2022-04-21 16:53:28 +02:00
<!DOCTYPE html>
< html lang = "en" >
< head >
< meta charset = "utf-8" / >
< meta name = "generator" content = "pandoc" / >
< meta name = "viewport" content = "width=device-width, initial-scale=1" / >
< link href = "https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel = "stylesheet" integrity = "sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC" crossorigin = "anonymous" >
2022-11-21 14:48:20 +01:00
< title > GTK 4 tutorial< / title >
2022-04-21 16:53:28 +02:00
< style >
code{white-space: pre-wrap;}
span.smallcaps{font-variant: small-caps;}
span.underline{text-decoration: underline;}
div.column{display: inline-block; vertical-align: top; width: 50%;}
div.hanging-indent{margin-left: 1.5em; text-indent: -1.5em;}
ul.task-list{list-style: none;}
pre{overflow: visible;}
pre > code.sourceCode { white-space: pre; position: relative; }
pre > code.sourceCode > span { display: inline-block; line-height: 1.25; }
pre > code.sourceCode > span:empty { height: 1.2em; }
code.sourceCode > span { color: inherit; text-decoration: inherit; }
div.sourceCode { margin: 1em 0; }
pre.sourceCode { margin: 0; }
@media screen {
div.sourceCode { overflow: auto; }
2022-04-17 13:54:42 +02:00
}
2022-04-21 16:53:28 +02:00
@media print {
pre > code.sourceCode { white-space: pre-wrap; }
pre > code.sourceCode > span { text-indent: -5em; padding-left: 5em; }
}
pre.numberSource code
{ counter-reset: source-line 0; }
pre.numberSource code > span
{ position: relative; left: -4em; counter-increment: source-line; }
pre.numberSource code > span > a:first-child::after
{ content: counter(source-line);
position: relative; left: -1em; text-align: right; vertical-align: baseline;
border: none; display: inline-block;
-webkit-touch-callout: none; -webkit-user-select: none;
-khtml-user-select: none; -moz-user-select: none;
-ms-user-select: none; user-select: none;
padding: 0 4px; width: 4em;
color: #aaaaaa;
}
pre.numberSource { margin-left: 3em; border-left: 1px solid #aaaaaa; padding-left: 4px; }
div.sourceCode
{ }
@media screen {
pre > code.sourceCode > span > a:first-child::before { text-decoration: underline; }
}
code span.al { color: #ff0000; font-weight: bold; } /* Alert */
code span.an { color: #60a0b0; font-weight: bold; font-style: italic; } /* Annotation */
code span.at { color: #7d9029; } /* Attribute */
code span.bn { color: #40a070; } /* BaseN */
code span.bu { } /* BuiltIn */
code span.cf { color: #007020; font-weight: bold; } /* ControlFlow */
code span.ch { color: #4070a0; } /* Char */
code span.cn { color: #880000; } /* Constant */
code span.co { color: #60a0b0; font-style: italic; } /* Comment */
code span.cv { color: #60a0b0; font-weight: bold; font-style: italic; } /* CommentVar */
code span.do { color: #ba2121; font-style: italic; } /* Documentation */
code span.dt { color: #902000; } /* DataType */
code span.dv { color: #40a070; } /* DecVal */
code span.er { color: #ff0000; font-weight: bold; } /* Error */
code span.ex { } /* Extension */
code span.fl { color: #40a070; } /* Float */
code span.fu { color: #06287e; } /* Function */
code span.im { } /* Import */
code span.in { color: #60a0b0; font-weight: bold; font-style: italic; } /* Information */
code span.kw { color: #007020; font-weight: bold; } /* Keyword */
code span.op { color: #666666; } /* Operator */
code span.ot { color: #007020; } /* Other */
code span.pp { color: #bc7a00; } /* Preprocessor */
code span.sc { color: #4070a0; } /* SpecialChar */
code span.ss { color: #bb6688; } /* SpecialString */
code span.st { color: #4070a0; } /* String */
code span.va { color: #19177c; } /* Variable */
code span.vs { color: #4070a0; } /* VerbatimString */
code span.wa { color: #60a0b0; font-weight: bold; font-style: italic; } /* Warning */
div.sourceCode { margin: 10px; padding: 16px 10px 8px 10px; border: 2px solid silver; background-color: ghostwhite; overflow-x:scroll}
