docs: add more info about state list drawable and onclick attribute to Button

bug:1062898

Change-Id: I633c38fc20a2ebf894237f86648cc0fdc9488b1a

Author: scottamain

core/java/android/widget/Button.java

@@ -25,13 +25,13 @@
 
 
 /**
- * <p>
- * <code>Button</code> represents a push-button widget. Push-buttons can be
- * pressed, or clicked, by the user to perform an action. A typical use of a
- * push-button in an activity would be the following:
+ * Represents a push-button widget. Push-buttons can be
+ * pressed, or clicked, by the user to perform an action.
+
+ * <p>A typical use of a push-button in an activity would be the following:
  * </p>
  *
- * <pre class="prettyprint">
+ * <pre>
  * public class MyActivity extends Activity {
  *     protected void onCreate(Bundle icicle) {
  *         super.onCreate(icicle);
@@ -45,16 +45,52 @@
  *             }
  *         });
  *     }
- * }
- * </pre>
+ * }</pre>
+ *
+ * <p>However, instead of applying an {@link android.view.View.OnClickListener OnClickListener} to
+ * the button in your activity, you can assign a method to your button in the XML layout,
+ * using the {@link android.R.attr#onClick android:onClick} attribute. For example:</p>
+ *
+ * <pre>
+ * &lt;Button
+ *     android:layout_height="wrap_content"
+ *     android:layout_width="wrap_content"
+ *     android:text="@string/self_destruct"
+ *     android:onClick="selfDestruct" /&gt;</pre>
+ *
+ * <p>Now, when a user clicks the button, the Android system calls the activity's {@code
+ * selfDestruct(View)} method. In order for this to work, the method must be public and accept
+ * a {@link android.view.View} as its only parameter. For example:</p>
  *
- * <p>See the <a href="{@docRoot}resources/tutorials/views/hello-formstuff.html">Form Stuff
- * tutorial</a>.</p>
+ * <pre>
+ * public void selfDestruct(View view) {
+ *     // Kabloey
+ * }</pre>
+ *
+ * <p>The {@link android.view.View} passed into the method is a reference to the widget
+ * that was clicked.</p>
+ *
+ * <h3>Button style</h3>
+ *
+ * <p>Every Button is styled using the system's default button background, which is often different
+ * from one device to another and from one version of the platform to another. If you're not
+ * satisfied with the default button style and want to customize it to match the design of your
+ * application, then you can replace the button's background image with a <a
+ * href="{@docRoot}guide/topics/resources/drawable-resource.html#StateList">state list drawable</a>.
+ * A state list drawable is a drawable resource defined in XML that changes its image based on
+ * the current state of the button. Once you've defined a state list drawable in XML, you can apply
+ * it to your Button with the {@link android.R.attr#background android:background}
+ * attribute. For more information and an example, see <a
+ * href="{@docRoot}guide/topics/resources/drawable-resource.html#StateList">State List
+ * Drawable</a>.</p>
+ *
+ * <p>Also see the <a href="{@docRoot}resources/tutorials/views/hello-formstuff.html">Form Stuff
+ * tutorial</a> for an example implementation of a button.</p>
  *
  * <p><strong>XML attributes</strong></p>
- * <p> 
- * See {@link android.R.styleable#Button Button Attributes}, 
- * {@link android.R.styleable#TextView TextView Attributes},  
+ * <p>
+ * See {@link android.R.styleable#Button Button Attributes},
+ * {@link android.R.styleable#TextView TextView Attributes},
  * {@link android.R.styleable#View View Attributes}
  * </p>
  */

docs/html/guide/topics/resources/drawable-resource.jd

@@ -434,7 +434,7 @@ screen).</dd>
 <h2 id="LayerList">Layer List</h2>
 
 <p>A {@link android.graphics.drawable.LayerDrawable} is a drawable object
-that manages an array of other drawables. Each drawable in the list is drawn in the order of the 
+that manages an array of other drawables. Each drawable in the list is drawn in the order of the
 list&mdash;the last drawable in the list is drawn on top.</p>
 
 <p>Each drawable is represented by an {@code &lt;item&gt;} element inside a single {@code
@@ -641,7 +641,7 @@ In XML: <code>@[<em>package</em>:]drawable/<em>filename</em></code>
         android:state_checkable=["true" | "false"]
         android:state_checked=["true" | "false"]
         android:state_enabled=["true" | "false"]
-        android:state_window_focused=["true" | "false"] /> 
+        android:state_window_focused=["true" | "false"] />
 &lt;/selector>
 </pre>
 </dd>
@@ -729,12 +729,12 @@ default value should always be last (as demonstrated in the following example).<
 &lt;/selector>
 </pre>
 
-<p>This layout XML applies the drawable to a View:</p>
+<p>This layout XML applies the state list drawable to a Button:</p>
 <pre>
-&lt;ImageView
+&lt;Button
     android:layout_height="wrap_content"
     android:layout_width="wrap_content"
-    android:src="@drawable/button" />
+    android:background="@drawable/button" />
 </pre>
 </dd> <!-- end example -->
 
@@ -1670,13 +1670,13 @@ android:dashGap} is set.</dd>
 &lt;?xml version="1.0" encoding="utf-8"?>
 &lt;shape xmlns:android="http://schemas.android.com/apk/res/android"
     android:shape="rectangle">
-    &lt;gradient 
-        android:startColor="#FFFF0000" 
+    &lt;gradient
+        android:startColor="#FFFF0000"
         android:endColor="#80FF00FF"
         android:angle="45"/>
-    &lt;padding android:left="7dp" 
+    &lt;padding android:left="7dp"
         android:top="7dp"
-        android:right="7dp" 
+        android:right="7dp"
         android:bottom="7dp" />
     &lt;corners android:radius="8dp" />
 &lt;/shape>