forked from AuroraMiddleware/gtk
555 lines
21 KiB
XML
555 lines
21 KiB
XML
<?xml version="1.0"?>
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<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
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"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
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<!ENTITY % local.common.attrib "xmlns:xi CDATA #FIXED 'http://www.w3.org/2003/XInclude'">
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]>
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<chapter id="gtk-migrating-3-to-4">
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<title>Migrating from GTK+ 3.x to GTK+ 4</title>
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<para>
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GTK+ 4 is a major new version of GTK+ that breaks both API and ABI
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compared to GTK+ 3.x. Thankfully, most of the changes are not hard
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to adapt to and there are a number of steps that you can take to
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prepare your GTK+ 3.x application for the switch to GTK+ 4. After
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that, there's a small number of adjustments that you may have to do
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when you actually switch your application to build against GTK+ 4.
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</para>
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<section>
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<title>Preparation in GTK+ 3.x</title>
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<para>
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The steps outlined in the following sections assume that your
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application is working with GTK+ 3.24, which is the final stable
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release of GTK+ 3.x. It includes all the necessary APIs and tools
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to help you port your application to GTK+ 4. If you are still using
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an older version of GTK+ 3.x, you should first get your application
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to build and work with the latest minor release in the 3.24 series.
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</para>
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<section>
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<title>Do not use deprecated symbols</title>
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<para>
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Over the years, a number of functions, and in some cases, entire
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widgets have been deprecated. These deprecations are clearly spelled
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out in the API reference, with hints about the recommended replacements.
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The API reference for GTK+ 3 also includes an
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<ulink url="https://developer.gnome.org/gtk3/3.24/api-index-deprecated.html">index</ulink> of all deprecated symbols.
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</para>
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<para>
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To verify that your program does not use any deprecated symbols,
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you can use defines to remove deprecated symbols from the header files,
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as follows:
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<programlisting>
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make CFLAGS+="-DGDK_DISABLE_DEPRECATED -DGTK_DISABLE_DEPRECATED"
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</programlisting>
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</para>
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<para>
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Note that some parts of our API, such as enumeration values, are
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not well covered by the deprecation warnings. In most cases, using
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them will require you to also use deprecated functions, which will
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trigger warnings.
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</para>
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</section>
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<section>
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<title>Enable diagnostic warnings</title>
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<para>
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Deprecations of properties and signals cannot be caught at compile
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time, as both properties and signals are installed and used after
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types have been instantiated. In order to catch deprecations and
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changes in the run time components, you should use the
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<envar>G_ENABLE_DIAGNOSTIC</envar> environment variable when
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running your application, e.g.:
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<programlisting>
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G_ENABLE_DIAGNOSTIC=1 ./your-app
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</programlisting>
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</para>
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</section>
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<section>
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<title>Do not use widget style properties</title>
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<para>
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Style properties do not exist in GTK+ 4. You should stop using them in
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your custom CSS and in your code.
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</para>
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</section>
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<section>
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<title>Review your window creation flags</title>
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<para>
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GTK+ 4 removes the GDK_WA_CURSOR flag. Instead, just use
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gdk_window_set_cursor() to set a cursor on the window after
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creating it.
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</para>
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<para>
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GTK+ 4 also removes the GDK_WA_VISUAL flag, and always uses
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an RGBA visual for windows. To prepare your code for this,
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use gdk_window_set_visual (gdk_screen_get_rgba_visual ()) after
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creating your window.
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</para>
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<para>
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GTK+ 4 also removes the GDK_WA_WMCLASS flag. If you need this
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X11-specific functionality, use XSetClassHint() directly.
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</para>
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</section>
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<section>
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<title>Stop using non-RGBA visuals</title>
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<para>
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GTK+ 4 always uses RGBA visuals for its windows; you should make
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sure that your code works with that.
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</para>
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<para>
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At the same time, you should stop using GdkVisual APIs, this object
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not longer exist in GTK+ 4. Most of its APIs are deprecated already
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and not useful when dealing with RGBA visuals.
