gtk2/docs/reference/gtk/migrating-3xtoy.xml
Tristan Van Berkom fd065f63b0 Revert "Add a release note for scrolled windows"
This reverts commit 76af907676.

The behavioral change described in the migration guide
has now been made optional with new scrolled window API,
so no need to mention this in the migration guide.
2016-09-06 21:09:26 +09:00

444 lines
17 KiB
XML

<?xml version="1.0"?>
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
<!ENTITY % local.common.attrib "xmlns:xi CDATA #FIXED 'http://www.w3.org/2003/XInclude'">
]>
<chapter id="gtk-migrating-3-x-to-y">
<title>Migrating from one GTK+ 3 release to another</title>
<para>
GTK+ 3 has seen considerable development over multiple stable releases.
While we try to maintain compatibility as far as possible, some minor
adjustments may be necessary when moving an application from one release
of GTK+ 3 to the next.
</para>
<para>
The following sections list noteworthy changes in GTK+ 3.x release that
may or may not require applications to be updated.
</para>
<section>
<title>Changes in GTK+ 3.2</title>
<para>
The accessible implementations for GTK+ widgets have been integrated
into libgtk itself, and the gail module does not exist anymore. This
change should not affect applications very much.
</para>
</section>
<section>
<title>Changes in GTK+ 3.4</title>
<para>
Scroll events have been separated from button events, and smooth
scrolling has been added with a separate event mask. Widgets now
need to have either GDK_SCROLL_MASK or GDK_SMOOTH_SCROLL_MASK in
their event mask to receive scroll events. In addition, the
GdkScrollDirection enumeration has gained a new member,
GDK_SCROLL_SMOOTH, so switch statements will have to be amended
to cover this case.
</para>
<para>
GTK+ now uses &lt;Primary&gt; instead of &lt;Control&gt; in keyboard
accelerators, for improved cross-platform handling. This should not
affect applications, unless they parse or create these accelerator
manually.
</para>
<para>
The tacit assumption that the Alt key corresponds to the MOD1
modifier under X11 is now a hard requirement.
</para>
<para>
The beagle search backend for the file chooser has been dropped.
Tracker is the only supported search backend on Linux now.
</para>
<para>
GtkNotebook has been changed to destroy its action widgets when
it gets destroyed itself. If your application is using action
widgets in notebooks, you may have to adjust your code to take
this into account.
</para>
<para>
GtkApplication no longer uses the gtk_ mainloop wrappers, so
it is no longer possible to use gtk_main_quit() to stop it.
</para>
<para>
The -uninstalled variants of the pkg-config files have been dropped.
</para>
<para>
Excessive dependencies have been culled from Requires: lines
in .pc files. Dependent modules may have to declare dependencies
that there were getting 'for free' in the past.
</para>
</section>
<section>
<title>Changes in GTK+ 3.6</title>
<para>
The accessibility bridge code that exports accessible objects
on the bus is now used by default; atk-bridge has been converted
into a library that GTK+ links against. To void the linking,
pass --without-atk-bridge when configuring GTK+.
</para>
<para>
GDK threading support has been deprecated. It is recommended to
use g_idle_add(), g_main_context_invoke() and similar funtions
to make all GTK+ calls from the main thread.
</para>
<para>
GTK+ now follows the XDG Base Directory specification for
user configuration and data files. In detail,
<itemizedlist>
<listitem>$XDG_CONFIG_HOME/gtk-3.0/custom-papers is the new location
for $HOME/.gtk-custom-papers</listitem>
<listitem>$XDG_CONFIG_HOME/gtk-3.0/bookmarks is the new location
for $HOME/.gtk-bookmarks</listitem>
<listitem>$XDG_DATA_HOME/themes is preferred over $HOME/.themes</listitem>
<listitem>$XDG_DATA_HOME/icons is preferred over $HOME/.icons.</listitem>
</itemizedlist>
Existing files from the old location will still be read
if the new location does not exist.
</para>
<para>
$HOME/.gtk-3.0 is no longer in the default module load path.
If you want to load modules from there, add it to the GTK_PATH
environment variable.
</para>
</section>
<section>
<title>Changes in GTK+ 3.8</title>
<para>
GtkIconInfo has changed from being a boxed type to a GObject.
This is technically an ABI change, but basically all existing code
will keep working if its used as a boxed type, and it is not
possible to instantiate GtkIconInfos outside GTK+, so this is
not expected to be a big problem.
</para>
</section>
<section>
<title>Changes in GTK+ 3.10</title>
<para>
GDK has been changed to allow only a single screen per display.
Only the X11 backend had multiple screens before, and multi-screen
setups (not multi-monitor!) are very rare nowadays. If you really
need multiple X screens, open them as separate displays.
</para>
<para>
The behavior of GtkBox::expand has been changed to never propagate
up. Previously, this was happening inconsistently. If you want the
expand to propagate, use the GtkWidget h/v expand properties.
