    }

    cairo_glyph_path(ctx, &glyphs[0], aBuffer.mNumGlyphs);

    RefPtr<PathCairo> newPath = new PathCairo(ctx);
    if (isNewContext) {
      cairo_destroy(ctx);
    }

    return newPath;
  }
#endif
  return nullptr;
}

static void
gnc_header_draw_offscreen (GncHeader *header)
{
    SheetBlockStyle *style = header->style;
    Table *table = header->sheet->table;
    VirtualLocation virt_loc;
    VirtualCell *vcell;
    guint32 color_type;
    GtkStyleContext *stylectxt = gtk_widget_get_style_context (GTK_WIDGET(header));
    GdkRGBA color;
    int row_offset;
    CellBlock *cb;
    int i;
    cairo_t *cr;

    virt_loc.vcell_loc.virt_row = 0;
    virt_loc.vcell_loc.virt_col = 0;
    virt_loc.phys_row_offset = 0;
    virt_loc.phys_col_offset = 0;

    gtk_style_context_save (stylectxt);

    // Get the background color type and apply the css class
    color_type = gnc_table_get_bg_color (table, virt_loc, NULL);
    gnucash_get_style_classes (header->sheet, stylectxt, color_type);

    if (header->surface)
        cairo_surface_destroy (header->surface);
    header->surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
                                                header->width,
                                                header->height);

    cr = cairo_create (header->surface);

    // Fill background color of header
    gtk_render_background (stylectxt, cr, 0, 0, header->width, header->height);

    gdk_rgba_parse (&color, "black");
    cairo_set_source_rgb (cr, color.red, color.green, color.blue);
    cairo_rectangle (cr, 0.5, 0.5, header->width - 1.0, header->height - 1.0);
    cairo_set_line_width (cr, 1.0);
    cairo_stroke (cr);

    // Draw bottom horizontal line, makes bottom line thicker
    cairo_move_to (cr, 0.5, header->height - 1.5);
    cairo_line_to (cr, header->width - 1.0, header->height - 1.5);
    cairo_set_line_cap (cr, CAIRO_LINE_CAP_SQUARE);
    cairo_set_line_width (cr, 1.0);
    cairo_stroke (cr);

    /*font = gnucash_register_font;*/

    vcell = gnc_table_get_virtual_cell
            (table, table->current_cursor_loc.vcell_loc);
    cb = vcell ? vcell->cellblock : NULL;
    row_offset = 0;

    for (i = 0; i < style->nrows; i++)
    {
        int col_offset = 0;
        int h = 0, j;
        virt_loc.phys_row_offset = i;

        /* TODO: This routine is duplicated in several places.
           Can we abstract at least the cell drawing routine?
           That way we'll be sure everything is drawn
           consistently, and cut down on maintenance issues. */

        for (j = 0; j < style->ncols; j++)
        {
            CellDimensions *cd;
            double text_x, text_y, text_w, text_h;
            BasicCell *cell;
            const char *text;
            int w;
            PangoLayout *layout;

            virt_loc.phys_col_offset = j;

            cd = gnucash_style_get_cell_dimensions (style, i, j);
            h = cd->pixel_height;
            if (header->in_resize && (j == header->resize_col))
                w = header->resize_col_width;
            else
                w = cd->pixel_width;

            cell = gnc_cellblock_get_cell (cb, i, j);
            if (!cell || !cell->cell_name)
            {
                col_offset += w;
                continue;
            }

            cairo_rectangle (cr, col_offset - 0.5, row_offset + 0.5, w, h);
            cairo_set_line_width (cr, 1.0);
            cairo_stroke (cr);

            virt_loc.vcell_loc =
                table->current_cursor_loc.vcell_loc;
            text = gnc_table_get_label (table, virt_loc);
//.........这里部分代码省略.........

static GstFlowReturn
gst_rsvg_overlay_transform_ip (GstBaseTransform * btrans, GstBuffer * buf)
{
  GstRsvgOverlay *overlay = GST_RSVG_OVERLAY (btrans);
  cairo_surface_t *surface;
  cairo_t *cr;
  double applied_x_offset = (double) overlay->x_offset;
  double applied_y_offset = (double) overlay->y_offset;
  int applied_width = overlay->width;
  int applied_height = overlay->height;

