public class UIBuilder

Object
UIBuilder

The UI builder can create a user interface based on the UI designed in the resource editor and allows us to bind to said UI. Notice that if a Component was used in the GUI that is not a part of the com.codename1.ui package (even a Component from sub packages such as table or tree) it MUST be registered before loading a GUI!

Fields

`public static final` `String FORM_STATE_KEY_NAME = "$name"`	A key in the form state hashtable used in the back command navigation
`public static final` `String FORM_STATE_KEY_TITLE = "$title"`	A key in the form state hashtable used in the back command navigation
`public static final` `String FORM_STATE_KEY_FOCUS = "$focus"`	A key in the form state hashtable used in the back command navigation
`public static final` `String FORM_STATE_KEY_SELECTION = "$sel"`	A key in the form state hashtable used in the back command navigation
`public static final int BACK_COMMAND_ID = 99999999`

Constructors

public UIBuilder()

Methods

`public static boolean isBlockAnalytics()`	Enables blocking analytics in the UIBuilder, this is useful for the designer tool.
`public static void setBlockAnalytics(boolean aBlockAnalytics)`	Enables blocking analytics in the UIBuilder, this is useful for the designer tool.
`public static void registerCustomComponent(String name, Class cmp)`	This method allows the UIBuilder to package a smaller portion of Codename One into the JAR and add support for additional 3rd party components to the GUI builder.
`protected void popNavigationStack()`	Removes a navigation frame from the stack, this is useful in case you want to go back to a form in the middle of the navigation stack.
`protected void setBackDestination(String formName)`	Pops the navigation stack until it finds form name and the back button will match form name if form name isn’t in the stack this method will fail
`protected` `String formNavigationStackDebug()`	Useful method for logging form navigation, it returns a string representing the navigation state which can be used to analyze crash reports
`public boolean isBackCommandEnabled()`	Seamlessly inserts a back command to all the forms
`public void setBackCommandEnabled(boolean back)`	Seamlessly inserts a back command to all the forms
`protected void analyticsCallback(String page, String referrer)`	Invokes the analytics service if it is enabled and if
`public` `Container createContainer(String resPath, String resourceName)`	Creates the container defined under the given name in the res file
`public` `Container createContainer(Resources res, String resourceName)`	Creates the container defined under the given name in the res file
`public` `Component findByName(String name, Component rootComponent)`	Finds the given component by its name
`public` `Component findByName(String name, Container rootComponent)`	Finds the given component by its name
`protected` `Component createComponentInstance(String componentType, Class cls)`	This method can be overriden to create custom components in a custom way, the component type is a shorthand for the component name and not the full name of the class.
`protected void postCreateComponent(Component cmp)`	Callback to allow binding custom logic/listeners to a component after its major properties were set (notice that not all properties or the full hierarchy will be available at this stage).
`protected void bindListenerToComponent(Component cmp, Object listener)`	Binds the given listener object to the component, this works seamlessly for common Codename One events but might be an issue with custom components and custom listener types so this method can be overloaded to add support for such cases.
`protected boolean setListModel(List cmp)`	Allows a subclass to set the list model for the given component
`protected boolean setListModel(ContainerList cmp)`	Allows a subclass to set the list model for the given component
`protected` `Command createCommand(String commandName, Image icon, int commandId, String action)`	Creates a command instance.
`protected` `Resources fetchResourceFile()`	This method may be overriden by subclasses to provide a way to dynamically load a resource file.
`public` `String getResourceFilePath()`	Allows the navigation code to avoid storing the resource file and lets the GC remove it from memory when its not in use
`public void setResourceFilePath(String resourceFilePath)`	Allows the navigation code to avoid storing the resource file and lets the GC remove it from memory when its not in use
`protected void setResourceFile(Resources res)`	Sets the resource file if keep in rum or no path is defined
`protected void processCommand(ActionEvent ev, Command cmd)`	Invoked to process a given command before naviation or any other internal processing occurs.
`public void addCommandListener(ActionListener l)`	Adds a command listener that would be bound to all forms in the GUI seamlessly
`public void removeCommandListener(ActionListener l)`	Removes a command listener
`public void addComponentListener(String formName, String componentName, Object listener)`	Adds a component listener that would be bound when a UI for this form is created.
`public void removeComponentListener(String formName, String componentName, Object listener)`	Removes a component listener bound to a specific component
`public void addCommandListener(String formName, ActionListener l)`	Adds a command listener to be invoked for commands on a specific form
`public void removeCommandListener(String formName, ActionListener l)`	Removes a command listener on a specific form
