Calendar - Simple creation with C++ binding

As a first example, let's just display a calendar in our window, explaining all steps required to do so.

The first part consists of including the headers. In this case we are only working with the Elementary C++ binding and thus we need only to include him.

#include <Elementary.hh>

Attention
If necessary the C and/or the C++ headers should be include here as well.

Now we need to actually start the code and set the elm_policy, which defines for a given policy group/identifier a new policy's value, respectively. In this example the only policy we need to set a value for is ELM_POLICY_QUIT, possibles values for it are:

EAPI_MAIN int
elm_main (int argc, char *argv[])
{
elm_policy_set(ELM_POLICY_QUIT, ELM_POLICY_QUIT_LAST_WINDOW_HIDDEN);

As you can see, the policy we chose was to quit when the last win is hidden as opose to examples with the C bindings where we perpetually set it to quit when last win was closed. This changed was necessary because in C++ binding as the elm mainloop stop running all object are destroyed, references are unreferenced and events are stopped at ELM_MAIN().

See also
For more details consult elm_policy_set

Next step is creating an Elementary window, in this example we use the C++ binding method with the elm_win_util_standard_add that is a elm_win_legacy function, better explained below. And then we set the autohide state for it.

elm_win_util_standard_add (const char *name, const char *tittle) Adds a window object with standard setup. Parameters:

This creates a window but also puts in a standard background with elm_bg_add(), as well as setting the window title to title. The window type created is of type ELM_WIN_BASIC, with the NULL as the parent widget. Returns the created object or NULL on failure.

The autohide works similarly to autodel, automatically handling "delete,request" signals when set to true, with the difference that it will hide the window, instead of destroying it.

It is specially designed to work together with ELM_POLICY_QUIT_LAST_WINDOW_HIDDEN which allows exiting Elementary's main loop when all the windows are hidden.

win.title_set("Calendar Creation Example");
win.autohide_set(true);

Note
autodel and autohide are not mutually exclusive. The window will be destructed if both autodel and autohide is set to EINA_TRUE or true.

Now, the exciting part, let's create the calendar with the C++ binding method, passing our window object as parent.

::elm::calendar cal(efl::eo::parent = win);

The function size_hint_weight_set for C++ bindings originated from C bindings function evas_object_size_hint_weight_set, that is EFL Evas type function. With this function we set the hints for an object's weight. The parameters are:

This is not a size enforcement in any way, it's just a hint that should be used whenever appropriate. This is a hint on how a container object should resize a given child within its area.

Containers may adhere to the simpler logic of just expanding the child object's dimensions to fit its own (see the EVAS_HINT_EXPAND helper weight macro in the EFL Evas Documentation) or the complete one of taking each child's weight hint as real weights to how much of its size to allocate for them in each axis. A container is supposed to, after normalizing the weights of its children (with weight hints), distribute the space it has to layout them by those factors – most weighted children get larger in this process than the least ones.

cal.size_hint_weight_set(EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);

Note
Default weight hint values are 0.0, for both axis.

Now we add the calendar as a resize-object to win informing that when the size of the win changes so should the calendar's size. And finally we make it visible.

Finally we just have to start the elm mainloop, starting to handle events and drawing operations.

Our example will look like this:

calendar_cxx_example_01.png

See the full source code calendar_cxx_example_01.cc here.