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1 /*
2  * Copyright (C) 2007 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package android.view;
18 
19 import com.android.internal.R;
20 
21 import org.xmlpull.v1.XmlPullParser;
22 import org.xmlpull.v1.XmlPullParserException;
23 
24 import android.annotation.LayoutRes;
25 import android.annotation.Nullable;
26 import android.content.Context;
27 import android.content.res.Resources;
28 import android.content.res.TypedArray;
29 import android.content.res.XmlResourceParser;
30 import android.graphics.Canvas;
31 import android.os.Handler;
32 import android.os.Message;
33 import android.os.Trace;
34 import android.util.AttributeSet;
35 import android.util.Log;
36 import android.util.TypedValue;
37 import android.util.Xml;
38 import android.widget.FrameLayout;
39 
40 import java.io.IOException;
41 import java.lang.reflect.Constructor;
42 import java.util.HashMap;
43 
44 /**
45  * Instantiates a layout XML file into its corresponding {@link android.view.View}
46  * objects. It is never used directly. Instead, use
47  * {@link android.app.Activity#getLayoutInflater()} or
48  * {@link Context#getSystemService} to retrieve a standard LayoutInflater instance
49  * that is already hooked up to the current context and correctly configured
50  * for the device you are running on.  For example:
51  *
52  * <pre>LayoutInflater inflater = (LayoutInflater)context.getSystemService
53  *      (Context.LAYOUT_INFLATER_SERVICE);</pre>
54  *
55  * <p>
56  * To create a new LayoutInflater with an additional {@link Factory} for your
57  * own views, you can use {@link #cloneInContext} to clone an existing
58  * ViewFactory, and then call {@link #setFactory} on it to include your
59  * Factory.
60  *
61  * <p>
62  * For performance reasons, view inflation relies heavily on pre-processing of
63  * XML files that is done at build time. Therefore, it is not currently possible
64  * to use LayoutInflater with an XmlPullParser over a plain XML file at runtime;
65  * it only works with an XmlPullParser returned from a compiled resource
66  * (R.<em>something</em> file.)
67  *
68  * @see Context#getSystemService
69  */
70 public abstract class LayoutInflater {
71 
72     private static final String TAG = LayoutInflater.class.getSimpleName();
73     private static final boolean DEBUG = false;
74 
75     /**
76      * This field should be made private, so it is hidden from the SDK.
77      * {@hide}
78      */
79     protected final Context mContext;
80 
81     // these are optional, set by the caller
82     private boolean mFactorySet;
83     private Factory mFactory;
84     private Factory2 mFactory2;
85     private Factory2 mPrivateFactory;
86     private Filter mFilter;
87 
88     final Object[] mConstructorArgs = new Object[2];
89 
90     static final Class<?>[] mConstructorSignature = new Class[] {
91             Context.class, AttributeSet.class};
92 
93     private static final HashMap<String, Constructor<? extends View>> sConstructorMap =
94             new HashMap<String, Constructor<? extends View>>();
95 
96     private HashMap<String, Boolean> mFilterMap;
97 
98     private TypedValue mTempValue;
99 
100     private static final String TAG_MERGE = "merge";
101     private static final String TAG_INCLUDE = "include";
102     private static final String TAG_1995 = "blink";
103     private static final String TAG_REQUEST_FOCUS = "requestFocus";
104     private static final String TAG_TAG = "tag";
105 
106     private static final String ATTR_LAYOUT = "layout";
107 
108     private static final int[] ATTRS_THEME = new int[] {
109             com.android.internal.R.attr.theme };
110 
111     /**
112      * Hook to allow clients of the LayoutInflater to restrict the set of Views that are allowed
113      * to be inflated.
114      *
115      */
116     public interface Filter {
117         /**
118          * Hook to allow clients of the LayoutInflater to restrict the set of Views
119          * that are allowed to be inflated.
120          *
121          * @param clazz The class object for the View that is about to be inflated
122          *
123          * @return True if this class is allowed to be inflated, or false otherwise
124          */
125         @SuppressWarnings("unchecked")
onLoadClass(Class clazz)126         boolean onLoadClass(Class clazz);
127     }
128 
129     public interface Factory {
130         /**
131          * Hook you can supply that is called when inflating from a LayoutInflater.
132          * You can use this to customize the tag names available in your XML
133          * layout files.
134          *
135          * <p>
136          * Note that it is good practice to prefix these custom names with your
137          * package (i.e., com.coolcompany.apps) to avoid conflicts with system
138          * names.
139          *
140          * @param name Tag name to be inflated.
141          * @param context The context the view is being created in.
142          * @param attrs Inflation attributes as specified in XML file.
143          *
144          * @return View Newly created view. Return null for the default
145          *         behavior.
146          */
onCreateView(String name, Context context, AttributeSet attrs)147         public View onCreateView(String name, Context context, AttributeSet attrs);
148     }
149 
150     public interface Factory2 extends Factory {
151         /**
152          * Version of {@link #onCreateView(String, Context, AttributeSet)}
153          * that also supplies the parent that the view created view will be
154          * placed in.
155          *
156          * @param parent The parent that the created view will be placed
157          * in; <em>note that this may be null</em>.