pre:not(.sourceCode) { margin: 10px; padding: 16px 10px 8px 10px; border: 2px solid silver; background-color: ghostwhite; overflow-x:scroll}
table {margin-left: auto; margin-right: auto; border-collapse: collapse; border: 1px solid;}
th {padding: 2px 6px; border: 1px solid; background-color: ghostwhite;}
td {padding: 2px 6px; border: 1px solid;}
img {display: block; margin-left: auto; margin-right: auto;}
figcaption {text-align: center;}
< / style >
< / head >
< body style = "padding-top: 70px;" >
< div class = "container" >
< nav class = "navbar fixed-top navbar-expand-lg navbar-dark bg-primary" >
< div class = "container-fluid" >
< span class = "navbar-brand" > Gtk4 tutorial< / span >
< button class = "navbar-toggler" type = "button" data-bs-toggle = "collapse" data-bs-target = "#navbarSupportedContent" aria-controls = "navbarSupportedContent" aria-expanded = "false" aria-label = "Toggle navigation" >
< span class = "navbar-toggler-icon" > < / span >
< / button >
< div class = "collapse navbar-collapse" id = "navbarSupportedContent" >
< ul class = "navbar-nav me-auto mb-2 mb-lg-0" >
< li class = "nav-item" >
< a class = "nav-link" href = "index.html" > Home< / a >
< / li >
< li class = "nav-item" >
< a class = "nav-link" href = "sec2.html" > Prev: section2< / a >
< / li >
< li class = "nav-item" >
< a class = "nav-link" href = "sec4.html" > Next: section4< / a >
< / li >
< / ul >
< / div >
< / div >
< / nav >
2022-11-21 14:48:20 +01:00
< h1 id = "gtkapplication-and-gtkapplicationwindow" > GtkApplication and
GtkApplicationWindow< / h1 >
2022-04-17 13:54:42 +02:00
< h2 id = "gtkapplication" > GtkApplication< / h2 >
2022-11-21 14:48:20 +01:00
< h3 id = "gtkapplication-and-g_application_run" > GtkApplication and
g_application_run< / h3 >
< p > Usually people write programming code to make an application. What
are applications? Applications are software that runs using libraries,
which includes the OS, frameworks and so on. In GTK 4 programming, the
GtkApplication is a program (or executable) that runs using Gtk
libraries.< / p >
2022-04-17 13:54:42 +02:00
< p > The basic way to write a GtkApplication is as follows.< / p >
< ul >
< li > Create a GtkApplication instance.< / li >
< li > Run the application.< / li >
< / ul >
2022-11-21 14:48:20 +01:00
< p > That’
scenario above.< / p >
< div class = "sourceCode" id = "cb1" > < pre
class="sourceCode numberSource C numberLines">< code class = "sourceCode c" > < span id = "cb1-1" > < a href = "#cb1-1" > < / a > < span class = "pp" > #include < / span > < span class = "im" > < gtk/gtk.h> < / span > < / span >
2022-04-17 13:54:42 +02:00
< span id = "cb1-2" > < a href = "#cb1-2" > < / a > < / span >
< span id = "cb1-3" > < a href = "#cb1-3" > < / a > < span class = "dt" > int< / span > < / span >
2022-11-21 14:48:20 +01:00
< span id = "cb1-4" > < a href = "#cb1-4" > < / a > main < span class = "op" > (< / span > < span class = "dt" > int< / span > argc< span class = "op" > ,< / span > < span class = "dt" > char< / span > < span class = "op" > **< / span > argv< span class = "op" > )< / span > < span class = "op" > {< / span > < / span >
< span id = "cb1-5" > < a href = "#cb1-5" > < / a > GtkApplication < span class = "op" > *< / span > app< span class = "op" > ;< / span > < / span >
< span id = "cb1-6" > < a href = "#cb1-6" > < / a > < span class = "dt" > int< / span > stat< span class = "op" > ;< / span > < / span >
2022-04-17 13:54:42 +02:00
< span id = "cb1-7" > < a href = "#cb1-7" > < / a > < / span >
2022-11-21 14:48:20 +01:00
< span id = "cb1-8" > < a href = "#cb1-8" > < / a > app < span class = "op" > =< / span > gtk_application_new < span class = "op" > (< / span > < span class = "st" > " com.github.ToshioCP.pr1" < / span > < span class = "op" > ,< / span > G_APPLICATION_FLAGS_NONE< span class = "op" > );< / span > < / span >
