Added template helpers, examples and fix for compiler error

examples/widget-template-manual/box.blp

@@ -0,0 +1,11 @@
+using Gtk 4.0;
+
+template $My_Box: Gtk.Box {
+    halign: center;
+    valign: center;
+
+    Button my-button {
+        label: _("Hi! Click me and look at the terminal!");
+        clicked => $my_button_clicked();
+    }
+}

examples/widget-template-manual/box.gresource.xml

@@ -0,0 +1,5 @@
+<gresources>
+  <gresource prefix="/example">
+    <file>box.ui</file>
+  </gresource>
+</gresources>

examples/widget-template-manual/box.ui

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+DO NOT EDIT!
+This file was @generated by blueprint-compiler. Instead, edit the
+corresponding .blp file and regenerate this file with blueprint-compiler.
+-->
+<interface>
+  <requires lib="gtk" version="4.0"/>
+  <template class="My_Box" parent="GtkBox">
+    <property name="halign">3</property>
+    <property name="valign">3</property>
+    <child>
+      <object class="GtkButton" id="my-button">
+        <property name="label" translatable="yes">Hi! Click me and look at the terminal!</property>
+        <signal name="clicked" handler="my_button_clicked"/>
+      </object>
+    </child>
+  </template>
+</interface>

examples/widget-template-manual/window.odin

@@ -0,0 +1,147 @@
+package template
+
+@require import "base:runtime"
+@require import "core:fmt"
+@require import adw "../../adwaita"
+@require import "../../glib"
+@require import gobj "../../glib/gobject"
+@require import "../../glib/gio"
+@require import "../../gtk"
+
+// Return the GType of our widget, and register it if it isn't already.
+my_box_get_type :: proc "c" () -> (g_type: gobj.Type) {
+    @static static_g_type: gobj.Type
+
+    // If the type is already registered, we just return the type id.
+    if static_g_type != 0 { return static_g_type }
+
+    info := gobj.TypeInfo{
+        class_size = size_of(My_Box_Class),
+        class_init = class_init,
+
+        instance_size = size_of(My_Box),
+        instance_init = instance_init,
+    }
+    // We the type id so it sticks.
+    static_g_type = gobj.type_register_static(gtk.box_get_type(), "My_Box", &info, .NONE)
+    g_type = static_g_type
+    return
+
+    // Constructors
+    // These could be defined outside of this proc too, but it's nicer to have them contained here.
+
+    // This handles everything that's related to the overall widget class.
+    class_init :: proc "c" (class: glib.pointer, data: glib.pointer) {
+        gtk.widget_class_set_template_from_resource(cast(^gtk.WidgetClass)class, "/example/box.ui")
+
+        // We can set the click action here. See the blueprint `box.blp` for more information.
+        // Alternatively, we could set it in the `instance_init` proc as well.
+        widget_class := cast(^gtk.WidgetClass)class
+        offset := cast(glib.ssize)offset_of(My_Box, button)
+
+        gtk.widget_class_bind_template_child_full(
+            widget_class,
+            name = "my-button",
+            internal_child = false, // I have no idea what this does. Both work (shrug).
+            struct_offset = offset, // This will automatically bind our button into our My_Box struct. How cool!
+        )
+
+        // We set up our button's clicked action defined in the blueprint.
+        // Refer to the `instance_init` proc if you want to set it without blueprint.
+        clicked_callback := cast(gobj.Callback)my_button_clicked
+        gtk.widget_class_bind_template_callback_full(widget_class, "my_button_clicked", clicked_callback)
+
+        // Rest of your class setup and virtual methods etc. go here as well.
+    }
+
+    // This handles the individual instances of the widget.
+    instance_init :: proc "c" (instance: ^gobj.TypeInstance, class_data: glib.pointer) {
+        gtk.widget_init_template(cast(^gtk.Widget)instance)
+
+        /*
+        // We could also set up our child button here instead, if we wanted to.
+
+        button := cast(^gtk.Button)(
+            gtk.widget_get_template_child(cast(^gtk.Widget)instance, my_button_get_type(), "my-button")
+        )
+        my_box := cast(^My_Box)instance
+        my_box.button = button
+
+        // It is, however, important to note that we would need to unset the `my_button_clicked` signal
+        // in the blueprint. It's either-or. Both cannot be true at once, GTK will yell at us otherwise.
+
+        clicked_callback := cast(gobj.Callback)my_button_clicked
+        gobj.signal_connect(button, "clicked", clicked_callback, nil)
+        */
+
+        // Rest of your instance overrides and setup go here as well.
+    }
+
+    // This will get called when we click the button.
+    my_button_clicked :: proc "c"(button: ^gtk.Button, data: glib.pointer) {
+        parent := gtk.widget_get_parent(cast(^gtk.Widget)button)
+        my_box := cast(^My_Box)parent
+
+        my_box.button_clicked += 1
+
+        context = runtime.default_context()
+        fmt.printfln("Button clicked %d times!", my_box.button_clicked)
+
+        // GTK copies our string, so we are responsible for freeing the memory.
+        button_clicked_cstring := fmt.caprintf("Clicked %d times!", my_box.button_clicked)
+        defer delete(button_clicked_cstring)
+
+        gtk.button_set_label(button, button_clicked_cstring)
+    }
+}
+
+// Needed by GTK internally.
+My_Box_Class :: struct {
+    parent_class: gtk.BoxClass,
+}
+
+// The box instance.
+// Note: `parent` field has to be the first.
+My_Box :: struct {
+    parent_instance: gtk.Box,
+    button_clicked: int,
+    button: ^gtk.Button, // this field is set by us in the `class_init` proc.
+}
+
+main :: proc() {
+    context = glib.create_context()
+
+    // We must initialise GTK, otherwise our parent class, `gtk.Box` is not valid.
+    gtk.init()
+
+    // We load the resource file that was compiled by `glib-compile-resources`
+    // The `.ui` file was created by blueprint-compiler.
+    // use the `#load` directive for release builds, to bundle it into the app.
+    resource := gio.resource_load("box.gresource", nil)
+    gio.resources_register(resource)
+
+    app := adw.application_new("some.example", .NONE)
+    defer gobj.object_unref(app)
+
+    gobj.signal_connect(app, "activate", cast(gobj.Callback)show_window, nil)
+    status := gio.application_run(cast(^gio.Application)app, 0, nil)
+
+    if status != 0 {
+        fmt.eprintfln("%#v", "oh no!")
+    }
+}
+
+// We set up and show the main window here. This could be split up to multiple procs, obviously.
+show_window :: proc "c" (app: ^adw.Application) {
+    // GTK is very cast heavy, unfortunately.
+    // I like to prefix generic variables with `_` as a note to myself.
+    _window := adw.application_window_new(cast(^gtk.Application)(app))
+    window := cast(^adw.ApplicationWindow)_window
+
+    // We create our custom box here, initialised as per its init function.
+    my_box_g_type := my_box_get_type()
+    _my_box := gobj.object_new(my_box_g_type, nil)
+
+    adw.application_window_set_content(window, cast(^gtk.Widget)_my_box)
+    gtk.window_present(cast(^gtk.Window)_window)
+}