`protected void handleComponentAction(Component c, ActionEvent event)`	This method is invoked for every component to which an action event listener can be bound and delivers the event data for the given component seamlessly.
`protected void asyncCommandProcess(Command cmd, ActionEvent sourceEvent)`	Warning: This method is invoked OFF the EDT and is intended for usage with asynchronous command processing.
`protected void postAsyncCommand(Command cmd, ActionEvent sourceEvent)`	This method is invoked in conjunction with asyncCommandProcess after the command was handled asynchronously on the separate thread.
`protected boolean processBackground(Form f)`	Warning: this method is invoked on a separate thread.
`protected` `Hashtable getFormState(Form f)`	Returns the state of the current form which we are about to leave as part of the navigation logic.
`protected void restoreComponentState(Component c, Hashtable destination)`	By default Codename One stores the states of components in the navigation graph as it moves between forms.
`protected void storeComponentState(Component c, Hashtable destination)`	By default Codename One stores the states of components in the navigation graph as it moves between forms.
`protected boolean shouldAutoStoreState()`	Indicates whether the UIBuilder should try storing states for forms on its own by seeking lists, tabs and other statefull elements and keeping their selection
`protected void setFormState(Form f, Hashtable state)`	Sets the state of the current form to which we are returing as part of the navigation logic.
`protected` `Hashtable getContainerState(Container cnt)`	This method is the container navigation equivalent of getFormState() see that method for details.
`protected void setContainerState(Container cnt, Hashtable state)`	This method is the container navigation equivalent of setFormState() see that method for details.
`public` `String getHomeForm()`	When reaching the home form the navigation stack is cleared
`public void setHomeForm(String homeForm)`	When reaching the home form the navigation stack is cleared
`public void back()`	This method effectively pops the form navigation stack and goes back to the previous form if back navigation is enabled and there is a previous form.
`public void back(Component sourceComponent)`	This method effectively pops the form navigation stack and goes back to the previous form if back navigation is enabled and there is a previous form.
`protected` `String getBackCommandText(String previousFormTitle)`	Returns the text for the back command string.
`protected void setBackCommand(Form f, Command backCommand)`	Invoked internally to set the back command on the form, this method allows subclasses to change the behavior of back command adding or disable it
`public` `Container showContainer(String resourceName, Command sourceCommand, Component sourceComponent)`	This method is equivalent to the internal navigation behavior, it adds functionality such as the back command into the given form resource and shows it.
`public void reloadContainer(Component cnt)`	Useful tool to refresh the current state of a container shown using show container without pushing another instance to the back stack
`public void reloadForm()`	Useful tool to refresh the current state of a form shown using show form without pushing another instance to the back stack
`public` `LazyValue<Form> createBackLazyValue(Form f)`	This is useful for swipe back navigation behavior
`protected boolean allowBackTo(String formName)`	Indicates whether a back command to this form should be generated automatically when leaving said form.
`protected boolean isSameBackDestination(Container source, Container destination)`	When navigating from one form/container to another we sometimes might not want the back command to return to the previous container/form but rather to the one before source.
`public` `Form showForm(String resourceName, Command sourceCommand)`	This method is equivalent to the internal navigation behavior, it adds functionality such as the back command into the given form resource and shows it.
`protected void exitForm(Form f)`	This method allows binding an action that should occur before leaving the given form, e.g. memory cleanup
`protected void beforeShow(Form f)`	This method allows binding an action that should occur before showing the given form
`protected void onBackNavigation()`	This callback is invoked to indicate that the upcoming form is shown as part of a “back” navigation.
`protected boolean shouldAddBackCommandToMenu()`	Back commands are set implicitly (see allowBackTo to disable that), this method allows subclasses to disable the behavior where the back command is also added to the menu (not just set to the back button).
`protected void postShow(Form f)`	This method allows binding an action that should occur immediately after showing the given form
`protected void beforeShowContainer(Container c)`	This method allows binding an action that should occur before showing the given container
`protected void postShowContainer(Container c)`	This method allows binding an action that should occur immediately after showing the given container
`protected void onCreateRoot(String rootName)`	This method allows binding logic that should occur before creating the root object e.g. a case where a created form needs data fetched for it.
`public boolean isKeepResourcesInRam()`	Indicates that the UIBuilder should cache resources in memory and never release them.
`public void setKeepResourcesInRam(boolean keepResourcesInRam)`	Indicates that the UIBuilder should cache resources in memory and never release them.
`protected` `Container getRootAncestor(Component c)`	Returns either the parent form or the component below the embedded container above c.

