Android 从图像视图中获取可绘制性
执行文档ImageView.getDrawable中描述的剪辑可绘制示例时,始终返回null。有人能帮我吗 在MainActivity.java onCreate中Android 从图像视图中获取可绘制性,android,android-layout,android-drawable,Android,Android Layout,Android Drawable,执行文档ImageView.getDrawable中描述的剪辑可绘制示例时,始终返回null。有人能帮我吗 在MainActivity.java onCreate中 @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main);
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ImageView imageview = (ImageView) findViewById(R.id.image);
ClipDrawable drawable = (ClipDrawable) imageview.getDrawable();
drawable.setLevel(drawable.getLevel() + 1000); //Line number 21
}
Logcat
02-04 12:16:31.156: E/AndroidRuntime(4611): FATAL EXCEPTION: main02-04 12:16:31.156: E/AndroidRuntime(4611): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test/com.example.test.MainActivity}: java.lang.NullPointerException
02-04 12:16:31.156: E/AndroidRuntime(4611): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
02-04 12:16:31.156: E/AndroidRuntime(4611): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
02-04 12:16:31.156: E/AndroidRuntime(4611): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
02-04 12:16:31.156: E/AndroidRuntime(4611): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
02-04 12:16:31.156: E/AndroidRuntime(4611): at android.os.Handler.dispatchMessage(Handler.java:99)
02-04 12:16:31.156: E/AndroidRuntime(4611): at android.os.Looper.loop(Looper.java:123)
02-04 12:16:31.156: E/AndroidRuntime(4611): at android.app.ActivityThread.main(ActivityThread.java:3683)
02-04 12:16:31.156: E/AndroidRuntime(4611): at java.lang.reflect.Method.invokeNative(Native Method)
02-04 12:16:31.156: E/AndroidRuntime(4611): at java.lang.reflect.Method.invoke(Method.java:507)
02-04 12:16:31.156: E/AndroidRuntime(4611): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-04 12:16:31.156: E/AndroidRuntime(4611): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-04 12:16:31.156: E/AndroidRuntime(4611): at dalvik.system.NativeStart.main(Native Method)
02-04 12:16:31.156: E/AndroidRuntime(4611): Caused by: java.lang.NullPointerException
02-04 12:16:31.156: E/AndroidRuntime(4611): at com.example.test.MainActivity.onCreate(MainActivity.java:21)
02-04 12:16:31.156: E/AndroidRuntime(4611): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-04 12:16:31.156: E/AndroidRuntime(4611): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
02-04 12:16:31.156: E/AndroidRuntime(4611): ... 11 more
可能您将获得
null drawable
,因此将发生此错误
首先将
任何图像
设置为图像视图
,这样您就可以进行绘图了
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ImageView imageview = (ImageView) findViewById(R.id.image);
imageview.setBackgroundResource(R.drawable.icon);
ClipDrawable drawable = (ClipDrawable) imageview.getDrawable();
if(drawable != null){
drawable.setLevel(drawable.getLevel() + 1000); //Line number 21
}
}
您必须重写onWindowsFocusChanged() 尝试获取其值(可绘制图像)时,imageView尚未正确显示。
onWindowsFocusChanged()将通知用户视图已加载,此时您可以获取其数据。如果可以使用视图的id成员变量,这是一种简单的方法:只需使用v.setId()存储R.drawable id即可。然后用v.getId()把它取回来。到目前为止,没有一个答案是正确的 这里的问题是,在图像视图中,drawable是使用
android:background=“@drawable/clip”
附加的,它是使用ClipDrawable drawable=(ClipDrawable)imageview.getDrawable()检索的代码>
修正:
更改imageview xml
android:background=“@drawable/clip”
->android:src=“@drawable/clip”
或
更改按钮回调代码
ClipDrawable-drawable=(ClipDrawable)imageview.getDrawable()代码>->ClipDrawable drawable=(ClipDrawable)imageview.getBackground()代码>
不要同时更改两者,否则问题将再次出现。改变任何一个。分享你的日志,也分享你的一部分code@Dinesh你想拍摄imageview的快照吗???@UsmanKurd我添加了日志catoutput@TGMCians不,我只是在探索clip-drawable在MainActivity.java中的第21行是什么?查看此链接以获取clip-drawable示例,我在图像中也做了同样的操作,我没有给出src取而代之的是我给了背景剪辑drawableandroid:background=“@drawable/clip”你设置了这个吗?我更新了上面的代码,而不是imageview.getDrawable
改为image.getBackground()
。谢谢@SheSmile这很好,我已经在按钮中添加了一个按钮单击我已经完成了drawable.setLevel
@Override
public void onWindowFocusChanged(boolean hasWindowFocus) {
super.onWindowFocusChanged(hasWindowFocus);
ClipDrawable drawable = (ClipDrawable) imageview.getBackground();
drawable.setLevel(drawable.getLevel() + 1000); //Line number 21
}