com.android.ide.common.rendering.api

Class LayoutlibCallback

java.lang.Object

com.android.ide.common.rendering.api.LayoutlibCallback

All Implemented Interfaces:

XmlParserFactory

public abstract class LayoutlibCallback
extends java.lang.Object
implements XmlParserFactory

Intermediary class implementing parts of both the old and new ProjectCallback from the LayoutLib API.

Even newer LayoutLibs use this directly instead of the the interface. This allows the flexibility to add newer methods without having to update LayoutLib API version.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LayoutlibCallback.ViewAttribute

Constructor Summary

Constructors

Constructor and Description
LayoutlibCallback()

Method Summary

Modifier and Type	Method and Description
java.lang.Class<?>	findClass(java.lang.String name) Finds a custom class in the project.
abstract ActionBarCallback	getActionBarCallback() Returns a callback for Action Bar information needed by the Layout Library.
abstract AdapterBinding	getAdapterBinding(ResourceReference adapterViewRef, java.lang.Object adapterCookie, java.lang.Object viewObject) Returns an adapter binding for a given adapter view.
java.lang.Object	getAdapterItemValue(ResourceReference adapterView, java.lang.Object adapterCookie, ResourceReference itemRef, int fullPosition, int positionPerType, int fullParentPosition, int parentPositionPerType, ResourceReference viewRef, LayoutlibCallback.ViewAttribute viewAttribute, java.lang.Object defaultValue) Returns the value of an item used by an adapter.
<T> T	getFlag(SessionParams.Key<T> key) A callback to query arbitrary data.
ResourceNamespace.Resolver	getImplicitNamespaces() Returns an optional ResourceNamespace.Resolver that knows namespace prefixes assumed to be declared in every resource file.
abstract java.lang.String	getNamespace() Returns the namespace URI of the application.
abstract int	getOrGenerateResourceId(ResourceReference resource) Returns the numeric id for the given resource, potentially generating a fresh ID.
abstract ILayoutPullParser	getParser(ResourceValue layoutResource) Returns a custom parser for a value
boolean	hasAndroidXAppCompat() Returns true if the module depends on androidx.appcompat.
boolean	hasLegacyAppCompat() Returns true if the module depends on android.support.v7.appcompat.
boolean	isResourceNamespacingRequired() Returns true if the module uses namespaced resources.
java.lang.Object	loadClass(java.lang.String name, java.lang.Class[] constructorSignature, java.lang.Object[] constructorArgs) Like loadView(String, Class[], Object[]), but intended for loading classes that may not be custom views.
abstract java.lang.Object	loadView(java.lang.String name, java.lang.Class[] constructorSignature, java.lang.Object[] constructorArgs) Loads a custom class with the given constructor signature and arguments.
abstract ResourceReference	resolveResourceId(int id) Finds the resource with a given id.
abstract boolean	supports(int ideFeature) Returns if the IDE supports the requested feature.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.android.ide.common.rendering.api.XmlParserFactory

createXmlParser, createXmlParserForFile, createXmlParserForPsiFile

Constructor Detail

LayoutlibCallback

public LayoutlibCallback()

Method Detail

loadView

@Nullable
public abstract java.lang.Object loadView(@NonNull
                                                    java.lang.String name,
                                                    @NonNull
                                                    java.lang.Class[] constructorSignature,
                                                    java.lang.Object[] constructorArgs)
                                             throws java.lang.Exception

Loads a custom class with the given constructor signature and arguments.

Despite the name, the method is used not just for views (android.view.View), but potentially any class in the project's namespace. However, when the method is used for loading non-view classes the error messages reported may not be ideal, since the the IDE may assume those classes to be a view and try to use a different constructor or replace it with a MockView.

This is done so that LayoutLib can continue to work on older versions of the IDE. Newer versions of LayoutLib should call loadClass(String, Class[], Object[]) in such a case.

Parameters:

name - the fully qualified name of the class.

constructorSignature - the signature of the class to use

constructorArgs - the arguments to use on the constructor

Returns:

a newly instantiated object.

Throws:

java.lang.Exception

getNamespace

@NonNull
public abstract java.lang.String getNamespace()

Returns the namespace URI of the application.

Used by the Layoutlib to load custom attributes for custom views.

resolveResourceId

@Nullable
public abstract ResourceReference resolveResourceId(int id)

Finds the resource with a given id.

getOrGenerateResourceId

public abstract int getOrGenerateResourceId(@NonNull
                                            ResourceReference resource)

Returns the numeric id for the given resource, potentially generating a fresh ID.

Calling this method for equal references will always produce the same result.

getParser

@Nullable
public abstract ILayoutPullParser getParser(@NonNull
                                                      ResourceValue layoutResource)

Returns a custom parser for a value

Parameters:

layoutResource - Layout or a value referencing an _aapt attribute.

