Package ej.widget.container

Class Canvas

java.lang.Object

ej.mwt.Widget

ej.mwt.Container

ej.widget.container.Canvas

public class Canvas
extends Container

Lays out any number of children freely.

Each child is laid out at the position it has been given.

In a canvas, each child will have the size it has been given, or if desired, its optimal size.

Nested Class Summary

Nested classes/interfaces inherited from class ej.mwt.Widget

Widget.WidgetListener

Field Summary

Fields inherited from class ej.mwt.Widget

DEBUG_WIDGET_ENABLED_CONSTANT, DEBUG_WIDGET_MONITOR_CONSTANT, NO_CONSTRAINT

Constructor Summary

Constructors

Constructor	Description
Canvas()	Creates a canvas.

Method Summary

Modifier and Type	Method	Description
void	addChild(Widget child, int x, int y, int width, int height)	Adds the specified widget to this canvas.
void	changeChildIndex(Widget child, int index)	Changes the position of the specified widget in the list of children of this container.
protected void	computeContentOptimalSize(Size size)	Computes the optimal size of the widget.
protected void	layOutChildren(int contentWidth, int contentHeight)	Lays out the children of this container.
void	removeAllChildren()	Removes all the children of this container.
void	removeChild(Widget child)	Removes the specified widget from the list of children of this container.

Methods inherited from class ej.mwt.Container

addChild, computeChildOptimalSize, getChild, getChildIndex, getChildren, getChildrenCount, getContentBounds, getContentHeight, getContentWidth, getContentX, getContentY, getWidgetAt, insertChild, layOutAlignedChild, layOutChild, renderChild, renderContent, replaceChild, setHiddenChild, setHiddenChildren, setShownChild, setShownChildren, updateStyle

Methods inherited from class ej.mwt.Widget

addClassSelector, 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, setX, setY

Methods inherited from class java.lang.Object

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

Constructor Detail

Canvas

public Canvas()

Creates a canvas.

Method Detail

addChild

public void addChild(Widget child,
                     int x,
                     int y,
                     int width,
                     int height)

Adds the specified widget to this canvas. The widget is laid out with the given bounds.

If the given width or height is Widget.NO_CONSTRAINT, the widget is fitted to its optimal width/height.

Parameters:

child - the widget to add.

x - the x coordinate of the widget.

y - the y coordinate of the widget.

width - the width of the widget, or Widget.NO_CONSTRAINT to use the widget optimal width.

height - the height of the widget, or Widget.NO_CONSTRAINT to use the widget optimal height.

Throws:

NullPointerException - if the specified widget is null.

IllegalArgumentException - if the specified widget is already in a hierarchy (already contained in a container or desktop).

See Also:

Container.addChild(Widget)

removeChild

public void removeChild(Widget child)

Description copied from class: Container

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.

Overrides:

removeChild in class Container

Parameters:

child - the widget to remove.

See Also:

Widget.requestLayOut()

removeAllChildren

public void removeAllChildren()

Description copied from class: Container

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.

Overrides:

removeAllChildren in class Container

See Also:

Widget.requestLayOut()

changeChildIndex

public void changeChildIndex(Widget child,
                             int index)

Description copied from class: Container

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

Overrides:

changeChildIndex in class Container

Parameters:

child - the child to move.

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

computeContentOptimalSize

protected void computeContentOptimalSize(Size size)

Description copied from class: Widget

Computes the optimal size of the widget.

This method does not consider the border, margin, padding and dimension specified in the style.

The given size is the available size for this widget in its parent. A width or a height equal to Widget#NO_CONSTRAINT means that there is no constraint on this dimension.

The given size is modified to set the optimal size.

Specified by:

computeContentOptimalSize in class Widget

Parameters:

size - the size available for the content.

layOutChildren

protected void layOutChildren(int contentWidth,
                              int contentHeight)

Description copied from class: Container

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 Container.layOutChild(Widget, int, int, int, int).

Specified by:

layOutChildren in class Container

Parameters:

contentWidth - the width available for the content.

contentHeight - the height available for the content.