android screenshot? [closed]

问题:

      Button button = (Button)findViewById(R.id.btnTakeScreenshot);
      button.setOnClickListener(new View.OnClickListener() {
      //@Override
      public void onClick(View v) {
      final View content = findViewById(R.id.layoutroot);
      content.setDrawingCacheEnabled(true);
       Bitmap bitmap = content.getDrawingCache();
       File file = new File(Environment.getExternalStorageDirectory() + "/test.png");
       try 
       {
           file.createNewFile();
           FileOutputStream ostream = new FileOutputStream(file);
           bitmap.compress(CompressFormat.PNG, 100, ostream);
           ostream.close();
           Toast.makeText(content.getContext(), "HELLO", Toast.LENGTH_SHORT);
       } 
       catch (Exception e) 
       {
        System.out.print("error");
           e.printStackTrace();
       }
}
});

above code is to capture a screenshot, but it creates blank file of zero kb?

回答1:

file.createNewFile(); does exactly what you asked of it: creates a blank, empty file. Then if the drawing cache is empty you will get nothing in the file. Try this:

Button button = (Button)findViewById(R.id.btnTakeScreenshot);
      final View content = findViewById(R.id.layoutroot);
      content.setDrawingCacheEnabled(true);
      button.setOnClickListener(new View.OnClickListener() {
      //@Override
      public void onClick(View v) {
       Bitmap bitmap = content.getDrawingCache();
       File file = new File(Environment.getExternalStorageDirectory() + "/test.png");
       try 
       {
           file.createNewFile();
           FileOutputStream ostream = new FileOutputStream(file);
           bitmap.compress(CompressFormat.PNG, 100, ostream);
           ostream.close();
           Toast.makeText(content.getContext(), "HELLO", Toast.LENGTH_SHORT);
       } 
       catch (Exception e) 
       {
        System.out.print("error");
           e.printStackTrace();
       }
}
});