Inherited methods

From Object

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

Field details

FORM_STATE_KEY_NAME

public static final String FORM_STATE_KEY_NAME = "$name"

A key in the form state hashtable used in the back command navigation

FORM_STATE_KEY_TITLE

public static final String FORM_STATE_KEY_TITLE = "$title"

A key in the form state hashtable used in the back command navigation

FORM_STATE_KEY_FOCUS

public static final String FORM_STATE_KEY_FOCUS = "$focus"

A key in the form state hashtable used in the back command navigation

FORM_STATE_KEY_SELECTION

public static final String FORM_STATE_KEY_SELECTION = "$sel"

A key in the form state hashtable used in the back command navigation

BACK_COMMAND_ID

public static final int BACK_COMMAND_ID = 99999999

Constructor details

UIBuilder

public UIBuilder()

Method details

isBlockAnalytics

public static boolean isBlockAnalytics()

Enables blocking analytics in the UIBuilder, this is useful for the designer tool.

Returns

the blockAnalytics

setBlockAnalytics

public static void setBlockAnalytics(boolean aBlockAnalytics)

Enables blocking analytics in the UIBuilder, this is useful for the designer tool.

Parameters

aBlockAnalytics boolean: the blockAnalytics to set

registerCustomComponent

public static void registerCustomComponent(String name, Class cmp)

This method allows the UIBuilder to package a smaller portion of Codename One into the JAR and add support for additional 3rd party components to the GUI builder. Components must be registered using their UIID name, by default all the content of com.codename1.ui is registered however subpackages and 3rd party components are not. Registration is essential for obfuscation to work properly!

Parameters

name String: the name of the component (UIID)
cmp Class: the class for the given component

popNavigationStack

protected void popNavigationStack()

Removes a navigation frame from the stack, this is useful in case you want to go back to a form in the middle of the navigation stack.

setBackDestination

protected void setBackDestination(String formName)

Pops the navigation stack until it finds form name and the back button will match form name if form name isn’t in the stack this method will fail

Parameters

formName String: the name of the form to navigate back to.

formNavigationStackDebug

protected String formNavigationStackDebug()

Useful method for logging form navigation, it returns a string representing the navigation state which can be used to analyze crash reports

Returns

A string representing form states

isBackCommandEnabled

public boolean isBackCommandEnabled()

Seamlessly inserts a back command to all the forms

Returns

true if a back command is automatically added

setBackCommandEnabled

public void setBackCommandEnabled(boolean back)

Seamlessly inserts a back command to all the forms

Parameters

back boolean: true to automatically add a back command

analyticsCallback

protected void analyticsCallback(String page, String referrer)

Invokes the analytics service if it is enabled and if

Parameters

page String: the page visited
referrer String: the source page

createContainer

public Container createContainer(String resPath, String resourceName)

Creates the container defined under the given name in the res file

Parameters

resPath String: the path to the res file containing the UI widget
resourceName String: the name of the widget in the res file

Returns

a Codename One container instance

createContainer

public Container createContainer(Resources res, String resourceName)

Creates the container defined under the given name in the res file

Parameters

res Resources: the res file containing the UI widget
resourceName String: the name of the widget in the res file

Returns

a Codename One container instance

findByName

public Component findByName(String name, Component rootComponent)

Finds the given component by its name

Parameters

name String: the name of the component as defined in the resource editor
rootComponent Component: the root container

Returns

the component matching the given name or null if its not found

findByName

public Component findByName(String name, Container rootComponent)

Finds the given component by its name

Parameters

name String: the name of the component as defined in the resource editor
rootComponent Container: the root container

Returns

the component matching the given name or null if its not found

createComponentInstance

protected Component createComponentInstance(String componentType, Class cls)

This method can be overriden to create custom components in a custom way, the component type is a shorthand for the component name and not the full name of the class. By default this method returns null which indicates Codename One should try to reolve the component on its own.