158          * @param name Tag name to be inflated.
159          * @param context The context the view is being created in.
160          * @param attrs Inflation attributes as specified in XML file.
161          *
162          * @return View Newly created view. Return null for the default
163          *         behavior.
164          */
onCreateView(View parent, String name, Context context, AttributeSet attrs)165         public View onCreateView(View parent, String name, Context context, AttributeSet attrs);
166     }
167 
168     private static class FactoryMerger implements Factory2 {
169         private final Factory mF1, mF2;
170         private final Factory2 mF12, mF22;
171 
FactoryMerger(Factory f1, Factory2 f12, Factory f2, Factory2 f22)172         FactoryMerger(Factory f1, Factory2 f12, Factory f2, Factory2 f22) {
173             mF1 = f1;
174             mF2 = f2;
175             mF12 = f12;
176             mF22 = f22;
177         }
178 
onCreateView(String name, Context context, AttributeSet attrs)179         public View onCreateView(String name, Context context, AttributeSet attrs) {
180             View v = mF1.onCreateView(name, context, attrs);
181             if (v != null) return v;
182             return mF2.onCreateView(name, context, attrs);
183         }
184 
onCreateView(View parent, String name, Context context, AttributeSet attrs)185         public View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
186             View v = mF12 != null ? mF12.onCreateView(parent, name, context, attrs)
187                     : mF1.onCreateView(name, context, attrs);
188             if (v != null) return v;
189             return mF22 != null ? mF22.onCreateView(parent, name, context, attrs)
190                     : mF2.onCreateView(name, context, attrs);
191         }
192     }
193 
194     /**
195      * Create a new LayoutInflater instance associated with a particular Context.
196      * Applications will almost always want to use
197      * {@link Context#getSystemService Context.getSystemService()} to retrieve
198      * the standard {@link Context#LAYOUT_INFLATER_SERVICE Context.INFLATER_SERVICE}.
199      *
200      * @param context The Context in which this LayoutInflater will create its
201      * Views; most importantly, this supplies the theme from which the default
202      * values for their attributes are retrieved.
203      */
LayoutInflater(Context context)204     protected LayoutInflater(Context context) {
205         mContext = context;
206     }
207 
208     /**
209      * Create a new LayoutInflater instance that is a copy of an existing
210      * LayoutInflater, optionally with its Context changed.  For use in
211      * implementing {@link #cloneInContext}.
212      *
213      * @param original The original LayoutInflater to copy.
214      * @param newContext The new Context to use.
215      */
LayoutInflater(LayoutInflater original, Context newContext)216     protected LayoutInflater(LayoutInflater original, Context newContext) {
217         mContext = newContext;
218         mFactory = original.mFactory;
219         mFactory2 = original.mFactory2;
220         mPrivateFactory = original.mPrivateFactory;
221         setFilter(original.mFilter);
222     }
223 
224     /**
225      * Obtains the LayoutInflater from the given context.
226      */
from(Context context)227     public static LayoutInflater from(Context context) {
228         LayoutInflater LayoutInflater =
229                 (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
230         if (LayoutInflater == null) {
231             throw new AssertionError("LayoutInflater not found.");
232         }
233         return LayoutInflater;
234     }
235 
236     /**
237      * Create a copy of the existing LayoutInflater object, with the copy
238      * pointing to a different Context than the original.  This is used by
239      * {@link ContextThemeWrapper} to create a new LayoutInflater to go along
240      * with the new Context theme.
241      *
242      * @param newContext The new Context to associate with the new LayoutInflater.
243      * May be the same as the original Context if desired.
244      *
245      * @return Returns a brand spanking new LayoutInflater object associated with
246      * the given Context.
247      */
cloneInContext(Context newContext)248     public abstract LayoutInflater cloneInContext(Context newContext);
249 
250     /**
251      * Return the context we are running in, for access to resources, class
252      * loader, etc.
253      */
getContext()254     public Context getContext() {
255         return mContext;
256     }
257 
258     /**
259      * Return the current {@link Factory} (or null). This is called on each element
260      * name. If the factory returns a View, add that to the hierarchy. If it
261      * returns null, proceed to call onCreateView(name).
262      */
getFactory()263     public final Factory getFactory() {
264         return mFactory;
265     }
266 
267     /**
268      * Return the current {@link Factory2}.  Returns null if no factory is set
269      * or the set factory does not implement the {@link Factory2} interface.
270      * This is called on each element
271      * name. If the factory returns a View, add that to the hierarchy. If it
272      * returns null, proceed to call onCreateView(name).
273      */
getFactory2()274     public final Factory2 getFactory2() {
275         return mFactory2;
276     }
277 
278     /**
279      * Attach a custom Factory interface for creating views while using
280      * this LayoutInflater.  This must not be null, and can only be set once;
281      * after setting, you can not change the factory.  This is
282      * called on each element name as the xml is parsed. If the factory returns
283      * a View, that is added to the hierarchy. If it returns null, the next
284      * factory default {@link #onCreateView} method is called.
285      *
286      * <p>If you have an existing
287      * LayoutInflater and want to add your own factory to it, use
288      * {@link #cloneInContext} to clone the existing instance and then you
289      * can use this function (once) on the returned new instance.  This will
290      * merge your own factory with whatever factory the original instance is
291      * using.