< span id = "cb1-9" > < a href = "#cb1-9" > < / a > stat < span class = "op" > =< / span > g_application_run < span class = "op" > (< / span > G_APPLICATION < span class = "op" > (< / span > app< span class = "op" > ),< / span > argc< span class = "op" > ,< / span > argv< span class = "op" > );< / span > < / span >
< span id = "cb1-10" > < a href = "#cb1-10" > < / a > g_object_unref < span class = "op" > (< / span > app< span class = "op" > );< / span > < / span >
< span id = "cb1-11" > < a href = "#cb1-11" > < / a > < span class = "cf" > return< / span > stat< span class = "op" > ;< / span > < / span >
< span id = "cb1-12" > < a href = "#cb1-12" > < / a > < span class = "op" > }< / span > < / span > < / code > < / pre > < / div >
< p > The first line says that this program includes the header files of
the Gtk libraries. The function < code > main< / code > above is a startup
function in C language. The variable < code > app< / code > is defined as a
pointer to a GtkApplication instance. The function
< code > gtk_application_new< / code > creates a GtkApplication instance and
returns a pointer to the instance. The GtkApplication instance is a C
structure data in which the information about the application is stored.
The meaning of the arguments will be explained later. The function
< code > g_application_run< / code > runs an application that the instance
defined. (We often say that the function runs < code > app< / code > .
Actually, < code > app< / code > is not an application but a pointer to the
instance of the application. However, it is simple and short, and
probably no confusion occurs.)< / p >
< p > To compile this, the following command needs to be run. The string
< code > pr1.c< / code > is the filename of the C source code above.< / p >
2022-04-17 13:54:42 +02:00
< pre > < code > $ gcc `pkg-config --cflags gtk4` pr1.c `pkg-config --libs gtk4`< / code > < / pre >
2022-11-21 14:48:20 +01:00
< p > The C compiler gcc generates an executable file, < code > a.out< / code > .
Let’ < / p >
2022-04-17 13:54:42 +02:00
< pre > < code > $ ./a.out
(a.out:13533): GLib-GIO-WARNING **: 15:30:17.449: Your application does not implement
g_application_activate() and has no handlers connected to the " activate" signal.
It should do one of these.
$< / code > < / pre >
2022-11-21 14:48:20 +01:00
< p > Oh, it just produces an error message. This error message means that
the GtkApplication object ran, without a doubt. Now, let’
what this message means.< / p >
2022-04-17 13:54:42 +02:00
< h3 id = "signal" > signal< / h3 >
< p > The message tells us that:< / p >
< ol type = "1" >
2022-11-21 14:48:20 +01:00
< li > The application GtkApplication doesn’
< code > g_application_activate()< / code > ,< / li >
2022-04-17 13:54:42 +02:00
< li > It has no handlers connected to the “activate” signal, and< / li >
< li > You will need to solve at least one of these.< / li >
< / ol >
2022-11-21 14:48:20 +01:00
< p > These two causes of the error are related to signals. So, I will
explain that to you first.< / p >
< p > A signal is emitted when something happens. For example, a window is
created, a window is destroyed and so on. The signal “activate” is
emitted when the application is activated, or started. If the signal is
connected to a function, which is called a signal handler or simply
handler, then the function is invoked when the signal emits.< / p >
2022-04-17 13:54:42 +02:00
< p > The flow is like this:< / p >
< ol type = "1" >
< li > Something happens.< / li >
2022-11-21 14:48:20 +01:00
< li > If it’
emitted.< / li >
< li > If the signal as been connected to a handler, then the handler is
invoked.< / li >
2022-04-17 13:54:42 +02:00
< / ol >
2022-11-21 14:48:20 +01:00
< p > Signals are defined in objects. For example, the “activate” signal
belongs to the GApplication object, which is a parent object of
GtkApplication object.< / p >
< p > The GApplication object is a child object of the GObject object.