If you experience sizing problems with widgets in ported code,
carefully check the expand and fill flags of your boxes.
</para>
<para>
GtkBin no longer provides default implementations for
get_height_for_width, subclasses now have to provide their own
implementation if they need height-for-width functionality.
</para>
<para>
Widget state propagation has been changed. Historically, all of
active, prelight, selected, insensitive, inconsistent and backdrop
have been propagated to children. This has now been restricted
to just the insensitive and backdrop states. This mostly affects
theming.
</para>
<para>
The way widget drawing happens has changed. Earlier versions handled
one expose event per GdkWindow, each with a separate cairo_t. Now we
only handle the expose event on the toplevel and reuse the same
cairo_t (with the right translation and clipping) for the entire
widget hierarchy, recursing down via the GtkWidget::draw signal.
Having all rendering in the same call tree allows effects like
opacity and offscreen rendering of entire widget sub-hierarchies.
Generally this should not require any changes in widgets, but
code looking at e.g. the current expose event may see different
behavior than before.
</para>
<para>
The Gtk+ scrolling implementation has changed. gdk_window_scroll()
and gdk_window_move_region() no longer copy the region on the
window, but rather invalidate the entire scrolled region. This is
slightly slower, but allowed us to implement a offscreen surface
scrolling method which better fits modern hardware. Most scrolling
widgets in Gtk+ have been converted to use this model for scrolling,
but external widgets implementing scrolling using GdkWindow may see
some slowdown.
</para>
</section>
<section>
<title>Changes in GTK+ 3.12</title>
<para>
GtkWidget had a hack where if opacity is 0.999 we set up an opacity
group when rendering the widget. This is no longer needed in 3.10,
and GtkStack doesn't use it anymore. It has been removed in 3.12.
GdStack is using it, so applications should be ported from GdStack
to GtkStack in 3.12.
</para>
<para>
GtkHeaderBar in 3.10 was not ordering its pack-end children in
the right way. This has been fixed in 3.12. Applications which
pack multiple widgets at the end of a headerbar will have to
be updated.
</para>
<para>
gtk_text_view_add_child_in_window has changed behaviour a bit.
It now always positions the child in buffer coordinates, where
it used to inconsistently scroll with the buffer but then go
reposition to a window-relative position on redraw.
</para>
<para>
A number of container widgets have been made more compliant with
the uniform CSS rendering model by making them render backgrounds
and borders. This may require some adjustments in applications that
were making assumptions about containers never rendering backgrounds.
</para>
</section>
<section>
<title>Changes in GTK+ 3.14</title>
<para>
A new state, GTK_STATE_FLAG_CHECKED, has been added for checked states
of radio and check buttons and menuitems. Applications that are using
GTK+ styles without widgets will need adjustments.
</para>
<para>
Adwaita is now the default theme on all platforms.
</para>
<para>
The icon theme code has become a little pickier about sizes and is not
automatically scaling icons beyond the limits defined in the icon theme
unless explicitly asked to do so with GTK_ICON_LOOKUP_FORCE_SIZE.
</para>
<para>
GTK+ now includes an interactive debugger which can be activated with
the keyboard shortcuts Ctrl-Shift-d or Ctrl-Shift-i. If these shortcuts
interfere with application keybindings, they can be disabled with the
setting org.gtk.Settings.Debug.enable-inspector-keybinding.
</para>
<para>
Most widgets have been ported to use the new gesture framework internally
for event handling. Traditional event handlers in derived widgets are still
being called.
</para>
<para>
Using GTK+ under X11 without the X Render extension has been observed
to be problematic. This combination is using code paths in cairo and
graphics drivers which are rarely tested and likely buggy.
</para>
<para>
GtkTextView is now using a pixel-cache internally, and is drawing
a background underneath the text. This can cause problems for applications
which assumed that they could draw things below and above the text
by chaining up in the ::draw implementation of their GtkTextView subclass.
As a short-term workaround, you can make the application apply a
custom theme to the text view with a transparent background. For
a proper fix, use the new ::draw_layer vfunc.
</para>
</section>
<section>
<title>Changes in GTK+ 3.16</title>
<para>
GTK+ now includes an OpenGL rendering widget. To support GL on various
platforms, GTK+ uses libepoxy.
</para>
<para>
GTK+ no longer uses gtk-update-icon-cache during its build. The
--enable-gtk2-dependency configure option has been removed.
</para>
<para>
The introspection annotations for the x and y parameters of
GtkMenuPositionFunc have been corrected from 'out' to 'inout'.
If you are using such a function from language-bindings, this
may require adjustments.
</para>
<para>
The lookup order for actions that are activated via keyboard
accelerators has been changed to start at the currently focused
widget. If your application is making use fo nested action groups
via gtk_widget_insert_action_group, you may want to check that
this change does not upset your accelerators.