292      */
setFactory(Factory factory)293     public void setFactory(Factory factory) {
294         if (mFactorySet) {
295             throw new IllegalStateException("A factory has already been set on this LayoutInflater");
296         }
297         if (factory == null) {
298             throw new NullPointerException("Given factory can not be null");
299         }
300         mFactorySet = true;
301         if (mFactory == null) {
302             mFactory = factory;
303         } else {
304             mFactory = new FactoryMerger(factory, null, mFactory, mFactory2);
305         }
306     }
307 
308     /**
309      * Like {@link #setFactory}, but allows you to set a {@link Factory2}
310      * interface.
311      */
setFactory2(Factory2 factory)312     public void setFactory2(Factory2 factory) {
313         if (mFactorySet) {
314             throw new IllegalStateException("A factory has already been set on this LayoutInflater");
315         }
316         if (factory == null) {
317             throw new NullPointerException("Given factory can not be null");
318         }
319         mFactorySet = true;
320         if (mFactory == null) {
321             mFactory = mFactory2 = factory;
322         } else {
323             mFactory = mFactory2 = new FactoryMerger(factory, factory, mFactory, mFactory2);
324         }
325     }
326 
327     /**
328      * @hide for use by framework
329      */
setPrivateFactory(Factory2 factory)330     public void setPrivateFactory(Factory2 factory) {
331         if (mPrivateFactory == null) {
332             mPrivateFactory = factory;
333         } else {
334             mPrivateFactory = new FactoryMerger(factory, factory, mPrivateFactory, mPrivateFactory);
335         }
336     }
337 
338     /**
339      * @return The {@link Filter} currently used by this LayoutInflater to restrict the set of Views
340      * that are allowed to be inflated.
341      */
getFilter()342     public Filter getFilter() {
343         return mFilter;
344     }
345 
346     /**
347      * Sets the {@link Filter} to by this LayoutInflater. If a view is attempted to be inflated
348      * which is not allowed by the {@link Filter}, the {@link #inflate(int, ViewGroup)} call will
349      * throw an {@link InflateException}. This filter will replace any previous filter set on this
350      * LayoutInflater.
351      *
352      * @param filter The Filter which restricts the set of Views that are allowed to be inflated.
353      *        This filter will replace any previous filter set on this LayoutInflater.
354      */
setFilter(Filter filter)355     public void setFilter(Filter filter) {
356         mFilter = filter;
357         if (filter != null) {
358             mFilterMap = new HashMap<String, Boolean>();
359         }
360     }
361 
362     /**
363      * Inflate a new view hierarchy from the specified xml resource. Throws
364      * {@link InflateException} if there is an error.
365      *
366      * @param resource ID for an XML layout resource to load (e.g.,
367      *        <code>R.layout.main_page</code>)
368      * @param root Optional view to be the parent of the generated hierarchy.
369      * @return The root View of the inflated hierarchy. If root was supplied,
370      *         this is the root View; otherwise it is the root of the inflated
371      *         XML file.
372      */
inflate(@ayoutRes int resource, @Nullable ViewGroup root)373     public View inflate(@LayoutRes int resource, @Nullable ViewGroup root) {
374         return inflate(resource, root, root != null);
375     }
376 
377     /**
378      * Inflate a new view hierarchy from the specified xml node. Throws
379      * {@link InflateException} if there is an error. *
380      * <p>
381      * <em><strong>Important</strong></em>&nbsp;&nbsp;&nbsp;For performance
382      * reasons, view inflation relies heavily on pre-processing of XML files
383      * that is done at build time. Therefore, it is not currently possible to
384      * use LayoutInflater with an XmlPullParser over a plain XML file at runtime.
385      *
386      * @param parser XML dom node containing the description of the view
387      *        hierarchy.
388      * @param root Optional view to be the parent of the generated hierarchy.
389      * @return The root View of the inflated hierarchy. If root was supplied,
390      *         this is the root View; otherwise it is the root of the inflated
391      *         XML file.
392      */
inflate(XmlPullParser parser, @Nullable ViewGroup root)393     public View inflate(XmlPullParser parser, @Nullable ViewGroup root) {
394         return inflate(parser, root, root != null);
395     }
396 
397     /**
398      * Inflate a new view hierarchy from the specified xml resource. Throws
399      * {@link InflateException} if there is an error.
400      *
401      * @param resource ID for an XML layout resource to load (e.g.,
402      *        <code>R.layout.main_page</code>)
403      * @param root Optional view to be the parent of the generated hierarchy (if
404      *        <em>attachToRoot</em> is true), or else simply an object that
405      *        provides a set of LayoutParams values for root of the returned
406      *        hierarchy (if <em>attachToRoot</em> is false.)
407      * @param attachToRoot Whether the inflated hierarchy should be attached to
408      *        the root parameter? If false, root is only used to create the
409      *        correct subclass of LayoutParams for the root view in the XML.
410      * @return The root View of the inflated hierarchy. If root was supplied and
411      *         attachToRoot is true, this is root; otherwise it is the root of
412      *         the inflated XML file.
