Adding upstream version 43.9.upstream/43.9upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 804 insertions, 0 deletions

diff --git a/src/st/st-private.c b/src/st/st-private.c
new file mode 100644
index 0000000..bb98151
--- /dev/null
+++ b/src/st/st-private.c
@@ -0,0 +1,804 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+/*
+ * st-private.h: Private declarations and functions
+ *
+ * Copyright 2009, 2010 Red Hat, Inc.
+ * Copyright 2010 Florian Müllner
+ * Copyright 2010 Intel Corporation
+ * Copyright 2010 Giovanni Campagna
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU Lesser General Public License,
+ * version 2.1, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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 program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <math.h>
+#include <string.h>
+
+#include "st-private.h"
+
+/**
+ * _st_actor_get_preferred_width:
+ * @actor: a #ClutterActor
+ * @for_height: as with clutter_actor_get_preferred_width()
+ * @y_fill: %TRUE if @actor will fill its allocation vertically
+ * @min_width_p: as with clutter_actor_get_preferred_width()
+ * @natural_width_p: as with clutter_actor_get_preferred_width()
+ *
+ * Like clutter_actor_get_preferred_width(), but if @y_fill is %FALSE,
+ * then it will compute a width request based on the assumption that
+ * @actor will be given an allocation no taller than its natural
+ * height.
+ */
+void
+_st_actor_get_preferred_width  (ClutterActor *actor,
+                                gfloat        for_height,
+                                gboolean      y_fill,
+                                gfloat       *min_width_p,
+                                gfloat       *natural_width_p)
+{
+  if (!y_fill && for_height != -1)
+    {
+      ClutterRequestMode mode;
+      gfloat natural_height;
+
+      mode = clutter_actor_get_request_mode (actor);
+      if (mode == CLUTTER_REQUEST_WIDTH_FOR_HEIGHT)
+        {
+          clutter_actor_get_preferred_height (actor, -1, NULL, &natural_height);
+          if (for_height > natural_height)
+            for_height = natural_height;
+        }
+    }
+
+  clutter_actor_get_preferred_width (actor, for_height, min_width_p, natural_width_p);
+}
+
+/**
+ * _st_actor_get_preferred_height:
+ * @actor: a #ClutterActor
+ * @for_width: as with clutter_actor_get_preferred_height()
+ * @x_fill: %TRUE if @actor will fill its allocation horizontally
+ * @min_height_p: as with clutter_actor_get_preferred_height()
+ * @natural_height_p: as with clutter_actor_get_preferred_height()
+ *
+ * Like clutter_actor_get_preferred_height(), but if @x_fill is
+ * %FALSE, then it will compute a height request based on the
+ * assumption that @actor will be given an allocation no wider than
+ * its natural width.
+ */
+void
+_st_actor_get_preferred_height (ClutterActor *actor,
+                                gfloat        for_width,
+                                gboolean      x_fill,
+                                gfloat       *min_height_p,
+                                gfloat       *natural_height_p)
+{
+  if (!x_fill && for_width != -1)
+    {
+      ClutterRequestMode mode;
+      gfloat natural_width;
+
+      mode = clutter_actor_get_request_mode (actor);
+      if (mode == CLUTTER_REQUEST_HEIGHT_FOR_WIDTH)
+        {
+          clutter_actor_get_preferred_width (actor, -1, NULL, &natural_width);
+          if (for_width > natural_width)
+            for_width = natural_width;
+        }
+    }
+
+  clutter_actor_get_preferred_height (actor, for_width, min_height_p, natural_height_p);
+}
+
+/**
+ * _st_set_text_from_style:
+ * @text: Target #ClutterText
+ * @theme_node: Source #StThemeNode
+ *
+ * Set various GObject properties of the @text object using
+ * CSS information from @theme_node.
+ */
+void
+_st_set_text_from_style (ClutterText *text,
+                         StThemeNode *theme_node)
+{
+
+  ClutterColor color;
+  StTextDecoration decoration;
+  PangoAttrList *attribs = NULL;
+  const PangoFontDescription *font;
+  PangoAttribute *foreground;
+  StTextAlign align;
+  gdouble spacing;
+  gchar *font_features;
+
+  font = st_theme_node_get_font (theme_node);
+  clutter_text_set_font_description (text, (PangoFontDescription *) font);
+
+  attribs = pango_attr_list_new ();
+
+  st_theme_node_get_foreground_color (theme_node, &color);
+  clutter_text_set_cursor_color (text, &color);
+  foreground = pango_attr_foreground_new (color.red * 255,
+                                          color.green * 255,
+                                          color.blue * 255);
+  pango_attr_list_insert (attribs, foreground);
+
+  if (color.alpha != 255)
+    {
+      PangoAttribute *alpha;
+
+      /* An alpha value of 0 means "system inherited", so the
+       * minimum regular value is 1.