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</para>
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</section>
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<section>
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<title>Stop using GtkBox:padding, GtkBox:fill and GtkBox:expand</title>
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<para>
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GTK+4 removes these #GtkBox child properties, so you should not use them.
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You can replace GtkBox:padding using the #GtkWidget:margin properties
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on your #GtkBox child widgets.
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</para>
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<para>
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The fill child property can be replaced by setting appropriate values
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for the #GtkWidget:halign and #GtkWidget:valign properties of the child
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widgets. If you previously set the fill child property to %TRUE, you can
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achieve the same effect by setting the halign or valign properties to
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%GTK_ALIGN_FILL, depending on the parent box -- halign for a horizontal
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box, valign for a vertical one.
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</para>
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<para>
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#GtkBox also uses the expand child property. It can be replaced by setting
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#GtkWidget:hexpand or #GtkWidget:vexpand on the child widgets. To match the
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old behavior of the #GtkBox's expand child property, you need to set
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#GtkWidget:hexpand on the child widgets of a horizontal #GtkBox and
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#GtkWidget:vexpand on the child widgets of a vertical #GtkBox.
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</para>
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<para>
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Note that there's a subtle but important difference between #GtkBox's
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expand and fill child properties and the ones in #GtkWidget: setting
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#GtkWidget:hexpand or #GtkWidget:vexpand to %TRUE will propagate up
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the widget hierarchy, so a pixel-perfect port might require you to reset
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the expansion flags to %FALSE in a parent widget higher up the hierarchy.
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</para>
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</section>
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<section>
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<title>Stop using the state argument of GtkStyleContext getters</title>
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<para>
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The getters in the GtkStyleContext API, such as
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gtk_style_context_get_property(), gtk_style_context_get(),
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or gtk_style_context_get_color() only accept the context's current
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state for their state argument. You should update all callers to pass
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the current state.
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</para>
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</section>
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<section>
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<title>Stop using gdk_pixbuf_get_from_window() and gdk_cairo_set_source_surface()</title>
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<para>
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These functions are not supported in GTK+ 4. Instead, either use backend-specific
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APIs, or render your widgets using gtk_widget_render().
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</para>
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</section>
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<section>
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<title>Stop using GtkButton's image-related API</title>
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<para>
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The functions and properties related to automatically add a GtkImage
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to a GtkButton, and using a GtkSetting to control its visibility, are
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not supported in GTK+ 4. Instead, you can just pack a GtkImage inside
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a GtkButton, and control its visibility like you would for any other
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widget. If you only want to add a named icon to a GtkButton, you can
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use gtk_button_set_icon_name().
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</para>
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</section>
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<section>
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<title>Stop using GtkWidget event signals</title>
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<para>
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Event controllers and #GtkGestures replace event signals in GTK+ 4. They
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have been backported to GTK+ 3.x so you can prepare for this change.
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</para>
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</section>
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<section>
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<title>Set a proper app_id</title>
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<para>
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In GTK+4 we want the application's #GApplication
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'application-id' (and therefore the D-Bus name), the desktop
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file basename and Wayland's xdg-shell app_id to match. In
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order to achieve this with GTK+3 call g_set_prgname() with the same
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application id you passed to #GtkApplication. Rename your
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desktop files to match the application id if needed.
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</para>
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<para>
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The call to g_set_prgname() can be removed once you fully migrated
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to GTK+4.
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</para>
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</section>
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</section>
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<section>
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<title>Changes that need to be done at the time of the switch</title>
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<para>
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This section outlines porting tasks that you need to tackle when
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you get to the point that you actually build your application against
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GTK+ 4. Making it possible to prepare for these in GTK+ 3 would
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have been either impossible or impractical.