  GST_RSVG_LOCK (overlay);
  if (!overlay->handle) {
    GST_RSVG_UNLOCK (overlay);
    return GST_FLOW_OK;
  }

  surface =
      cairo_image_surface_create_for_data (GST_BUFFER_DATA (buf),
      CAIRO_FORMAT_ARGB32, overlay->caps_width, overlay->caps_height,
      overlay->caps_width * 4);
  if (G_UNLIKELY (!surface))
    return GST_FLOW_ERROR;

  cr = cairo_create (surface);
  if (G_UNLIKELY (!cr)) {
    cairo_surface_destroy (surface);
    return GST_FLOW_ERROR;
  }

  /* Compute relative dimensions if absolute dimensions are not set */
  if (!applied_x_offset && overlay->x_relative) {
    applied_x_offset = overlay->x_relative * overlay->caps_width;
  }
  if (!applied_y_offset && overlay->y_relative) {
    applied_y_offset = overlay->y_relative * overlay->caps_height;
  }
  if (!applied_width && overlay->width_relative) {
    applied_width = (int) (overlay->width_relative * overlay->caps_width);
  }
  if (!applied_height && overlay->height_relative) {
    applied_height = (int) (overlay->height_relative * overlay->caps_height);
  }

  if (applied_x_offset || applied_y_offset) {
    cairo_translate (cr, applied_x_offset, applied_y_offset);
  }

  /* Scale when necessary, i.e. an absolute or relative dimension has been specified. */
  if ((applied_width || applied_height) && overlay->svg_width
      && overlay->svg_height) {
    /* If may happen that only one of the dimension is specified. Use
       the original SVG size for the other dimension. */
    if (!applied_width)
      applied_width = overlay->svg_width;
    if (!applied_height)
      applied_height = overlay->svg_height;

    cairo_scale (cr, (double) applied_width / overlay->svg_width,
        (double) applied_height / overlay->svg_height);
  }
  rsvg_handle_render_cairo (overlay->handle, cr);
  GST_RSVG_UNLOCK (overlay);

  cairo_destroy (cr);
  cairo_surface_destroy (surface);

  return GST_FLOW_OK;
}

int
main (int argc, char *argv[])
{
        cairo_surface_t *surface = //Sets the Cairo surface context
            cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 421, 615); //Creates Cairo image surface, sets image resolution.
        cairo_t *cr = //Declare *cr as a Cairo context.
            cairo_create (surface); //Sets the Cairo context as a pointer, *cr.

	/* Declaration of first triangle pointer */
	cairo_surface_t *one; 

	/* Declaration of second triangle pointer */
	cairo_surface_t *two; 

	/* Declaration of third triangle pointer */
	cairo_surface_t *three; 

	/* Declaration of fourth triangle pointer */
	cairo_surface_t *four; 

	/* Declaration of fifth triangle pointer */
	cairo_surface_t *five; 

	/* Declaration of sixth triangle pointer */
	cairo_surface_t *six; 

	/* Declaration of seventh triangle pointer */
	cairo_surface_t *seven;	

	/* Declaration of text triangle pointer */
	cairo_surface_t *text; 

	/* Assigns the image of first triangle to the declared pointer */
	cairo_push_group (cr); //Push the image to a surface
	one = cairo_image_surface_create_from_png ("../images/triangle1-color.png"); //Assign generated image to the pointer declared above
	cairo_pop_group_to_source (cr); //Pop it to the image you see

	/* Assigns the image of second triangle to the declared pointer */
	cairo_push_group (cr); //Push the image to a surface
	two = cairo_image_surface_create_from_png ("../images/triangle2-color.png"); //Assign generated image to the pointer declared above
	cairo_pop_group_to_source (cr); //Pop it to the image you see