413      */
inflate(@ayoutRes int resource, @Nullable ViewGroup root, boolean attachToRoot)414     public View inflate(@LayoutRes int resource, @Nullable ViewGroup root, boolean attachToRoot) {
415         final Resources res = getContext().getResources();
416         if (DEBUG) {
417             Log.d(TAG, "INFLATING from resource: \"" + res.getResourceName(resource) + "\" ("
418                     + Integer.toHexString(resource) + ")");
419         }
420 
421         final XmlResourceParser parser = res.getLayout(resource);
422         try {
423             return inflate(parser, root, attachToRoot);
424         } finally {
425             parser.close();
426         }
427     }
428 
429     /**
430      * Inflate a new view hierarchy from the specified XML node. Throws
431      * {@link InflateException} if there is an error.
432      * <p>
433      * <em><strong>Important</strong></em>&nbsp;&nbsp;&nbsp;For performance
434      * reasons, view inflation relies heavily on pre-processing of XML files
435      * that is done at build time. Therefore, it is not currently possible to
436      * use LayoutInflater with an XmlPullParser over a plain XML file at runtime.
437      *
438      * @param parser XML dom node containing the description of the view
439      *        hierarchy.
440      * @param root Optional view to be the parent of the generated hierarchy (if
441      *        <em>attachToRoot</em> is true), or else simply an object that
442      *        provides a set of LayoutParams values for root of the returned
443      *        hierarchy (if <em>attachToRoot</em> is false.)
444      * @param attachToRoot Whether the inflated hierarchy should be attached to
445      *        the root parameter? If false, root is only used to create the
446      *        correct subclass of LayoutParams for the root view in the XML.
447      * @return The root View of the inflated hierarchy. If root was supplied and
448      *         attachToRoot is true, this is root; otherwise it is the root of
449      *         the inflated XML file.
450      */
inflate(XmlPullParser parser, @Nullable ViewGroup root, boolean attachToRoot)451     public View inflate(XmlPullParser parser, @Nullable ViewGroup root, boolean attachToRoot) {
452         synchronized (mConstructorArgs) {
453             Trace.traceBegin(Trace.TRACE_TAG_VIEW, "inflate");
454 
455             final Context inflaterContext = mContext;
456             final AttributeSet attrs = Xml.asAttributeSet(parser);
457             Context lastContext = (Context) mConstructorArgs[0];
458             mConstructorArgs[0] = inflaterContext;
459             View result = root;
460 
461             try {
462                 // Look for the root node.
463                 int type;
464                 while ((type = parser.next()) != XmlPullParser.START_TAG &&
465                         type != XmlPullParser.END_DOCUMENT) {
466                     // Empty
467                 }
468 
469                 if (type != XmlPullParser.START_TAG) {
470                     throw new InflateException(parser.getPositionDescription()
471                             + ": No start tag found!");
472                 }
473 
474                 final String name = parser.getName();
475 
476                 if (DEBUG) {
477                     System.out.println("**************************");
478                     System.out.println("Creating root view: "
479                             + name);
480                     System.out.println("**************************");
481                 }
482 
483                 if (TAG_MERGE.equals(name)) {
484                     if (root == null || !attachToRoot) {
485                         throw new InflateException("<merge /> can be used only with a valid "
486                                 + "ViewGroup root and attachToRoot=true");
487                     }
488 
489                     rInflate(parser, root, inflaterContext, attrs, false);
490                 } else {
491                     // Temp is the root view that was found in the xml
492                     final View temp = createViewFromTag(root, name, inflaterContext, attrs);
493 
494                     ViewGroup.LayoutParams params = null;
495 
496                     if (root != null) {
497                         if (DEBUG) {
498                             System.out.println("Creating params from root: " +
499                                     root);
500                         }
501                         // Create layout params that match root, if supplied
502                         params = root.generateLayoutParams(attrs);
503                         if (!attachToRoot) {
504                             // Set the layout params for temp if we are not
505                             // attaching. (If we are, we use addView, below)
506                             temp.setLayoutParams(params);
507                         }
508                     }
509 
510                     if (DEBUG) {
511                         System.out.println("-----> start inflating children");
512                     }
513 
514                     // Inflate all children under temp against its context.
515                     rInflateChildren(parser, temp, attrs, true);
516 
517                     if (DEBUG) {
518                         System.out.println("-----> done inflating children");
519                     }
520 
521                     // We are supposed to attach all the views we found (int temp)
522                     // to root. Do that now.
523                     if (root != null && attachToRoot) {
524                         root.addView(temp, params);
525                     }
526 
527                     // Decide whether to return the root that was passed in or the
528                     // top view found in xml.
529                     if (root == null || !attachToRoot) {
530                         result = temp;
531                     }
532                 }
533 
534             } catch (XmlPullParserException e) {
535                 InflateException ex = new InflateException(e.getMessage());
536                 ex.initCause(e);
537                 throw ex;
538             } catch (Exception e) {
539                 InflateException ex = new InflateException(
540                         parser.getPositionDescription()
541                                 + ": " + e.getMessage());
542                 ex.initCause(e);
543                 throw ex;
544             } finally {
545                 // Don't retain static reference on context.
