com.codename1.ui.layouts

Class FlowLayout

java.lang.Object

com.codename1.ui.layouts.Layout

com.codename1.ui.layouts.FlowLayout

public class FlowLayout
extends Layout

FlowLayout is the default layout manager for Codename One Containers and Forms. It places components in a row one after another based on their preferred size. When it reaches the edge of the container it will break a line and start a new row.

Since flow layout isn't a constraint based layout it has a bunch of very useful enclose methods that can significantly reduce the code required to create the same UI e.g.:

This class works nicely for simple elements, however since Codename One doesn't reflow recursively (for performance) it can't accurately handle complex layouts. As a result when an element of varying size is placed in a flow layout this confuses the line breaking logic and fails in odd ways. That is why this layout should only be used for relatively simple use cases.

Flow layout supports aligning the component horizontally and vertically, it defaults to the top left alignment for LTR languages. E.g. the following alignments are supported thru the usage of setAlign & setValign.

E.g. you can align to the center

You can align to the right

You can align to the center and the middle horizontally

There are quite a few additional combinations that are possible with these API's.

See Also:

see the box layout X which is often a better choice than flow layout.

Constructor Summary

Constructors

Constructor and Description
FlowLayout() Creates a new instance of FlowLayout with left alignment
FlowLayout(int orientation) Creates a new instance of FlowLayout with the given orientation one of LEFT, RIGHT or CENTER
FlowLayout(int orientation, int valign) Creates a new instance of FlowLayout with the given orientation one of LEFT, RIGHT or CENTER and the vertical orientation
FlowLayout(int orientation, int valign, boolean vAlignByRow) Creates a new instance of FlowLayout with the given orientation one of LEFT, RIGHT or CENTER and the vertical orientation

Method Summary

Modifier and Type	Method and Description
static Container	encloseBottom(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.BOTTOM), cmps);
static Container	encloseBottomByRow(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.BOTTOM, true), cmps);
static Container	encloseCenter(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER), cmps);
static Container	encloseCenterBottom(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.BOTTOM), cmps);
static Container	encloseCenterBottomByRow(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.BOTTOM, true), cmps);
static Container	encloseCenterMiddle(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.CENTER), cmps);
static Container	encloseCenterMiddleByRow(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.CENTER, true), cmps);
static Container	encloseIn(Component... cmps) Shorthand for Container.encloseIn(com.codename1.ui.layouts.Layout, com.codename1.ui.Component...) with a FlowLayout instance see:
static Container	encloseLeftMiddle(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER), cmps);
static Container	encloseLeftMiddleByRow(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER, true), cmps);
static Container	encloseMiddle(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER), cmps);
static Container	encloseMiddleByRow(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER, true), cmps);
static Container	encloseRight(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT), cmps);
static Container	encloseRightBottom(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.BOTTOM), cmps);
static Container	encloseRightBottomByRow(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.BOTTOM, true), cmps);
static Container	encloseRightMiddle(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.CENTER), cmps);
static Container	encloseRightMiddleByRow(Component... cmps) Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.CENTER, true), cmps);
boolean	equals(Object o) Indicates whether some other object is "equal to" this one.
protected void	fillRow(Container target, int width, int start, int end) This method tries to fill up the available space in a row.
int	getAlign() Alignment of the flow layout, defaults to LEFT
Dimension	getPreferredSize(Container parent) Returns the container preferred size
int	getValign() Indicates vertical alignment within the flow layout
boolean	isFillRows() Indicates whether the layout manager should try to fill up the available space in the row
boolean	isValignByRow() Returns whether vertical alignment is done internally or externally
void	layoutContainer(Container parent) Layout the given parent container children
void	setAlign(int orientation) Alignment of the flow layout, defaults to LEFT
void	setFillRows(boolean fillRows) Indicates whether the layout manager should try to fill up the available space in the row
void	setValign(int valign) Indicates vertical alignment within the flow layout
void	setValignByRow(boolean internal) When set to true vertical alignment will be performed by row (components within the container will be aligned vertically to each other in the same row) When set to false (which is default) vertical alignment relates to the alignment of this container in regards to external components
String	toString() Returns a string representation of the object.

