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gtk/demos/gtk-demo/images.c
Matthias Clasen 609e04ddcf gtk-demo: Cosmetic changes 
Clean up the code of many examples in minor ways, fix some memory
leaks, and avoid the use of dialogs where a regular toplevel works
just as well.
2015-06-28 17:41:35 -04:00

445 lines
14 KiB
C
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/* Images
*
* GtkImage is used to display an image; the image can be in a number of formats.
* Typically, you load an image into a GdkPixbuf, then display the pixbuf.
*
* This demo code shows some of the more obscure cases, in the simple
* case a call to gtk_image_new_from_file() is all you need.
*
* If you want to put image data in your program as a C variable,
* use the make-inline-pixbuf program that comes with GTK+.
* This way you won't need to depend on loading external files, your
* application binary can be self-contained.
*/
#include <gtk/gtk.h>
#include <glib/gstdio.h>
#include <stdio.h>
#include <errno.h>
static GtkWidget *window = NULL;
static GdkPixbufLoader *pixbuf_loader = NULL;
static guint load_timeout = 0;
static GInputStream * image_stream = NULL;
static void
progressive_prepared_callback (GdkPixbufLoader *loader,
gpointer data)
{
GdkPixbuf *pixbuf;
GtkWidget *image;
image = GTK_WIDGET (data);
pixbuf = gdk_pixbuf_loader_get_pixbuf (loader);
/* Avoid displaying random memory contents, since the pixbuf
* isn't filled in yet.
*/
gdk_pixbuf_fill (pixbuf, 0xaaaaaaff);
gtk_image_set_from_pixbuf (GTK_IMAGE (image), pixbuf);
}
static void
progressive_updated_callback (GdkPixbufLoader *loader,
gint x,
gint y,
gint width,
gint height,
gpointer data)
{
GtkWidget *image;
GdkPixbuf *pixbuf;
image = GTK_WIDGET (data);
/* We know the pixbuf inside the GtkImage has changed, but the image
* itself doesn't know this; so give it a hint by setting the pixbuf
* again. Queuing a redraw used to be sufficient, but nowadays GtkImage
* uses GtkIconHelper which caches the pixbuf state and will just redraw
* from the cache.
*/
pixbuf = gtk_image_get_pixbuf (GTK_IMAGE (image));
g_object_ref (pixbuf);
gtk_image_set_from_pixbuf (GTK_IMAGE (image), pixbuf);
g_object_unref (pixbuf);
}
static gint
progressive_timeout (gpointer data)
{
GtkWidget *image;
image = GTK_WIDGET (data);
/* This shows off fully-paranoid error handling, so looks scary.
* You could factor out the error handling code into a nice separate
* function to make things nicer.
*/
if (image_stream)
{
gssize bytes_read;
guchar buf[256];
GError *error = NULL;
bytes_read = g_input_stream_read (image_stream, buf, 256, NULL, &error);
if (bytes_read < 0)
{
GtkWidget *dialog;
dialog = gtk_message_dialog_new (GTK_WINDOW (window),
GTK_DIALOG_DESTROY_WITH_PARENT,
GTK_MESSAGE_ERROR,
GTK_BUTTONS_CLOSE,
"Failure reading image file 'alphatest.png': %s",
error->message);
g_error_free (error);
g_signal_connect (dialog, "response",
G_CALLBACK (gtk_widget_destroy), NULL);
g_object_unref (image_stream);
image_stream = NULL;
gtk_widget_show (dialog);
load_timeout = 0;
return FALSE; /* uninstall the timeout */
}
if (!gdk_pixbuf_loader_write (pixbuf_loader,
buf, bytes_read,
&error))
{
GtkWidget *dialog;
dialog = gtk_message_dialog_new (GTK_WINDOW (window),
GTK_DIALOG_DESTROY_WITH_PARENT,
GTK_MESSAGE_ERROR,
GTK_BUTTONS_CLOSE,
"Failed to load image: %s",
error->message);
g_error_free (error);
g_signal_connect (dialog, "response",
G_CALLBACK (gtk_widget_destroy), NULL);
g_object_unref (image_stream);
image_stream = NULL;
gtk_widget_show (dialog);
load_timeout = 0;
return FALSE; /* uninstall the timeout */
}
if (bytes_read == 0)
{
/* Errors can happen on close, e.g. if the image
* file was truncated we'll know on close that
* it was incomplete.
