gstreamer/ext/cairo/gsttextoverlay.c
Andy Wingo 7ebd7b97d4 All plugins updated for element state changes.
Original commit message from CVS:
2005-09-02  Andy Wingo  <wingo@pobox.com>

* All plugins updated for element state changes.
2005-09-02 15:44:50 +00:00

705 lines
22 KiB
C

/* GStreamer
* Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
* Copyright (C) <2003> David Schleef <ds@schleef.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <string.h>
#include <strings.h>
#include <gst/gst.h>
#include "gsttextoverlay.h"
static GstElementDetails textoverlay_details = {
"Text Overlay",
"Filter/Editor/Video",
"Adds text strings on top of a video buffer",
"David Schleef <ds@schleef.org>"
};
enum
{
ARG_0,
ARG_TEXT,
ARG_VALIGN,
ARG_HALIGN,
ARG_X0,
ARG_Y0,
ARG_FONT_DESC
};
static GstStaticPadTemplate textoverlay_src_template_factory =
GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("video/x-raw-yuv, "
"format = (fourcc) I420, "
"width = (int) [ 1, MAX ], " "height = (int) [ 1, MAX ]")
);
static GstStaticPadTemplate video_sink_template_factory =
GST_STATIC_PAD_TEMPLATE ("video_sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("video/x-raw-yuv, "
"format = (fourcc) I420, "
"width = (int) [ 1, MAX ], " "height = (int) [ 1, MAX ]")
);
static GstStaticPadTemplate text_sink_template_factory =
GST_STATIC_PAD_TEMPLATE ("text_sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("text/plain")
);
static void gst_textoverlay_base_init (gpointer g_class);
static void gst_textoverlay_class_init (GstTextOverlayClass * klass);
static void gst_textoverlay_init (GstTextOverlay * overlay);
static void gst_textoverlay_set_property (GObject * object,
guint prop_id, const GValue * value, GParamSpec * pspec);
static void gst_textoverlay_get_property (GObject * object,
guint prop_id, GValue * value, GParamSpec * pspec);
static GstStateChangeReturn gst_textoverlay_change_state (GstElement * element);
static void gst_textoverlay_finalize (GObject * object);
static GstElementClass *parent_class = NULL;
/*static guint gst_textoverlay_signals[LAST_SIGNAL] = { 0 }; */
GType
gst_textoverlay_get_type (void)
{
static GType textoverlay_type = 0;
if (!textoverlay_type) {
static const GTypeInfo textoverlay_info = {
sizeof (GstTextOverlayClass),
gst_textoverlay_base_init,
NULL,
(GClassInitFunc) gst_textoverlay_class_init,
NULL,
NULL,
sizeof (GstTextOverlay),
0,
(GInstanceInitFunc) gst_textoverlay_init,
};
textoverlay_type =
g_type_register_static (GST_TYPE_ELEMENT, "GstTextOverlay",
&textoverlay_info, 0);
}
return textoverlay_type;
}
static void
gst_textoverlay_base_init (gpointer g_class)
{
GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
gst_element_class_add_pad_template (element_class,
gst_static_pad_template_get (&textoverlay_src_template_factory));
gst_element_class_add_pad_template (element_class,
gst_static_pad_template_get (&video_sink_template_factory));
gst_element_class_add_pad_template (element_class,
gst_static_pad_template_get (&text_sink_template_factory));
gst_element_class_set_details (element_class, &textoverlay_details);
}
static void
gst_textoverlay_class_init (GstTextOverlayClass * klass)
{
GObjectClass *gobject_class;
GstElementClass *gstelement_class;
gobject_class = (GObjectClass *) klass;
gstelement_class = (GstElementClass *) klass;
parent_class = g_type_class_peek_parent (klass);
gobject_class->finalize = gst_textoverlay_finalize;
gobject_class->set_property = gst_textoverlay_set_property;
gobject_class->get_property = gst_textoverlay_get_property;
gstelement_class->change_state = gst_textoverlay_change_state;
g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_TEXT,
g_param_spec_string ("text", "text",
"Text to be display.", "", G_PARAM_WRITABLE));
g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_VALIGN,
g_param_spec_string ("valign", "vertical alignment",
"Vertical alignment of the text. "
"Can be either 'baseline', 'bottom', or 'top'",
"baseline", G_PARAM_WRITABLE));
g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_HALIGN,
g_param_spec_string ("halign", "horizontal alignment",
"Horizontal alignment of the text. "
"Can be either 'left', 'right', or 'center'",
"center", G_PARAM_WRITABLE));
g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_X0,
g_param_spec_int ("x0", "X position",
"Initial X position."
