Wt
3.2.1
|
A widget that holds and manages child widgets. More...
#include <Wt/WContainerWidget>
Public Types | |
enum | Overflow { OverflowVisible = 0x0, OverflowAuto = 0x1, OverflowHidden = 0x2, OverflowScroll = 0x3 } |
How to handle overflow of inner content. More... | |
Public Member Functions | |
WContainerWidget (WContainerWidget *parent=0) | |
Creates a container with optional parent. | |
~WContainerWidget () | |
Destructor. | |
void | setLayout (WLayout *layout) |
Sets a layout manager for the container. | |
void | setLayout (WLayout *layout, WFlags< AlignmentFlag > alignment) |
Sets a layout manager for the container. | |
WLayout * | layout () |
Returns the layout manager that was set for the container. | |
virtual void | addWidget (WWidget *widget) |
Adds a child widget to this container. | |
virtual void | insertBefore (WWidget *widget, WWidget *before) |
Inserts a child widget in this container, before another widget. | |
virtual void | insertWidget (int index, WWidget *widget) |
Inserts a child widget in this container at given index. | |
virtual void | removeWidget (WWidget *widget) |
Removes a child widget from this container. | |
virtual void | clear () |
Removes and deletes all child widgets. | |
virtual int | indexOf (WWidget *widget) const |
Returns the index of a widget. | |
virtual WWidget * | widget (int index) const |
Returns the widget at index | |
virtual int | count () const |
Returns the number of widgets in this container. | |
void | setContentAlignment (WFlags< AlignmentFlag > contentAlignment) |
Specifies how child widgets must be aligned within the container. | |
void | setPadding (const WLength &padding, WFlags< Side > sides=All) |
Sets padding inside the widget. | |
WLength | padding (Side side) const |
Returns the padding set for the widget. | |
WFlags< AlignmentFlag > | contentAlignment () const |
Returns the alignment of children. | |
void | setOverflow (Overflow overflow, WFlags< Orientation > orientation=(Horizontal|Vertical)) |
Sets how overflow of contained children must be handled. | |
void | setList (bool list, bool ordered=false) |
Renders the container as an HTML list. | |
bool | isList () const |
Returns if this container is rendered as a List. | |
bool | isUnorderedList () const |
Returns if this container is rendered as an Unordered List. | |
bool | isOrderedList () const |
Returns if this container is rendered as an Ordered List. | |
EventSignal< WScrollEvent > & | scrolled () |
Event signal emitted when scrolling in the widget. |
A widget that holds and manages child widgets.
A WContainerWidget acts as a container for child widgets. Child widgets may be added directly to the container or using a layout manager.
Use addWidget() or pass the container as constructor argument to a widget to directly add children to the container, without using a layout manager. In that case, CSS-based layout is used, and the resulting display is determined by properties of the children and the container. By default, a WContainerWidget is displayed as a block and manages its children within a rectangle. Inline child widgets are layed out in lines, wrapping around as needed, while block child widgets are stacked vertically. The container may add padding at the container edges using setPadding(), and provide alignment of contents using setContentAlignment(). A container is rendered by default using a HTML div
tag, but this may be changed to an HTML ul
or ol
tag to make use of other CSS layout techniques, using setList(). In addition, specializations of this class as implemented by WAnchor, WGroupBox, WStackedWidget and WTableCell provide other alternative rendering of the container.
When setting the WContainerWidget inline the container only acts as a conceptual container, offering a common style to its children. Inline children are still layed out inline within the flow of the parent container of this container, as if they were inserted directly into that parent container. Block children are then not allowed (according to the HTML specification).
To use a layout manager instead of CSS-based layout, use setLayout() or pass the container as constructor argument to a layout manager. In that case you should not define any padding for the container, and widgets and nested layout managers must be added to the layout manager, instead of to the container directly.
Usage example:
// Example 1: // Instantiate a container widget and add some children whose layout // is governed based on HTML/CSS rules. Wt::WContainerWidget *container1 = new Wt::WContainerWidget(); container1->addWidget(new Wt::WText("Some text")); container1->addWidget(new Wt::WImage("images/img.png")); Wt::WContainerWidget *child3 = new Wt::WContainerWidget(container1); // Example 2: // Instantiate a container widget which uses a layout manager Wt::WContainerWidget *container2 = new Wt::WContainerWidget(); container2->resize(WLength::Auto, 600); // give the container a fixed height. Wt::WVBoxLayout *layout = new Wt::WVBoxLayout(); layout->addWidget(new Wt::WText("Some text")); layout->addWidget(new Wt::WImage("images/img.png")); container2->setLayout(layout); // set the layout to the container.
When using a layout manager, you need to carefully consider the alignment of the layout manager with respect to the container: when the container's height is unconstrained (not specified explicitly using resize() or a style class, and the container is not included in a layout manager), you should pass AlignTop to setLayout().
Depending on its configuration and usage, the widget corresponds to the following HTML tags:
<div>
tag.<span>
.<ul>
.<ol>
.<li>
.This widget does not provide styling, and can be styled using inline or external CSS as appropriate.
void Wt::WContainerWidget::addWidget | ( | WWidget * | widget | ) | [virtual] |
Adds a child widget to this container.
