Java tutorial
/* * 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.annotation.LayoutRes; import android.annotation.NonNull; import android.annotation.Nullable; import android.annotation.SystemService; import android.annotation.TestApi; import android.annotation.UnsupportedAppUsage; import android.content.Context; import android.content.res.Resources; import android.content.res.TypedArray; import android.content.res.XmlResourceParser; import android.graphics.Canvas; import android.os.Handler; import android.os.Message; import android.os.SystemProperties; import android.os.Trace; import android.util.AttributeSet; import android.util.Log; import android.util.TypedValue; import android.util.Xml; import android.widget.FrameLayout; import com.android.internal.R; import dalvik.system.PathClassLoader; import java.io.File; import java.lang.reflect.Method; import org.xmlpull.v1.XmlPullParser; import org.xmlpull.v1.XmlPullParserException; import java.io.IOException; import java.lang.reflect.Constructor; import java.util.HashMap; /** * Instantiates a layout XML file into its corresponding {@link android.view.View} * objects. It is never used directly. Instead, 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. * * <p> * 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. * * <p> * 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.<em>something</em> file.) */ @SystemService(Context.LAYOUT_INFLATER_SERVICE) public abstract class LayoutInflater { private static final String TAG = LayoutInflater.class.getSimpleName(); private static final boolean DEBUG = false; private static final String USE_PRECOMPILED_LAYOUT_SYSTEM_PROPERTY = "view.precompiled_layout_enabled"; private static final String COMPILED_VIEW_DEX_FILE_NAME = "/compiled_view.dex"; /** Empty stack trace used to avoid log spam in re-throw exceptions. */ private static final StackTraceElement[] EMPTY_STACK_TRACE = new StackTraceElement[0]; /** * This field should be made private, so it is hidden from the SDK. * {@hide} */ @UnsupportedAppUsage protected final Context mContext; // these are optional, set by the caller @UnsupportedAppUsage private boolean mFactorySet; @UnsupportedAppUsage private Factory mFactory; @UnsupportedAppUsage private Factory2 mFactory2; @UnsupportedAppUsage private Factory2 mPrivateFactory; private Filter mFilter; // Indicates whether we should try to inflate layouts using a precompiled layout instead of // inflating from the XML resource. private boolean mUseCompiledView; // This variable holds the classloader that will be used to look for precompiled layouts. The // The classloader includes the generated compiled_view.dex file. private ClassLoader mPrecompiledClassLoader; @UnsupportedAppUsage final Object[] mConstructorArgs = new Object[2]; @UnsupportedAppUsage static final Class<?>[] mConstructorSignature = new Class[] { Context.class, AttributeSet.class }; @UnsupportedAppUsage private static final HashMap<String, Constructor<? extends View>> sConstructorMap = new HashMap<String, Constructor<? extends View>>(); private HashMap<String, Boolean> mFilterMap; private TypedValue mTempValue; private static final String TAG_MERGE = "merge"; private static final String TAG_INCLUDE = "include"; private static final String TAG_1995 = "blink"; private static final String TAG_REQUEST_FOCUS = "requestFocus"; private static final String TAG_TAG = "tag"; private static final String ATTR_LAYOUT = "layout"; @UnsupportedAppUsage private static final int[] ATTRS_THEME = new int[] { com.android.internal.R.attr.theme }; /** * 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 */ @SuppressWarnings("unchecked") 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. * * <p> * 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); } public interface Factory2 extends Factory { /** * Version of {@link #onCreateView(String, Context, AttributeSet)} * that also supplies the parent that the view created view will be * placed in. * * @param parent The parent that the created view will be placed * in; <em>note that this may be null</em>. * @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(View parent, String name, Context context, AttributeSet attrs); } private static class FactoryMerger implements Factory2 { private final Factory mF1, mF2; private final Factory2 mF12, mF22; FactoryMerger(Factory f1, Factory2 f12, Factory f2, Factory2 f22) { mF1 = f1; mF2 = f2; mF12 = f12; mF22 = f22; } 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); } public View onCreateView(View parent, String name, Context context, AttributeSet