*/
error = NULL;
if (!g_input_stream_close (image_stream, NULL, &error))
{
GtkWidget *dialog;
dialog = gtk_message_dialog_new (GTK_WINDOW (window),
GTK_DIALOG_DESTROY_WITH_PARENT,
GTK_MESSAGE_ERROR,
GTK_BUTTONS_CLOSE,
"Failed to load image: %s",
error->message);
g_error_free (error);
g_signal_connect (dialog, "response",
G_CALLBACK (gtk_widget_destroy), NULL);
gtk_widget_show (dialog);
g_object_unref (image_stream);
image_stream = NULL;
g_object_unref (pixbuf_loader);
pixbuf_loader = NULL;
load_timeout = 0;
return FALSE; /* uninstall the timeout */
}
g_object_unref (image_stream);
image_stream = NULL;
/* Errors can happen on close, e.g. if the image
* file was truncated we'll know on close that
* it was incomplete.
*/
error = NULL;
if (!gdk_pixbuf_loader_close (pixbuf_loader,
&error))
{
GtkWidget *dialog;
dialog = gtk_message_dialog_new (GTK_WINDOW (window),
GTK_DIALOG_DESTROY_WITH_PARENT,
GTK_MESSAGE_ERROR,
GTK_BUTTONS_CLOSE,
"Failed to load image: %s",
error->message);
g_error_free (error);
g_signal_connect (dialog, "response",
G_CALLBACK (gtk_widget_destroy), NULL);
gtk_widget_show (dialog);
g_object_unref (pixbuf_loader);
pixbuf_loader = NULL;
load_timeout = 0;
return FALSE; /* uninstall the timeout */
}
g_object_unref (pixbuf_loader);
pixbuf_loader = NULL;
}
}
else
{
GError *error = NULL;
image_stream = g_resources_open_stream ("/images/alphatest.png", 0, &error);
if (image_stream == NULL)
{
GtkWidget *dialog;
dialog = gtk_message_dialog_new (GTK_WINDOW (window),
GTK_DIALOG_DESTROY_WITH_PARENT,
GTK_MESSAGE_ERROR,
GTK_BUTTONS_CLOSE,
"%s", error->message);
g_error_free (error);
g_signal_connect (dialog, "response",
G_CALLBACK (gtk_widget_destroy), NULL);
gtk_widget_show (dialog);
load_timeout = 0;
return FALSE; /* uninstall the timeout */
}
if (pixbuf_loader)
{
gdk_pixbuf_loader_close (pixbuf_loader, NULL);
g_object_unref (pixbuf_loader);
}
pixbuf_loader = gdk_pixbuf_loader_new ();
g_signal_connect (pixbuf_loader, "area-prepared",
G_CALLBACK (progressive_prepared_callback), image);
g_signal_connect (pixbuf_loader, "area-updated",
G_CALLBACK (progressive_updated_callback), image);
}
/* leave timeout installed */
return TRUE;
}
static void
start_progressive_loading (GtkWidget *image)
{
/* This is obviously totally contrived (we slow down loading
* on purpose to show how incremental loading works).
* The real purpose of incremental loading is the case where
* you are reading data from a slow source such as the network.
* The timeout simply simulates a slow data source by inserting
* pauses in the reading process.