Parameters

componentType String: the type of the component from the UI builder
cls Class: assumed component class based on the component registry

Returns

a new component instance or null

postCreateComponent

protected void postCreateComponent(Component cmp)

Callback to allow binding custom logic/listeners to a component after its major properties were set (notice that not all properties or the full hierarchy will be available at this stage). This is the perfect place to bind models/renderers etc. to components.

Parameters

cmp Component: the component

bindListenerToComponent

protected void bindListenerToComponent(Component cmp, Object listener)

Binds the given listener object to the component, this works seamlessly for common Codename One events but might be an issue with custom components and custom listener types so this method can be overloaded to add support for such cases.

Parameters

cmp Component: the component to bind the listener to
listener Object: the listener object

setListModel

protected boolean setListModel(List cmp)

Allows a subclass to set the list model for the given component

Parameters

cmp List: the list whose model may be set

Returns

true if a model was set by this method

setListModel

protected boolean setListModel(ContainerList cmp)

Allows a subclass to set the list model for the given component

Parameters

cmp ContainerList: the list whose model may be set

Returns

true if a model was set by this method

createCommand

protected Command createCommand(String commandName, Image icon, int commandId, String action)

Creates a command instance. This method is invoked by the loading code and can be overriden to create a subclass of the Command class.

Parameters

commandName String: the label on the command
icon Image: the icon for the command
commandId int: the id of the command
action String: the action assigned to the command if such an action is defined

Returns

a new command instance

fetchResourceFile

protected Resources fetchResourceFile()

This method may be overriden by subclasses to provide a way to dynamically load a resource file. Normally the navigation feature of the UIBuilder requires the resource file present in RAM. However, that might be expensive to maintain. By implementing this method and replacing the storeResourceFile() with an empty implementation the resource file storage can be done strictly in RAM.

Returns

the instance of the resource file

getResourceFilePath

public String getResourceFilePath()

Allows the navigation code to avoid storing the resource file and lets the GC remove it from memory when its not in use

Returns

the resourceFilePath

setResourceFilePath

public void setResourceFilePath(String resourceFilePath)

Allows the navigation code to avoid storing the resource file and lets the GC remove it from memory when its not in use

Parameters

resourceFilePath String: the resourceFilePath to set

setResourceFile

protected void setResourceFile(Resources res)

Sets the resource file if keep in rum or no path is defined

Parameters

res Resources: the resource file

processCommand

protected void processCommand(ActionEvent ev, Command cmd)

Invoked to process a given command before naviation or any other internal processing occurs. The event can be consumed to prevent further processing.

Parameters

ev ActionEvent: the action event source of the command
cmd Command: the command to process

addCommandListener

public void addCommandListener(ActionListener l)

Adds a command listener that would be bound to all forms in the GUI seamlessly

Parameters

l ActionListener: the listener to bind

removeCommandListener

public void removeCommandListener(ActionListener l)

Removes a command listener

Parameters

l ActionListener: the listener to remove

addComponentListener

public void addComponentListener(String formName, String componentName, Object listener)

Adds a component listener that would be bound when a UI for this form is created. Notice that this method is only effective before the form was created and would do nothing for an existing form

Parameters

formName String: the name of the form to which the listener should be bound
componentName String: the name of the component to bind to
listener Object: the listener to bind, common listener types are supported

removeComponentListener

public void removeComponentListener(String formName, String componentName, Object listener)

Removes a component listener bound to a specific component

Parameters

formName String: the name of the form
componentName String: the name of the component
listener Object: the listener instance

addCommandListener

public void addCommandListener(String formName, ActionListener l)

Adds a command listener to be invoked for commands on a specific form

Parameters

formName String: the name of the form to which the listener should be bound
l ActionListener: the listener to bind

removeCommandListener

public void removeCommandListener(String formName, ActionListener l)

Removes a command listener on a specific form

Parameters

formName String: the name of the form
l ActionListener: the listener to remove

handleComponentAction

protected void handleComponentAction(Component c, ActionEvent event)

This method is invoked for every component to which an action event listener can be bound and delivers the event data for the given component seamlessly.