" Horizontal aligment takes this point"
" as reference.", G_MININT, G_MAXINT, 0, G_PARAM_WRITABLE));
g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_Y0,
g_param_spec_int ("y0", "Y position",
"Initial Y position."
" Vertical aligment takes this point"
" as reference.", G_MININT, G_MAXINT, 0, G_PARAM_WRITABLE));
g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_FONT_DESC,
g_param_spec_string ("font-desc", "font description",
"Pango font description of font "
"to be used for rendering. "
"See documentation of "
"pango_font_description_from_string"
" for syntax.", "", G_PARAM_WRITABLE));
}
#if 0
static void
resize_bitmap (GstTextOverlay * overlay, int width, int height)
{
FT_Bitmap *bitmap = &overlay->bitmap;
int pitch = (width | 3) + 1;
int size = pitch * height;
/* no need to keep reallocating; just keep the maximum size so far */
if (size <= overlay->bitmap_buffer_size) {
bitmap->rows = height;
bitmap->width = width;
bitmap->pitch = pitch;
memset (bitmap->buffer, 0, overlay->bitmap_buffer_size);
return;
}
if (!bitmap->buffer) {
/* initialize */
bitmap->pixel_mode = ft_pixel_mode_grays;
bitmap->num_grays = 256;
}
if (bitmap->buffer)
bitmap->buffer = g_realloc (bitmap->buffer, size);
else
bitmap->buffer = g_malloc (size);
bitmap->rows = height;
bitmap->width = width;
bitmap->pitch = pitch;
memset (bitmap->buffer, 0, size);
overlay->bitmap_buffer_size = size;
}
#endif
static void
gst_textoverlay_render_text (GstTextOverlay * overlay, gchar * text,
int textlen)
{
cairo_text_extents_t extents;
char *string;
double x, y;
string = g_strndup (text, textlen);
if (overlay->text_fill_image)
g_free (overlay->text_fill_image);
overlay->text_fill_image =
g_malloc (4 * overlay->width * overlay->text_height);
cairo_set_target_image (overlay->cr, overlay->text_fill_image,
CAIRO_FORMAT_ARGB32, overlay->width, overlay->text_height,
overlay->width * 4);
cairo_save (overlay->cr);
cairo_rectangle (overlay->cr, 0, 0, overlay->width, overlay->text_height);
cairo_set_rgb_color (overlay->cr, 0, 0, 0);
cairo_set_alpha (overlay->cr, 1.0);
cairo_set_operator (overlay->cr, CAIRO_OPERATOR_SRC);
cairo_fill (overlay->cr);
cairo_restore (overlay->cr);
cairo_save (overlay->cr);
cairo_text_extents (overlay->cr, string, &extents);
cairo_set_rgb_color (overlay->cr, 1, 1, 1);
cairo_set_alpha (overlay->cr, 1.0);
switch (overlay->halign) {
case GST_TEXT_OVERLAY_HALIGN_LEFT:
x = overlay->x0;
break;
case GST_TEXT_OVERLAY_HALIGN_CENTER:
x = overlay->x0 - extents.width / 2;
break;
case GST_TEXT_OVERLAY_HALIGN_RIGHT:
x = overlay->x0 - extents.width;
break;
default:
x = 0;
}
y = overlay->text_height - 2;
cairo_move_to (overlay->cr, x, y);
cairo_show_text (overlay->cr, string);
cairo_restore (overlay->cr);
if (overlay->text_outline_image)
