/* * Copyright (C) 2007 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package android.view; import android.content.Context; import android.content.res.TypedArray; import android.content.res.XmlResourceParser; import android.util.AttributeSet; import android.util.Xml; import org.xmlpull.v1.XmlPullParser; import org.xmlpull.v1.XmlPullParserException; import java.io.IOException; import java.lang.reflect.Constructor; import java.util.HashMap; /** * This class is used to instantiate layout XML file into its corresponding View * objects. It is never be used directly -- use * {@link android.app.Activity#getLayoutInflater()} or * {@link Context#getSystemService} to retrieve a standard LayoutInflater instance * that is already hooked up to the current context and correctly configured * for the device you are running on. For example: * *
LayoutInflater inflater = (LayoutInflater)context.getSystemService
 *      Context.LAYOUT_INFLATER_SERVICE);
* *

* To create a new LayoutInflater with an additional {@link Factory} for your * own views, you can use {@link #cloneInContext} to clone an existing * ViewFactory, and then call {@link #setFactory} on it to include your * Factory. * *

* For performance reasons, view inflation relies heavily on pre-processing of * XML files that is done at build time. Therefore, it is not currently possible * to use LayoutInflater with an XmlPullParser over a plain XML file at runtime; * it only works with an XmlPullParser returned from a compiled resource * (R.something file.) * * @see Context#getSystemService */ public abstract class LayoutInflater { private final boolean DEBUG = false; /** * This field should be made private, so it is hidden from the SDK. * {@hide} */ protected final Context mContext; // these are optional, set by the caller private boolean mFactorySet; private Factory mFactory; private Filter mFilter; private final Object[] mConstructorArgs = new Object[2]; private static final Class[] mConstructorSignature = new Class[] { Context.class, AttributeSet.class}; private static final HashMap sConstructorMap = new HashMap(); private HashMap mFilterMap; private static final String TAG_MERGE = "merge"; private static final String TAG_INCLUDE = "include"; private static final String TAG_REQUEST_FOCUS = "requestFocus"; /** * Hook to allow clients of the LayoutInflater to restrict the set of Views that are allowed * to be inflated. * */ public interface Filter { /** * Hook to allow clients of the LayoutInflater to restrict the set of Views * that are allowed to be inflated. * * @param clazz The class object for the View that is about to be inflated * * @return True if this class is allowed to be inflated, or false otherwise */ boolean onLoadClass(Class clazz); } public interface Factory { /** * Hook you can supply that is called when inflating from a LayoutInflater. * You can use this to customize the tag names available in your XML * layout files. * *

* Note that it is good practice to prefix these custom names with your * package (i.e., com.coolcompany.apps) to avoid conflicts with system * names. * * @param name Tag name to be inflated. * @param context The context the view is being created in. * @param attrs Inflation attributes as specified in XML file. * * @return View Newly created view. Return null for the default * behavior. */ public View onCreateView(String name, Context context, AttributeSet attrs); } private static class FactoryMerger implements Factory { private final Factory mF1, mF2; FactoryMerger(Factory f1, Factory f2) { mF1 = f1; mF2 = f2; } public View onCreateView(String name, Context context, AttributeSet attrs) { View v = mF1.onCreateView(name, context, attrs); if (v != null) return v; return mF2.onCreateView(name, context, attrs); } } /** * Create a new LayoutInflater instance associated with a particular Context. * Applications will almost always want to use * {@link Context#getSystemService Context.getSystemService()} to retrieve * the standard {@link Context#LAYOUT_INFLATER_SERVICE Context.INFLATER_SERVICE}. * * @param context The Context in which this LayoutInflater will create its * Views; most importantly, this supplies the theme from which the default * values for their attributes are retrieved. */ protected LayoutInflater(Context context) { mContext = context; } /** * Create a new LayoutInflater instance that is a copy of an existing * LayoutInflater, optionally with its Context changed. For use in * implementing {@link #cloneInContext}. * * @param original The original