Returns:

returns a custom parser or null if no custom parsers are needed.

getAdapterItemValue

@Nullable
public java.lang.Object getAdapterItemValue(ResourceReference adapterView,
                                                      java.lang.Object adapterCookie,
                                                      ResourceReference itemRef,
                                                      int fullPosition,
                                                      int positionPerType,
                                                      int fullParentPosition,
                                                      int parentPositionPerType,
                                                      ResourceReference viewRef,
                                                      LayoutlibCallback.ViewAttribute viewAttribute,
                                                      java.lang.Object defaultValue)

Returns the value of an item used by an adapter.

Parameters:

adapterView - the ResourceReference for the adapter view info.

adapterCookie - the view cookie for this particular view.

itemRef - the ResourceReference for the layout used by the adapter item.

fullPosition - the position of the item in the full list.

positionPerType - the position of the item if only items of the same type are considered. If there is only one type of items, this is the same as fullPosition.

fullParentPosition - the full position of the item's parent. This is only valid if the adapter view is an ExpandableListView.

parentPositionPerType - the position of the parent's item, only considering items of the same type. This is only valid if the adapter view is an ExpandableListView. If there is only one type of items, this is the same as fullParentPosition.

viewRef - the ResourceReference for the view we're trying to fill.

viewAttribute - the attribute being queried.

defaultValue - the default value for this attribute. The object class matches the class associated with the LayoutlibCallback.ViewAttribute.

Returns:

the item value or null if there's no value.

See Also:

LayoutlibCallback.ViewAttribute.getAttributeClass()

getAdapterBinding

@Nullable
public abstract AdapterBinding getAdapterBinding(ResourceReference adapterViewRef,
                                                           java.lang.Object adapterCookie,
                                                           java.lang.Object viewObject)

Returns an adapter binding for a given adapter view. This is only called if SessionParams does not have an AdapterBinding for the given ResourceReference already.

Parameters:

adapterViewRef - the reference of adapter view to return the adapter binding for.

adapterCookie - the view cookie for this particular view.

viewObject - the view object for the adapter.

Returns:

an adapter binding for the given view or null if there's no data.

getActionBarCallback

public abstract ActionBarCallback getActionBarCallback()

Returns a callback for Action Bar information needed by the Layout Library. The callback provides information like the menus to add to the Action Bar.

Since:

API 11

loadClass

public java.lang.Object loadClass(@NonNull
                                  java.lang.String name,
                                  @Nullable
                                  java.lang.Class[] constructorSignature,
                                  @Nullable
                                  java.lang.Object[] constructorArgs)
                           throws java.lang.ClassNotFoundException

Like loadView(String, Class[], Object[]), but intended for loading classes that may not be custom views.

Parameters:

name - className in binary format (see ClassLoader)

Returns:

an new instance created by calling the given constructor.

Throws:

java.lang.ClassNotFoundException - any exceptions thrown when creating the instance is wrapped in a ClassNotFoundException.

Since:

API 15

supports

public abstract boolean supports(int ideFeature)

Returns if the IDE supports the requested feature.

Since:

API 15

See Also:

Features

getFlag

@Nullable
public <T> T getFlag(@NonNull
                               SessionParams.Key<T> key)

A callback to query arbitrary data. This is similar to RenderParams.setFlag(SessionParams.Key, Object). The main difference is that when using this, the IDE doesn't have to compute the value in advance and thus may save on some computation.

Since:

API 15

findClass

@NonNull
public java.lang.Class<?> findClass(@NonNull
                                             java.lang.String name)
                                      throws java.lang.ClassNotFoundException

Finds a custom class in the project.

Like loadClass(String, Class[], Object[]), but doesn't instantiate an object and just returns the class found.

Parameters:

name - className in binary format. (see ClassLoader.

Throws:

java.lang.ClassNotFoundException

Since:

API 15

getImplicitNamespaces

@NonNull
public ResourceNamespace.Resolver getImplicitNamespaces()

Returns an optional ResourceNamespace.Resolver that knows namespace prefixes assumed to be declared in every resource file.

For backwards compatibility, in non-namespaced projects this contains the "tools" prefix mapped to ResourceNamespace.TOOLS. Before the IDE understood resource namespaces, this prefix was used for referring to sample data, even if the user didn't define the "tools" prefix using xmlns:tools="...".

In namespaced projects this method returns an empty resolver, which means sample data won't work without an explicit definition of a namespace prefix for the ResourceNamespace.TOOLS URI.

hasLegacyAppCompat

public boolean hasLegacyAppCompat()

Returns true if the module depends on android.support.v7.appcompat.

hasAndroidXAppCompat

public boolean hasAndroidXAppCompat()

Returns true if the module depends on androidx.appcompat.

isResourceNamespacingRequired

public boolean isResourceNamespacingRequired()

Returns true if the module uses namespaced resources.