	/* Assigns the image of third triangle to the declared pointer */
	cairo_push_group (cr); //Push the image to a surface
	three = cairo_image_surface_create_from_png ("../images/triangle3-color.png"); //Assign generated image to the pointer declared above
	cairo_pop_group_to_source (cr); //Pop it to the image you see

	/* Assigns the image of fourth triangle to the declared pointer */
	cairo_push_group (cr); //Push the image to a surface
	four = cairo_image_surface_create_from_png ("../images/triangle4-color.png"); //Assign generated image to the pointer declared above
	cairo_pop_group_to_source (cr); //Pop it to the image you see

	/* Assigns the image of fifth triangle to the declared pointer */
	cairo_push_group (cr); //Push the image to a surface
	five = cairo_image_surface_create_from_png ("../images/triangle5-color.png"); //Assign generated image to the pointer declared above
	cairo_pop_group_to_source (cr); //Pop it to the image you see

	/* Assigns the image of sixth triangle to the declared pointer */
	cairo_push_group (cr); //Push the image to a surface
	six = cairo_image_surface_create_from_png ("../images/triangle6-color.png"); //Assign generated image to the pointer declared above
	cairo_pop_group_to_source (cr); //Pop it to the image you see

	/* Assigns the image of seventh triangle to the declared pointer */
	cairo_push_group (cr); //Push the image to a surface
	seven = cairo_image_surface_create_from_png ("../images/triangle7-color.png"); //Assign generated image to the pointer declared above
	cairo_pop_group_to_source (cr); //Pop it to the image you see

	/* Assigns the image of the generated logo's text to the declared pointer */
	cairo_push_group (cr); //Push the image to a surface
	text = cairo_image_surface_create_from_png ("../images/text.png"); //Assign generated image to the pointer declared above
	cairo_pop_group_to_source (cr); //Pop it to the image you see

	/* Assign pointer to source */
	cairo_set_source_surface (cr, one, 0, 0); //Makes sure the pointers appear all together and make the image using their assigned file
	cairo_paint (cr); //Transfers these images to the final output that you see, it paints the image that you see when compiled/outpuuted

	/* Assign pointer to source */
	cairo_set_source_surface (cr, two, 0, 0); //Makes sure the pointers appear all together and make the image using their assigned file
	cairo_paint (cr); //Transfers these images to the final output that you see, it paints the image that you see when compiled/outpuuted

	/* Assign pointer to source */
	cairo_set_source_surface (cr, three, 0, 0); //Makes sure the pointers appear all together and make the image using their assigned file
	cairo_paint (cr); //Transfers these images to the final output that you see, it paints the image that you see when compiled/outpuuted

	/* Assign pointer to source */
	cairo_set_source_surface (cr, four, 0, 0); //Makes sure the pointers appear all together and make the image using their assigned file
	cairo_paint (cr); //Transfers these images to the final output that you see, it paints the image that you see when compiled/outpuuted

	/* Assign pointer to source */
	cairo_set_source_surface (cr, five, 0, 0); //Makes sure the pointers appear all together and make the image using their assigned file
	cairo_paint (cr); //Transfers these images to the final output that you see, it paints the image that you see when compiled/outpuuted

	/* Assign pointer to source */
	cairo_set_source_surface (cr, six, 0, 0); //Makes sure the pointers appear all together and make the image using their assigned file
	cairo_paint (cr); //Transfers these images to the final output that you see, it paints the image that you see when compiled/outpuuted

	/* Assign pointer to source */
	cairo_set_source_surface (cr, seven, 0, 0); //Makes sure the pointers appear all together and make the image using their assigned file
	cairo_paint (cr); //Transfers these images to the final output that you see, it paints the image that you see when compiled/outpuuted

//.........这里部分代码省略.........