546                 mConstructorArgs[0] = lastContext;
547                 mConstructorArgs[1] = null;
548             }
549 
550             Trace.traceEnd(Trace.TRACE_TAG_VIEW);
551 
552             return result;
553         }
554     }
555 
556     /**
557      * Low-level function for instantiating a view by name. This attempts to
558      * instantiate a view class of the given <var>name</var> found in this
559      * LayoutInflater's ClassLoader.
560      *
561      * <p>
562      * There are two things that can happen in an error case: either the
563      * exception describing the error will be thrown, or a null will be
564      * returned. You must deal with both possibilities -- the former will happen
565      * the first time createView() is called for a class of a particular name,
566      * the latter every time there-after for that class name.
567      *
568      * @param name The full name of the class to be instantiated.
569      * @param attrs The XML attributes supplied for this instance.
570      *
571      * @return View The newly instantiated view, or null.
572      */
createView(String name, String prefix, AttributeSet attrs)573     public final View createView(String name, String prefix, AttributeSet attrs)
574             throws ClassNotFoundException, InflateException {
575         Constructor<? extends View> constructor = sConstructorMap.get(name);
576         Class<? extends View> clazz = null;
577 
578         try {
579             Trace.traceBegin(Trace.TRACE_TAG_VIEW, name);
580 
581             if (constructor == null) {
582                 // Class not found in the cache, see if it's real, and try to add it
583                 clazz = mContext.getClassLoader().loadClass(
584                         prefix != null ? (prefix + name) : name).asSubclass(View.class);
585 
586                 if (mFilter != null && clazz != null) {
587                     boolean allowed = mFilter.onLoadClass(clazz);
588                     if (!allowed) {
589                         failNotAllowed(name, prefix, attrs);
590                     }
591                 }
592                 constructor = clazz.getConstructor(mConstructorSignature);
593                 constructor.setAccessible(true);
594                 sConstructorMap.put(name, constructor);
595             } else {
596                 // If we have a filter, apply it to cached constructor
597                 if (mFilter != null) {
598                     // Have we seen this name before?
599                     Boolean allowedState = mFilterMap.get(name);
600                     if (allowedState == null) {
601                         // New class -- remember whether it is allowed
602                         clazz = mContext.getClassLoader().loadClass(
603                                 prefix != null ? (prefix + name) : name).asSubclass(View.class);
604 
605                         boolean allowed = clazz != null && mFilter.onLoadClass(clazz);
606                         mFilterMap.put(name, allowed);
607                         if (!allowed) {
608                             failNotAllowed(name, prefix, attrs);
609                         }
610                     } else if (allowedState.equals(Boolean.FALSE)) {
611                         failNotAllowed(name, prefix, attrs);
612                     }
613                 }
614             }
615 
616             Object[] args = mConstructorArgs;
617             args[1] = attrs;
618 
619             final View view = constructor.newInstance(args);
620             if (view instanceof ViewStub) {
621                 // Use the same context when inflating ViewStub later.
622                 final ViewStub viewStub = (ViewStub) view;
623                 viewStub.setLayoutInflater(cloneInContext((Context) args[0]));
624             }
625             return view;
626 
627         } catch (NoSuchMethodException e) {
628             InflateException ie = new InflateException(attrs.getPositionDescription()
629                     + ": Error inflating class "
630                     + (prefix != null ? (prefix + name) : name));
631             ie.initCause(e);
632             throw ie;
633 
634         } catch (ClassCastException e) {
635             // If loaded class is not a View subclass
636             InflateException ie = new InflateException(attrs.getPositionDescription()
637                     + ": Class is not a View "
638                     + (prefix != null ? (prefix + name) : name));
639             ie.initCause(e);
640             throw ie;
641         } catch (ClassNotFoundException e) {
642             // If loadClass fails, we should propagate the exception.
643             throw e;
644         } catch (Exception e) {
645             InflateException ie = new InflateException(attrs.getPositionDescription()
646                     + ": Error inflating class "
647                     + (clazz == null ? "<unknown>" : clazz.getName()));
648             ie.initCause(e);
649             throw ie;
650         } finally {
651             Trace.traceEnd(Trace.TRACE_TAG_VIEW);
652         }
653     }
654 
655     /**
656      * Throw an exception because the specified class is not allowed to be inflated.
657      */
failNotAllowed(String name, String prefix, AttributeSet attrs)658     private void failNotAllowed(String name, String prefix, AttributeSet attrs) {
659         throw new InflateException(attrs.getPositionDescription()
660                 + ": Class not allowed to be inflated "
661                 + (prefix != null ? (prefix + name) : name));
662     }
663 
664     /**
665      * This routine is responsible for creating the correct subclass of View
666      * given the xml element name. Override it to handle custom view objects. If
667      * you override this in your subclass be sure to call through to
668      * super.onCreateView(name) for names you do not recognize.
669      *
670      * @param name The fully qualified class name of the View to be create.
671      * @param attrs An AttributeSet of attributes to apply to the View.
672      *
673      * @return View The View created.