g_free (overlay->text_outline_image);
overlay->text_outline_image =
g_malloc (4 * overlay->width * overlay->text_height);
cairo_set_target_image (overlay->cr, overlay->text_outline_image,
CAIRO_FORMAT_ARGB32, overlay->width, overlay->text_height,
overlay->width * 4);
cairo_save (overlay->cr);
cairo_rectangle (overlay->cr, 0, 0, overlay->width, overlay->text_height);
cairo_set_rgb_color (overlay->cr, 0, 0, 0);
cairo_set_alpha (overlay->cr, 1.0);
cairo_set_operator (overlay->cr, CAIRO_OPERATOR_SRC);
cairo_fill (overlay->cr);
cairo_restore (overlay->cr);
cairo_save (overlay->cr);
cairo_move_to (overlay->cr, x, y);
cairo_set_rgb_color (overlay->cr, 1, 1, 1);
cairo_set_alpha (overlay->cr, 1.0);
cairo_set_line_width (overlay->cr, 1.0);
cairo_text_path (overlay->cr, string);
cairo_stroke (overlay->cr);
cairo_restore (overlay->cr);
g_free (string);
}
/* static GstPadLinkReturn */
/* gst_textoverlay_text_sinkconnect (GstPad *pad, GstCaps *caps) */
/* { */
/* return GST_PAD_LINK_DONE; */
/* } */
static GstPadLinkReturn
gst_textoverlay_video_sinkconnect (GstPad * pad, const GstCaps * caps)
{
GstTextOverlay *overlay;
GstStructure *structure;
overlay = GST_TEXTOVERLAY (gst_pad_get_parent (pad));
structure = gst_caps_get_structure (caps, 0);
overlay->width = overlay->height = 0;
gst_structure_get_int (structure, "width", &overlay->width);
gst_structure_get_int (structure, "height", &overlay->height);
return gst_pad_try_set_caps (overlay->srcpad, caps);
}
static void
gst_text_overlay_blit_1 (GstTextOverlay * overlay, guchar * dest,
guchar * text_image, int val)
{
int i;
int j;
int x, a, y;
int y0 = 0;
y = val;
for (i = 0; i < overlay->text_height; i++) {
for (j = 0; j < overlay->width; j++) {
x = dest[(i + y0) * overlay->width + j];
a = text_image[4 * (i * overlay->width + j) + 1];
dest[(i + y0) * overlay->width + j] = (y * a + x * (255 - a)) / 255;
}
}
}
static void
gst_text_overlay_blit_sub2x2 (GstTextOverlay * overlay, guchar * dest,
guchar * text_image, int val)
{
int i;
int j;
int x, a, y;
int y0 = 0;
y = val;
for (i = 0; i < overlay->text_height; i += 2) {
for (j = 0; j < overlay->width; j += 2) {
x = dest[(i / 2 + y0) * (overlay->width / 2) + j / 2];
a = (text_image[4 * (i * overlay->width + j) + 1] +
text_image[4 * (i * overlay->width + j + 1) + 1] +
text_image[4 * ((i + 1) * overlay->width + j) + 1] +
text_image[4 * ((i + 1) * overlay->width + j + 1) + 1] + 2) / 4;
dest[(i / 2 + y0) * (overlay->width / 2) + j / 2] =
(y * a + x * (255 - a)) / 255;
}
}
}
static void
gst_textoverlay_video_chain (GstPad * pad, GstData * _data)
{
GstBuffer *buf = GST_BUFFER (_data);
GstTextOverlay *overlay;
guchar *pixbuf;
gint y;
g_return_if_fail (pad != NULL);
g_return_if_fail (GST_IS_PAD (pad));