GObject is the top object in the hierarchy of all the objects.< / p >
2022-04-17 13:54:42 +02:00
< pre > < code > GObject -- GApplication -- GtkApplication
< ---parent ---> child< / code > < / pre >
2022-11-21 14:48:20 +01:00
< p > A child object inherits signals, functions, properties and so on from
its parent object. So, GtkApplication also has the “activate”
signal.< / p >
< p > Now we can solve the problem in < code > pr1.c< / code > . We need to
connect the “activate” signal to a handler. We use a function
< code > g_signal_connect< / code > which connects a signal to a handler.< / p >
< div class = "sourceCode" id = "cb5" > < pre
class="sourceCode numberSource C numberLines">< code class = "sourceCode c" > < span id = "cb5-1" > < a href = "#cb5-1" > < / a > < span class = "pp" > #include < / span > < span class = "im" > < gtk/gtk.h> < / span > < / span >
2022-04-17 13:54:42 +02:00
< span id = "cb5-2" > < a href = "#cb5-2" > < / a > < / span >
< span id = "cb5-3" > < a href = "#cb5-3" > < / a > < span class = "dt" > static< / span > < span class = "dt" > void< / span > < / span >
2022-11-21 14:48:20 +01:00
< span id = "cb5-4" > < a href = "#cb5-4" > < / a > app_activate < span class = "op" > (< / span > GApplication < span class = "op" > *< / span > app< span class = "op" > ,< / span > gpointer < span class = "op" > *< / span > user_data< span class = "op" > )< / span > < span class = "op" > {< / span > < / span >
< span id = "cb5-5" > < a href = "#cb5-5" > < / a > g_print < span class = "op" > (< / span > < span class = "st" > " GtkApplication is activated.< / span > < span class = "sc" > \n< / span > < span class = "st" > " < / span > < span class = "op" > );< / span > < / span >
< span id = "cb5-6" > < a href = "#cb5-6" > < / a > < span class = "op" > }< / span > < / span >
2022-04-17 13:54:42 +02:00
< span id = "cb5-7" > < a href = "#cb5-7" > < / a > < / span >
< span id = "cb5-8" > < a href = "#cb5-8" > < / a > < span class = "dt" > int< / span > < / span >
2022-11-21 14:48:20 +01:00
< span id = "cb5-9" > < a href = "#cb5-9" > < / a > main < span class = "op" > (< / span > < span class = "dt" > int< / span > argc< span class = "op" > ,< / span > < span class = "dt" > char< / span > < span class = "op" > **< / span > argv< span class = "op" > )< / span > < span class = "op" > {< / span > < / span >
< span id = "cb5-10" > < a href = "#cb5-10" > < / a > GtkApplication < span class = "op" > *< / span > app< span class = "op" > ;< / span > < / span >
< span id = "cb5-11" > < a href = "#cb5-11" > < / a > < span class = "dt" > int< / span > stat< span class = "op" > ;< / span > < / span >
2022-04-17 13:54:42 +02:00
< span id = "cb5-12" > < a href = "#cb5-12" > < / a > < / span >
2022-11-21 14:48:20 +01:00
< span id = "cb5-13" > < a href = "#cb5-13" > < / a > app < span class = "op" > =< / span > gtk_application_new < span class = "op" > (< / span > < span class = "st" > " com.github.ToshioCP.pr2" < / span > < span class = "op" > ,< / span > G_APPLICATION_FLAGS_NONE< span class = "op" > );< / span > < / span >
< span id = "cb5-14" > < a href = "#cb5-14" > < / a > g_signal_connect < span class = "op" > (< / span > app< span class = "op" > ,< / span > < span class = "st" > " activate" < / span > < span class = "op" > ,< / span > G_CALLBACK < span class = "op" > (< / span > app_activate< span class = "op" > ),< / span > NULL< span class = "op" > );< / span > < / span >