674      */
onCreateView(String name, AttributeSet attrs)675     protected View onCreateView(String name, AttributeSet attrs)
676             throws ClassNotFoundException {
677         return createView(name, "android.view.", attrs);
678     }
679 
680     /**
681      * Version of {@link #onCreateView(String, AttributeSet)} that also
682      * takes the future parent of the view being constructed.  The default
683      * implementation simply calls {@link #onCreateView(String, AttributeSet)}.
684      *
685      * @param parent The future parent of the returned view.  <em>Note that
686      * this may be null.</em>
687      * @param name The fully qualified class name of the View to be create.
688      * @param attrs An AttributeSet of attributes to apply to the View.
689      *
690      * @return View The View created.
691      */
onCreateView(View parent, String name, AttributeSet attrs)692     protected View onCreateView(View parent, String name, AttributeSet attrs)
693             throws ClassNotFoundException {
694         return onCreateView(name, attrs);
695     }
696 
697     /**
698      * Convenience method for calling through to the five-arg createViewFromTag
699      * method. This method passes {@code false} for the {@code ignoreThemeAttr}
700      * argument and should be used for everything except {@code &gt;include>}
701      * tag parsing.
702      */
createViewFromTag(View parent, String name, Context context, AttributeSet attrs)703     private View createViewFromTag(View parent, String name, Context context, AttributeSet attrs) {
704         return createViewFromTag(parent, name, context, attrs, false);
705     }
706 
707     /**
708      * Creates a view from a tag name using the supplied attribute set.
709      * <p>
710      * <strong>Note:</strong> Default visibility so the BridgeInflater can
711      * override it.
712      *
713      * @param parent the parent view, used to inflate layout params
714      * @param name the name of the XML tag used to define the view
715      * @param context the inflation context for the view, typically the
716      *                {@code parent} or base layout inflater context
717      * @param attrs the attribute set for the XML tag used to define the view
718      * @param ignoreThemeAttr {@code true} to ignore the {@code android:theme}
719      *                        attribute (if set) for the view being inflated,
720      *                        {@code false} otherwise
721      */
createViewFromTag(View parent, String name, Context context, AttributeSet attrs, boolean ignoreThemeAttr)722     View createViewFromTag(View parent, String name, Context context, AttributeSet attrs,
723             boolean ignoreThemeAttr) {
724         if (name.equals("view")) {
725             name = attrs.getAttributeValue(null, "class");
726         }
727 
728         // Apply a theme wrapper, if allowed and one is specified.
729         if (!ignoreThemeAttr) {
730             final TypedArray ta = context.obtainStyledAttributes(attrs, ATTRS_THEME);
731             final int themeResId = ta.getResourceId(0, 0);
732             if (themeResId != 0) {
733                 context = new ContextThemeWrapper(context, themeResId);
734             }
735             ta.recycle();
736         }
737 
738         if (name.equals(TAG_1995)) {
739             // Let's party like it's 1995!
740             return new BlinkLayout(context, attrs);
741         }
742 
743         try {
744             View view;
745             if (mFactory2 != null) {
746                 view = mFactory2.onCreateView(parent, name, context, attrs);
747             } else if (mFactory != null) {
748                 view = mFactory.onCreateView(name, context, attrs);
749             } else {
750                 view = null;
751             }
752 
753             if (view == null && mPrivateFactory != null) {
754                 view = mPrivateFactory.onCreateView(parent, name, context, attrs);
755             }
756 
757             if (view == null) {
758                 final Object lastContext = mConstructorArgs[0];
759                 mConstructorArgs[0] = context;
760                 try {
761                     if (-1 == name.indexOf('.')) {
762                         view = onCreateView(parent, name, attrs);
763                     } else {
764                         view = createView(name, null, attrs);
765                     }
766                 } finally {
767                     mConstructorArgs[0] = lastContext;
768                 }
769             }
770 
771             return view;
772         } catch (InflateException e) {
773             throw e;
774 
775         } catch (ClassNotFoundException e) {
776             final InflateException ie = new InflateException(attrs.getPositionDescription()
777                     + ": Error inflating class " + name);
778             ie.initCause(e);
779             throw ie;
780 
781         } catch (Exception e) {
782             final InflateException ie = new InflateException(attrs.getPositionDescription()
783                     + ": Error inflating class " + name);
784             ie.initCause(e);
785             throw ie;
786         }
787     }
788 
789     /**
790      * Recursive method used to inflate internal (non-root) children. This
791      * method calls through to {@link #rInflate} using the parent context as
792      * the inflation context.
793      * <strong>Note:</strong> Default visibility so the BridgeInflater can
794      * call it.
795      */
rInflateChildren(XmlPullParser parser, View parent, AttributeSet attrs, boolean finishInflate)796     final void rInflateChildren(XmlPullParser parser, View parent, AttributeSet attrs,
797             boolean finishInflate) throws XmlPullParserException, IOException {
798         rInflate(parser, parent, parent.getContext(), attrs, finishInflate);
799     }
800 
801     /**
802      * Recursive method used to descend down the xml hierarchy and instantiate
803      * views, instantiate their children, and then call onFinishInflate().
804      * <p>
805      * <strong>Note:</strong> Default visibility so the BridgeInflater can
806      * override it.
