在activity中可以调用View.getWidth、View.getHeight()、View.getMeasuredWidth() 、View.getgetMeasuredHeight()来获得某个view的宽度或高度，但是在onCreate()、onStrart()、onResume()方法中会返回0，这是应为当前activity所代表的界面还没显示出来没有添加到WindowPhone的DecorView上或要获取的view没有被添加到DecorView上或者该View的visibility属性为gone 或者该view的width或height真的为0
所以只有上述条件都不成立时才能得到非0的width和height
所以要想获取到的width和height为真实有效的 则有以下方法
1.在该View的事件回调里使用 这时候该view已经被显示即被添加到DecorView上 如点击事件 触摸事件 焦点事件等
View view=findViewById(R.id.tv);
view.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
int width = v.getWidth();
}
});
2.在activity被显示出来时即添加到了DecorView上时获取宽和高如onWindowFocusChanged() 回调方法
@Override
public void onWindowFocusChanged(boolean hasFocus) {
View iv1 = findViewById(R.id.iv1);
View iv2=findViewById(R.id.iv2);
String msg1="iv1' width:"+iv1.getWidth()+" height:"+iv1.getHeight()+" measuredWidth:"+iv1.getMeasuredWidth()+"measuredHeight:"+iv1.getMeasuredHeight();
String msg2="iv2' width:"+iv2.getWidth()+" height:"+iv2.getHeight()+" measuredWidth:"+iv2.getMeasuredWidth()+"measuredHeight:"+iv2.getMeasuredHeight();
i("onWindowFocusChanged() "+msg1);
i("onWindowFocusChanged() "+msg2);
super.onWindowFocusChanged(hasFocus);
}
3.或在onResume方法最后开线程300毫秒左右后获取宽和高 因为onResume执行完后300毫秒后 界面就显示出来了
当然地2种和地3种方法要保证获取宽高的view是在setContentView时设进去的View或它的子View
view.postDelayed(new Runnable() {
@Override
public void run() {
View iv1 = findViewById(R.id.iv1);
View iv2=findViewById(R.id.iv2);
String msg1="iv1' width:"+iv1.getWidth()+" height:"+iv1.getHeight()+" measuredWidth:"+iv1.getMeasuredWidth()+"measuredHeight:"+iv1.getMeasuredHeight();
String msg2="iv2' width:"+iv2.getWidth()+" height:"+iv2.getHeight()+" measuredWidth:"+iv2.getMeasuredWidth()+"measuredHeight:"+iv2.getMeasuredHeight();
i("onWindowFocusChanged() "+msg1);
i("onWindowFocusChanged() "+msg2);
}
}, 300);
4.在onCreate()或onResume()等方法中需要获取宽高时使用getViewTreeObserver().addOnGlobalLayoutListener()来添为view加回调在回调里获得宽度或者高度获取完后让view删除该回调
view.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
view.postDelayed(new Runnable() {
@Override
public void run() {
View iv1 = findViewById(R.id.iv1);
View iv2=findViewById(R.id.iv2);
String msg1="iv1' width:"+iv1.getWidth()+" height:"+iv1.getHeight()+" measuredWidth:"+iv1.getMeasuredWidth()+"measuredHeight:"+iv1.getMeasuredHeight();
String msg2="iv2' width:"+iv2.getWidth()+" height:"+iv2.getHeight()+" measuredWidth:"+iv2.getMeasuredWidth()+"measuredHeight:"+iv2.getMeasuredHeight();
i("onWindowFocusChanged() "+msg1);
i("onWindowFocusChanged() "+msg2);
}
}, 300);
}
});
Activity中获取view的高度和宽度为0的原因以及解决方案,布布扣,bubuko.com