g_return_if_fail (buf != NULL);
overlay = GST_TEXTOVERLAY (gst_pad_get_parent (pad));
g_return_if_fail (overlay != NULL);
g_return_if_fail (GST_IS_TEXTOVERLAY (overlay));
if (!GST_IS_BUFFER (_data))
return;
pixbuf = GST_BUFFER_DATA (buf);
y = overlay->y0;
switch (overlay->valign) {
case GST_TEXT_OVERLAY_VALIGN_BOTTOM:
y -= overlay->text_height;
break;
case GST_TEXT_OVERLAY_VALIGN_BASELINE:
#define BASELINE 2
y -= (overlay->text_height - BASELINE);
break;
case GST_TEXT_OVERLAY_VALIGN_TOP:
break;
}
gst_text_overlay_blit_1 (overlay,
pixbuf + y * overlay->width, overlay->text_outline_image, 0);
gst_text_overlay_blit_sub2x2 (overlay,
pixbuf + (overlay->height * overlay->width) +
(y / 2) * overlay->width / 2, overlay->text_outline_image, 128);
gst_text_overlay_blit_sub2x2 (overlay, pixbuf +
(overlay->height * overlay->width) +
(overlay->height * overlay->width) / 4 + (y / 2) * overlay->width / 2,
overlay->text_outline_image, 128);
gst_text_overlay_blit_1 (overlay, pixbuf + y * overlay->width,
overlay->text_fill_image, 255);
gst_text_overlay_blit_sub2x2 (overlay,
pixbuf + (overlay->height * overlay->width) +
(y / 2) * overlay->width / 2, overlay->text_fill_image, 128);
gst_text_overlay_blit_sub2x2 (overlay,
pixbuf + (overlay->height * overlay->width) +
(overlay->height * overlay->width) / 4 + (y / 2) * overlay->width / 2,
overlay->text_fill_image, 128);
gst_pad_push (overlay->srcpad, GST_DATA (buf));
}
#define PAST_END(buffer, time) \
(GST_BUFFER_TIMESTAMP (buffer) != GST_CLOCK_TIME_NONE && \
GST_BUFFER_DURATION (buffer) != GST_CLOCK_TIME_NONE && \
GST_BUFFER_TIMESTAMP (buffer) + GST_BUFFER_DURATION (buffer) \
< (time))
static void
gst_textoverlay_loop (GstElement * element)
{
GstTextOverlay *overlay;
GstBuffer *video_frame;
guint64 now;
g_return_if_fail (element != NULL);
g_return_if_fail (GST_IS_TEXTOVERLAY (element));
overlay = GST_TEXTOVERLAY (element);
do {
GST_DEBUG ("Attempting to pull next video frame");
video_frame = GST_BUFFER (gst_pad_pull (overlay->video_sinkpad));
if (GST_IS_EVENT (video_frame)) {
GstEvent *event = GST_EVENT (video_frame);
GstEventType type = GST_EVENT_TYPE (event);
gst_pad_event_default (overlay->video_sinkpad, event);
GST_DEBUG ("Received event of type %d", type);
if (type == GST_EVENT_EOS || type == GST_EVENT_INTERRUPT)
return;
video_frame = NULL;
}
} while (!video_frame);
now = GST_BUFFER_TIMESTAMP (video_frame);
GST_DEBUG ("Got video frame, time=%" GST_TIME_FORMAT, GST_TIME_ARGS (now));
/*
* This state machine has a bug that can't be resolved easily.
* (Needs a more complicated state machine.) Basically, if the
* text that came from a buffer from the sink pad is being
* displayed, and the default text is changed by set_parameter,
* we'll incorrectly display the default text.