LayoutInflater to copy. * @param newContext The new Context to use. */ protected LayoutInflater(LayoutInflater original, Context newContext) { mContext = newContext; mFactory = original.mFactory; mFilter = original.mFilter; } /** * Obtains the LayoutInflater from the given context. */ public static LayoutInflater from(Context context) { LayoutInflater LayoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); if (LayoutInflater == null) { throw new AssertionError("LayoutInflater not found."); } return LayoutInflater; } /** * Create a copy of the existing LayoutInflater object, with the copy * pointing to a different Context than the original. This is used by * {@link ContextThemeWrapper} to create a new LayoutInflater to go along * with the new Context theme. * * @param newContext The new Context to associate with the new LayoutInflater. * May be the same as the original Context if desired. * * @return Returns a brand spanking new LayoutInflater object associated with * the given Context. */ public abstract LayoutInflater cloneInContext(Context newContext); /** * Return the context we are running in, for access to resources, class * loader, etc. */ public Context getContext() { return mContext; } /** * Return the current factory (or null). This is called on each element * name. If the factory returns a View, add that to the hierarchy. If it * returns null, proceed to call onCreateView(name). */ public final Factory getFactory() { return mFactory; } /** * Attach a custom Factory interface for creating views while using * this LayoutInflater. This must not be null, and can only be set once; * after setting, you can not change the factory. This is * called on each element name as the xml is parsed. If the factory returns * a View, that is added to the hierarchy. If it returns null, the next * factory default {@link #onCreateView} method is called. * *

If you have an existing * LayoutInflater and want to add your own factory to it, use * {@link #cloneInContext} to clone the existing instance and then you * can use this function (once) on the returned new instance. This will * merge your own factory with whatever factory the original instance is * using. */ public void setFactory(Factory factory) { if (mFactorySet) { throw new IllegalStateException("A factory has already been set on this LayoutInflater"); } if (factory == null) { throw new NullPointerException("Given factory can not be null"); } mFactorySet = true; if (mFactory == null) { mFactory = factory; } else { mFactory = new FactoryMerger(factory, mFactory); } } /** * @return The {@link Filter} currently used by this LayoutInflater to restrict the set of Views * that are allowed to be inflated. */ public Filter getFilter() { return mFilter; } /** * Sets the {@link Filter} to by this LayoutInflater. If a view is attempted to be inflated * which is not allowed by the {@link Filter}, the {@link #inflate(int, ViewGroup)} call will * throw an {@link InflateException}. This filter will replace any previous filter set on this * LayoutInflater. * * @param filter The Filter which restricts the set of Views that are allowed to be inflated. * This filter will replace any previous filter set on this LayoutInflater. */ public void setFilter(Filter filter) { mFilter = filter; if (filter != null) { mFilterMap = new HashMap(); } } /** * Inflate a new view hierarchy from the specified xml resource. Throws * {@link InflateException} if there is an error. * * @param resource ID for an XML layout resource to load (e.g., * R.layout.main_page) * @param root Optional view to be the parent of the generated hierarchy. * @return The root View of the inflated hierarchy. If root was supplied, * this is the root View; otherwise it is the root of the inflated * XML file. */ public View inflate(int resource, ViewGroup root) { return inflate(resource, root, root != null); } /** * Inflate a new view hierarchy from the specified xml node. Throws * {@link InflateException} if there is an error. * *