807      */
rInflate(XmlPullParser parser, View parent, Context context, AttributeSet attrs, boolean finishInflate)808     void rInflate(XmlPullParser parser, View parent, Context context,
809             AttributeSet attrs, boolean finishInflate) throws XmlPullParserException, IOException {
810 
811         final int depth = parser.getDepth();
812         int type;
813 
814         while (((type = parser.next()) != XmlPullParser.END_TAG ||
815                 parser.getDepth() > depth) && type != XmlPullParser.END_DOCUMENT) {
816 
817             if (type != XmlPullParser.START_TAG) {
818                 continue;
819             }
820 
821             final String name = parser.getName();
822 
823             if (TAG_REQUEST_FOCUS.equals(name)) {
824                 parseRequestFocus(parser, parent);
825             } else if (TAG_TAG.equals(name)) {
826                 parseViewTag(parser, parent, attrs);
827             } else if (TAG_INCLUDE.equals(name)) {
828                 if (parser.getDepth() == 0) {
829                     throw new InflateException("<include /> cannot be the root element");
830                 }
831                 parseInclude(parser, context, parent, attrs);
832             } else if (TAG_MERGE.equals(name)) {
833                 throw new InflateException("<merge /> must be the root element");
834             } else {
835                 final View view = createViewFromTag(parent, name, context, attrs);
836                 final ViewGroup viewGroup = (ViewGroup) parent;
837                 final ViewGroup.LayoutParams params = viewGroup.generateLayoutParams(attrs);
838                 rInflateChildren(parser, view, attrs, true);
839                 viewGroup.addView(view, params);
840             }
841         }
842 
843         if (finishInflate) {
844             parent.onFinishInflate();
845         }
846     }
847 
848     /**
849      * Parses a <code>&lt;request-focus&gt;</code> element and requests focus on
850      * the containing View.
851      */
parseRequestFocus(XmlPullParser parser, View view)852     private void parseRequestFocus(XmlPullParser parser, View view)
853             throws XmlPullParserException, IOException {
854         view.requestFocus();
855 
856         consumeChildElements(parser);
857     }
858 
859     /**
860      * Parses a <code>&lt;tag&gt;</code> element and sets a keyed tag on the
861      * containing View.
862      */
parseViewTag(XmlPullParser parser, View view, AttributeSet attrs)863     private void parseViewTag(XmlPullParser parser, View view, AttributeSet attrs)
864             throws XmlPullParserException, IOException {
865         final Context context = view.getContext();
866         final TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ViewTag);
867         final int key = ta.getResourceId(R.styleable.ViewTag_id, 0);
868         final CharSequence value = ta.getText(R.styleable.ViewTag_value);
869         view.setTag(key, value);
870         ta.recycle();
871 
872         consumeChildElements(parser);
873     }
874 
parseInclude(XmlPullParser parser, Context context, View parent, AttributeSet attrs)875     private void parseInclude(XmlPullParser parser, Context context, View parent,
876             AttributeSet attrs) throws XmlPullParserException, IOException {
877         int type;
878 
879         if (parent instanceof ViewGroup) {
880             // Apply a theme wrapper, if requested. This is sort of a weird
881             // edge case, since developers think the <include> overwrites
882             // values in the AttributeSet of the included View. So, if the
883             // included View has a theme attribute, we'll need to ignore it.
884             final TypedArray ta = context.obtainStyledAttributes(attrs, ATTRS_THEME);
885             final int themeResId = ta.getResourceId(0, 0);
886             final boolean hasThemeOverride = themeResId != 0;
887             if (hasThemeOverride) {
888                 context = new ContextThemeWrapper(context, themeResId);
889             }
890             ta.recycle();
891 
892             // If the layout is pointing to a theme attribute, we have to
893             // massage the value to get a resource identifier out of it.
894             int layout = attrs.getAttributeResourceValue(null, ATTR_LAYOUT, 0);
895             if (layout == 0) {
896                 final String value = attrs.getAttributeValue(null, ATTR_LAYOUT);
897                 if (value == null || value.length() <= 0) {
898                     throw new InflateException("You must specify a layout in the"
899                             + " include tag: <include layout=\"@layout/layoutID\" />");
900                 }
901 
902                 // Attempt to resolve the "?attr/name" string to an identifier.
903                 layout = context.getResources().getIdentifier(value.substring(1), null, null);
904             }
905 
906             // The layout might be referencing a theme attribute.
907             if (mTempValue == null) {
908                 mTempValue = new TypedValue();
909             }
910             if (layout != 0 && context.getTheme().resolveAttribute(layout, mTempValue, true)) {
911                 layout = mTempValue.resourceId;
912             }
913 
914             if (layout == 0) {
915                 final String value = attrs.getAttributeValue(null, ATTR_LAYOUT);
916                 throw new InflateException("You must specify a valid layout "
917                         + "reference. The layout ID " + value + " is not valid.");
918             } else {
919                 final XmlResourceParser childParser = context.getResources().getLayout(layout);
920 
921                 try {
922                     final AttributeSet childAttrs = Xml.asAttributeSet(childParser);
923 
924                     while ((type = childParser.next()) != XmlPullParser.START_TAG &&
925                             type != XmlPullParser.END_DOCUMENT) {
926                         // Empty.