Parameters

c Component: the component broadcasting the event
event ActionEvent: the event meta data

asyncCommandProcess

protected void asyncCommandProcess(Command cmd, ActionEvent sourceEvent)

Warning: This method is invoked OFF the EDT and is intended for usage with asynchronous command processing. This method is invoked when the UI indicates that an operation should occur in the background. To finish the processing of the operation within the EDT one should override the postAsyncCommand() method.

Parameters

cmd Command: the command requiring background processing
sourceEvent ActionEvent: the triggering event

postAsyncCommand

protected void postAsyncCommand(Command cmd, ActionEvent sourceEvent)

This method is invoked in conjunction with asyncCommandProcess after the command was handled asynchronously on the separate thread. Here Codename One code can be execute to update the UI with the results from the separate thread.

Parameters

cmd Command: the command
sourceEvent ActionEvent: the source event

processBackground

protected boolean processBackground(Form f)

Warning: this method is invoked on a separate thread. This method is invoked when a next form property is defined, this property indicates a background process for a form of a transitional nature should take place (e.g. splash screen, IO etc.) after which the next form should be shown. After this method completes the next form is shown.

Parameters

f Form: the form for which the background thread was constructed, notice that most methods are not threadsafe and one should use callSerially* in this method when mutating the form.

Returns

if false is returned from this method navigation should not proceed to that given form

getFormState

protected Hashtable getFormState(Form f)

Returns the state of the current form which we are about to leave as part of the navigation logic. When a back command will return to this form the state would be restored using setFormState. The default implementation of this method restores focus and list selection. You can add arbitrary keys to the form state, keys starting with a $ sign are reserved for the UIBuilder base class use.

Parameters

f Form: the form whose state should be preserved

Returns

arbitrary state object

restoreComponentState

protected void restoreComponentState(Component c, Hashtable destination)

By default Codename One stores the states of components in the navigation graph as it moves between forms. However, some components aren’t recognized by Codename One by default to enable smaller executable size. This method can be overriden to enable storing the state of custom components

Parameters

c Component: the component whose state should be restored
destination Hashtable: the hashtable containing the state

storeComponentState

protected void storeComponentState(Component c, Hashtable destination)

Parameters

c Component: the component whose state should be stored
destination Hashtable: the destination hashtable

shouldAutoStoreState

protected boolean shouldAutoStoreState()

Indicates whether the UIBuilder should try storing states for forms on its own by seeking lists, tabs and other statefull elements and keeping their selection

Returns

true to handle state automatically, false otherwise

setFormState

protected void setFormState(Form f, Hashtable state)

Sets the state of the current form to which we are returing as part of the navigation logic. When a back command is pressed this form state should be restored, it was obtained via getFormState. The default implementation of this method restores focus and list selection.

Parameters

f Form: the form whose state should be preserved
state Hashtable: arbitrary state object

getContainerState

protected Hashtable getContainerState(Container cnt)

This method is the container navigation equivalent of getFormState() see that method for details.

Parameters

cnt Container: the container

Returns

the state

setContainerState

protected void setContainerState(Container cnt, Hashtable state)

This method is the container navigation equivalent of setFormState() see that method for details.

Parameters

cnt Container: the container
state Hashtable: the state

getHomeForm

public String getHomeForm()

When reaching the home form the navigation stack is cleared

Returns

the homeForm

setHomeForm

public void setHomeForm(String homeForm)

When reaching the home form the navigation stack is cleared

Parameters

homeForm String: the homeForm to set

back

public void back()

This method effectively pops the form navigation stack and goes back to the previous form if back navigation is enabled and there is a previous form.

back

public void back(Component sourceComponent)

This method effectively pops the form navigation stack and goes back to the previous form if back navigation is enabled and there is a previous form.

Parameters

sourceComponent Component: the component that triggered the back command which effectively allows us to find the EmbeddedContainer for a case of container navigation. Null can be used if not applicable.

getBackCommandText

protected String getBackCommandText(String previousFormTitle)

Returns the text for the back command string. This can be controlled in the theme by the “backUsesTitleBool” constant

Parameters

previousFormTitle String: the title of the previous form

Returns

the string for the back command inserted implicitly

setBackCommand

protected void setBackCommand(Form f, Command backCommand)

Invoked internally to set the back command on the form, this method allows subclasses to change the behavior of back command adding or disable it

Parameters

f Form: the form
backCommand Command: the back command

showContainer

public Container showContainer(String resourceName, Command sourceCommand, Component sourceComponent)

This method is equivalent to the internal navigation behavior, it adds functionality such as the back command into the given form resource and shows it. If the source command is the back command the showBack() method will run. Notice that container navigation (none-form) doesn’t support the back() method or the form stack. However a command marked as back command will be respected.

