+
+/************************************************************
+ * !!! This design is experimental and not yet fully implemented !!!!!!!!!!!!!
+ *
+ * DATA ORGANISATION :
+ * Areas in tint2 are similar to widgets in a GUI.
+ * All graphical objects (panel, taskbar, task, systray, clock, ...) 'inherit' an abstract class 'Area'.
+ * This class 'Area' manage the background, border, size, position and padding.
+ * Area is at the begining of each object (&object == &area).
+ *
+ * tint2 define one panel per monitor. And each panel have a tree of Area.
+ * The root of the tree is Panel.Area. And task, clock, systray, taskbar,... are nodes.
+ *
+ * The tree give the localisation of each object :
+ * - tree's root is in the background while tree's leafe are foreground objects
+ * - position of a node/Area depend on the layout : parent's position (posx, posy), size of previous brothers and parent's padding
+ * - size of a node/Area depend on the content (SIZE_BY_CONTENT objects) or on the layout (SIZE_BY_LAYOUT objects)
+ *
+ * DRAWING AND LAYERING ENGINE :
+ * Redrawing an object (like the clock) could come from an 'external event' (date change)
+ * or from a 'layering event' (position change).
+ * The following 'drawing engine' take care of all 'layering event'.
+ * 1) browse tree SIZE_BY_CONTENT
+ * - resize SIZE_BY_CONTENT node : children are resized before parent
+ * - if 'size' changed then 'resize = 1' on the parent
+ * 2) browse tree SIZE_BY_LAYOUT and POSITION
+ * - resize SIZE_BY_LAYOUT node : parent is resized before children
+ * - if 'size' changed then 'resize = 1' on childs with SIZE_BY_LAYOUT
+ * - calculate position (posx,posy) : parent is calculated before children
+ * - if 'position' changed then 'redraw = 1'
+ * 3) browse tree REDRAW
+ * - redraw needed objects : parent is drawn before children
+ *
+ * CONFIGURE PANEL'S LAYOUT :
+ * 'panel_items' parameter (in config) define the list and the order of nodes in tree's panel.
+ * 'panel_items = SC' define a panel with just Systray and Clock.
+ * So the tree 'Panel.Area' will have 2 childs (Systray and Clock).
+ *
+ * 1) ok
+ * 2) ??
+ * 3) ??
+ * répartition entre niveau global et niveau local ??
+ * size_by_content peut-il modifier redraw=1 en cas de changement ? ou est ce géré par chaque composant ?
+ * size_by_layout peut-il modifier redraw ?
+ *
+ ************************************************************/
+
+
+void size_by_content (Area *a)
+{
+ // don't resize hiden objects
+ if (!a->on_screen) return;
+
+ // children node are resized before its parent
+ GSList *l;
+ for (l = a->list; l ; l = l->next)
+ size_by_content(l->data);
+
+ // calculate area's size
+ if (a->resize && a->size_mode == SIZE_BY_CONTENT) {
+ a->resize = 0;
+
+ if (a->_resize) {
+ if (a->_resize(a)) {
+ // 'size' changed then 'resize = 1' on the parent
+ ((Area*)a->parent)->resize = 1;
+ }
+ a->redraw = 1;
+ }
+ }
+}
+
+
+void size_by_layout (Area *a)
+{
+ // don't resize hiden objects
+ if (!a->on_screen) return;
+
+ // parent node is resized before its children
+ // calculate area's size
+ GSList *l;
+ if (a->resize && a->size_mode == SIZE_BY_LAYOUT) {
+ a->resize = 0;
+
+ if (a->_resize) {
+ if (a->_resize(a)) {
+ // if 'size' changed then 'resize = 1' on childs with SIZE_BY_LAYOUT
+ for (l = a->list; l ; l = l->next) {
+ if (((Area*)l->data)->size_mode == SIZE_BY_LAYOUT)
+ ((Area*)l->data)->resize = 1;
+ }
+ }
+ }
+ }
+
+ for (l = a->list; l ; l = l->next)
+ size_by_layout(l->data);
+}
+
+