Otherwise, requesting a min size in em where the equivalent in px had a
fractional part would lead to the widget getting allocated 1 too few px.
You could see this in the CSS property vs. allocation in the Inspector.
Note that margin/border/padding are left alone: the rationale is that we
do as browsers do, and Benjamin said we already do that for those,
whereas his tests on min-(width|height) showed otherwise. My subsequent
analysis indicated it to be far less clear-cut than that, but he remains
unconvinced that we should ceil() all the things! So just do these ones.
https://gitlab.gnome.org/GNOME/gtk/issues/1088
Remove all the old 2.x and 3.x version annotations.
GTK+ 4 is a new start, and from the perspective of a
GTK+ 4 developer all these APIs have been around since
the beginning.
Both GtkWidget and GtkContainer had similar docs regarding hfw/wfh
geometry management. Move these just to GtkWidget. Also make sure the
examples compile, port everything from gtk_preferred_* to measure and
replace some occurrences of "container" with "widget" where container
was just used to refer to a widget with child widgets.
The GtkWidgetClass::measure vfunc is not required to assign a value to
any of the (out) parameters, so we need to initialize the locals we pass
to it, otherwise we can end up with a garbage size request.
The reported minimum baseline is for the reported min height, but if the
css min-height is greater than that, we need to account for that fact
when saving the baseline.
Since the reported baseline is relative to the widget's origin, we also
need to add the top values for margin, border and padding to the
reported baseline.
We need to adjust the passed for_size to fit into the content allocation
of the widget.
That also means that we can't call gtk_widget_measure(widget) inside
gtk_widget_measure(widget) since now the for_size will be adjusted
twice.
Instead of mentioning the old _get_preferred_xxx functions, mention
measure() and print the for_size value as well. The orientation is given
by printing either "width" for GTK_ORIENTATION_HORIZONTAL or "height"
for GTK_ORIENTATION_VERTICAL.
Add a new ::measure vfunc similar to GtkCssGadget's that widget
implementations have to override instead of the old get_preferred_width,
get_preferred_height, get_preferred_width_for_height,
get_preferred_height_for_width and
get_preferred_height_and_baseline_for_width.
The g_print documentation explicitly says not to do this, since
g_print is meant to be redirected by applications. Instead use
g_message for logging that can be triggered via GTK_DEBUG.
... and API to set and unset it.
It is set when gtk_widget_queue_resize() is called.
It is unset when gtk_widget_get_preferred_width/height() is called.
So far it is not used.
gtk_widget_preferred_size() is only useful if you want to quickly port a
widget from GTK2 sizing code to GTK3 but does not properly work with
height-for-width as used in GTK. So we don't want to encourage people to
use it. In particular we want people to convert to height-for-width
before adding baseline support to their widgets.