Parameters

resourceName String: the name of the resource for the form to show
sourceCommand Command: the command of the resource (may be null)
sourceComponent Component: the component that activated the show (may be null)

Returns

the container thats being shown, notice that you can still manipulate some states of the container before it actually appears

reloadContainer

public void reloadContainer(Component cnt)

Useful tool to refresh the current state of a container shown using show container without pushing another instance to the back stack

Parameters

cnt Component: the container thats embedded into the application

reloadForm

public void reloadForm()

Useful tool to refresh the current state of a form shown using show form without pushing another instance to the back stack

createBackLazyValue

public LazyValue<Form> createBackLazyValue(Form f)

This is useful for swipe back navigation behavior

Parameters

f Form: the form from which we should go back

Returns

a lazy value that will return the back form

allowBackTo

protected boolean allowBackTo(String formName)

Indicates whether a back command to this form should be generated automatically when leaving said form.

Parameters

formName String: the name of the form

Returns

true to autogenerate and add a back command to the destination form

isSameBackDestination

protected boolean isSameBackDestination(Container source, Container destination)

When navigating from one form/container to another we sometimes might not want the back command to return to the previous container/form but rather to the one before source. A good example would be a “refresh” command or a toggle button that changes the form state.

Parameters

source Container: the form or container we are leaving
destination Container: the container or form we are navigating to

Returns

false if we want a standard back button to source, true if we want to use the same back button as the one in source

showForm

public Form showForm(String resourceName, Command sourceCommand)

Parameters

resourceName String: the name of the resource for the form to show
sourceCommand Command: the command of the resource (may be null)

Returns

the form thats being shown, notice that you can still manipulate some states of the form before it actually appears

exitForm

protected void exitForm(Form f)

This method allows binding an action that should occur before leaving the given form, e.g. memory cleanup

Parameters

f Form: the form being left

beforeShow

protected void beforeShow(Form f)

This method allows binding an action that should occur before showing the given form

Parameters

f Form: the form about to be shown

onBackNavigation

protected void onBackNavigation()

This callback is invoked to indicate that the upcoming form is shown as part of a “back” navigation. This is useful for the case of a breadcrumb UI where the navigation stack is shown at the top of the UI, in that case this method can be used to pop out the breadcrumb stack.

shouldAddBackCommandToMenu

protected boolean shouldAddBackCommandToMenu()

Back commands are set implicitly (see allowBackTo to disable that), this method allows subclasses to disable the behavior where the back command is also added to the menu (not just set to the back button).

postShow

protected void postShow(Form f)

This method allows binding an action that should occur immediately after showing the given form

Parameters

f Form: the form that was just shown

beforeShowContainer

protected void beforeShowContainer(Container c)

This method allows binding an action that should occur before showing the given container

Parameters

c Container: the container about to be shown

postShowContainer

protected void postShowContainer(Container c)

This method allows binding an action that should occur immediately after showing the given container

Parameters

c Container: the container that was just shown

onCreateRoot

protected void onCreateRoot(String rootName)

This method allows binding logic that should occur before creating the root object e.g. a case where a created form needs data fetched for it.

Parameters

rootName String: the name of the root to be created from the resource file

isKeepResourcesInRam

public boolean isKeepResourcesInRam()

Indicates that the UIBuilder should cache resources in memory and never release them. This is useful with small resource files or high RAM devices since it saves the cost of constantly fetching the res file from the jar whenever moving between forms. This can be toggled in the properties (e.g. jad) using the flag: cacheResFile (true/false) which defaults to false.

Returns

the keepResourcesInRam

setKeepResourcesInRam

public void setKeepResourcesInRam(boolean keepResourcesInRam)

Parameters

keepResourcesInRam boolean: the keepResourcesInRam to set

getRootAncestor

protected Container getRootAncestor(Component c)

Returns either the parent form or the component below the embedded container above c.

Parameters

c Component: the component whose root ancestor we should find

Returns

the root