/* 
 * render functions 
 */ 
static void
begin_render(DiaRenderer *self, const Rectangle *update)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  real onedu = 0.0;
  real lmargin = 0.0, tmargin = 0.0;
  gboolean paginated = renderer->surface && /* only with our own pagination, not GtkPrint */
    cairo_surface_get_type (renderer->surface) == CAIRO_SURFACE_TYPE_PDF && !renderer->skip_show_page;

  if (renderer->surface && !renderer->cr)
    renderer->cr = cairo_create (renderer->surface);
  else
    g_assert (renderer->cr);

  /* remember current state, so we can start from new with every page */
  cairo_save (renderer->cr);

  if (paginated && renderer->dia) {
    DiagramData *data = renderer->dia;
    /* Dia's paper.width already contains the scale, cairo needs it without 
     * Similar for margins, Dia's without, but cairo wants them?
     */
    real width = (data->paper.lmargin + data->paper.width * data->paper.scaling + data->paper.rmargin)
          * (72.0 / 2.54) + 0.5;
    real height = (data->paper.tmargin + data->paper.height * data->paper.scaling + data->paper.bmargin)
           * (72.0 / 2.54) + 0.5;
    /* "Changes the size of a PDF surface for the current (and
     * subsequent) pages." Pagination setup? */
    cairo_pdf_surface_set_size (renderer->surface, width, height);
    lmargin = data->paper.lmargin / data->paper.scaling;
    tmargin = data->paper.tmargin / data->paper.scaling;
  }

  cairo_scale (renderer->cr, renderer->scale, renderer->scale);
  /* to ensure no clipping at top/left we need some extra gymnastics,
   * otherwise a box with a line witdh one one pixel might loose the
   * top/left border as in bug #147386 */
  ensure_minimum_one_device_unit (renderer, &onedu);

  if (update && paginated) {
    cairo_rectangle (renderer->cr, lmargin, tmargin,
                     update->right - update->left, update->bottom - update->top);
    cairo_clip (renderer->cr);
    cairo_translate (renderer->cr, -update->left + lmargin, -update->top + tmargin);
  } else
    cairo_translate (renderer->cr, -renderer->dia->extents.left + onedu, -renderer->dia->extents.top + onedu);
  /* no more blurred UML diagrams */
  cairo_set_antialias (renderer->cr, CAIRO_ANTIALIAS_NONE);

  /* clear background */
  if (renderer->with_alpha)
    {
      cairo_set_operator (renderer->cr, CAIRO_OPERATOR_SOURCE);
      cairo_set_source_rgba (renderer->cr,
                             renderer->dia->bg_color.red, 
                             renderer->dia->bg_color.green, 
                             renderer->dia->bg_color.blue,
                             0.0);
    }
  else
    {
      cairo_set_source_rgba (renderer->cr,
                             renderer->dia->bg_color.red, 
                             renderer->dia->bg_color.green, 
                             renderer->dia->bg_color.blue,
                             1.0);
    }
  cairo_paint (renderer->cr);
  if (renderer->with_alpha)
    {
      /* restore to default drawing */
      cairo_set_operator (renderer->cr, CAIRO_OPERATOR_OVER);
      cairo_set_source_rgba (renderer->cr,
                             renderer->dia->bg_color.red, 
                             renderer->dia->bg_color.green, 
                             renderer->dia->bg_color.blue,
                             1.0);
    }
#ifdef HAVE_PANGOCAIRO_H
  if (!renderer->layout)
    renderer->layout = pango_cairo_create_layout (renderer->cr);
#endif

  cairo_set_fill_rule (renderer->cr, CAIRO_FILL_RULE_EVEN_ODD);

#if 0 /* try to work around bug #341481 - no luck */
  {
    cairo_font_options_t *fo = cairo_font_options_create ();
    cairo_get_font_options (renderer->cr, fo);
    /* try to switch off kerning */
    cairo_font_options_set_hint_style (fo, CAIRO_HINT_STYLE_NONE);
    cairo_font_options_set_hint_metrics (fo, CAIRO_HINT_METRICS_OFF);

    cairo_set_font_options (renderer->cr, fo);
    cairo_font_options_destroy (fo);
#ifdef HAVE_PANGOCAIRO_H
    pango_cairo_update_context (renderer->cr, pango_layout_get_context (renderer->layout));
//.........这里部分代码省略.........