+       */
+      if (color.alpha == 0)
+        alpha = pango_attr_foreground_alpha_new (1);
+      else
+        alpha = pango_attr_foreground_alpha_new (color.alpha * 255);
+
+      pango_attr_list_insert (attribs, alpha);
+    }
+
+  decoration = st_theme_node_get_text_decoration (theme_node);
+  if (decoration)
+    {
+      if (decoration & ST_TEXT_DECORATION_UNDERLINE)
+        {
+          PangoAttribute *underline = pango_attr_underline_new (PANGO_UNDERLINE_SINGLE);
+          pango_attr_list_insert (attribs, underline);
+        }
+      if (decoration & ST_TEXT_DECORATION_LINE_THROUGH)
+        {
+          PangoAttribute *strikethrough = pango_attr_strikethrough_new (TRUE);
+          pango_attr_list_insert (attribs, strikethrough);
+        }
+      /* Pango doesn't have an equivalent attribute for _OVERLINE, and we deliberately
+       * skip BLINK (for now...)
+       */
+    }
+
+  spacing = st_theme_node_get_letter_spacing (theme_node);
+  if (spacing)
+    {
+      PangoAttribute *letter_spacing = pango_attr_letter_spacing_new ((int)(.5 + spacing) * PANGO_SCALE);
+      pango_attr_list_insert (attribs, letter_spacing);
+    }
+
+  font_features = st_theme_node_get_font_features (theme_node);
+  if (font_features)
+    {
+      pango_attr_list_insert (attribs, pango_attr_font_features_new (font_features));
+      g_free (font_features);
+    }
+
+  clutter_text_set_attributes (text, attribs);
+
+  if (attribs)
+    pango_attr_list_unref (attribs);
+
+  align = st_theme_node_get_text_align (theme_node);
+  if (align == ST_TEXT_ALIGN_JUSTIFY)
+    {
+      clutter_text_set_justify (text, TRUE);
+      clutter_text_set_line_alignment (text, PANGO_ALIGN_LEFT);
+    }
+  else
+    {
+      clutter_text_set_justify (text, FALSE);
+      clutter_text_set_line_alignment (text, (PangoAlignment) align);
+    }
+}
+
+/**
+ * _st_create_texture_pipeline:
+ * @src_texture: The CoglTexture for the pipeline
+ *
+ * Creates a simple pipeline which contains the given texture as a
+ * single layer.
+ */
+CoglPipeline *
+_st_create_texture_pipeline (CoglTexture *src_texture)
+{
+  static CoglPipeline *texture_pipeline_template = NULL;
+  CoglPipeline *pipeline;
+
+  g_return_val_if_fail (src_texture != NULL, NULL);
+
+  /* The only state used in the pipeline that would affect the shader
+     generation is the texture type on the layer. Therefore we create
+     a template pipeline which sets this state and all texture
+     pipelines are created as a copy of this. That way Cogl can find
+     the shader state for the pipeline more quickly by looking at the
+     pipeline ancestry instead of resorting to the shader cache. */
+  if (G_UNLIKELY (texture_pipeline_template == NULL))
+    {
+      CoglContext *ctx =
+        clutter_backend_get_cogl_context (clutter_get_default_backend ());
+
+      texture_pipeline_template = cogl_pipeline_new (ctx);
+      cogl_pipeline_set_layer_null_texture (texture_pipeline_template, 0);
+    }
+
+  pipeline = cogl_pipeline_copy (texture_pipeline_template);
+
+  if (src_texture != NULL)
+    cogl_pipeline_set_layer_texture (pipeline, 0, src_texture);
+
+  return pipeline;
+}
+
+/*****
+ * Shadows
+ *****/
+
+static gdouble *
