android   动态改变图片大小

在oncreate中，使用getheight等函数不能获得控件大小，得到的为0

应使用其他方法

Resources res = getResources();

final ImageView view=(ImageView)findViewById(R.id.IV_about);

final Drawable drawable=res.getDrawable(R.drawable.ic_about);

DisplayMetrics dm = new DisplayMetrics();

getWindowManager().getDefaultDisplay().getMetrics(dm);

final int screen_height = dm.heightPixels ;//高度

ViewTreeObserver vto = view.getViewTreeObserver(); 

vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() { 

public boolean onPreDraw() { 

int height = (int) ((float) view.getMeasuredWidth()/drawable.getMinimumWidth() * drawable.getMinimumHeight());

int width = view.getMeasuredWidth(); 

LinearLayout.LayoutParams linearParams =(LinearLayout.LayoutParams) view.getLayoutParams(); //取控件textView当前的布局参数  

linearParams.height = height;

linearParams.width = view.getMeasuredWidth();

linearParams.topMargin=screen_height/10;

view.setLayoutParams(linearParams);

view.setImageResource(R.drawable.ic_about);