</para>
<para>
The GtkScrollable interface has gained a new vfunc, get_border,
that is used to position overshoot and undershoot indications that
are drawn over the content by GtkScrolledWindow. Unless your scrollable
has non-scrolling parts similar to treeview headers, there is no need
to implement this vfunc.
</para>
<para>
The GtkSearchEntry widget has gained a number of new signals that
are emitted when certain key sequences are seen. In particular, it
now handles the Escape key and emits ::stop-search. Applications that
expect to handle Escape themselves will need to be updated.
</para>
</section>
<section>
<title>Changes in GTK+ 3.18</title>
<para>
The GtkListBox model support that was introduced in 3.16 has been
changed to no longer call gtk_widget_show_all on rows created by
the create_widget_func. You need to manage the visibility of child
widgets yourself in your create_widget_func.
</para>
<para>
The alpha component of foreground colors that are applied to
GtkCellRendererText is no longer ignored. If you don't want your
text to be translucent, use opaque colors.
</para>
</section>
<section>
<title>Changes in GTK+ 3.20</title>
<para>
The way theming works in GTK+ has been reworked fundamentally, to
implement many more CSS features and make themes more expressive.
As a result, custom CSS that is shipped with applications and third-party
themes will need adjustments. Widgets now use element names much more
than style classes; type names are no longer used in style matching.
Every widget now documents the element names it has and the style classes
it uses. The GTK+ inspector can also help with finding this information.
</para>
<para>
GTK+ now uses internal subobjects (also known as gadgets) for allocating
and drawing widget parts. Applications that subclass GTK+ widgets may see
warnings if they override the size_allocate vfunc and don't chain up.
The proper way to subclass is to chain up in size_allocate. If you do not
want to do that for some reason, you have to override the draw vfunc as
well.
</para>
<para>
Several fixes for window sizing and window placement with client-side
decorations may affect applications that are saving and restoring window
sizes. The recommended best practice for this which is known to work with
client-side and server-side decorations and with older and newer versions
of GTK+ is to use gtk_window_get_size() to save window sizes and
gtk_window_set_default_size() to restore it.
See https://wiki.gnome.org/HowDoI/SaveWindowState for a detailed example.
</para>
<para>
Geometry handling in GtkWindow has been removed. If you are using the
functions gtk_window_resize_to_geometry, gtk_window_set_default_geometry,
gtk_window_parse_geometry or gtk_window_set_geometry_hints, you may need
to make some changes to your code.
</para>
<para>
GtkDrawingArea used to implicitly render the theme background before
calling the ::draw handler. This is no longer the case. If you rely
on having a theme-provided background, call gtk_render_background()
from your ::draw handler.
</para>
<para>
The GtkFileChooser interface prerequisite changed from GtkWidget
to GObject, allowing non-widget implementations of this interface.
This is a minor change in ABI, as applications are no longer guaranteed
that a GtkFileChooser also supports all GtkWidget methods. However, all
previously existing implementations still derive from GtkWidget, so no
existing code should break.
</para>
<para>
The way in which GtkLevelBar determines the offset to apply was a bit
inconsistent in the past; this has been fixed. Applications that are using
custom offsets should double-check that their levels look as expected.
</para>
</section>
<section>
<title>Changes in GTK+ 3.22</title>
<para>
The CSS parser has gotten a bit more selective in what it accepts as
valid values for the font: shorthand. Following the CSS specification,
at least a size and a family name are required now. If you want to
change an individual facet of the font, like the weight, use the
individual CSS properties: font-weight, font-size, font-family, etc.
</para>
<para>
The CSS parser now warns about some more constructs that are not according
to the CSS spec, such as gradients with a single color stop. Instead,
you can just use image(&lt;color&gt;).
</para>
<para>
The #GtkSizeGroup:ignore-hidden property has not been working properly
for a long time, and we've not documented it as broken and deprecated.
The recommended alternative for reserving space of widgets that are not
currently shown in the UI is to use a #GtkStack (with some 'filler'
widget, e.g. an empty #GtkBox, in another page).
</para>
<para>
GtkHeaderBar now respects the hexpand property for its custom title
widget and its packed children. This change may inadvertently cause the
layout of those children to change, if they unintentionally had hexpand
set before.
</para>
<para>
The behavior of the expand flag in #GtkTables #GtkAttachOptions has been
changed to (again) match the behavior in #GtkBox and in GTK+ 2.x. These
options don't cause the table itself to expand.
</para>
<para>
The way GtkPopover behaved during a call to gtk_widget_hide() violated
some of the internal assumptions GTK+ makes about widget visibility.
gtk_popover_popup() and gtk_popover_popdown() have been introduced to
show or hide the popover with a transition, while gtk_widget_show()
and gtk_widget_hide() on a GtkPopover now work the same way they do
on any other widget and immediately hide (or show) the popover.
</para>
</section>
</chapter>