*
* Otherwise, this is a pretty decent state machine that handles
* buffer timestamps and durations correctly. (I think)
*/
while ((!overlay->current_buffer ||
PAST_END (overlay->current_buffer, now)) &&
overlay->next_buffer == NULL) {
GST_DEBUG ("attempting to pull a buffer");
/* read all text buffers until we get one "in the future" */
if (!GST_PAD_IS_USABLE (overlay->text_sinkpad)) {
break;
}
do {
overlay->next_buffer = GST_BUFFER (gst_pad_pull (overlay->text_sinkpad));
if (GST_IS_EVENT (overlay->next_buffer)) {
GstEvent *event = GST_EVENT (overlay->next_buffer);
GstEventType type = GST_EVENT_TYPE (event);
gst_pad_event_default (overlay->text_sinkpad, event);
if (type == GST_EVENT_EOS || type == GST_EVENT_INTERRUPT)
return;
overlay->next_buffer = NULL;
}
} while (!overlay->next_buffer);
if (PAST_END (overlay->next_buffer, now)) {
GST_DEBUG ("Received buffer is past end (%" GST_TIME_FORMAT " + %"
GST_TIME_FORMAT " < %" GST_TIME_FORMAT ")",
GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (overlay->next_buffer)),
GST_TIME_ARGS (GST_BUFFER_DURATION (overlay->next_buffer)),
GST_TIME_ARGS (now));
gst_buffer_unref (overlay->next_buffer);
overlay->next_buffer = NULL;
} else {
GST_DEBUG ("Received new text buffer of time %" GST_TIME_FORMAT
"and duration %" GST_TIME_FORMAT,
GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (overlay->next_buffer)),
GST_TIME_ARGS (GST_BUFFER_DURATION (overlay->next_buffer)));
}
}
if (overlay->next_buffer &&
(GST_BUFFER_TIMESTAMP (overlay->next_buffer) <= now ||
GST_BUFFER_TIMESTAMP (overlay->next_buffer) == GST_CLOCK_TIME_NONE)) {
GST_DEBUG ("using new buffer");
if (overlay->current_buffer) {
gst_buffer_unref (overlay->current_buffer);
}
overlay->current_buffer = overlay->next_buffer;
overlay->next_buffer = NULL;
GST_DEBUG ("rendering '%*s'",
GST_BUFFER_SIZE (overlay->current_buffer),
GST_BUFFER_DATA (overlay->current_buffer));
gst_textoverlay_render_text (overlay,
GST_BUFFER_DATA (overlay->current_buffer),
GST_BUFFER_SIZE (overlay->current_buffer));
overlay->need_render = FALSE;
}
if (overlay->current_buffer && PAST_END (overlay->current_buffer, now)) {
GST_DEBUG ("dropping old buffer");
gst_buffer_unref (overlay->current_buffer);
overlay->current_buffer = NULL;
overlay->need_render = TRUE;
}
if (overlay->need_render) {
GST_DEBUG ("rendering '%s'", overlay->default_text);
gst_textoverlay_render_text (overlay,
overlay->default_text, strlen (overlay->default_text));
overlay->need_render = FALSE;
}
gst_textoverlay_video_chain (overlay->srcpad, GST_DATA (video_frame));
}
static void
gst_textoverlay_font_init (GstTextOverlay * overlay)
{
cairo_font_extents_t font_extents;
cairo_select_font (overlay->cr, overlay->font, overlay->slant,
overlay->weight);
cairo_scale_font (overlay->cr, overlay->scale);
cairo_current_font_extents (overlay->cr, &font_extents);
overlay->text_height = font_extents.height;
if (overlay->text_height & 1)
overlay->text_height++;
overlay->need_render = TRUE;
}
static GstStateChangeReturn
gst_textoverlay_change_state (GstElement * element, GstStateChange transition)
{
GstTextOverlay *overlay;
overlay = GST_TEXTOVERLAY (element);
switch (transition) {
case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
break;
case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
break;
case GST_STATE_CHANGE_PAUSED_TO_READY:
break;
}
parent_class->change_state (element, transition);
return GST_STATE_CHANGE_SUCCESS;