attrs) { View v = mF12 != null ? mF12.onCreateView(parent, name, context, attrs) : mF1.onCreateView(name, context, attrs); if (v != null) return v; return mF22 != null ? mF22.onCreateView(parent, name, context, attrs) : 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; initPrecompiledViews(); } /** * 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; mFactory2 = original.mFactory2; mPrivateFactory = original.mPrivateFactory; setFilter(original.mFilter); initPrecompiledViews(); } /** * 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 {@link 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; } /** * Return the current {@link Factory2}. Returns null if no factory is set * or the set factory does not implement the {@link Factory2} interface. * 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 Factory2 getFactory2() { return mFactory2; } /** * 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. * * <p>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, null, mFactory, mFactory2); } } /** * Like {@link #setFactory}, but allows you to set a {@link Factory2} * interface. */ public void setFactory2(Factory2 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 = mFactory2 = factory; } else { mFactory = mFactory2 = new FactoryMerger(factory, factory, mFactory, mFactory2); } } /** * @hide for use by framework */ @UnsupportedAppUsage public void setPrivateFactory(Factory2 factory) { if (mPrivateFactory == null) { mPrivateFactory = factory; } else { mPrivateFactory = new FactoryMerger(factory, factory, mPrivateFactory, mPrivateFactory); } } /** * @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<String, Boolean>(); } } private void initPrecompiledViews() { initPrecompiledViews(SystemProperties.getBoolean(USE_PRECOMPILED_LAYOUT_SYSTEM_PROPERTY, false)); } private void initPrecompiledViews(boolean enablePrecompiledViews) { mUseCompiledView = enablePrecompiledViews; try { if (mUseCompiledView) { mPrecompiledClassLoader = mContext.getClassLoader(); String dexFile = mContext.getCodeCacheDir() + COMPILED_VIEW_DEX_FILE_NAME; if (new File(dexFile).exists()) { mPrecompiledClassLoader = new PathClassLoader(dexFile, mPrecompiledClassLoader); } else { // If the precompiled layout file doesn't exist, then disable precompiled // layouts. mUseCompiledView = false; } } } catch (Throwable e) { if (DEBUG) { Log.e(TAG, "Failed to initialized precompiled views layouts", e); } mUseCompiledView = false; } if (!mUseCompiledView) { mPrecompiledClassLoader = null; } } /** * @hide for use by CTS tests */ @TestApi public void setPrecompiledLayoutsEnabledForTesting(boolean enablePrecompiledLayouts) { initPrecompiledViews(enablePrecompiledLayouts); } /** * 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., * <code>R.layout.main_page</code>) * @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(@LayoutRes int resource, @Nullable 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. * * <p> * <em><strong>Important</strong></em> 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, @Nullable 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., * <code>R.layout.main_page</code>) * @param root Optional view to be the parent of the generated hierarchy (if * <em>attachToRoot</em> is true), or else simply an object that * provides a set of LayoutParams values for root of the returned * hierarchy (if <em>attachToRoot</em> 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(@LayoutRes int resource, @Nullable ViewGroup root, boolean attachToRoot) { final Resources res = getContext().getResources(); if (DEBUG) { Log.d(TAG, "INFLATING from resource: \"" + res.getResourceName(resource) + "\" (" + Integer.toHexString(resource) + ")"); } View view = tryInflatePrecompiled(resource, res, root, attachToRoot); if (view != null) { return view; } XmlResourceParser parser = res.getLayout(resource); try { return inflate(parser, root, attachToRoot); } finally { parser.close(); } } private @Nullable View tryInflatePrecompiled(@LayoutRes int resource, Resources res, @Nullable ViewGroup root, boolean attachToRoot) { if (!mUseCompiledView) { return null; } Trace.traceBegin(Trace.TRACE_TAG_VIEW, "inflate (precompiled)"); // Try to inflate using a precompiled layout. String pkg = res.getResourcePackageName(resource); String layout = res.getResourceEntryName(resource); try { Class clazz = Class.forName("" + pkg + ".CompiledView", false, mPrecompiledClassLoader); Method inflater = clazz.getMethod(layout, Context.class, int.class); View view = (View) inflater.invoke(null, mContext, resource); if (view != null && root != null) { // We were able to use the precompiled inflater, but now we need to do some work to // attach the view to the root correctly. XmlResourceParser parser = res.getLayout(resource); try { AttributeSet attrs = Xml.asAttributeSet(parser); advanceToRootNode(parser); ViewGroup.LayoutParams params = root.generateLayoutParams(attrs); if (attachToRoot) { root.addView(view, params); } else { view.setLayoutParams(params); } } finally { parser.close(); } } return view; } catch (Throwable e) { if (DEBUG) { Log.e(TAG, "Failed to use precompiled view", e); } } finally { Trace.traceEnd(Trace.TRACE_TAG_VIEW); } return null; } /** * Advances the given parser to the first START_TAG. Throws InflateException if no start tag is * found. */ private void advanceToRootNode(XmlPullParser parser) throws InflateException, IOException, XmlPullParserException { // 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!"); } } /** * Inflate a new view hierarchy from the specified XML node. Throws * {@link InflateException} if there is an error. * <p> * <em><strong>Important</strong></em> 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 * <em>attachToRoot</em> is true), or else simply an object that * provides a set of LayoutParams values for root of the returned * hierarchy (if <em>attachToRoot</em> 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, @Nullable ViewGroup root, boolean attachToRoot) { synchronized (mConstructorArgs) { Trace.traceBegin(Trace.TRACE_TAG_VIEW, "inflate"); final Context inflaterContext = mContext; final AttributeSet attrs = Xml.asAttributeSet(parser); Context lastContext = (Context) mConstructorArgs[0]; mConstructorArgs[0] = inflaterContext; View result = root; try { advanceToRootNode(parser); 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("<merge /> can be used only with a valid " + "ViewGroup root and attachToRoot=true"); } rInflate(parser, root, inflaterContext, attrs, false); } else { // Temp is the root view that was found in the xml final View temp = createViewFromTag(root, name, inflaterContext, 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 against its context. rInflateChildren(parser, temp, attrs, true); 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) { final InflateException ie = new InflateException(e.getMessage(), e); ie.setStackTrace(EMPTY_STACK_TRACE); throw ie; } catch (Exception e) { final InflateException ie = new InflateException( parser.getPositionDescription() + ": " + e.getMessage(), e); ie.setStackTrace(EMPTY_STACK_TRACE); throw ie; } finally { // Don't retain static reference on context. mConstructorArgs[0] = lastContext; mConstructorArgs[1] = null; Trace.traceEnd(Trace.TRACE_TAG_VIEW); } return result; } } private static final ClassLoader BOOT_CLASS_LOADER = LayoutInflater.class.getClassLoader(); private final boolean verifyClassLoader(Constructor<? extends View> constructor) { final ClassLoader constructorLoader = constructor.getDeclaringClass().getClassLoader(); if (constructorLoader == BOOT_CLASS_LOADER) { // fast path for boot class loader (most common case?) - always ok return true; } // in all normal cases (no dynamic code loading), we will exit the following loop on the // first iteration (i.e. when the declaring classloader is the contexts class loader). ClassLoader cl = mContext.getClassLoader(); do { if (constructorLoader == cl) { return true; } cl = cl.getParent(); } while (cl != null); return false; } /** * Low-level function for instantiating a view by name. This attempts to * instantiate a view class of the given <var>name</var> found in this * LayoutInflater's ClassLoader. * * <p> * 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 instantiated view, or null. */ public final View createView(String name, String prefix, AttributeSet attrs) throws ClassNotFoundException, InflateException { Constructor<? extends View> constructor = sConstructorMap.get(name); if (constructor != null && !verifyClassLoader(constructor)) { constructor = null; sConstructorMap.remove(name); } Class<? extends View> clazz = null; try { Trace.traceBegin(Trace.TRACE_TAG_VIEW, name); if (constructor == null) { // Class not found in the cache, see if it's real, and try to add it clazz = Class.forName(prefix != null ? (prefix + name) : name, false, mContext.getClassLoader()) .asSubclass(View.class); if (mFilter != null && clazz != null) { boolean allowed = mFilter.onLoadClass(clazz); if (!allowed) { failNotAllowed(name, prefix, attrs); } } constructor = clazz.getConstructor(mConstructorSignature); constructor.setAccessible(true); 