*/
load_timeout = gdk_threads_add_timeout (150,
progressive_timeout,
image);
g_source_set_name_by_id (load_timeout, "[gtk+] progressive_timeout");
}
static void
cleanup_callback (GObject *object,
gpointer data)
{
if (load_timeout)
{
g_source_remove (load_timeout);
load_timeout = 0;
}
if (pixbuf_loader)
{
gdk_pixbuf_loader_close (pixbuf_loader, NULL);
g_object_unref (pixbuf_loader);
pixbuf_loader = NULL;
}
if (image_stream)
{
g_object_unref (image_stream);
image_stream = NULL;
}
}
static void
toggle_sensitivity_callback (GtkWidget *togglebutton,
gpointer user_data)
{
GtkContainer *container = user_data;
GList *list;
GList *tmp;
list = gtk_container_get_children (container);
tmp = list;
while (tmp != NULL)
{
/* don't disable our toggle */
if (GTK_WIDGET (tmp->data) != togglebutton)
gtk_widget_set_sensitive (GTK_WIDGET (tmp->data),
!gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (togglebutton)));
tmp = tmp->next;
}
g_list_free (list);
}
GtkWidget *
do_images (GtkWidget *do_widget)
{
GtkWidget *frame;
GtkWidget *vbox;
GtkWidget *image;
GtkWidget *label;
GtkWidget *button;
GIcon *gicon;
if (!window)
{
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_screen (GTK_WINDOW (window),
gtk_widget_get_screen (do_widget));
gtk_window_set_title (GTK_WINDOW (window), "Images");
g_signal_connect (window, "destroy",
G_CALLBACK (gtk_widget_destroyed), &window);
g_signal_connect (window, "destroy",
G_CALLBACK (cleanup_callback), NULL);
gtk_container_set_border_width (GTK_CONTAINER (window), 8);
vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 8);
gtk_container_set_border_width (GTK_CONTAINER (vbox), 8);
gtk_container_add (GTK_CONTAINER (window), vbox);
label = gtk_label_new (NULL);
gtk_label_set_markup (GTK_LABEL (label),
"<u>Image loaded from a file</u>");
gtk_box_pack_start (GTK_BOX (vbox), label, FALSE, FALSE, 0);
frame = gtk_frame_new (NULL);
gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
gtk_widget_set_halign (frame, GTK_ALIGN_CENTER);
gtk_widget_set_valign (frame, GTK_ALIGN_CENTER);
gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
image = gtk_image_new_from_icon_name ("gtk3-demo", GTK_ICON_SIZE_DIALOG);
gtk_container_add (GTK_CONTAINER (frame), image);
/* Animation */
label = gtk_label_new (NULL);
gtk_label_set_markup (GTK_LABEL (label),
"<u>Animation loaded from a file</u>");
gtk_box_pack_start (GTK_BOX (vbox), label, FALSE, FALSE, 0);
frame = gtk_frame_new (NULL);
gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
gtk_widget_set_halign (frame, GTK_ALIGN_CENTER);
gtk_widget_set_valign (frame, GTK_ALIGN_CENTER);
gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
image = gtk_image_new_from_resource ("/images/floppybuddy.gif");
gtk_container_add (GTK_CONTAINER (frame), image);
/* Symbolic icon */
label = gtk_label_new (NULL);
gtk_label_set_markup (GTK_LABEL (label),
"<u>Symbolic themed icon</u>");
gtk_box_pack_start (GTK_BOX (vbox), label, FALSE, FALSE, 0);
frame = gtk_frame_new (NULL);
gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
gtk_widget_set_halign (frame, GTK_ALIGN_CENTER);
gtk_widget_set_valign (frame, GTK_ALIGN_CENTER);
gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
gicon = g_themed_icon_new_with_default_fallbacks ("battery-caution-charging-symbolic");
image = gtk_image_new_from_gicon (gicon, GTK_ICON_SIZE_DIALOG);
gtk_container_add (GTK_CONTAINER (frame), image);
/* Progressive */
label = gtk_label_new (NULL);
gtk_label_set_markup (GTK_LABEL (label),
"<u>Progressive image loading</u>");
gtk_box_pack_start (GTK_BOX (vbox), label, FALSE, FALSE, 0);
frame = gtk_frame_new (NULL);
gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
gtk_widget_set_halign (frame, GTK_ALIGN_CENTER);
gtk_widget_set_valign (frame, GTK_ALIGN_CENTER);
gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
/* Create an empty image for now; the progressive loader
* will create the pixbuf and fill it in.
*/
image = gtk_image_new_from_pixbuf (NULL);
gtk_container_add (GTK_CONTAINER (frame), image);
start_progressive_loading (image);
/* Sensitivity control */
button = gtk_toggle_button_new_with_mnemonic ("_Insensitive");
gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
g_signal_connect (button, "toggled",
G_CALLBACK (toggle_sensitivity_callback),
vbox);
}
if (!gtk_widget_get_visible (window))
gtk_widget_show_all (window);
else
gtk_widget_destroy (window);
return window;
}
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