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</para>
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<section>
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<title>Stop using GdkScreen</title>
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<para>
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The GdkScreen object has been removed in GTK+ 4. Most of its APIs already
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had replacements in GTK+ 3 and were deprecated, a few remaining replacements
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have been added to GdkDisplay.
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</para>
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</section>
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<section>
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<title>Stop using the root window</title>
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<para>
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The root window is an X11-centric concept that is no longer exposed in the
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backend-neutral GDK API. gdk_surface_get_parent() will return %NULL for toplevel
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windows. If you need to interact with the X11 root window, you can use
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gdk_x11_display_get_xrootwindow() to get its XID.
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</para>
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</section>
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<section>
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<title>Stop using GdkVisual</title>
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<para>
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This object is not useful with current GTK+ drawing APIs and has been removed
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without replacement.
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</para>
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</section>
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<section>
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<title>Stop using GdkDeviceManager</title>
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<para>
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The GdkDeviceManager object has been removed in GTK+ 4. Most of its APIs already
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had replacements in GTK+ 3 and were deprecated in favor of GdkSeat.
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</para>
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</section>
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<section>
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<title>Adapt to GdkWindow API changes</title>
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<para>
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GdkWindow has been renamed to GdkSurface.
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</para>
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<para>
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The gdk_window_new() function has been replaced by a number of more
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specialized constructors: gdk_surface_new_toplevel(), gdk_surface_new_popup(),
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gdk_surface_new_temp(), gdk_surface_new_child(), gdk_surface_new_input(),
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gdk_wayland_surface_new_subsurface(). Use the appropriate ones to create
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your windows.
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</para>
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<para>
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Native and foreign subwindows are no longer supported. These concepts were
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complicating the code and could not be supported across backends.
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</para>
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<para>
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gdk_window_reparent() is no longer available.
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</para>
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</section>
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<section>
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<title>Stop accessing GdkEvent fields</title>
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<para>
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Direct access to GdkEvent structs is no longer possible in GTK+ 4. Some
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frequently-used fields already had accessors in GTK+ 3, and the remaining
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fields have gained accessors in GTK+ 4.
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</para>
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</section>
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<section>
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<title>Stop using gdk_surface_set_event_compression</title>
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<para>
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Event compression is now always enabled. If you need to see the uncoalesced
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motion history, use gdk_event_get_motion_history().
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</para>
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</section>
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<section>
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<title>Adapt to GdkKeymap API changes</title>
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<para>
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The way to get a keymap has changed slightly. gdk_keymap_get_for_display() has
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been renamed to gdk_display_get_keymap().
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</para>
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</section>
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<section>
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<title>Stop using GtkEventBox</title>
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<para>
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GtkEventBox is no longer needed and has been removed.
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All widgets receive all events.
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</para>
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</section>
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<section>
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<title>Adapt to GtkHeaderBar API changes</title>
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<para>
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The gtk_header_bar_set_show_close_button() function has been renamed to
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the more accurate name gtk_header_bar_set_show_title_buttons(). The corresponding
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getter and the property itself have also been renamed.
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</para>
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</section>
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<section>
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<title>Adapt to GtkStyleContext API changes</title>
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<para>
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The getters in the GtkStyleContext API, such as
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gtk_style_context_get_property(), gtk_style_context_get(),
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or gtk_style_context_get_color() have lost their state argument,
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and always use the context's current state. Update all callers
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to omit the state argument.
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</para>
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</section>
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<section>
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<title>Adapt to GtkCssProvider API changes</title>
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<para>
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In GTK+ 4, the various #GtkCssProvider load functions have lost
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their #GError argument. If you want to handle CSS loading errors,
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use the #GtkCssProvider::parsing-error signal instead.
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</para>
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</section>
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<section>
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<title>Stop using GtkContainer::border-width</title>
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<para>
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GTK+ 4 has removed the #GtkContainer::border-width property.
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Use other means to influence the spacing of your containers,
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such as the CSS margin and padding properties on child widgets.