+calculate_gaussian_kernel (gdouble   sigma,
+                           guint     n_values)
+{
+  gdouble *ret, sum;
+  gdouble exp_divisor;
+  int half, i;
+
+  g_return_val_if_fail (sigma > 0, NULL);
+
+  half = n_values / 2;
+
+  ret = g_malloc (n_values * sizeof (gdouble));
+  sum = 0.0;
+
+  exp_divisor = 2 * sigma * sigma;
+
+  /* n_values of 1D Gauss function */
+  for (i = 0; i < (int)n_values; i++)
+    {
+      ret[i] = exp (-(i - half) * (i - half) / exp_divisor);
+      sum += ret[i];
+    }
+
+  /* normalize */
+  for (i = 0; i < (int)n_values; i++)
+    ret[i] /= sum;
+
+  return ret;
+}
+
+static guchar *
+blur_pixels (guchar  *pixels_in,
+             gint     width_in,
+             gint     height_in,
+             gint     rowstride_in,
+             gdouble  blur,
+             gint    *width_out,
+             gint    *height_out,
+             size_t  *rowstride_out)
+{
+  guchar *pixels_out;
+  gdouble sigma;
+
+  /* The CSS specification defines (or will define) the blur radius as twice
+   * the Gaussian standard deviation. See:
+   *
+   * http://lists.w3.org/Archives/Public/www-style/2010Sep/0002.html
+   */
+  sigma = blur / 2.;
+
+  if ((guint) blur == 0)
+    {
+      *width_out  = width_in;
+      *height_out = height_in;
+      *rowstride_out = rowstride_in;
+      pixels_out = g_memdup2 (pixels_in, *rowstride_out * *height_out);
+    }
+  else
+    {
+      gdouble *kernel;
+      guchar  *line;
+      gint     n_values, half;
+      gint     x_in, y_in, x_out, y_out, i;
+
+      n_values = (gint) 5 * sigma;
+      half = n_values / 2;
+
+      *width_out  = width_in  + 2 * half;
+      *height_out = height_in + 2 * half;
+      *rowstride_out = (*width_out + 3) & ~3;
+
+      pixels_out = g_malloc0 (*rowstride_out * *height_out);
+      line       = g_malloc0 (*rowstride_out);
+
+      kernel = calculate_gaussian_kernel (sigma, n_values);
+
+      /* vertical blur */
+      for (x_in = 0; x_in < width_in; x_in++)
+        for (y_out = 0; y_out < *height_out; y_out++)
+          {
+            guchar *pixel_in, *pixel_out;
+            gint i0, i1;
+
+            y_in = y_out - half;
+
+            /* We read from the source at 'y = y_in + i - half'; clamp the
+             * full i range [0, n_values) so that y is in [0, height_in).
+             */
+            i0 = MAX (half - y_in, 0);
+            i1 = MIN (height_in + half - y_in, n_values);
+
+            pixel_in  =  pixels_in + (y_in + i0 - half) * rowstride_in + x_in;
+            pixel_out =  pixels_out + y_out * *rowstride_out + (x_in + half);
+
+            for (i = i0; i < i1; i++)
+              {
+                *pixel_out += *pixel_in * kernel[i];
+                pixel_in += rowstride_in;
+              }
+          }
+
+      /* horizontal blur */
+      for (y_out = 0; y_out < *height_out; y_out++)
+        {
+          memcpy (line, pixels_out + y_out * *rowstride_out, *rowstride_out);
+
+          for (x_out = 0; x_out < *width_out; x_out++)
+            {
+              gint i0, i1;
+              guchar *pixel_out, *pixel_in;
+
+              /* We read from the source at 'x = x_out + i - half'; clamp the
+               * full i range [0, n_values) so that x is in [0, width_out).