examples/widget-template-with-helper/box.blp

@@ -0,0 +1,11 @@
+using Gtk 4.0;
+
+template $My_Box: Gtk.Box {
+    halign: center;
+    valign: center;
+
+    Button my-button {
+        label: bind template.button-label;
+        clicked => $my_button_clicked();
+    }
+}

examples/widget-template-with-helper/box.gresource.xml

@@ -0,0 +1,5 @@
+<gresources>
+  <gresource prefix="/example">
+    <file>box.ui</file>
+  </gresource>
+</gresources>

examples/widget-template-with-helper/box.ui

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+DO NOT EDIT!
+This file was @generated by blueprint-compiler. Instead, edit the
+corresponding .blp file and regenerate this file with blueprint-compiler.
+-->
+<interface>
+  <requires lib="gtk" version="4.0"/>
+  <template class="My_Box" parent="GtkBox">
+    <property name="halign">3</property>
+    <property name="valign">3</property>
+    <child>
+      <object class="GtkButton" id="my-button">
+        <property name="label" bind-source="My_Box" bind-property="button-label" bind-flags="sync-create"/>
+        <signal name="clicked" handler="my_button_clicked"/>
+      </object>
+    </child>
+  </template>
+</interface>

examples/widget-template-with-helper/window.odin

@@ -0,0 +1,144 @@
+package template
+
+@require import "base:runtime"
+@require import "core:fmt"
+@require import adw "../../adwaita"
+@require import "../../glib"
+@require import gobj "../../glib/gobject"
+@require import "../../glib/gio"
+@require import "../../gtk"
+
+// The box instance.
+// Note: `parent` field has to be the first.
+My_Box :: struct {
+    parent_instance: gtk.Box,
+    button_clicked: int,
+    button: ^gtk.Button,  // This field is populated automatically.
+    button_label: cstring `gproperty:"1,button-label"`,
+}
+
+main :: proc() {
+    context = glib.create_context()
+
+    // We must initialise GTK, otherwise our parent class, `gtk.Box` is not valid.
+    gtk.init()
+
+    // We load the resource file that was compiled by `glib-compile-resources`
+    // The `.ui` file was created by blueprint-compiler.
+    // use the `#load` directive for release builds, to bundle it into the app.
+    resource := gio.resource_load("box.gresource", nil)
+    gio.resources_register(resource)
+
+    app := adw.application_new("some.example", .NONE)
+    defer gobj.object_unref(app)
+
+    gobj.signal_connect(app, "activate", cast(gobj.Callback)show_window, nil)
+    status := gio.application_run(cast(^gio.Application)app, 0, nil)
+
+    if status != 0 {
+        fmt.eprintfln("%#v", "oh no!")
+    }
+   }
+
+// We set up and show the main window here. This could be split up to multiple procs, obviously.
+show_window :: proc "c" (app: ^adw.Application) {
+    // GTK is very cast heavy, unfortunately.
+    // I like to prefix generic variables with `_` as a note to myself.
+    _window := adw.application_window_new(cast(^gtk.Application)(app))
+    window := cast(^adw.ApplicationWindow)_window
+
+    // Context is needed for reflection used by the setup.
+    context = runtime.default_context()
+
+    // If we only care about registering the child, and don't want to bind it to our struct,
+    // we can leave `field_name` empty.
+    template_children := []gtk.Template_Child{
+        {
+            id         = "my-button",
+            field_name = "button",
+        },
+    }
+    // See gtk.Template_Data for more information about what this is.
+    template_data := gtk.Template_Data{
+        resource_path = "/example/box.ui",
+        children = template_children,
+        type = My_Box,
+    }