Methods inherited from class com.codename1.ui.layouts.Layout

addLayoutComponent, cloneConstraint, getChildrenInTraversalOrder, getComponentConstraint, hashCode, isConstraintTracking, isOverlapSupported, obscuresPotential, overridesTabIndices, removeLayoutComponent, updateTabIndices

Methods inherited from class java.lang.Object

clone, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

FlowLayout

public FlowLayout()

Creates a new instance of FlowLayout with left alignment

FlowLayout

public FlowLayout(int orientation)

Creates a new instance of FlowLayout with the given orientation one of LEFT, RIGHT or CENTER

Parameters:

orientation - the orientation value

FlowLayout

public FlowLayout(int orientation,
                  int valign)

Creates a new instance of FlowLayout with the given orientation one of LEFT, RIGHT or CENTER and the vertical orientation

Parameters:

orientation - the orientation value

valign - the vertical orientation one of Component.TOP/BOTTOM/CENTER

FlowLayout

public FlowLayout(int orientation,
                  int valign,
                  boolean vAlignByRow)

Creates a new instance of FlowLayout with the given orientation one of LEFT, RIGHT or CENTER and the vertical orientation

Parameters:

orientation - the orientation value

valign - the vertical orientation one of Component.TOP/BOTTOM/CENTER

vAlignByRow - whether vertical alignment should be computed by row elements

Method Detail

layoutContainer

public void layoutContainer(Container parent)

Layout the given parent container children

Specified by:

layoutContainer in class Layout

Parameters:

parent - the given parent container

fillRow

protected void fillRow(Container target,
                       int width,
                       int start,
                       int end)

This method tries to fill up the available space in a row. This method is called if isFillRows() returns true.

Parameters:

target - the parent container

width - the width of the row to fill

start - the index of the first component in this row

end - the index of the last component in this row

getPreferredSize

public Dimension getPreferredSize(Container parent)

Returns the container preferred size

Specified by:

getPreferredSize in class Layout

Parameters:

parent - the parent container

Returns:

the container preferred size

toString

public String toString()

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method. The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of: getClass().getName() + '@' + Integer.toHexString(hashCode())

Overrides:

toString in class Object

isFillRows

public boolean isFillRows()

Indicates whether the layout manager should try to fill up the available space in the row

Returns:

the fillRows

setFillRows

public void setFillRows(boolean fillRows)

Indicates whether the layout manager should try to fill up the available space in the row

Parameters:

fillRows - the fillRows to set

getValign

public int getValign()

Indicates vertical alignment within the flow layout

Returns:

Component.TOP/BOTTOM/CENTER

setValign

public void setValign(int valign)

Indicates vertical alignment within the flow layout

Parameters:

valign - one of Component.TOP/BOTTOM/CENTER

setValignByRow

public void setValignByRow(boolean internal)

When set to true vertical alignment will be performed by row (components within the container will be aligned vertically to each other in the same row) When set to false (which is default) vertical alignment relates to the alignment of this container in regards to external components

Parameters:

internal - true for internal, false otherwise

isValignByRow

public boolean isValignByRow()

Returns whether vertical alignment is done internally or externally

Returns:

whether vertical alignment is done internally or externally

getAlign

public int getAlign()

Alignment of the flow layout, defaults to LEFT

Returns:

the orientation

setAlign

public void setAlign(int orientation)

Alignment of the flow layout, defaults to LEFT

Parameters:

orientation - the orientation to set

equals

public boolean equals(Object o)

Indicates whether some other object is "equal to" this one. The equals method implements an equivalence relation: It is reflexive: for any reference value x, x.equals(x) should return true. It is symmetric: for any reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true. It is transitive: for any reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true. It is consistent: for any reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the object is modified. For any non-null reference value x, x.equals(null) should return false. The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any reference values x and y, this method returns true if and only if x and y refer to the same object (x==y has the value true).

Overrides:

equals in class Layout

encloseIn

public static Container encloseIn(Component... cmps)

Shorthand for Container.encloseIn(com.codename1.ui.layouts.Layout, com.codename1.ui.Component...) with a FlowLayout instance see:

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseCenter

public static Container encloseCenter(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseRight

public static Container encloseRight(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseMiddle

public static Container encloseMiddle(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseMiddleByRow

public static Container encloseMiddleByRow(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER, true), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseCenterMiddle

public static Container encloseCenterMiddle(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.CENTER), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseCenterMiddleByRow

public static Container encloseCenterMiddleByRow(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.CENTER, true), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseRightMiddle

public static Container encloseRightMiddle(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.CENTER), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseRightMiddleByRow

public static Container encloseRightMiddleByRow(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.CENTER, true), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseLeftMiddle

public static Container encloseLeftMiddle(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseLeftMiddleByRow

public static Container encloseLeftMiddleByRow(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER, true), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseBottom

public static Container encloseBottom(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.BOTTOM), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseCenterBottom

public static Container encloseCenterBottom(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.BOTTOM), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseRightBottom

public static Container encloseRightBottom(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.BOTTOM), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseBottomByRow

public static Container encloseBottomByRow(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.BOTTOM, true), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseCenterBottomByRow

public static Container encloseCenterBottomByRow(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.BOTTOM, true), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container

encloseRightBottomByRow

public static Container encloseRightBottomByRow(Component... cmps)

Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.BOTTOM, true), cmps);

Parameters:

cmps - the components to enclose in a new container

Returns:

the new container