+               */
+              i0 = MAX (half - x_out, 0);
+              i1 = MIN (*width_out + half - x_out, n_values);
+
+              pixel_in  = line + x_out + i0 - half;
+              pixel_out = pixels_out + *rowstride_out * y_out + x_out;
+
+              *pixel_out = 0;
+              for (i = i0; i < i1; i++)
+                {
+                  *pixel_out += *pixel_in * kernel[i];
+                  pixel_in++;
+                }
+            }
+        }
+      g_free (kernel);
+      g_free (line);
+    }
+
+  return pixels_out;
+}
+
+CoglPipeline *
+_st_create_shadow_pipeline (StShadow    *shadow_spec,
+                            CoglTexture *src_texture,
+                            float        resource_scale)
+{
+  ClutterBackend *backend = clutter_get_default_backend ();
+  CoglContext *ctx = clutter_backend_get_cogl_context (backend);
+  g_autoptr (ClutterPaintNode) texture_node = NULL;
+  g_autoptr (ClutterPaintNode) blur_node = NULL;
+  g_autoptr (CoglOffscreen) offscreen = NULL;
+  g_autoptr (GError) error = NULL;
+  ClutterPaintContext *paint_context;
+  CoglFramebuffer *fb;
+  CoglPipeline *pipeline;
+  CoglTexture *texture;
+  float sampling_radius;
+  float sigma;
+  int src_height, dst_height;
+  int src_width, dst_width;
+  CoglPipeline *texture_pipeline;
+
+  static CoglPipelineKey texture_pipeline_key =
+    "st-create-shadow-pipeline-saturate-alpha";
+  static CoglPipeline *shadow_pipeline_template = NULL;
+
+  g_return_val_if_fail (shadow_spec != NULL, NULL);
+  g_return_val_if_fail (src_texture != NULL, NULL);
+
+  sampling_radius = resource_scale * shadow_spec->blur;
+  sigma = sampling_radius / 2.f;
+  sampling_radius = ceilf (sampling_radius);
+
+  src_width = cogl_texture_get_width (src_texture);
+  src_height = cogl_texture_get_height (src_texture);
+  dst_width = src_width + 2 * sampling_radius;
+  dst_height = src_height + 2 * sampling_radius;
+
+  texture = cogl_texture_2d_new_with_size (ctx, dst_width, dst_height);
+  if (!texture)
+    return NULL;
+
+  offscreen = cogl_offscreen_new_with_texture (texture);
+  fb = COGL_FRAMEBUFFER (offscreen);
+  if (!cogl_framebuffer_allocate (fb, &error))
+    {
+      cogl_clear_object (&texture);
+      return NULL;
+    }
+
+  cogl_framebuffer_clear4f (fb, COGL_BUFFER_BIT_COLOR, 0.f, 0.f, 0.f, 0.f);
+  cogl_framebuffer_orthographic (fb, 0, 0, dst_width, dst_height, 0, 1.0);
+
+  /* Blur */
+  blur_node = clutter_blur_node_new (dst_width, dst_height, sigma);
+  clutter_paint_node_add_rectangle (blur_node,
+                                    &(ClutterActorBox) {
+                                      0.f, 0.f,
+                                      dst_width, dst_height,
+                                    });
+
+  /* Texture */
+  texture_pipeline = cogl_context_get_named_pipeline (ctx,
+                                                      &texture_pipeline_key);
+
+  if (G_UNLIKELY (texture_pipeline == NULL))
+    {
+      CoglSnippet *snippet;
+
+      snippet = cogl_snippet_new (COGL_SNIPPET_HOOK_FRAGMENT,
+                                  "",
+                                  "if (cogl_color_out.a > 0.0)\n"
+                                  "  cogl_color_out.a = 1.0;");
+
+      texture_pipeline = cogl_pipeline_new (ctx);
+      cogl_pipeline_add_snippet (texture_pipeline, snippet);
+      cogl_object_unref (snippet);
+
+      cogl_context_set_named_pipeline (ctx,
+                                       &texture_pipeline_key,
+                                       texture_pipeline);
+    }
+
+  /* No need to unref texture_pipeline since the named pipeline hash
+   * doesn't change its ref count from 1. Also no need to copy texture_pipeline
+   * since we'll be completely finished with it after clutter_paint_node_paint.
