ej.mwt

Class Container

java.lang.Object

ej.mwt.Widget

ej.mwt.Container

Direct Known Subclasses:

Canvas, Dock, Flow, Grid, List, OverlapContainer, SimpleDock

public abstract class Container
extends Widget

A container is a widget that can contain other Widget instances, following the composite pattern.

The children are stored in a list. The order of the list defines the front-to-back stacking order of the widgets within the container. The first widget in the list is at the back of the stacking order.

A widget cannot be added two times in a hierarchy.

Field Summary

Fields inherited from class ej.mwt.Widget

NO_CONSTRAINT

Constructor Summary

Constructors

Constructor and Description
Container() Creates a new container. Its bounds will be set to 0.

Method Summary

Modifier and Type	Method and Description
protected void	addChild(Widget child) Adds the specified widget to the end of the list of children of this container.
protected void	changeChildIndex(Widget child, int index) Changes the position of the specified widget in the list of children of this container.
protected void	computeChildOptimalSize(Widget child, int availableWidth, int availableHeight) Computes the optimal size of a child of this container.
Widget	getChild(int index) Gets the widget at the specified index in this container.
int	getChildIndex(Widget child) Gets the index of the specified widget in the list of children of this container.
protected Widget[]	getChildren() Gets the list of children in this container.
int	getChildrenCount() Gets the number of children in this container.
Rectangle	getContentBounds() Gets the content bounds of this widget (the bounds minus the outlines).
int	getContentHeight() Gets the content height of this container.
int	getContentWidth() Gets the content width of this container.
int	getContentX() Gets the content x of this container.
int	getContentY() Gets the content y of this container.
Widget	getWidgetAt(int x, int y) Returns the child widget that is at the specified position.
protected void	insertChild(Widget child, int index) Inserts the specified widget at the specified index in the list of children of this container.
protected void	layOutChild(Widget child, int x, int y, int width, int height) Lays out a child of this container.
protected abstract void	layOutChildren(int contentWidth, int contentHeight) Lays out the children of this container.
protected void	removeAllChildren() Removes all the children of this container.
protected void	removeChild(Widget child) Removes the specified widget from the list of children of this container.
protected void	renderChild(Widget child, GraphicsContext g) Renders a child of this container.
protected void	renderContent(GraphicsContext g, int contentWidth, int contentHeight) Renders the content of the widget without the border, margin and padding specified in the style.
protected void	replaceChild(int index, Widget child) Replaces the child at the specified index in the list of children of this container by the specified widget.
protected void	setHiddenChild(Widget child) Sets a child as hidden.
protected void	setHiddenChildren() Automatically declares children as hidden when this container is hidden.
protected void	setShownChild(Widget child) Sets a child as shown.
protected void	setShownChildren() Automatically declares children as shown when this container is shown.
void	updateStyle() Updates the style of this widget.

Methods inherited from class ej.mwt.Widget

addClassSelector, computeContentOptimalSize, contains, containsWidget, getAbsoluteX, getAbsoluteY, getDesktop, getHeight, getParent, getStyle, getWidth, getX, getY, handleEvent, hasClassSelector, isAttached, isEnabled, isInState, isShown, isTransparent, onAttached, onDetached, onHidden, onLaidOut, onShown, removeAllClassSelectors, removeClassSelector, render, requestLayOut, requestRender, requestRender, setClassSelectors, setEnabled, setPosition, setStyle

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Container

public Container()

Creates a new container.
Its bounds will be set to 0.

Method Detail

addChild

protected void addChild(Widget child)

Adds the specified widget to the end of the list of children of this container.

The container needs to be laid out again.

Should be called in the display thread to avoid concurrency issues.

Parameters:

child - the widget to add.

Throws:

IllegalArgumentException - if the specified widget is already attached.

See Also:

Widget.requestLayOut(), Widget.isAttached()

changeChildIndex

protected void changeChildIndex(Widget child,
                                int index)

Changes the position of the specified widget in the list of children of this container.

Parameters:

child - the child to move.

index - the index at which the widget should be moved.

Throws:

IllegalArgumentException - if the given widget is not a child of this container.

computeChildOptimalSize

protected void computeChildOptimalSize(Widget child,
                                       int availableWidth,
                                       int availableHeight)

Computes the optimal size of a child of this container.

An assertion checks that the given widget is actually a child of this container.

Parameters:

child - the child.

availableWidth - the width available for this child or Widget.NO_CONSTRAINT.

availableHeight - the height available for this child or Widget.NO_CONSTRAINT.

See Also:

Desktop.requestLayOut(), Widget.requestLayOut()

getChild

public Widget getChild(int index)

Gets the widget at the specified index in this container.

Parameters:

index - the index of the widget to return.

Returns:

the widget at the specified index in this container.

Throws:

IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= getChildrenCount()).

getChildIndex

public int getChildIndex(Widget child)

Gets the index of the specified widget in the list of children of this container.

Parameters:

child - the child.

Returns:

the index of the given child.

Throws:

IllegalArgumentException - if the specified widget is not a child of this container.

getChildren

protected Widget[] getChildren()

Gets the list of children in this container.

Beware, the returned array is the field, it should not be modified.

Returns:

the list of children.

getChildrenCount

public int getChildrenCount()

Gets the number of children in this container.

Returns:

the number of children.

getContentBounds

public Rectangle getContentBounds()

Description copied from class: Widget

Gets the content bounds of this widget (the bounds minus the outlines).

Overrides:

getContentBounds in class Widget

Returns:

the content bounds of this widget.

getContentHeight

public int getContentHeight()

Gets the content height of this container. That means the height minus the sum of the different outlines vertically (top and bottom).