< span id = "cb5-15" > < a href = "#cb5-15" > < / a > stat < span class = "op" > =< / span > g_application_run < span class = "op" > (< / span > G_APPLICATION < span class = "op" > (< / span > app< span class = "op" > ),< / span > argc< span class = "op" > ,< / span > argv< span class = "op" > );< / span > < / span >
< span id = "cb5-16" > < a href = "#cb5-16" > < / a > g_object_unref < span class = "op" > (< / span > app< span class = "op" > );< / span > < / span >
< span id = "cb5-17" > < a href = "#cb5-17" > < / a > < span class = "cf" > return< / span > stat< span class = "op" > ;< / span > < / span >
< span id = "cb5-18" > < a href = "#cb5-18" > < / a > < span class = "op" > }< / span > < / span > < / code > < / pre > < / div >
< p > First, we define the handler < code > app_activate< / code > which simply
displays a message. In the function < code > main< / code > , we add
< code > g_signal_connect< / code > before < code > g_application_run< / code > . The
function < code > g_signal_connect< / code > has four arguments.< / p >
2022-04-17 13:54:42 +02:00
< ol type = "1" >
< li > An instance to which the signal belongs.< / li >
< li > The name of the signal.< / li >
2022-11-21 14:48:20 +01:00
< li > A handler function (also called callback), which needs to be casted
by < code > G_CALLBACK< / code > .< / li >
< li > Data to pass to the handler. If no data is necessary, NULL should be
given.< / li >
2022-04-17 13:54:42 +02:00
< / ol >
2022-11-21 14:48:20 +01:00
< p > You can find the description of each signal in the API reference
manual. For example, “activate” signal is in GApplication section in < a
href="https://docs.gtk.org/gio/signal.Application.activate.html">GIO API
Reference< / a > . The handler function is described in it.< / p >
< p > In addition, < code > g_signal_connect< / code > is described in < a
href="https://docs.gtk.org/gobject/func.signal_connect.html">GObject API
Reference< / a > . API reference manual is very important. You should see
and understand it to write Gtk applications. They are located in < a
href="https://docs.gtk.org/">‘ ’ < / a > .< / p >
< p > Let’ < code > pr2.c< / code > ) and run
it.< / p >
2022-04-17 13:54:42 +02:00
< pre > < code > $ gcc `pkg-config --cflags gtk4` pr2.c `pkg-config --libs gtk4`
$ ./a.out
GtkApplication is activated.
$< / code > < / pre >
2022-11-21 14:48:20 +01:00
< p > OK, well done. However, you may have noticed that it’
type such a long line to compile. It is a good idea to use shell script
to solve this problem. Make a text file which contains the following
line.< / p >
2022-04-17 13:54:42 +02:00
< pre > < code > gcc `pkg-config --cflags gtk4` $1.c `pkg-config --libs gtk4`< / code > < / pre >
2022-11-21 14:48:20 +01:00
< p > Then, save it under the directory $HOME/bin, which is usually
/home/(username)/bin. (If your user name is James, then the directory is
/home/james/bin). And turn on the execute bit of the file. If the
filename is < code > comp< / code > , do like this:< / p >
2022-04-17 13:54:42 +02:00
< pre > < code > $ chmod 755 $HOME/bin/comp
$ ls -log $HOME/bin
... ... ...