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</para>
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</section>
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<section>
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<title>Adapt to GtkWidget's size request changes</title>
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<para>
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GTK+ 3 used five different virtual functions in GtkWidget to
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implement size requisition, namely the gtk_widget_get_preferred_width()
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family of functions. To simplify widget implementations, GTK+4 uses
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only one virtual function, GtkWidgetClass::measure() that widgets
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have to implement.
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</para>
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</section>
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<section>
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<title>Adapt to GtkWidget's size allocation changes</title>
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<para>
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The #GtkWidget::size-allocate signal now takes the baseline as an
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argument, so you no longer need to call gtk_widget_get_allocated_baseline()
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to get it.
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</para>
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</section>
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<section>
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<title>Switch to GtkWidget's children APIs</title>
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<para>
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Instead of the GtkContainer subclass, in GTK+ 4, any widget can
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have children, and there is new API to navigate the widget tree:
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gtk_widget_get_first_child(), gtk_widget_get_last_child(),
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gtk_widget_get_next_sibling(), gtk_widget_get_prev_sibling().
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The GtkContainer API still works, but if you are implementing
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your own widgets, you should consider using the new APIs.
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</para>
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</section>
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<section>
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<title>Don't use -gtk-gradient in your CSS</title>
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<para>
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GTK+ now supports standard CSS syntax for both linear and radial
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gradients, just use those.
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</para>
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</section>
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<section>
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<title>Don't use -gtk-icon-effect in your CSS</title>
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<para>
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GTK+ now supports a more versatile -gtk-icon-filter instead. Replace
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-gtk-icon-effect: dim; with -gtk-icon-filter: opacity(0.5); and
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-gtk-icon-effect: hilight; with -gtk-icon-filter: brightness(1.2);.
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</para>
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</section>
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<section>
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<title>Use gtk_widget_measure</title>
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<para>
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gtk_widget_measure() replaces the various gtk_widget_get_preferred_ functions
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for querying sizes.
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</para>
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</section>
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<section>
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<title>Adapt to drawing model changes</title>
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<para>
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This area has seen the most radical changes in the transition from GTK+ 3
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to GTK+ 4. Widgets no longer use a draw() function to render their contents
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to a cairo surface. Instead, they have a snapshot() function that creates
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one or more GskRenderNodes to represent their content. Third-party widgets
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that use a draw() function or a #GtkWidget::draw signal handler for custom
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drawing will need to be converted to use gtk_snapshot_append_cairo().
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</para>
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<para>
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The auxiliary #GtkSnapshot object has APIs to help with creating render
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nodes.
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</para>
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<para>
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If you are using a #GtkDrawingArea for custom drawing, you need to switch
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to using gtk_drawing_area_set_draw_func() to set a draw function instead
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of connnecting a handler to the #GtkWidget::draw signal.
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</para>
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</section>
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<section>
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<title>Stop using APIs to query GdkSurfaces</title>
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<para>
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A number of APIs for querying special-purpose windows have been removed,
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since these windows are no longer publically available:
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gtk_tree_view_get_bin_window(), gtk_viewport_get_bin_window(),
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gtk_viewport_get_view_window().
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</para>
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</section>
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<section>
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<title>Widgets are now visible by default</title>
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<para>
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The default value of #GtkWidget::visible in GTK+ 4 is %TRUE, so you no
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longer need to explicitly show all your widgets. On the flip side, you
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need to hide widgets that are not meant to be visible from the start.
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</para>
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<para>
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A convenient way to remove unnecessary property assignments like this
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from ui files it run the command <command>gtk4-builder-tool simplify --replace</command>
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on them.
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</para>
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<para>
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The function gtk_widget_show_all(), the #GtkWidget::no-show-all property
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and its getter and setter have been removed in GTK+ 4, so you should stop using them.
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</para>
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</section>
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<section>
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<title>Adapt to changes in animated hiding and showing of widgets</title>
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<para>
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Widgets that appear and disappear with an animation, such as GtkPopover,
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GtkInfoBar, GtkRevealer no longer use gtk_widget_show() and gtk_widget_hide()
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for this, but have gained dedicated APIs for this purpose that you should
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use.