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 = Class .forName(prefix != null ? (prefix + name) : name, false, mContext.getClassLoader()) .asSubclass(View.class); 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 lastContext = mConstructorArgs[0]; if (mConstructorArgs[0] == null) { // Fill in the context if not already within inflation. mConstructorArgs[0] = mContext; } Object[] args = mConstructorArgs; args[1] = attrs; final View view = constructor.newInstance(args); if (view instanceof ViewStub) { // Use the same context when inflating ViewStub later. final ViewStub viewStub = (ViewStub) view; viewStub.setLayoutInflater(cloneInContext((Context) args[0])); } mConstructorArgs[0] = lastContext; return view; } catch (NoSuchMethodException e) { final InflateException ie = new InflateException(attrs.getPositionDescription() + ": Error inflating class " + (prefix != null ? (prefix + name) : name), e); ie.setStackTrace(EMPTY_STACK_TRACE); throw ie; } catch (ClassCastException e) { // If loaded class is not a View subclass final InflateException ie = new InflateException(attrs.getPositionDescription() + ": Class is not a View " + (prefix != null ? (prefix + name) : name), e); ie.setStackTrace(EMPTY_STACK_TRACE); throw ie; } catch (ClassNotFoundException e) { // If loadClass fails, we should propagate the exception. throw e; } catch (Exception e) { final InflateException ie = new InflateException(attrs.getPositionDescription() + ": Error inflating class " + (clazz == null ? "<unknown>" : clazz.getName()), e); ie.setStackTrace(EMPTY_STACK_TRACE); throw ie; } finally { Trace.traceEnd(Trace.TRACE_TAG_VIEW); } } /** * Throw an exception because the specified class is not allowed to be inflated. */ private void failNotAllowed(String name, String prefix, AttributeSet attrs) { throw new InflateException(attrs.getPositionDescription() + ": Class not allowed to be inflated " + (prefix != null ? (prefix + name) : name)); } /** * 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); } /** * Version of {@link #onCreateView(String, AttributeSet)} that also * takes the future parent of the view being constructed. The default * implementation simply calls {@link #onCreateView(String, AttributeSet)}. * * @param parent The future parent of the returned view. <em>Note that * this may be null.</em> * @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(View parent, String name, AttributeSet attrs) throws ClassNotFoundException { return onCreateView(name, attrs); } /** * Convenience method for calling through to the five-arg createViewFromTag * method. This method passes {@code false} for the {@code ignoreThemeAttr} * argument and should be used for everything except {@code >include>} * tag parsing. */ @UnsupportedAppUsage private View createViewFromTag(View parent, String name, Context context, AttributeSet attrs) { return createViewFromTag(parent, name, context, attrs, false); } /** * Creates a view from a tag name using the supplied attribute set. * <p> * <strong>Note:</strong> Default visibility so the BridgeInflater can * override it. * * @param parent the parent view, used to inflate layout params * @param name the name of the XML tag used to define the view * @param context the inflation context for the view, typically the * {@code parent} or base layout inflater context * @param attrs the attribute set for the XML tag used to define the view * @param ignoreThemeAttr {@code true} to ignore the {@code android:theme} * attribute (if set) for the view being inflated, * {@code false} otherwise */ @UnsupportedAppUsage View createViewFromTag(View parent, String name, Context context, AttributeSet attrs, boolean ignoreThemeAttr) { if (name.equals("view")) { name = attrs.getAttributeValue(null, "class"); } // Apply a theme wrapper, if allowed and one is specified. if (!ignoreThemeAttr) { final TypedArray ta = context.obtainStyledAttributes(attrs, ATTRS_THEME); final int themeResId = ta.getResourceId(0, 0); if (themeResId != 0) { context = new ContextThemeWrapper(context, themeResId); } ta.recycle(); } try { View view = tryCreateView(parent, name, context, attrs); if (view == null) { final Object lastContext = mConstructorArgs[0]; mConstructorArgs[0] = context; try { if (-1 == name.indexOf('.')) { view = onCreateView(parent, name, attrs); } else { view = createView(name, null, attrs); } } finally { mConstructorArgs[0] = lastContext; } } return view; } catch (InflateException e) { throw e; } catch (ClassNotFoundException e) { final InflateException ie = new InflateException( attrs.getPositionDescription() + ": Error