+   */
+
+  cogl_pipeline_set_layer_texture (texture_pipeline, 0, src_texture);
+  texture_node = clutter_pipeline_node_new (texture_pipeline);
+  clutter_paint_node_add_child (blur_node, texture_node);
+  clutter_paint_node_add_rectangle (texture_node,
+                                    &(ClutterActorBox) {
+                                      .x1 = sampling_radius,
+                                      .y1 = sampling_radius,
+                                      .x2 = src_width + sampling_radius,
+                                      .y2 = src_height + sampling_radius,
+                                    });
+
+  paint_context =
+    clutter_paint_context_new_for_framebuffer (fb, NULL, CLUTTER_PAINT_FLAG_NONE);
+  clutter_paint_node_paint (blur_node, paint_context);
+  clutter_paint_context_destroy (paint_context);
+
+  if (G_UNLIKELY (shadow_pipeline_template == NULL))
+    {
+      shadow_pipeline_template = cogl_pipeline_new (ctx);
+
+      /* We set up the pipeline to blend the shadow texture with the combine
+       * constant, but defer setting the latter until painting, so that we can
+       * take the actor's overall opacity into account. */
+      cogl_pipeline_set_layer_combine (shadow_pipeline_template, 0,
+                                       "RGBA = MODULATE (CONSTANT, TEXTURE[A])",
+                                       NULL);
+    }
+
+  pipeline = cogl_pipeline_copy (shadow_pipeline_template);
+  cogl_pipeline_set_layer_texture (pipeline, 0, texture);
+
+  cogl_clear_object (&texture);
+
+  return pipeline;
+}
+
+CoglPipeline *
+_st_create_shadow_pipeline_from_actor (StShadow     *shadow_spec,
+                                       ClutterActor *actor)
+{
+  ClutterContent *image = NULL;
+  CoglPipeline *shadow_pipeline = NULL;
+  float resource_scale;
+  float width, height;
+  ClutterPaintContext *paint_context;
+
+  g_return_val_if_fail (clutter_actor_has_allocation (actor), NULL);
+
+  clutter_actor_get_size (actor, &width, &height);
+
+  if (width == 0 || height == 0)
+    return NULL;
+
+  resource_scale = clutter_actor_get_resource_scale (actor);
+
+  width = ceilf (width * resource_scale);
+  height = ceilf (height * resource_scale);
+
+  image = clutter_actor_get_content (actor);
+  if (image && CLUTTER_IS_IMAGE (image))
+    {
+      CoglTexture *texture;
+
+      texture = clutter_image_get_texture (CLUTTER_IMAGE (image));
+      if (texture &&
+          cogl_texture_get_width (texture) == width &&
+          cogl_texture_get_height (texture) == height)
+        shadow_pipeline = _st_create_shadow_pipeline (shadow_spec, texture,
+                                                      resource_scale);
+    }
+
+  if (shadow_pipeline == NULL)
+    {
+      CoglTexture *buffer;
+      CoglOffscreen *offscreen;
+      CoglFramebuffer *fb;
+      CoglContext *ctx;
+      CoglColor clear_color;
+      GError *catch_error = NULL;
+      float x, y;
+
+      ctx = clutter_backend_get_cogl_context (clutter_get_default_backend ());
+      buffer = cogl_texture_2d_new_with_size (ctx, width, height);
+
+      if (buffer == NULL)
+        return NULL;
+
+      offscreen = cogl_offscreen_new_with_texture (buffer);
+      fb = COGL_FRAMEBUFFER (offscreen);
+
+      if (!cogl_framebuffer_allocate (fb, &catch_error))
+        {
+          g_error_free (catch_error);
+          g_object_unref (offscreen);
+          cogl_object_unref (buffer);
+          return NULL;
+        }
+
+      cogl_color_init_from_4ub (&clear_color, 0, 0, 0, 0);
+      clutter_actor_get_position (actor, &x, &y);
+      x *= resource_scale;
+      y *= resource_scale;
+
+      cogl_framebuffer_clear (fb, COGL_BUFFER_BIT_COLOR, &clear_color);
+      cogl_framebuffer_translate (fb, -x, -y, 0);
+      cogl_framebuffer_orthographic (fb, 0, 0, width, height, 0, 1.0);
+      cogl_framebuffer_scale (fb, resource_scale, resource_scale, 1);
+
+      clutter_actor_set_opacity_override (actor, 255);
+
+      paint_context =
+        clutter_paint_context_new_for_framebuffer (fb, NULL,
+                                                   CLUTTER_PAINT_FLAG_NONE);
+      clutter_actor_paint (actor, paint_context);
+      clutter_paint_context_destroy (paint_context);
+
+      clutter_actor_set_opacity_override (actor, -1);
+
+      g_object_unref (fb);
+
+      shadow_pipeline = _st_create_shadow_pipeline (shadow_spec, buffer,
+                                                    resource_scale);
+
+      cogl_object_unref (buffer);
+    }
+
+  return shadow_pipeline;
+}
+
+/**
+ * _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_in,
+                                 cairo_pattern_t *src_pattern)
+{
+  g_autoptr(StShadow) shadow_spec = NULL;
+  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;
+  size_t           rowstride_out;