/**
 * _st_create_shadow_cairo_pattern:
 * @shadow_spec: the definition of the shadow
 * @src_pattern: surface pattern for which we create the shadow
 *               (must be a surface pattern)
 *
 * This is a utility function for creating shadows used by
 * st-theme-node.c; it's in this file to share the gaussian
 * blur implementation. The usage of this function is quite different
 * depending on whether shadow_spec->inset is %TRUE or not. If
 * shadow_spec->inset is %TRUE, the caller should pass in a @src_pattern
 * which is the <i>inverse</i> of what they want shadowed, and must take
 * care of the spread and offset from the shadow spec themselves. If
 * shadow_spec->inset is %FALSE then the caller should pass in what they
 * want shadowed directly, and this function takes care of the spread and
 * the offset.
 */
cairo_pattern_t *
_st_create_shadow_cairo_pattern (StShadow        *shadow_spec,
                                 cairo_pattern_t *src_pattern)
{
  static cairo_user_data_key_t shadow_pattern_user_data;
  cairo_t *cr;
  cairo_surface_t *src_surface;
  cairo_surface_t *surface_in;
  cairo_surface_t *surface_out;
  cairo_pattern_t *dst_pattern;
  guchar          *pixels_in, *pixels_out;
  gint             width_in, height_in, rowstride_in;
  gint             width_out, height_out, rowstride_out;
  cairo_matrix_t   shadow_matrix;
  int i, j;

  g_return_val_if_fail (shadow_spec != NULL, NULL);
  g_return_val_if_fail (src_pattern != NULL, NULL);

  if (cairo_pattern_get_surface (src_pattern, &src_surface) != CAIRO_STATUS_SUCCESS)
    /* The most likely reason we can't get the pattern is that sizing went hairwire
     * and the caller tried to create a surface too big for memory, leaving us with
     * a pattern in an error state; we return a transparent pattern for the shadow.
     */
    return cairo_pattern_create_rgba(1.0, 1.0, 1.0, 0.0);

  width_in  = cairo_image_surface_get_width  (src_surface);
  height_in = cairo_image_surface_get_height (src_surface);

  /* We want the output to be a color agnostic alpha mask,
   * so we need to strip the color channels from the input
   */
  if (cairo_image_surface_get_format (src_surface) != CAIRO_FORMAT_A8)
    {
      surface_in = cairo_image_surface_create (CAIRO_FORMAT_A8,
                                               width_in, height_in);

      cr = cairo_create (surface_in);
      cairo_set_source_surface (cr, src_surface, 0, 0);
      cairo_paint (cr);
      cairo_destroy (cr);
    }
  else
    {
      surface_in = cairo_surface_reference (src_surface);
    }

  pixels_in = cairo_image_surface_get_data (surface_in);
  rowstride_in = cairo_image_surface_get_stride (surface_in);

  pixels_out = blur_pixels (pixels_in, width_in, height_in, rowstride_in,
                            shadow_spec->blur,
                            &width_out, &height_out, &rowstride_out);
  cairo_surface_destroy (surface_in);

  /* Invert pixels for inset shadows */
  if (shadow_spec->inset)
    {
      for (j = 0; j < height_out; j++)
        {
          guchar *p = pixels_out + rowstride_out * j;
          for (i = 0; i < width_out; i++, p++)
            *p = ~*p;
        }
    }

  surface_out = cairo_image_surface_create_for_data (pixels_out,
                                                     CAIRO_FORMAT_A8,
                                                     width_out,
                                                     height_out,
                                                     rowstride_out);
  cairo_surface_set_user_data (surface_out, &shadow_pattern_user_data,
                               pixels_out, (cairo_destroy_func_t) g_free);

  dst_pattern = cairo_pattern_create_for_surface (surface_out);
  cairo_surface_destroy (surface_out);

  cairo_pattern_get_matrix (src_pattern, &shadow_matrix);

  if (shadow_spec->inset)
    {
      /* For inset shadows, offsets and spread radius have already been
       * applied to the original pattern, so all left to do is shift the
//.........这里部分代码省略.........