+    gtk.register_type_with_template(
+        My_Box,
+        gtk.BoxClass,
+        gtk.box_get_type(),
+        &template_data,
+
+        // We want to set a `clicked` signal to our button, so we must supply our own init proc.
+        class_init_proc = my_box_class_init,
+        instance_init_proc = my_box_instance_init,
+    )
+
+    // We create our custom box here, initialised as per its init function.
+    my_box_g_type := gtk.custom_type_get_type(My_Box)
+    _my_box := gobj.object_new(my_box_g_type, nil)
+
+    adw.application_window_set_content(window, cast(^gtk.Widget)_my_box)
+    gtk.window_present(cast(^gtk.Window)_window)
+}
+
+// Our custom class init proc, since we want to set the `clicked` action on our button.
+my_box_class_init :: proc "c" (class: glib.pointer, data: glib.pointer) {
+    // We register the getter and setter procs for our box's custom gproperties.
+    object_class := cast(^gobj.ObjectClass)class
+    object_class.get_property = my_box_property_get
+    object_class.set_property = my_box_property_set
+
+    // We call the default init proc, so that we don't have to do the child binding and template setup ourselves.
+    // This takes care of common use cases like registering children and annotated gproperties.
+    gtk.class_init_default_template(class, data)
+
+    // We register our proc as a callback to the signal defined in the blueprint.
+    // Alternatively, we could register the signal in the `instance_init` proc too.
+    widget_class := cast(^gtk.WidgetClass)class
+    clicked_callback := cast(gobj.Callback)my_button_clicked
+    gtk.widget_class_bind_template_callback_full(widget_class, "my_button_clicked", clicked_callback)
+}
+
+// This is called by GTK whenever it wants to know the value of any of the registered properties.
+my_box_property_get :: proc "c"(object: ^gobj.Object, property_id: glib.uint_, value: ^gobj.Value, pspec: ^gobj.ParamSpec) {
+    my_box := cast(^My_Box)object
+    switch property_id {
+    case 1: // We set the id of our property to 1.
+        gobj.value_set_string(value, my_box.button_label)
+    }
+}
+
+my_box_instance_init :: proc "c" (instance: ^gobj.TypeInstance, class_data: glib.pointer) {
+    // We call the default template to do the setup.
+    gtk.instance_init_default_template(instance, class_data)
+
+    // We set a default value for our label, since the binding sets none by itself.
+    my_box := cast(^My_Box)instance
+    gtk.button_set_label(my_box.button, "Click me!")
+}
+
+// We can leave this empty for now because we don't plan on setting it through GTK.
+my_box_property_set :: proc "c"(object: ^gobj.Object, property_id: glib.uint_, value: ^gobj.Value, pspec: ^gobj.ParamSpec) {}
+
+// This will get called when we click the button.
+my_button_clicked :: proc "c"(button: ^gtk.Button, data: glib.pointer) {
+    parent := gtk.widget_get_parent(cast(^gtk.Widget)button)
+    my_box := cast(^My_Box)parent
+
+    my_box.button_clicked += 1
+
+    context = runtime.default_context()
+    fmt.printfln("Button clicked %d times!", my_box.button_clicked)
+
+    button_clicked_cstring := fmt.caprintf("Clicked %d times!", my_box.button_clicked)
+
+    // We set the property of our box, and tell GTK that it changed, which will automatically update everything that depends on it.
+    delete(my_box.button_label)
+    my_box.button_label = button_clicked_cstring
+    gobj.object_notify(cast(^gobj.Object)my_box, "button-label")
+
+    // In this case, we could have set the button label directly too, via:
+    // gtk.button_set_label(button, button_clicked_cstring)
+}