如何使用音量按钮放大/缩小文本视图中的文本

Question

如何覆盖和使用音量按钮放大布局中的IN/OUT文本，就像在写/读SMS时一样？

Answer 1

请检查此解决方案。

public class MainActivity extends AppCompatActivity { 
    TextView txt; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     txt = (TextView) findViewById(R.id.OpenClose); 
    } 

    @Override 
    public boolean onKeyDown(int keyCode, KeyEvent event) { 
     if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN) { 
      float x = txt.getScaleX(); 
      float y = txt.getScaleY(); 

      txt.setScaleX(x - 1); 
      txt.setScaleY(y - 1); 
      return true; 
     } else if (keyCode == KeyEvent.KEYCODE_VOLUME_UP) { 
      float x = txt.getScaleX(); 
      float y = txt.getScaleY(); 

      txt.setScaleX(x + 1); 
      txt.setScaleY(y + 1); 
      return true; 
     } else { 
      return super.onKeyDown(keyCode, event); 
     } 
    } 
}