This is equivalent to passing this container as the parent when constructing the child. The widget is appended to the list of children, and thus also layed-out at the end.
Reimplemented in Wt::Ext::Splitter, and Wt::WStackedWidget.
void Wt::WContainerWidget::clear | ( | ) | [virtual] |
Removes and deletes all child widgets.
This deletes all children that have been added to this container.
If a layout was set, also the layout manager is deleted.
WFlags<AlignmentFlag> Wt::WContainerWidget::contentAlignment | ( | ) | const |
Returns the alignment of children.
Inserts a child widget in this container, before another widget.
The widget is inserted at the place of the before
widget, and subsequent widgets are shifted.
Reimplemented in Wt::Ext::Splitter.
void Wt::WContainerWidget::insertWidget | ( | int | index, |
WWidget * | widget | ||
) | [virtual] |
Inserts a child widget in this container at given index.
The widget is inserted at the given index
, and subsequent widgets are shifted.
Reimplemented in Wt::Ext::Splitter, and Wt::WStackedWidget.
bool Wt::WContainerWidget::isList | ( | ) | const |
Returns if this container is rendered as a List.
bool Wt::WContainerWidget::isOrderedList | ( | ) | const |
Returns if this container is rendered as an Ordered List.
bool Wt::WContainerWidget::isUnorderedList | ( | ) | const |
Returns if this container is rendered as an Unordered List.
WLayout* Wt::WContainerWidget::layout | ( | ) | [virtual] |
Returns the layout manager that was set for the container.
If no layout manager was previously set using setLayout(WLayout *), 0 is returned.
Reimplemented from Wt::WWidget.
Returns the padding set for the widget.
void Wt::WContainerWidget::removeWidget | ( | WWidget * | widget | ) | [virtual] |
Removes a child widget from this container.
This removes the widget from this container, but does not delete the widget !
EventSignal< WScrollEvent > & Wt::WContainerWidget::scrolled | ( | ) |
Event signal emitted when scrolling in the widget.
This event is emitted when the user scrolls in the widget (for setting the scroll bar policy, see setOverflow()). The event conveys details such as the new scroll bar position, the total contents height and the current widget height.
void Wt::WContainerWidget::setContentAlignment | ( | WFlags< AlignmentFlag > | contentAlignment | ) |
Specifies how child widgets must be aligned within the container.
For a WContainerWidget, only specifes the horizontal alignment of child widgets. Note that there is no way to specify vertical alignment: children are always pushed to the top of the container.
For a WTableCell, this may also specify the vertical alignment. The default alignment is (Wt::AlignTop | Wt::AlignLeft).
void Wt::WContainerWidget::setLayout | ( | WLayout * | layout | ) | [virtual] |
Sets a layout manager for the container.
Note that you can nest layout managers inside each other, to create a complex layout hierarchy.
If a previous layout manager was already set, it is first deleted. In that case, you will need to make sure that you either readd all widgets that were part of the previous layout to the new layout, or delete them, to avoid memory leaks.
The layout manager arranges children in the entire width and height of the container. This is equivalent to setLayout(layout, AlignJustify)
Reimplemented from Wt::WWidget.
void Wt::WContainerWidget::setLayout | ( | WLayout * | layout, |
WFlags< AlignmentFlag > | alignment | ||
) |
Sets a layout manager for the container.
The alignment
argument determines how the layout is aligned inside the container. By default, the layout manager arranges children over the entire width and height of the container, corresponding to a value of AlignJustify. This requires that the container has a specified height (either because it is managed by another layout manager, is the root container widget, or has a height set).
In general, alignment
is the logical OR of a horizontal and a vertical flag:
When using a horizontal alingment different from Wt::AlignJustify, and a vertical alignment different from '0', the widget is sized in that direction to fit the contents, instead of the contents being adjusted to the widget size. This is useful when the container does not have a specific size in that direction and when the layout manager does not contain any widgets that wish to consume all remaining space in that direction.
Only a single layout manager may be set. If you want to replace the current layout manager, you have to erase all contents first using clear(), which also deletes the layout manager.
Note that you can nest layout managers inside each other, to create a complex layout hierarchy.
The widget will take ownership of layout
.
void Wt::WContainerWidget::setList | ( | bool | list, |
bool | ordered = false |
||
) |
Renders the container as an HTML list.
Setting renderList
to true
will cause the container to be using an HTML <ul>
or <ol>
type, depending on the value of orderedList
. This must be set before the initial render of the container. When set, any contained WContainerWidget will be rendered as an HTML <li>
. Adding non-WContainerWidget children results in unspecified behaviour.
Note that CSS default layout rules for <ul>
and <ol>
add margin and padding to the container, which may look odd if you do not use bullets.
By default, a container is rendered using a <div>
element.
void Wt::WContainerWidget::setOverflow | ( | Overflow | overflow, |
WFlags< Orientation > | orientation = (Horizontal | Vertical) |
||
) |
Sets how overflow of contained children must be handled.
This is an alternative (CSS-ish) way to configure scroll bars on a container widget, compared to wrapping inside a WScrollArea.
Unlike WScrollArea, horizontal scrolling does not work reliably when the container widget is inserted in a layout manager: the layout manager will overflow rather than use scrollbars for this container widget. A solution then is to use WScrollArea instead.