927                     }
928 
929                     if (type != XmlPullParser.START_TAG) {
930                         throw new InflateException(childParser.getPositionDescription() +
931                                 ": No start tag found!");
932                     }
933 
934                     final String childName = childParser.getName();
935 
936                     if (TAG_MERGE.equals(childName)) {
937                         // The <merge> tag doesn't support android:theme, so
938                         // nothing special to do here.
939                         rInflate(childParser, parent, context, childAttrs, false);
940                     } else {
941                         final View view = createViewFromTag(parent, childName,
942                                 context, childAttrs, hasThemeOverride);
943                         final ViewGroup group = (ViewGroup) parent;
944 
945                         final TypedArray a = context.obtainStyledAttributes(
946                                 attrs, R.styleable.Include);
947                         final int id = a.getResourceId(R.styleable.Include_id, View.NO_ID);
948                         final int visibility = a.getInt(R.styleable.Include_visibility, -1);
949                         a.recycle();
950 
951                         // We try to load the layout params set in the <include /> tag.
952                         // If the parent can't generate layout params (ex. missing width
953                         // or height for the framework ViewGroups, though this is not
954                         // necessarily true of all ViewGroups) then we expect it to throw
955                         // a runtime exception.
956                         // We catch this exception and set localParams accordingly: true
957                         // means we successfully loaded layout params from the <include>
958                         // tag, false means we need to rely on the included layout params.
959                         ViewGroup.LayoutParams params = null;
960                         try {
961                             params = group.generateLayoutParams(attrs);
962                         } catch (RuntimeException e) {
963                             // Ignore, just fail over to child attrs.
964                         }
965                         if (params == null) {
966                             params = group.generateLayoutParams(childAttrs);
967                         }
968                         view.setLayoutParams(params);
969 
970                         // Inflate all children.
971                         rInflateChildren(childParser, view, childAttrs, true);
972 
973                         if (id != View.NO_ID) {
974                             view.setId(id);
975                         }
976 
977                         switch (visibility) {
978                             case 0:
979                                 view.setVisibility(View.VISIBLE);
980                                 break;
981                             case 1:
982                                 view.setVisibility(View.INVISIBLE);
983                                 break;
984                             case 2:
985                                 view.setVisibility(View.GONE);
986                                 break;
987                         }
988 
989                         group.addView(view);
990                     }
991                 } finally {
992                     childParser.close();
993                 }
994             }
995         } else {
996             throw new InflateException("<include /> can only be used inside of a ViewGroup");
997         }
998 
999         LayoutInflater.consumeChildElements(parser);
1000     }
1001 
1002     /**
1003      * <strong>Note:</strong> default visibility so that
1004      * LayoutInflater_Delegate can call it.
1005      */
consumeChildElements(XmlPullParser parser)1006     final static void consumeChildElements(XmlPullParser parser)
1007             throws XmlPullParserException, IOException {
1008         int type;
1009         final int currentDepth = parser.getDepth();
1010         while (((type = parser.next()) != XmlPullParser.END_TAG ||
1011                 parser.getDepth() > currentDepth) && type != XmlPullParser.END_DOCUMENT) {
1012             // Empty
1013         }
1014     }
1015 
1016     private static class BlinkLayout extends FrameLayout {
1017         private static final int MESSAGE_BLINK = 0x42;
1018         private static final int BLINK_DELAY = 500;
1019 
1020         private boolean mBlink;
1021         private boolean mBlinkState;
1022         private final Handler mHandler;
1023 
BlinkLayout(Context context, AttributeSet attrs)1024         public BlinkLayout(Context context, AttributeSet attrs) {
1025             super(context, attrs);
1026             mHandler = new Handler(new Handler.Callback() {
1027                 @Override
1028                 public boolean handleMessage(Message msg) {
1029                     if (msg.what == MESSAGE_BLINK) {
1030                         if (mBlink) {
1031                             mBlinkState = !mBlinkState;
1032                             makeBlink();
1033                         }
1034                         invalidate();
1035                         return true;
1036                     }
1037                     return false;
1038                 }
1039             });
1040         }
1041 
makeBlink()1042         private void makeBlink() {
1043             Message message = mHandler.obtainMessage(MESSAGE_BLINK);
1044             mHandler.sendMessageDelayed(message, BLINK_DELAY);
1045         }
1046 
1047         @Override
onAttachedToWindow()1048         protected void onAttachedToWindow() {
1049             super.onAttachedToWindow();
1050 
1051             mBlink = true;
1052             mBlinkState = true;
1053 
1054             makeBlink();
1055         }
1056 
1057         @Override
onDetachedFromWindow()1058         protected void onDetachedFromWindow() {
1059             super.onDetachedFromWindow();
1060 
1061             mBlink = false;
1062             mBlinkState = true;
1063 
1064             mHandler.removeMessages(MESSAGE_BLINK);
1065         }
1066 
1067         @Override
dispatchDraw(Canvas canvas)1068         protected void dispatchDraw(Canvas canvas) {
1069             if (mBlinkState) {
1070                 super.dispatchDraw(canvas);
1071             }
1072         }
1073     }
1074 }
1075