The content bounds of a container are computed when the bounds of the container are set. (Otherwise, the content bounds will be zeros.)

Returns:

the content height.

getContentWidth

public int getContentWidth()

Gets the content width of this container. That means the width minus the sum of the different outlines horizontally (left and right).

The content bounds of a container are computed when the bounds of the container are set. (Otherwise, the content bounds will be zeros.)

Returns:

the content width.

getContentX

public int getContentX()

Gets the content x of this container. That means the sum of the different outlines on the left.

The content bounds of a container are computed when the bounds of the container are set. (Otherwise, the content bounds will be zeros.)

Returns:

the content x.

getContentY

public int getContentY()

Gets the content y of this container. That means the sum of the different outlines on the top.

The content bounds of a container are computed when the bounds of the container are set. (Otherwise, the content bounds will be zeros.)

Returns:

the content y.

getWidgetAt

@Nullable
public Widget getWidgetAt(int x,
                                     int y)

Returns the child widget that is at the specified position.

If Widget.contains(int, int) is false for this container, null is returned. Otherwise, if there is a child for which Widget.contains(int, int) returns true then the result of invoking Widget.getWidgetAt(int, int) on that widget is returned. Otherwise this container is returned.

The position is relative to the position of this container's parent.

Overrides:

getWidgetAt in class Widget

Parameters:

x - x coordinate

y - y coordinate

Returns:

the child at the position, null if no child is found in this container hierarchy.

insertChild

protected void insertChild(Widget child,
                           int index)

Inserts the specified widget at the specified index in the list of children of this container.

The container needs to be laid out again.

Should be called in the display thread to avoid concurrency issues.

Parameters:

child - the widget to add.

index - the index at which the widget should be inserted.

Throws:

IllegalArgumentException - if the specified widget is already attached.

IndexOutOfBoundsException - if the index is out of range (index < 0 || index > getChildrenCount()).

See Also:

Widget.requestLayOut(), Widget.isAttached()

layOutChild

protected void layOutChild(Widget child,
                           int x,
                           int y,
                           int width,
                           int height)

Lays out a child of this container.

The bounds of a widget can only be set by its parent during the lay out.

An assertion checks that the given widget is actually a child of this container.

Parameters:

child - the child to set the bounds to.

x - the x coordinate to set.

y - the y coordinate to set.

width - the width to set.

height - the height to set.

See Also:

Desktop.requestLayOut(), Widget.requestLayOut()

layOutChildren

protected abstract void layOutChildren(int contentWidth,
                                       int contentHeight)

Lays out the children of this container.

The given size is the size of this container minus the border, margin and padding specified in the style.

When this method returns the children of this container have been lay out using layOutChild(Widget, int, int, int, int).

Parameters:

contentWidth - the width available for the content.

contentHeight - the height available for the content.

removeAllChildren

protected void removeAllChildren()

Removes all the children of this container.

The container needs to be laid out again.

Should be called in the display thread to avoid concurrency issues.

See Also:

Widget.requestLayOut()

removeChild

protected void removeChild(Widget child)

Removes the specified widget from the list of children of this container.

The container needs to be laid out again.

If the widget is not in the list of children of the container, nothing is done.

Should be called in the display thread to avoid concurrency issues.

Parameters:

child - the widget to remove.

See Also:

Widget.requestLayOut()

renderChild

protected void renderChild(Widget child,
                           GraphicsContext g)

Renders a child of this container.

The given graphics context is translated and clipped to the parent content area. The child is then responsible of translating to its location and clipping to its size.

An assertion checks that the given widget is actually a child of this container.

Parameters:

child - the child to render.

g - the graphics context where to render the content of the child.

renderContent

protected void renderContent(GraphicsContext g,
                             int contentWidth,
                             int contentHeight)

Renders the content of the widget without the border, margin and padding specified in the style.

The given graphics context is translated and clipped according to the given bounds (the border, margin and padding are applied on this graphics context before).

Renders the children of this container.

Specified by:

renderContent in class Widget

Parameters:

g - the graphics context where to render the content of the widget.

contentWidth - the width of the content area.

contentHeight - the height of the content area.

replaceChild

protected void replaceChild(int index,
                            Widget child)

Replaces the child at the specified index in the list of children of this container by the specified widget.

If the specified widget is already the child at the specified index of the list of children, nothing is done.

The container needs to be laid out again.

Should be called in the display thread to avoid concurrency issues.

Parameters:

index - the index of the child to replace.

child - the widget to add.

Throws:

IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= getChildrenCount()).

IllegalArgumentException - if the specified widget is already attached, unless it is already the child at the specified index.

See Also:

Widget.requestLayOut(), Widget.isAttached()

setHiddenChild

protected void setHiddenChild(Widget child)

Sets a child as hidden.

An assertion checks that the given widget is actually a child of this container.

Parameters:

child - the child to notify.

See Also:

Widget.onHidden()

setHiddenChildren

protected void setHiddenChildren()

Automatically declares children as hidden when this container is hidden.

It is not necessary to override this method, except for optimization. If this method is overridden, it should always make sure that every child is hidden before returning.

See Also:

Widget.onHidden()

setShownChild

protected void setShownChild(Widget child)

Sets a child as shown.

An assertion checks that the given widget is actually a child of this container.

Parameters:

child - the child to notify.

See Also:

Widget.onShown()

setShownChildren

protected void setShownChildren()

Automatically declares children as shown when this container is shown.

See Also:

Widget.onShown()

updateStyle

public void updateStyle()

Updates the style of this widget.

If the widget is not in a desktop, nothing is done.

The style of each child of this container is also updated.

Overrides:

updateStyle in class Widget