-rwxr-xr-x 1 62 May 23 08:21 comp
... ... ...< / code > < / pre >
2022-11-21 14:48:20 +01:00
< p > If this is the first time that you make a $HOME/bin directory and
save a file in it, then you need to logout and login again.< / p >
2022-04-17 13:54:42 +02:00
< pre > < code > $ comp pr2
$ ./a.out
GtkApplication is activated.
$< / code > < / pre >
2022-11-21 14:48:20 +01:00
< h2 id = "gtkwindow-and-gtkapplicationwindow" > GtkWindow and
GtkApplicationWindow< / h2 >
2022-04-17 13:54:42 +02:00
< h3 id = "gtkwindow" > GtkWindow< / h3 >
2022-11-21 14:48:20 +01:00
< p > A message “GtkApplication is activated.” was printed out in the
previous subsection. It was good in terms of a test of GtkApplication.
However, it is insufficient because Gtk is a framework for graphical
user interface (GUI). Now we go ahead with adding a window into this
program. What we need to do is:< / p >
2022-04-17 13:54:42 +02:00
< ol type = "1" >
< li > Create a GtkWindow.< / li >
< li > Connect it to GtkApplication.< / li >
< li > Show the window.< / li >
< / ol >
< p > Now rewrite the function < code > app_activate< / code > .< / p >
< h4 id = "create-a-gtkwindow" > Create a GtkWindow< / h4 >
2022-11-21 14:48:20 +01:00
< div class = "sourceCode" id = "cb10" > < pre
class="sourceCode numberSource C numberLines">< code class = "sourceCode c" > < span id = "cb10-1" > < a href = "#cb10-1" > < / a > < span class = "dt" > static< / span > < span class = "dt" > void< / span > < / span >
< span id = "cb10-2" > < a href = "#cb10-2" > < / a > app_activate < span class = "op" > (< / span > GApplication < span class = "op" > *< / span > app< span class = "op" > ,< / span > gpointer user_data< span class = "op" > )< / span > < span class = "op" > {< / span > < / span >
< span id = "cb10-3" > < a href = "#cb10-3" > < / a > GtkWidget < span class = "op" > *< / span > win< span class = "op" > ;< / span > < / span >
2022-04-17 13:54:42 +02:00
< span id = "cb10-4" > < a href = "#cb10-4" > < / a > < / span >
2022-11-21 14:48:20 +01:00
< span id = "cb10-5" > < a href = "#cb10-5" > < / a > win < span class = "op" > =< / span > gtk_window_new < span class = "op" > ();< / span > < / span >
< span id = "cb10-6" > < a href = "#cb10-6" > < / a > gtk_window_set_application < span class = "op" > (< / span > GTK_WINDOW < span class = "op" > (< / span > win< span class = "op" > ),< / span > GTK_APPLICATION < span class = "op" > (< / span > app< span class = "op" > ));< / span > < / span >
< span id = "cb10-7" > < a href = "#cb10-7" > < / a > gtk_widget_show < span class = "op" > (< / span > win< span class = "op" > );< / span > < / span >
< span id = "cb10-8" > < a href = "#cb10-8" > < / a > < span class = "op" > }< / span > < / span > < / code > < / pre > < / div >
< p > Widget is an abstract concept that includes all the GUI interfaces
such as windows, dialogs, buttons, multi-line text, containers and so
on. And GtkWidget is a base object from which all the GUI objects
derive.< / p >
2022-04-17 13:54:42 +02:00
< pre > < code > parent < -----> child
GtkWidget -- GtkWindow< / code > < / pre >
< p > GtkWindow includes GtkWidget at the top of its object.< / p >
< figure >
2022-11-21 14:48:20 +01:00
< img src = "image/window_widget.png" alt = "GtkWindow and GtkWidget" / >
< figcaption aria-hidden = "true" > GtkWindow and GtkWidget< / figcaption >
2022-04-17 13:54:42 +02:00
< / figure >
< p > The function < code > gtk_window_new< / code > is defined as follows.< / p >
2022-11-21 14:48:20 +01:00
< div class = "sourceCode" id = "cb12" > < pre class = "sourceCode c" > < code class = "sourceCode c" > < span id = "cb12-1" > < a href = "#cb12-1" aria-hidden = "true" tabindex = "-1" > < / a > GtkWidget < span class = "op" > *< / span > < / span >
< span id = "cb12-2" > < a href = "#cb12-2" aria-hidden = "true" tabindex = "-1" > < / a > gtk_window_new < span class = "op" > (< / span > < span class = "dt" > void< / span > < span class = "op" > );< / span > < / span > < / code > < / pre > < / div >
< p > By this definition, it returns a pointer to GtkWidget, not GtkWindow.