inflating class " + name, e); ie.setStackTrace(EMPTY_STACK_TRACE); throw ie; } catch (Exception e) { final InflateException ie = new InflateException( attrs.getPositionDescription() + ": Error inflating class " + name, e); ie.setStackTrace(EMPTY_STACK_TRACE); throw ie; } } /** * Tries to create a view from a tag name using the supplied attribute set. * * This method gives the factory provided by {@link LayoutInflater#setFactory} and * {@link LayoutInflater#setFactory2} a chance to create a view. However, it does not apply all * of the general view creation logic, and thus may return {@code null} for some tags. This * method is used by {@link LayoutInflater#inflate} in creating {@code View} objects. * * @hide for use by precompiled layouts. * * @param parent the parent view, used to inflate layout params * @param name the name of the XML tag used to define the view * @param context the inflation context for the view, typically the * {@code parent} or base layout inflater context * @param attrs the attribute set for the XML tag used to define the view */ @UnsupportedAppUsage(trackingBug = 122360734) @Nullable public final View tryCreateView(@Nullable View parent, @NonNull String name, @NonNull Context context, @NonNull AttributeSet attrs) { if (name.equals(TAG_1995)) { // Let's party like it's 1995! return new BlinkLayout(context, attrs); } View view; if (mFactory2 != null) { view = mFactory2.onCreateView(parent, name, context, attrs); } else if (mFactory != null) { view = mFactory.onCreateView(name, context, attrs); } else { view = null; } if (view == null && mPrivateFactory != null) { view = mPrivateFactory.onCreateView(parent, name, context, attrs); } return view; } /** * Recursive method used to inflate internal (non-root) children. This * method calls through to {@link #rInflate} using the parent context as * the inflation context. * <strong>Note:</strong> Default visibility so the BridgeInflater can * call it. */ final void rInflateChildren(XmlPullParser parser, View parent, AttributeSet attrs, boolean finishInflate) throws XmlPullParserException, IOException { rInflate(parser, parent, parent.getContext(), attrs, finishInflate); } /** * Recursive method used to descend down the xml hierarchy and instantiate * views, instantiate their children, and then call onFinishInflate(). * <p> * <strong>Note:</strong> Default visibility so the BridgeInflater can * override it. */ void rInflate(XmlPullParser parser, View parent, Context context, AttributeSet attrs, boolean finishInflate) throws XmlPullParserException, IOException { final int depth = parser.getDepth(); int type; boolean pendingRequestFocus = false; 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)) { pendingRequestFocus = true; consumeChildElements(parser); } else if (TAG_TAG.equals(name)) { parseViewTag(parser, parent, attrs); } else if (TAG_INCLUDE.equals(name)) { if (parser.getDepth() == 0) { throw new InflateException("<include /> cannot be the root element"); } parseInclude(parser, context, parent, attrs); } else if (TAG_MERGE.equals(name)) { throw new InflateException("<merge /> must be the root element"); } else { final View view = createViewFromTag(parent, name, context, attrs); final ViewGroup viewGroup = (ViewGroup) parent; final ViewGroup.LayoutParams params = viewGroup.generateLayoutParams(attrs); rInflateChildren(parser, view, attrs, true); viewGroup.addView(view, params); } } if (pendingRequestFocus) { parent.restoreDefaultFocus(); } if (finishInflate) { parent.onFinishInflate(); } } /** * Parses a <code><tag></code> element and sets a keyed tag on the * containing View. */ private void parseViewTag(XmlPullParser parser, View view, AttributeSet attrs) throws XmlPullParserException, IOException { final Context context = view.getContext(); final TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ViewTag); final int key = ta.getResourceId(R.styleable.ViewTag_id, 0); final CharSequence value = ta.getText(R.styleable.ViewTag_value); view.setTag(key, value); ta.recycle(); consumeChildElements(parser); } @UnsupportedAppUsage private void parseInclude(XmlPullParser parser, Context context, View parent, AttributeSet attrs) throws XmlPullParserException, IOException { int type; if (!