PtDivider

A container that divides space among its children

Class hierarchy:

PtWidget → PtBasic → PtContainer → PtCompound → PtDivider

For more information, see the diagram of the widget hierarchy.

PhAB icon:

Public header:

<photon/PtDivider.h>

Description:

The PtDivider widget is a container that lays out its children like a one-row or one-column PtGroup widget, but lets you resize the children by dragging “handles” placed between the children.

Two PtDivider widgets: one contains two lists, the other contains some buttons.

The PtDivider class inherits resources from the PtGroup class. Access to these resources is controlled through PtDivider's exporting mechanism.

A blocking mechanism lets PtDivider block the inheritance of certain resources from its subordinate PtGroup widget. This prevents any actions that would negatively affect the look and behavior of a PtDivider widget. For more information, see the “Exported subordinate children” section.

Examples

In this example, we use the Pt_CB_DIVIDER_HANDLE_CALLBACK callback to set the default widget sizes:

static int default_sizes[] = { 100, 50, 60, 200, ... };


int drag_handle_cb( PtWidget_t *dvdr, ApInfo_t *data,
    PtCallbackInfo_t *cbinfo ) ) {

        PtDividerHandleCallback_t  *cbdata = cbinfo->cbdata;
        PhEvent_t                  *ev = cbinfo->event;
        PhPointerEvent_t           *pe = PhGetData( ev );

        if( ev->type == Ph_EV_BUT_RELEASE
            && ev->subtype == Ph_EV_RELEASE_REAL
            && pe->click_count == 2

        ) {

            // Set the default size on a double click

            PtSetResource( cbdata->left, Pt_ARG_WIDTH,
                default_sizes[cbdata->index], 0 );

       }

}

New resources:

Pt_ARG_DIVIDER_FLAGS

Possible values:

Pt_DIVIDER_NORESIZE

Don't resize the children, just invoke the callback.

Pt_DIVIDER_RESIZE_BOTH

Resize both widgets: the one to the left and to the right (or above and below) the dragged handle. If this flag isn't set, only the left child is resized and the right child is moved.

Pt_DIVIDER_INVISIBLE

Never display the drag outline. This flag is useful mainly when Pt_DIVIDER_NORESIZE is also set.

Pt_DIVIDER_CASCADE

The re-sizing of a widget is “cascaded” to adjacent widgets when the widget has reached it's minimum size. At that point the adjacent widget starts to shrink until it reaches its minimum size, and then its neighbor is resized, and so on.

Pt_DIVIDER_LAST_IS_SPACER

Useful when the divider is in a PtList widget with a horizontal scrollbar. The last widget is a spacer. When the Pt_CB_DIVIDER_DRAG callback is invoked, this widget's size is always reported as 1, regardless of its actual size.

Pt_DIVIDER_NODRAG

The divider handles can't be dragged. They don't display a drag cursor when the pointer is hovering over them.

Pt_ARG_DIVIDER_OFFSET

This number is added to positions of child widgets (relative to the position of the PtDivider widget) when the values for the Pt_ARG_DIVIDER_SIZES resource are calculated. By setting Pt_ARG_DIVIDER_OFFSET, you can make the Pt_ARG_DIVIDER_SIZES relative to any arbitrary point.

Pt_ARG_DIVIDER_SIZES (read-only)

The array of positions and sizes of realized children of the divider. Each PtDividerSizes_t structure contains:

short from

The left side or top of the child, depending on the divider's orientation.

short to

The right or bottom of the child, depending on the divider's orientation.

Pt_CB_DIVIDER_DRAG

A list of PtCallback_t structures that define the callbacks that are invoked when the widget receives a drag event.

If the widget has the Pt_CALLBACKS_ACTIVE bit set in its Pt_ARG_FLAGS resource, these callbacks are also invoked when your application changes the size of a child by calling PtSetResource() or PtSetResources().

Each callback is passed a PtCallbackInfo_t structure that contains at least the following members:

reason

Pt_CB_DIVIDER_DRAG

reason_subtype

The subtype of the drag event (see Ph_EV_DRAG in the description of the PhEvent_t structure in the Photon Library Reference), or Pt_CB_DIVIDER_SETRESOURCES if a child is being resized through PtSetResources() and the widget has the Pt_CALLBACKS_ACTIVE bit set in its Pt_ARG_FLAGS resource.

event

A pointer to a PhEvent_t structure that describes the received drag event, or NULL if a child is being resized through a call to PtSetResources().

cbdata

A pointer to a PtDividerCallback_t structure that contains at least the following members:

PtWidget_t *left, *right;

The two widgets in the group separated by the divider.

int moved;

How far the widget on the right has been moved.

int resized;

The amount by which the widget on the left has been resized.

PtDividerSizes_t const *sizes;

The new value of the Pt_ARG_DIVIDER_SIZES resource.

int nsizes;

The number of items in the sizes array.

These callbacks should return Pt_CONTINUE.

Pt_CB_DIVIDER_HANDLE_CALLBACK

A list of PtCallback_t structures that define the callbacks that are invoked when you press the pointer button when pointing at widget's resize handles, and also when the button is released.

Each callback is passed a PtCallbackInfo_t structure that contains at least the following members:

reason

Pt_CB_DIVIDER_HANDLE_CALLBACK

reason_subtype

0 (not used).

event

A pointer to a PhEvent_t structure that describes the received pointer event.

cbdata

A pointer to a PtDividerHandleCallback_t structure that contains at least the following members:

int start_drag

Set to 1 when a drag operation is requested on a click; you can set to 0 to decline the drag operation.

int index

The drag handle index.

PtWidget_t *handle

The drag handle.

PtWidget_t *left, *right;

The two widgets in the group separated by the divider.

These callbacks should return Pt_CONTINUE.

Exported subordinate children:

Unless the resources are already defined in PtDivider, the PtDivider class uses the resources of its exported subordinate child, PtGroup.

Where PtDivider and PtGroup both define resources having the same name, the resource defined in PtDivider takes precedence.

Inherited resources:

If PtDivider modifies an inherited resource, the “Default override” column indicates the new value. If PtDivider inherits a resource from PtGroup, the default value assigned by PtGroup is inherited too; the “Default override” column shows this default value.

Pt_ARG_BANDWIDTH_THRESHOLD

Defines the “graphics bandwidth” threshold that determines whether the widget resizes the children after each received drag event or only once, when the drag is completed — see PtQuerySystemInfo().

Pt_ARG_GROUP_ORIENTATION

The value of this resource can be only Pt_GROUP_HORIZONTAL or Pt_GROUP_VERTICAL.