It actually creates a new GtkWindow instance (not GtkWidget) but returns
a pointer to GtkWidget. However,the pointer points the GtkWidget and at
the same time it also points GtkWindow that contains GtkWidget in
it.< / p >
< p > If you want to use < code > win< / code > as a pointer to the GtkWindow,
you need to cast it.< / p >
< div class = "sourceCode" id = "cb13" > < pre class = "sourceCode c" > < code class = "sourceCode c" > < span id = "cb13-1" > < a href = "#cb13-1" aria-hidden = "true" tabindex = "-1" > < / a > < span class = "op" > (< / span > GtkWindow < span class = "op" > *)< / span > win< / span > < / code > < / pre > < / div >
< p > Or you can use < code > GTK_WINDOW< / code > macro that performs a similar
function.< / p >
< div class = "sourceCode" id = "cb14" > < pre class = "sourceCode c" > < code class = "sourceCode c" > < span id = "cb14-1" > < a href = "#cb14-1" aria-hidden = "true" tabindex = "-1" > < / a > GTK_WINDOW < span class = "op" > (< / span > win< span class = "op" > )< / span > < / span > < / code > < / pre > < / div >
2022-04-17 13:54:42 +02:00
< p > This is a recommended way.< / p >
2022-11-21 14:48:20 +01:00
< h4 id = "connect-it-to-gtkapplication." > Connect it to
GtkApplication.< / h4 >
< p > The function < code > gtk_window_set_application< / code > is used to
connect GtkWindow to GtkApplication.< / p >
< div class = "sourceCode" id = "cb15" > < pre class = "sourceCode c" > < code class = "sourceCode c" > < span id = "cb15-1" > < a href = "#cb15-1" aria-hidden = "true" tabindex = "-1" > < / a > gtk_window_set_application < span class = "op" > (< / span > GTK_WINDOW < span class = "op" > (< / span > win< span class = "op" > ),< / span > GTK_APPLICATION < span class = "op" > (< / span > app< span class = "op" > ));< / span > < / span > < / code > < / pre > < / div >
< p > You need to cast < code > win< / code > to GtkWindow and < code > app< / code >
to GtkApplication. < code > GTK_WINDOW< / code > and
< code > GTK_APPLICATION< / code > macro is appropriate for that.< / p >
< p > GtkApplication continues to run until the related window is
destroyed. If you didn’
GtkApplication destroys itself immediately. Because no window is
connected to GtkApplication, GtkApplication doesn’
anything. As it destroys itself, the GtkWindow is also destroyed.< / p >
2022-04-17 13:54:42 +02:00
< h4 id = "show-the-window." > Show the window.< / h4 >
2022-11-21 14:48:20 +01:00
< p > The function < code > gtk_widget_show< / code > is used to show the
window.< / p >
< p > GTK 4 changes the default widget visibility to on, so every widget
doesn’ ’
Top window (this term will be explained later) isn’
created. So you need to use the function above to show the window.< / p >
2022-04-17 13:54:42 +02:00
< p > Save the program as < code > pr3.c< / code > and compile and run it.< / p >
< pre > < code > $ comp pr3
$ ./a.out< / code > < / pre >
< p > A small window appears.< / p >
< figure >
2022-11-21 14:48:20 +01:00
< img src = "image/screenshot_pr3.png" alt = "Screenshot of the window" / >
< figcaption aria-hidden = "true" > Screenshot of the window< / figcaption >
2022-04-17 13:54:42 +02:00
< / figure >
2022-11-21 14:48:20 +01:00
< p > Click on the close button then the window disappears and the program
finishes.< / p >
2022-04-17 13:54:42 +02:00