+  cairo_matrix_t   shadow_matrix;
+  double           xscale_in, yscale_in;
+  int i, j;
+
+  g_return_val_if_fail (shadow_spec_in != 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);
+
+  cairo_surface_get_device_scale (src_surface, &xscale_in, &yscale_in);
+
+  if (xscale_in != 1.0 || yscale_in != 1.0)
+    {
+      /* Scale the shadow specifications in a temporary copy so that
+       * we can work everywhere in absolute surface coordinates */
+      double scale = (xscale_in + yscale_in) / 2.0;
+      shadow_spec = st_shadow_new (&shadow_spec_in->color,
+                                   shadow_spec_in->xoffset * xscale_in,
+                                   shadow_spec_in->yoffset * yscale_in,
+                                   shadow_spec_in->blur * scale,
+                                   shadow_spec_in->spread * scale,
+                                   shadow_spec_in->inset);
+    }
+  else
+    {
+      shadow_spec = st_shadow_ref (shadow_spec_in);
+    }
+
+  /* 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_device_scale (surface_out, xscale_in, yscale_in);
+  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)
+    {
+      /* Scale the matrix in surface absolute coordinates */
+      cairo_matrix_scale (&shadow_matrix, 1.0 / xscale_in, 1.0 / yscale_in);
+
+      /* For inset shadows, offsets and spread radius have already been
+       * applied to the original pattern, so all left to do is shift the
+       * blurred image left, so that it aligns centered under the
+       * unblurred one
+       */
+      cairo_matrix_translate (&shadow_matrix,
+                              (width_out - width_in) / 2.0,
+                              (height_out - height_in) / 2.0);
+
+      /* Scale back the matrix in original coordinates */
+      cairo_matrix_scale (&shadow_matrix, xscale_in, yscale_in);
+
+      cairo_pattern_set_matrix (dst_pattern, &shadow_matrix);
+      return dst_pattern;
+    }
+
+  /* Read all the code from the cairo_pattern_set_matrix call
+   * at the end of this function to here from bottom to top,
+   * because each new affine transformation is applied in
+   * front of all the previous ones */
+
+  /* 6. Invert the matrix back */
+  cairo_matrix_invert (&shadow_matrix);
+
+  /* Scale the matrix in surface absolute coordinates */
+  cairo_matrix_scale (&shadow_matrix, 1.0 / xscale_in, 1.0 / yscale_in);
+
+  /* 5. Adjust based on specified offsets */
+  cairo_matrix_translate (&shadow_matrix,
+                          shadow_spec->xoffset,
+                          shadow_spec->yoffset);
+
+  /* 4. Recenter the newly scaled image */
+  cairo_matrix_translate (&shadow_matrix,
+                          - shadow_spec->spread,
+                          - shadow_spec->spread);
+
+  /* 3. Scale up the blurred image to fill the spread */
+  cairo_matrix_scale (&shadow_matrix,
+                      (width_in + 2.0 * shadow_spec->spread) / width_in,
+                      (height_in + 2.0 * shadow_spec->spread) / height_in);
+
+  /* 2. Shift the blurred image left, so that it aligns centered
+   * under the unblurred one */
+  cairo_matrix_translate (&shadow_matrix,
+                          - (width_out - width_in) / 2.0,
+                          - (height_out - height_in) / 2.0);
+
+  /* Scale back the matrix in scaled coordinates */
+  cairo_matrix_scale (&shadow_matrix, xscale_in, yscale_in);
+
+  /* 1. Invert the matrix so we can work with it in pattern space
+   */
+  cairo_matrix_invert (&shadow_matrix);
+
+  cairo_pattern_set_matrix (dst_pattern, &shadow_matrix);
+
+  return dst_pattern;
+}
+
+void
+_st_paint_shadow_with_opacity (StShadow        *shadow_spec,
+                               CoglFramebuffer *framebuffer,
+                               CoglPipeline    *shadow_pipeline,
+                               ClutterActorBox *box,
+                               guint8           paint_opacity)
+{
+  ClutterActorBox shadow_box;
+  CoglColor color;
+
+  g_return_if_fail (shadow_spec != NULL);
+  g_return_if_fail (shadow_pipeline != NULL);
+
+  st_shadow_get_box (shadow_spec, box, &shadow_box);
+
+  cogl_color_init_from_4ub (&color,
+                            shadow_spec->color.red   * paint_opacity / 255,
+                            shadow_spec->color.green * paint_opacity / 255,
+                            shadow_spec->color.blue  * paint_opacity / 255,
+                            shadow_spec->color.alpha * paint_opacity / 255);
+  cogl_color_premultiply (&color);
+  cogl_pipeline_set_layer_combine_constant (shadow_pipeline, 0, &color);
+  cogl_framebuffer_draw_rectangle (framebuffer,
+                                   shadow_pipeline,
+                                   shadow_box.x1, shadow_box.y1,
+                                   shadow_box.x2, shadow_box.y2);
+}