* Important   For performance * reasons, view inflation relies heavily on pre-processing of XML files * that is done at build time. Therefore, it is not currently possible to * use LayoutInflater with an XmlPullParser over a plain XML file at runtime. * * @param parser XML dom node containing the description of the view * hierarchy. * @param root Optional view to be the parent of the generated hierarchy. * @return The root View of the inflated hierarchy. If root was supplied, * this is the root View; otherwise it is the root of the inflated * XML file. */ public View inflate(XmlPullParser parser, ViewGroup root) { return inflate(parser, root, root != null); } /** * Inflate a new view hierarchy from the specified xml resource. Throws * {@link InflateException} if there is an error. * * @param resource ID for an XML layout resource to load (e.g., * R.layout.main_page) * @param root Optional view to be the parent of the generated hierarchy (if * attachToRoot is true), or else simply an object that * provides a set of LayoutParams values for root of the returned * hierarchy (if attachToRoot is false.) * @param attachToRoot Whether the inflated hierarchy should be attached to * the root parameter? If false, root is only used to create the * correct subclass of LayoutParams for the root view in the XML. * @return The root View of the inflated hierarchy. If root was supplied and * attachToRoot is true, this is root; otherwise it is the root of * the inflated XML file. */ public View inflate(int resource, ViewGroup root, boolean attachToRoot) { if (DEBUG) System.out.println("INFLATING from resource: " + resource); XmlResourceParser parser = getContext().getResources().getLayout(resource); try { return inflate(parser, root, attachToRoot); } finally { parser.close(); } } /** * Inflate a new view hierarchy from the specified XML node. Throws * {@link InflateException} if there is an error. *

* Important   For performance * reasons, view inflation relies heavily on pre-processing of XML files * that is done at build time. Therefore, it is not currently possible to * use LayoutInflater with an XmlPullParser over a plain XML file at runtime. * * @param parser XML dom node containing the description of the view * hierarchy. * @param root Optional view to be the parent of the generated hierarchy (if * attachToRoot is true), or else simply an object that * provides a set of LayoutParams values for root of the returned * hierarchy (if attachToRoot is false.) * @param attachToRoot Whether the inflated hierarchy should be attached to * the root parameter? If false, root is only used to create the * correct subclass of LayoutParams for the root view in the XML. * @return The root View of the inflated hierarchy. If root was supplied and * attachToRoot is true, this is root; otherwise it is the root of * the inflated XML file. */ public View inflate(XmlPullParser parser, ViewGroup root, boolean attachToRoot) { synchronized (mConstructorArgs) { final AttributeSet attrs = Xml.asAttributeSet(parser); Context lastContext = (Context)mConstructorArgs[0]; mConstructorArgs[0] = mContext; View result = root; try { // Look for the root node. int type; while ((type = parser.next()) != XmlPullParser.START_TAG && type != XmlPullParser.END_DOCUMENT) { // Empty } if (type != XmlPullParser.START_TAG) { throw new InflateException(parser.getPositionDescription() + ": No start tag found!"); } final String name = parser.getName(); if (DEBUG) { System.out.println("**************************"); System.out.println("Creating root view: " + name); System.out.println("**************************"); } if (TAG_MERGE.equals(name)) { if (root == null || !attachToRoot) { throw new InflateException(" can be used only with a valid " + "ViewGroup root and attachToRoot=true"); } rInflate(parser, root, attrs); } else { // Temp is the root view that was found in the xml View temp = createViewFromTag(name, attrs); ViewGroup.LayoutParams params = null; if (root != null) { if (DEBUG) { System.out.println("Creating params from root: " + root); } // Create layout params that match root, if supplied params = root.generateLayoutParams(attrs); if (!attachToRoot) { // Set the layout params for temp if we are not // attaching. (If we are, we use addView, below) temp.setLayoutParams(params); } } if (DEBUG) { System.out.println("-----> start inflating children"); } // Inflate all children under temp rInflate(parser, temp, attrs); if (DEBUG) { System.out.println("-----> done inflating children"); } // We are supposed to attach all the views we found (int temp) // to root. Do that now. if (root != null && attachToRoot) { root.addView(temp, params); } // Decide whether to return the root that was passed in or the // top view found in xml. if (root == null || !attachToRoot) { result = temp; } } } catch (XmlPullParserException e) { InflateException ex = new InflateException(e.getMessage()); ex.initCause(e); throw ex; } catch (IOException e) { InflateException ex = new InflateException( parser.getPositionDescription() + ": " + e.getMessage()); ex.initCause(e); throw ex; } finally { // Don't retain static reference on context. mConstructorArgs[0] = lastContext; mConstructorArgs[1] = null; } return result; } } /** * Low-level function for instantiating a view by name. This attempts to * instantiate a view class of the given name found in this * LayoutInflater's ClassLoader. * *

