在onCreate()方法中获得view的宽高

深碍√TFBOYSˉ_ 2022-07-20 12:26 192阅读 0赞

在onCreate()方法中获得view的宽高，用一般的方法，如下：

img = (ImageView) findViewById(R.id.test_img);
    int width=img.getWidth();
    int height=img.getHeight();

这时所获得的宽和高均为0，因为在onCreate方法时ImageView还没有绘制好，在这个时候获取得到的就是零。  
那是否有办法在onCreate()方法中获得宽、高呢？网上搜索了下，有如下4中方法可以在onCreate()中获得对应控件的宽、高。  
MainActivity中

private ImageView img;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            Log.i("imageview", "onCreate.....");
            img = (ImageView) findViewById(R.id.test_img);
            measure1();
            measure2();
            measure3();
            measure4();
        }

1.  方法一

private void measure1() {
            Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
                    R.drawable.songjiang);
            Log.i("imageview1", "width: " + bitmap.getWidth());
            Log.i("imageview1", "height: " + bitmap.getHeight());
        }

1.  方法二

private void measure2() {
            int w = View.MeasureSpec.makeMeasureSpec(0,
                    View.MeasureSpec.UNSPECIFIED);
            int h = View.MeasureSpec.makeMeasureSpec(0,
                    View.MeasureSpec.UNSPECIFIED);
            img.measure(w, h);
            Log.i("imageview2", "width: " + img.getMeasuredWidth());
            Log.i("imageview2", "height: " + img.getMeasuredHeight());
        }

1.  方法三

private void measure3() {
            ViewTreeObserver vto = img.getViewTreeObserver();
            vto.addOnPreDrawListener(new OnPreDrawListener() {
                @Override
                public boolean onPreDraw() {
                    int height = img.getMeasuredHeight();
                    int width = img.getMeasuredWidth();
                    Log.i("imageview3", "width: " + width);
                    Log.i("imageview3", "height: " + height);
                    return true;
                }
            });
        }

1.  方法四

private void measure4() {
            ViewTreeObserver vto = img.getViewTreeObserver();
            vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
                @Override
                public void onGlobalLayout() {
                    img.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                    Log.i("imageview4", "width: " + img.getWidth());
                    Log.i("imageview4", "height: " + img.getHeight());
                }
            });
        }