}
static void
gst_textoverlay_finalize (GObject * object)
{
GstTextOverlay *overlay = GST_TEXTOVERLAY (object);
if (overlay->cr) {
cairo_destroy (overlay->cr);
}
G_OBJECT_CLASS (parent_class)->finalize (object);
}
static void
gst_textoverlay_init (GstTextOverlay * overlay)
{
/* video sink */
overlay->video_sinkpad =
gst_pad_new_from_template (gst_static_pad_template_get
(&video_sink_template_factory), "video_sink");
gst_pad_set_link_function (overlay->video_sinkpad,
gst_textoverlay_video_sinkconnect);
gst_element_add_pad (GST_ELEMENT (overlay), overlay->video_sinkpad);
/* text sink */
overlay->text_sinkpad =
gst_pad_new_from_template (gst_static_pad_template_get
(&text_sink_template_factory), "text_sink");
gst_element_add_pad (GST_ELEMENT (overlay), overlay->text_sinkpad);
/* (video) source */
overlay->srcpad =
gst_pad_new_from_template (gst_static_pad_template_get
(&textoverlay_src_template_factory), "src");
gst_element_add_pad (GST_ELEMENT (overlay), overlay->srcpad);
overlay->cr = cairo_create ();
overlay->halign = GST_TEXT_OVERLAY_HALIGN_CENTER;
overlay->valign = GST_TEXT_OVERLAY_VALIGN_BASELINE;
overlay->x0 = overlay->y0 = 25;
overlay->default_text = g_strdup ("");
overlay->need_render = TRUE;
overlay->font = g_strdup ("sans");
overlay->slant = CAIRO_FONT_SLANT_NORMAL;
overlay->weight = CAIRO_FONT_WEIGHT_NORMAL;
overlay->scale = 20;
gst_textoverlay_font_init (overlay);
gst_element_set_loop_function (GST_ELEMENT (overlay), gst_textoverlay_loop);
}
static void
gst_textoverlay_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec)
{
GstTextOverlay *overlay;
g_return_if_fail (GST_IS_TEXTOVERLAY (object));
overlay = GST_TEXTOVERLAY (object);
switch (prop_id) {
case ARG_TEXT:
if (overlay->default_text) {
g_free (overlay->default_text);
}
overlay->default_text = g_strdup (g_value_get_string (value));
overlay->need_render = TRUE;
break;
case ARG_VALIGN:
if (strcasecmp (g_value_get_string (value), "baseline") == 0)
overlay->valign = GST_TEXT_OVERLAY_VALIGN_BASELINE;
else if (strcasecmp (g_value_get_string (value), "bottom") == 0)
overlay->valign = GST_TEXT_OVERLAY_VALIGN_BOTTOM;
else if (strcasecmp (g_value_get_string (value), "top") == 0)
overlay->valign = GST_TEXT_OVERLAY_VALIGN_TOP;
else
g_warning ("Invalid 'valign' property value: %s",
g_value_get_string (value));
overlay->need_render = TRUE;
break;
case ARG_HALIGN:
if (strcasecmp (g_value_get_string (value), "left") == 0)
overlay->halign = GST_TEXT_OVERLAY_HALIGN_LEFT;
else if (strcasecmp (g_value_get_string (value), "right") == 0)
overlay->halign = GST_TEXT_OVERLAY_HALIGN_RIGHT;
else if (strcasecmp (g_value_get_string (value), "center") == 0)
overlay->halign = GST_TEXT_OVERLAY_HALIGN_CENTER;
else
g_warning ("Invalid 'halign' property value: %s",
g_value_get_string (value));
overlay->need_render = TRUE;
break;
case ARG_X0:
overlay->x0 = g_value_get_int (value);
break;
case ARG_Y0:
overlay->y0 = g_value_get_int (value);
break;
case ARG_FONT_DESC:
if (overlay->font)
g_free (overlay->font);
overlay->font = g_strdup (g_value_get_string (value));
gst_textoverlay_font_init (overlay);
break;
default:
break;
}
}
static void
gst_textoverlay_get_property (GObject * object, guint prop_id, GValue * value,
GParamSpec * pspec)
{
GstTextOverlay *overlay;
g_return_if_fail (GST_IS_TEXTOVERLAY (object));
overlay = GST_TEXTOVERLAY (object);
switch (prop_id) {
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}