BreakpointBin

A widget that changes layout based on available size.

AdwBreakpointBin provides a way to use breakpoints without class@Window, class@ApplicationWindow or class@Dialog. It can be useful for limiting breakpoints to a single page and similar purposes. Most applications shouldn't need it.

AdwBreakpointBin is similar to class@Bin. It has one child, set via the property@BreakpointBin:child property.

When AdwBreakpointBin is resized, its child widget can rearrange its layout at specific thresholds.

The thresholds and layout changes are defined via class@Breakpoint objects. They can be added using method@BreakpointBin.add_breakpoint.

Each breakpoint has a condition, specifying the bin's size and/or aspect ratio, and setters that automatically set object properties when that happens. The signal@Breakpoint::apply and signal@Breakpoint::unapply can be used instead for more complex scenarios.

Breakpoints are only allowed to modify widgets inside the AdwBreakpointBin, but not on the AdwBreakpointBin itself or any other widgets.

If multiple breakpoints can be used for the current size, the last one is always picked. The current breakpoint can be tracked using the property@BreakpointBin:current-breakpoint property.

If none of the breakpoints can be used, that property will be set to NULL, and the original property values will be used instead.

Minimum Size

Adding a breakpoint to AdwBreakpointBin will result in it having no minimum size. The property@Gtk.Widget:width-request and property@Gtk.Widget:height-request properties must always be set when using breakpoints, indicating the smallest size you want to support.

The minimum size and breakpoint conditions must be carefully selected so that the child widget completely fits. If it doesn't, it will overflow and a warning message will be printed.

When choosing minimum size, consider translations and text scale factor changes. Make sure to leave enough space for text labels, and enable ellipsizing or wrapping if they might not fit.

For class@Gtk.Label this can be done via property@Gtk.Label:ellipsize, or via property@Gtk.Label:wrap together with property@Gtk.Label:wrap-mode.

For buttons, use property@Gtk.Button:can-shrink, property@Gtk.MenuButton:can-shrink, property@Adw.SplitButton:can-shrink, or property@Adw.ButtonContent:can-shrink.

Example

GtkWidget *bin, *child;
AdwBreakpoint *breakpoint;

bin = adw_breakpoint_bin_new ();
gtk_widget_set_size_request (bin, 150, 150);

child = gtk_label_new ("Wide");
gtk_label_set_ellipsize (GTK_LABEL (label), PANGO_ELLIPSIZE_END);
gtk_widget_add_css_class (child, "title-1");
adw_breakpoint_bin_set_child (ADW_BREAKPOINT_BIN (bin), child);

breakpoint = adw_breakpoint_new (adw_breakpoint_condition_parse ("max-width: 200px"));
adw_breakpoint_add_setters (breakpoint,
                            G_OBJECT (child), "label", "Narrow",
                            NULL);
adw_breakpoint_bin_add_breakpoint (ADW_BREAKPOINT_BIN (bin), breakpoint);

The bin has a single label inside it, displaying "Wide". When the bin's width is smaller than or equal to 200px, it changes to "Narrow".

AdwBreakpointBin as GtkBuildable

AdwBreakpointBin allows adding AdwBreakpoint objects as children.

Example of an AdwBreakpointBin UI definition:

<object class="AdwBreakpointBin">
  <property name="width-request">150</property>
  <property name="height-request">150</property>
  <property name="child">
    <object class="GtkLabel" id="child">
      <property name="label">Wide</property>
      <property name="ellipsize">end</property>
      <style>
        <class name="title-1"/>
      </style>
    </object>
  </property>
  <child>
    <object class="AdwBreakpoint">
      <condition>max-width: 200px</condition>
      <setter object="child" property="label">Narrow</setter>
    </object>
  </child>
</object>

See class@Breakpoint documentation for details.