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cssshadowvalue: Add a cache for blurred Pango layouts

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Drawing text with Pango is quite expensive, and drawing text and also
blurring it is *really* expensive. To prevent us from drawing a lot of
text and then blurring it a lot is *really* expensive.

We now cache the blurred pixels for the last layout and shadow we made,
which means we can repeatedly draw labels with a blurred text-shadow
extremely fast.

To detect whether the shadow is up-to-date, we track the serial of the
PangoLayout alongside the radius of the box shadow. We don't support
inset shadows nor spread on text-shadow, so we don't need to track
these.
This commit is contained in:
Jasper St. Pierre 2014-08-29 13:51:30 -07:00 committed by Benjamin Otte
parent 919bdff7ac
commit dadc37e64d
1 changed files with 110 additions and 12 deletions
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122
gtk/gtkcssshadowvalue.c
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@ -386,6 +386,92 @@ gtk_css_shadow_value_finish_drawing (const GtkCssValue *shadow,
return original_cr;
}
static const cairo_user_data_key_t radius_key;
static const cairo_user_data_key_t layout_serial_key;
G_DEFINE_QUARK (GtkCssShadowValue pango_cached_blurred_surface, pango_cached_blurred_surface)
static cairo_surface_t *
get_cached_pango_surface (PangoLayout *layout,
const GtkCssValue *shadow)
{
cairo_surface_t *cached_surface = g_object_get_qdata (G_OBJECT (layout), pango_cached_blurred_surface_quark ());
guint cached_radius, cached_serial;
guint radius, serial;
if (!cached_surface)
return NULL;
radius = _gtk_css_number_value_get (shadow->radius, 0);
cached_radius = GPOINTER_TO_UINT (cairo_surface_get_user_data (cached_surface, &radius_key));
if (radius != cached_radius)
return NULL;
serial = pango_layout_get_serial (layout);
cached_serial = GPOINTER_TO_UINT (cairo_surface_get_user_data (cached_surface, &layout_serial_key));
if (serial != cached_serial)
return NULL;
return cached_surface;
}
static cairo_surface_t *
make_blurred_pango_surface (cairo_t *existing_cr,
PangoLayout *layout,
const GtkCssValue *shadow)
{
cairo_surface_t *surface;
cairo_t *cr;
gdouble radius, clip_radius;
PangoRectangle ink_rect;
radius = _gtk_css_number_value_get (shadow->radius, 0);
pango_layout_get_pixel_extents (layout, &ink_rect, NULL);
clip_radius = _gtk_cairo_blur_compute_pixels (radius);
surface = cairo_surface_create_similar_image (cairo_get_target (existing_cr),
CAIRO_FORMAT_A8,
ink_rect.width + 2 * clip_radius,
ink_rect.height + 2 * clip_radius);
cairo_surface_set_device_offset (surface, -ink_rect.x + clip_radius, -ink_rect.y + clip_radius);
cr = cairo_create (surface);
cairo_move_to (cr, 0, 0);
_gtk_pango_fill_layout (cr, layout);
_gtk_cairo_blur_surface (surface, radius);
cairo_destroy (cr);
return surface;
}
static cairo_surface_t *
get_blurred_pango_surface (cairo_t *cr,
PangoLayout *layout,
const GtkCssValue *shadow)
{
cairo_surface_t *surface;
guint radius, serial;
surface = get_cached_pango_surface (layout, shadow);
if (!surface)
{
surface = make_blurred_pango_surface (cr, layout, shadow);
/* Cache the surface on the PangoLayout */
radius = _gtk_css_number_value_get (shadow->radius, 0);
cairo_surface_set_user_data (surface, &radius_key, GUINT_TO_POINTER (radius), NULL);
serial = pango_layout_get_serial (layout);
cairo_surface_set_user_data (surface, &layout_serial_key, GUINT_TO_POINTER (serial), NULL);
g_object_set_qdata_full (G_OBJECT (layout), pango_cached_blurred_surface_quark (),
surface, (GDestroyNotify) cairo_surface_destroy);
}
return surface;
}
void
_gtk_css_shadow_value_paint_layout (const GtkCssValue *shadow,
cairo_t *cr,
@ -398,20 +484,32 @@ _gtk_css_shadow_value_paint_layout (const GtkCssValue *shadow,
cairo_save (cr);
cairo_rel_move_to (cr,
_gtk_css_number_value_get (shadow->hoffset, 0),
_gtk_css_number_value_get (shadow->voffset, 0));
if (needs_blur (shadow))
{
cairo_surface_t *blurred_surface = get_blurred_pango_surface (cr, layout, shadow);
double x, y;
cairo_get_current_point (cr, &x, &y);
cairo_translate (cr, x, y);
cairo_translate (cr,
_gtk_css_number_value_get (shadow->hoffset, 0),
_gtk_css_number_value_get (shadow->voffset, 0));
gdk_cairo_set_source_rgba (cr, _gtk_css_rgba_value_get_rgba (shadow->color));
cr = gtk_css_shadow_value_start_drawing (shadow, cr);
gdk_cairo_set_source_rgba (cr, _gtk_css_rgba_value_get_rgba (shadow->color));
cairo_mask_surface (cr, blurred_surface, 0, 0);
}
else
{
/* The no blur case -- just paint directly. */
cairo_rel_move_to (cr,
_gtk_css_number_value_get (shadow->hoffset, 0),
_gtk_css_number_value_get (shadow->voffset, 0));
gdk_cairo_set_source_rgba (cr, _gtk_css_rgba_value_get_rgba (shadow->color));
_gtk_pango_fill_layout (cr, layout);
cairo_rel_move_to (cr,
- _gtk_css_number_value_get (shadow->hoffset, 0),
- _gtk_css_number_value_get (shadow->voffset, 0));
}
_gtk_pango_fill_layout (cr, layout);
cr = gtk_css_shadow_value_finish_drawing (shadow, cr);
cairo_rel_move_to (cr,
- _gtk_css_number_value_get (shadow->hoffset, 0),
- _gtk_css_number_value_get (shadow->voffset, 0));
cairo_restore (cr);
}