* There are two things that can happen in an error case: either the * exception describing the error will be thrown, or a null will be * returned. You must deal with both possibilities -- the former will happen * the first time createView() is called for a class of a particular name, * the latter every time there-after for that class name. * * @param name The full name of the class to be instantiated. * @param attrs The XML attributes supplied for this instance. * * @return View The newly instantied view, or null. */ public final View createView(String name, String prefix, AttributeSet attrs) throws ClassNotFoundException, InflateException { Constructor constructor = sConstructorMap.get(name); Class clazz = null; try { if (constructor == null) { // Class not found in the cache, see if it's real, and try to add it clazz = mContext.getClassLoader().loadClass( prefix != null ? (prefix + name) : name); if (mFilter != null && clazz != null) { boolean allowed = mFilter.onLoadClass(clazz); if (!allowed) { failNotAllowed(name, prefix, attrs); } } constructor = clazz.getConstructor(mConstructorSignature); sConstructorMap.put(name, constructor); } else { // If we have a filter, apply it to cached constructor if (mFilter != null) { // Have we seen this name before? Boolean allowedState = mFilterMap.get(name); if (allowedState == null) { // New class -- remember whether it is allowed clazz = mContext.getClassLoader().loadClass( prefix != null ? (prefix + name) : name); boolean allowed = clazz != null && mFilter.onLoadClass(clazz); mFilterMap.put(name, allowed); if (!allowed) { failNotAllowed(name, prefix, attrs); } } else if (allowedState.equals(Boolean.FALSE)) { failNotAllowed(name, prefix, attrs); } } } Object[] args = mConstructorArgs; args[1] = attrs; return (View) constructor.newInstance(args); } catch (NoSuchMethodException e) { InflateException ie = new InflateException(attrs.getPositionDescription() + ": Error inflating class " + (prefix != null ? (prefix + name) : name)); ie.initCause(e); throw ie; } catch (ClassNotFoundException e) { // If loadClass fails, we should propagate the exception. throw e; } catch (Exception e) { InflateException ie = new InflateException(attrs.getPositionDescription() + ": Error inflating class " + (clazz == null ? "" : clazz.getName())); ie.initCause(e); throw ie; } } /** * Throw an excpetion because the specified class is not allowed to be inflated. */ private void failNotAllowed(String name, String prefix, AttributeSet attrs) { InflateException ie = new InflateException(attrs.getPositionDescription() + ": Class not allowed to be inflated " + (prefix != null ? (prefix + name) : name)); throw ie; } /** * This routine is responsible for creating the correct subclass of View * given the xml element name. Override it to handle custom view objects. If * you override this in your subclass be sure to call through to * super.onCreateView(name) for names you do not recognize. * * @param name The fully qualified class name of the View to be create. * @param attrs An AttributeSet of attributes to apply to the View. * * @return View The View created. */ protected View onCreateView(String name, AttributeSet attrs) throws ClassNotFoundException { return createView(name, "android.view.", attrs); } /* * default visibility so the BridgeInflater can override it. */ View createViewFromTag(String name, AttributeSet attrs) { if (name.equals("view")) { name = attrs.getAttributeValue(null, "class"); } if (DEBUG) System.out.println("******** Creating view: " + name); try { View view = (mFactory == null) ? null : mFactory.onCreateView(name, mContext, attrs); if (view == null) { if (-1 == name.indexOf('.')) { view = onCreateView(name, attrs); } else { view = createView(name, null, attrs); } } if (DEBUG) System.out.println("Created view is: " + view); return view; } catch (InflateException e) { throw e; } catch (ClassNotFoundException e) { InflateException ie = new InflateException(attrs.getPositionDescription() + ": Error inflating class " + name); ie.initCause(e); throw ie; } catch (Exception e) { InflateException ie = new InflateException(attrs.getPositionDescription() + ": Error