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</para>
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</section>
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<section>
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<title>Stop passing commandline arguments to gtk_init</title>
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<para>
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The gtk_init() and gtk_init_check() functions no longer accept commandline
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arguments. Just call them without arguments. Other initialization functions
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that were purely related to commandline argument handling, such as
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gtk_parse_args() and gtk_get_option_group(), are gone. The APIs to
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initialize GDK separately are also gone, but it is very unlikely
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that you are affected by that.
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</para>
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</section>
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<section>
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<title>GdkPixbuf is deemphasized</title>
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<para>
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A number of #GdkPixbuf-based APIs have been removed. The available replacements
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are either using #GIcon, or the newly introduced #GdkTexture or #GdkPaintable
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classes instead.
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</para>
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<para>
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If you are dealing with pixbufs, you can use gdk_texture_new_for_pixbuf()
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to convert them to texture objects where needed.
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</para>
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</section>
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<section>
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<title>GtkWidget event signals are removed</title>
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<para>
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Event controllers and #GtkGestures have already been introduced in GTK+ 3 to handle
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input for many cases. In GTK+ 4, the traditional widget signals for handling input,
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such as #GtkWidget::motion-event or #GtkWidget::event have been removed.
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</para>
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</section>
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|
|
<section>
|
|
<title>Invalidation handling has changed</title>
|
|
<para>
|
|
Only gtk_widget_queue_draw() is left to mark a widget as needing redraw.
|
|
Variations like gtk_widget_queue_draw_rectangle() or gtk_widget_queue_draw_region()
|
|
are no longer available.
|
|
</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Stop using GtkWidget::draw</title>
|
|
<para>
|
|
The #GtkWidget::draw signal has been removed. Widgets need to implement the
|
|
#GtkWidget::snapshot function now. Connecting draw signal handlers is no longer possible.
|
|
</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Window content observation has changed</title>
|
|
<para>
|
|
Observing widget contents and widget size is now done by using the
|
|
#GtkWidgetPaintable object instead of connecting to widget signals.
|
|
</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>The gtk_window_fullscreen_on_monitor API has changed</title>
|
|
<para>
|
|
Instead of a monitor number, gtk_window_fullscreen_on_monitor() now takes a
|
|
#GdkMonitor argument.
|
|
</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Adapt to cursor API changes</title>
|
|
<para>
|
|
Use the new gtk_widget_set_cursor() function to set cursors, instead of
|
|
setting the cursor on the underlying window directly. This is necessary
|
|
because most widgets don't have their own window anymore, turning any
|
|
such calls into global cursor changes.
|
|
</para>
|
|
<para>
|
|
For creating standard cursors, gdk_cursor_new_for_display() has been removed,
|
|
you have to use cursor names instead of GdkCursorType. For creating custom cursors,
|
|
use gdk_cursor_new_from_texture(). The ability to get cursor images has been removed.
|
|
</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Adapt to icon size API changes</title>
|
|
<para>
|
|
Instead of the existing extensible set of symbolic icon sizes, GTK+ now only
|
|
supports normal and large icons with the #GtkIconSize enumeration. The actual sizes
|
|
can be defined by themes via the CSS property -gtk-icon-size.
|
|
</para>
|
|
<para>
|
|
GtkImage setters like gtk_image_set_from_icon_name() no longer take a #GtkIconSize
|
|
argument. You can use the separate gtk_image_set_icon_size() setter if you need
|
|
to override the icon size.
|
|
</para>
|
|
<para>
|
|
The ::stock-size property of GtkCellRendererPixbuf has been renamed to
|
|
#GtkCellRendererPixbuf:icon-size.
|
|
</para>
|
|
</section>
|
|
|
|
</section>
|
|
|
|
</chapter>
|
|
|