Drawable的例子，体现出Drawable的强大功能。Android SDK中说明了Drawable主要的作用是：在XML中定义各种动画，然后把 XML当作Drawable资源来读取，通过Drawable显示动画。
下面举个使用TransitionDrawable 的例子，创建一个Android工程，然后再这个工程的基础上修改，修改过程如下：
1、去掉layout/main.xml中的TextView，增加ImagView，如下：
<ImageViewandroid:layout_width=”wrap_content”android:layout_height=”wrap_content”android:tint=”#55ff0000″android:[email protected]/my_image”/>
2、创建一个XML文件，命名为expand_collapse.xml，内容如下：
<?xml version=”1.0″ encoding=”UTF-8″?><transition xmlns:android=”http://schemas.android.com/apk/res/android”><item android:[email protected]/image_expand”/><item android:[email protected]/image_collapse”/></transition>需要3张png图片，存放到res\drawable目录下，3张图片分别命名为：my_image.png、image_expand.png、image_collapse.png。
3、修改Activity中的代码，内容如下：
LinearLayout mLinearLayout;protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);mLinearLayout = new LinearLayout(this);ImageView i = new ImageView(this);i.setAdjustViewBounds(true);i.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));mLinearLayout.addView(i);setContentView(mLinearLayout);Resources res = getResources();TransitionDrawable transition =(TransitionDrawable) res.getDrawable(R.drawable.expand_collapse);i.setImageDrawable(transition);ansition.startTransition(10000);}4、如果修改的没有错误，运行程序，结果显示如下：
初始图片
过渡中的图片
最后的图片
屏幕上动画显示的是：从图片image_expand.png过渡到image_collapse.png，也就是我们在expand_collapse.xml中定义的一个transition动画。看完这个例子，你对Drawable的理解是否又深入些？这里提供这个程序的源代码，供大家下载，可以在这个例子的基础上去体会其他的Drawable，来加深对Drawable的理解。
总结说明
通过以上2个例子程序，相信对Drawable会有一定的认识了，在以后的篇幅中会介绍更多的例子，更加深入的学习和理解Drawable。具体还有哪些Drawable，大家到Android SDK去深入学习吧。
转贴至:http://www.moandroid.com/?p=784
实例:
实现上图效果:
xml部份文件:
<SlidingDrawer android:id="@+id/slidingdrawer" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="horizontal" android:handle="@+id/handle" android:content="@+id/content"> <ImageView android:id="@+id/handle" android:layout_width="56dip" android:layout_height="fill_parent" android:background="@drawable/handle" android:focusable="true" android:clickable="true" android:scaleType="center" android:src="@drawable/handle_icon" /> <LinearLayout android:id="@+id/content" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="#778899"> <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button" /> <EditText android:id="@+id/editText" android:layout_width="fill_parent" android:layout_height="wrap_content" /> </LinearLayout> </SlidingDrawer>
hand_icon.xml
<?xml version="1.0" encoding="utf-8"?><transition xmlns:android="http://schemas.android.com/apk/res/android"> <item android:drawable="@drawable/ic_tray_expand" /> <item android:drawable="@drawable/ic_tray_collapse" /></transition>
hand.xml
<?xml version="1.0" encoding="utf-8"?><selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:state_window_focused="false" android:state_enabled="true" android:drawable="@drawable/tray_handle_normal" /> <item android:state_pressed="true" android:drawable="@drawable/tray_handle_pressed" /> <item android:state_focused="true" android:state_enabled="true" android:drawable="@drawable/tray_handle_selected" /> <item android:state_enabled="true" android:drawable="@drawable/tray_handle_normal" /> <item android:state_focused="true" android:drawable="@drawable/tray_handle_selected" /></selector>
代码部份:
mDrawer = (SlidingDrawer) findViewById(R.id.slidingdrawer); final SlidingDrawer drawer = mDrawer; mLinearLayout = (LinearLayout) drawer.getContent(); final LinearLayout grid = mLinearLayout; mImageView = (ImageView) drawer.findViewById(R.id.handle); mHandleIcon = (TransitionDrawable) mImageView.getDrawable(); mHandleIcon.setCrossFadeEnabled(true); final DrawerManager drawerManager = new DrawerManager(); drawer.setOnDrawerOpenListener(drawerManager); drawer.setOnDrawerCloseListener(drawerManager); drawer.setOnDrawerScrollListener(drawerManager); private class DrawerManager implements SlidingDrawer.OnDrawerOpenListener, SlidingDrawer.OnDrawerCloseListener, SlidingDrawer.OnDrawerScrollListener { private boolean mOpen; public void onDrawerOpened() { Log.v(tag, "onDrawerOpened"); if (!mOpen) { mHandleIcon.reverseTransition(150); mOpen = true; } } private void offsetBoundsToDragLayer(Rect bounds, View view) { view.getDrawingRect(bounds); Log.v(tag, "offsetBoundsToDragLayer"); } public void onDrawerClosed() { Log.v(tag, "onDrawerClosed"); if (mOpen) { mHandleIcon.reverseTransition(150); mOpen = false; } } public void onScrollStarted() { if (PROFILE_DRAWER) { android.os.Debug.startMethodTracing("/sdcard/launcher-drawer"); } } public void onScrollEnded() { if (PROFILE_DRAWER) { android.os.Debug.stopMethodTracing(); } } }