inflating class " + name); ie.initCause(e); throw ie; } } /** * Recursive method used to descend down the xml hierarchy and instantiate * views, instantiate their children, and then call onFinishInflate(). */ private void rInflate(XmlPullParser parser, View parent, final AttributeSet attrs) throws XmlPullParserException, IOException { final int depth = parser.getDepth(); int type; while (((type = parser.next()) != XmlPullParser.END_TAG || parser.getDepth() > depth) && type != XmlPullParser.END_DOCUMENT) { if (type != XmlPullParser.START_TAG) { continue; } final String name = parser.getName(); if (TAG_REQUEST_FOCUS.equals(name)) { parseRequestFocus(parser, parent); } else if (TAG_INCLUDE.equals(name)) { if (parser.getDepth() == 0) { throw new InflateException(" cannot be the root element"); } parseInclude(parser, parent, attrs); } else if (TAG_MERGE.equals(name)) { throw new InflateException(" must be the root element"); } else { final View view = createViewFromTag(name, attrs); final ViewGroup viewGroup = (ViewGroup) parent; final ViewGroup.LayoutParams params = viewGroup.generateLayoutParams(attrs); rInflate(parser, view, attrs); viewGroup.addView(view, params); } } parent.onFinishInflate(); } private void parseRequestFocus(XmlPullParser parser, View parent) throws XmlPullParserException, IOException { int type; parent.requestFocus(); final int currentDepth = parser.getDepth(); while (((type = parser.next()) != XmlPullParser.END_TAG || parser.getDepth() > currentDepth) && type != XmlPullParser.END_DOCUMENT) { // Empty } } private void parseInclude(XmlPullParser parser, View parent, AttributeSet attrs) throws XmlPullParserException, IOException { int type; if (parent instanceof ViewGroup) { final int layout = attrs.getAttributeResourceValue(null, "layout", 0); if (layout == 0) { final String value = attrs.getAttributeValue(null, "layout"); if (value == null) { throw new InflateException("You must specifiy a layout in the" + " include tag: "); } else { throw new InflateException("You must specifiy a valid layout " + "reference. The layout ID " + value + " is not valid."); } } else { final XmlResourceParser childParser = getContext().getResources().getLayout(layout); try { final AttributeSet childAttrs = Xml.asAttributeSet(childParser); while ((type = childParser.next()) != XmlPullParser.START_TAG && type != XmlPullParser.END_DOCUMENT) { // Empty. } if (type != XmlPullParser.START_TAG) { throw new InflateException(childParser.getPositionDescription() + ": No start tag found!"); } final String childName = childParser.getName(); if (TAG_MERGE.equals(childName)) { // Inflate all children. rInflate(childParser, parent, childAttrs); } else { final View view = createViewFromTag(childName, childAttrs); final ViewGroup group = (ViewGroup) parent; // We try to load the layout params set in the tag. If // they don't exist, we will rely on the layout params set in the // included XML file. // During a layoutparams generation, a runtime exception is thrown // if either layout_width or layout_height is missing. We catch // this exception and set localParams accordingly: true means we // successfully loaded layout params from the tag, // false means we need to rely on the included layout params. ViewGroup.LayoutParams params = null; try { params = group.generateLayoutParams(attrs); } catch (RuntimeException e) { params = group.generateLayoutParams(childAttrs); } finally { if (params != null) { view.setLayoutParams(params); } } // Inflate all children. rInflate(childParser, view, childAttrs); // Attempt to override the included layout's android:id with the // one set on the tag itself. TypedArray a = mContext.obtainStyledAttributes(attrs, com.android.internal.R.styleable.View, 0, 0); int id = a.getResourceId(com.android.internal.R.styleable.View_id, View.NO_ID); // While we're at it, let's try to override android:visibility. int visibility = a.getInt(com.android.internal.R.styleable.View_visibility, -1); a.recycle(); if (id != View.NO_ID) { view.setId(id); } switch (visibility) { case 0: view.setVisibility(View.VISIBLE); break; case 1: view.setVisibility(View.INVISIBLE); break; case 2: view.setVisibility(View.GONE); break; } group.addView(view); } } finally { childParser.close(); } } } else { throw new InflateException(" can only be used inside of a ViewGroup"); } final int currentDepth = parser.getDepth(); while (((type = parser.next()) != XmlPullParser.END_TAG || parser.getDepth() > currentDepth) && type != XmlPullParser.END_DOCUMENT) { // Empty } } }