由网友(盐焗小星球)分享简介：我想知道如何以编程方式获取手机屏幕。我只是一派，才知道，我必须使用view.getDrawingCache（）。但getDrawingCache（）始终返回null。I want to know how to capture phone screen programmatically. I just googled...

我想知道如何以编程方式获取手机屏幕。我只是一派，才知道，我必须使用view.getDrawingCache（）。但getDrawingCache（）始终返回null。

I want to know how to capture phone screen programmatically. I just googled and got to know that I have to use view.getDrawingCache(). But getDrawingCache() always returns null.

我的XML布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/screenlayout">
<ImageView  
android:layout_width="fill_parent" 
android:layout_height="fill_parent" 
android:id="@+id/screen"
/>
</LinearLayout>

Java文件中::

java file::

 public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    View vScreen = findViewById(R.id.screenlayout);
    ImageView imageview = (ImageView)findViewById(R.id.screen);

    Bitmap bitmap;
    View v1 = vScreen.getRootView();
    v1.setDrawingCacheEnabled(true);
    bitmap = Bitmap.createBitmap(v1.getDrawingCache());   //getting null here     
    v1.setDrawingCacheEnabled(false)      
    imageview.setImageBitmap(bitmap);

}

可有人请纠正我，我要去的地方错了？

Can someone please correct me where I am going wrong?

推荐答案

使用下面的code，以避免空的位图：

Use the following code to avoid a null bitmap:

public class AndroidWebImage extends Activity {

ImageView bmImage; 
LinearLayout view;
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);

      view = (LinearLayout)findViewById(R.id.screen);
      bmImage = (ImageView)findViewById(R.id.image);

      view.setDrawingCacheEnabled(true);
      // this is the important code :)  
      // Without it the view will have a dimension of 0,0 and the bitmap will be null          

      view.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), 
            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));

      view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight()); 

      view.buildDrawingCache(true);
      Bitmap b = Bitmap.createBitmap(view.getDrawingCache());
      view.setDrawingCacheEnabled(false); // clear drawing cache

      bmImage.setImageBitmap(b);   

};


}

好好看看，你必须使用：

Take a good look, you have to use:

 view.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), 
                MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));

 view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight()); 

我用下面的的main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
   android:id="@+id/screen"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
<TextView
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:text="@string/hello"
  />
<ImageView
  android:id="@+id/image"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
/>
</LinearLayout>

的结果是：

Reference

The outcome is:

Reference