(parent instanceof ViewGroup)) { throw new InflateException("<include /> can only be used inside of a ViewGroup"); } // Apply a theme wrapper, if requested. This is sort of a weird // edge case, since developers think the <include> overwrites // values in the AttributeSet of the included View. So, if the // included View has a theme attribute, we'll need to ignore it. final TypedArray ta = context.obtainStyledAttributes(attrs, ATTRS_THEME); final int themeResId = ta.getResourceId(0, 0); final boolean hasThemeOverride = themeResId != 0; if (hasThemeOverride) { context = new ContextThemeWrapper(context, themeResId); } ta.recycle(); // If the layout is pointing to a theme attribute, we have to // massage the value to get a resource identifier out of it. int layout = attrs.getAttributeResourceValue(null, ATTR_LAYOUT, 0); if (layout == 0) { final String value = attrs.getAttributeValue(null, ATTR_LAYOUT); if (value == null || value.length() <= 0) { throw new InflateException("You must specify a layout in the" + " include tag: <include layout=\"@layout/layoutID\" />"); } // Attempt to resolve the "?attr/name" string to an attribute // within the default (e.g. application) package. layout = context.getResources().getIdentifier(value.substring(1), "attr", context.getPackageName()); } // The layout might be referencing a theme attribute. if (mTempValue == null) { mTempValue = new TypedValue(); } if (layout != 0 && context.getTheme().resolveAttribute(layout, mTempValue, true)) { layout = mTempValue.resourceId; } if (layout == 0) { final String value = attrs.getAttributeValue(null, ATTR_LAYOUT); throw new InflateException( "You must specify a valid layout " + "reference. The layout ID " + value + " is not valid."); } final View precompiled = tryInflatePrecompiled(layout, context.getResources(), (ViewGroup) parent, /*attachToRoot=*/true); if (precompiled == null) { final XmlResourceParser childParser = context.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)) { // The <merge> tag doesn't support android:theme, so // nothing special to do here. rInflate(childParser, parent, context, childAttrs, false); } else { final View view = createViewFromTag(parent, childName, context, childAttrs, hasThemeOverride); final ViewGroup group = (ViewGroup) parent; final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.Include); final int id = a.getResourceId(R.styleable.Include_id, View.NO_ID); final int visibility = a.getInt(R.styleable.Include_visibility, -1); a.recycle(); // We try to load the layout params set in the <include /> tag. // If the parent can't generate layout params (ex. missing width // or height for the framework ViewGroups, though this is not // necessarily true of all ViewGroups) then we expect it to throw // a runtime exception. // We catch this exception and set localParams accordingly: true // means we successfully loaded layout params from the <include> // tag, false means we need to rely on the included layout params. ViewGroup.LayoutParams params = null; try { params = group.generateLayoutParams(attrs); } catch (RuntimeException e) { // Ignore, just fail over to child attrs. } if (params == null) { params = group.generateLayoutParams(childAttrs); } view.setLayoutParams(params); // Inflate all children. rInflateChildren(childParser, view, childAttrs, true); 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(); } } LayoutInflater.consumeChildElements(parser); } /** * <strong>Note:</strong> default visibility so that * LayoutInflater_Delegate can call it. */ final static void consumeChildElements(XmlPullParser parser) throws XmlPullParserException, IOException { int type; final int currentDepth = parser.getDepth(); while (((type = parser.next()) != XmlPullParser.END_TAG || parser.getDepth() > currentDepth) && type != XmlPullParser.END_DOCUMENT) { // Empty } } private static class BlinkLayout extends FrameLayout { private static final int MESSAGE_BLINK = 0x42; private static final int BLINK_DELAY = 500; private boolean mBlink; private boolean mBlinkState; private final Handler mHandler; public BlinkLayout(Context context, AttributeSet attrs) { super(context, attrs); mHandler = new Handler(new Handler.Callback() { @Override public boolean handleMessage(Message msg) { if (msg.what == MESSAGE_BLINK) { if (mBlink) { mBlinkState = !mBlinkState; makeBlink(); } invalidate(); return true; } return false; } }); } private void makeBlink() { Message message = mHandler.obtainMessage(MESSAGE_BLINK); mHandler.sendMessageDelayed(message, BLINK_DELAY); } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); mBlink = true; mBlinkState = true; makeBlink(); } @Override protected void onDetachedFromWindow() { super.onDetachedFromWindow(); mBlink = false; mBlinkState = true; mHandler.removeMessages(MESSAGE_BLINK); } @Override protected void dispatchDraw(Canvas canvas) { if (mBlinkState) { super.dispatchDraw(canvas); } } } }