< h3 id = "gtkapplicationwindow" > GtkApplicationWindow< / h3 >
2022-11-21 14:48:20 +01:00
< p > GtkApplicationWindow is a child object of GtkWindow. It has some
extra functionality for better integration with GtkApplication. It is
recommended to use it instead of GtkWindow when you use
GtkApplication.< / p >
2022-05-01 16:13:26 +02:00
< p > Now rewrite the program and use GtkApplicationWindow.< / p >
2022-11-21 14:48:20 +01:00
< div class = "sourceCode" id = "cb17" > < pre
class="sourceCode numberSource C numberLines">< code class = "sourceCode c" > < span id = "cb17-1" > < a href = "#cb17-1" > < / a > < span class = "dt" > static< / span > < span class = "dt" > void< / span > < / span >
< span id = "cb17-2" > < a href = "#cb17-2" > < / a > app_activate < span class = "op" > (< / span > GApplication < span class = "op" > *< / span > app< span class = "op" > ,< / span > gpointer user_data< span class = "op" > )< / span > < span class = "op" > {< / span > < / span >
< span id = "cb17-3" > < a href = "#cb17-3" > < / a > GtkWidget < span class = "op" > *< / span > win< span class = "op" > ;< / span > < / span >
2022-04-17 13:54:42 +02:00
< span id = "cb17-4" > < a href = "#cb17-4" > < / a > < / span >
2022-11-21 14:48:20 +01:00
< span id = "cb17-5" > < a href = "#cb17-5" > < / a > win < span class = "op" > =< / span > gtk_application_window_new < span class = "op" > (< / span > GTK_APPLICATION < span class = "op" > (< / span > app< span class = "op" > ));< / span > < / span >
< span id = "cb17-6" > < a href = "#cb17-6" > < / a > gtk_window_set_title < span class = "op" > (< / span > GTK_WINDOW < span class = "op" > (< / span > win< span class = "op" > ),< / span > < span class = "st" > " pr4" < / span > < span class = "op" > );< / span > < / span >
< span id = "cb17-7" > < a href = "#cb17-7" > < / a > gtk_window_set_default_size < span class = "op" > (< / span > GTK_WINDOW < span class = "op" > (< / span > win< span class = "op" > ),< / span > < span class = "dv" > 400< / span > < span class = "op" > ,< / span > < span class = "dv" > 300< / span > < span class = "op" > );< / span > < / span >
< span id = "cb17-8" > < a href = "#cb17-8" > < / a > gtk_widget_show < span class = "op" > (< / span > win< span class = "op" > );< / span > < / span >
< span id = "cb17-9" > < a href = "#cb17-9" > < / a > < span class = "op" > }< / span > < / span > < / code > < / pre > < / div >
< p > When you create GtkApplicationWindow, you need to give GtkApplication
instance as an argument. Then it automatically connect these two
instances. So you don’
< code > gtk_window_set_application< / code > any more.< / p >
< p > The program sets the title and the default size of the window.
Compile it and run < code > a.out< / code > , then you will see a bigger window
with its title “pr4”.< / p >
2022-04-17 13:54:42 +02:00
< figure >
2022-11-21 14:48:20 +01:00
< img src = "image/screenshot_pr4.png" alt = "Screenshot of the window" / >
< figcaption aria-hidden = "true" > Screenshot of the window< / figcaption >
2022-04-17 13:54:42 +02:00
< / figure >
2022-04-21 16:53:28 +02:00
< / div >
< script src = "https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js" integrity = "sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM" crossorigin = "anonymous" > < / script >
< / body >
< / html >
