java - 无法使用 View 树观察器获取 View 大小

Question

我试图使用 ViewTreeObserver 获取适配器中 View 的宽度和高度，而 View 尚未完全膨胀，但我总是得到零值。宽度和高度将在调整适配器 ListView 中 ImageView 位图大小的方法中使用。这是我的代码:

public View getView(int position, View convertView, ViewGroup parent) {

	newView = convertView;
	ViewHolder holder;

	if (null == convertView) {
		holder = new ViewHolder();
		newView = inflater.inflate(R.layout.selfie_list_view, null);
		holder.selfieView = (ImageView) newView.findViewById(R.id.selfie_bitmap);
		holder.selfieName = (TextView) newView.findViewById(R.id.selfie_name);
		newView.setTag(holder);
		
	} else {
		holder = (ViewHolder) newView.getTag();
	}
	
	SelfieRecord curr = list.get(position);
	String selfieName = curr.getBitmapName();
	String selfiePath = curr.getBitmapPath();
	Bitmap selfie = setPic(newView, selfiePath);
	
	holder.selfieView.setImageBitmap(selfie);
	holder.selfieName.setText(selfieName);

	return newView;
}


private Bitmap setPic(final View view, String path) {
	
	ViewTreeObserver vto = view.getViewTreeObserver();
	if (vto.isAlive()) {
		vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
			
			@Override
			public void onGlobalLayout() {
				view.getViewTreeObserver().removeOnGlobalLayoutListener(this);
				targetW = view.getWidth();
				targetH = view.getHeight();
				Log.i(TAG, "view_width = " + targetW + " view_height =" + targetH);   
				
			}
		});
	}
	
    // Get the dimensions of the bitmap
    BitmapFactory.Options bmOptions = new BitmapFactory.Options();
    bmOptions.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(path, bmOptions);
    int photoW = bmOptions.outWidth;
    int photoH = bmOptions.outHeight;

    // Determine how much to scale down the image
    int scaleFactor = Math.min(photoW/targetW, photoH/targetH);

    // Decode the image file into a Bitmap sized to fill the View
    bmOptions.inJustDecodeBounds = false;
    bmOptions.inSampleSize = scaleFactor;
    bmOptions.inPurgeable = true;

    Bitmap bitmap = BitmapFactory.decodeFile(path, bmOptions);
  
	return bitmap;
}
	   

任何想法将不胜感激。

Answer 1

好吧，我使用 onPreDrawListener 解决了这个问题，并将位图解码和 ImageView 放入其中。这是解决方案，以防有人需要。不管怎样还是谢谢你:

public View getView(int position, View convertView, ViewGroup parent) {

    newView = convertView;
    final ViewHolder holder;

    if (null == convertView) {
        holder = new ViewHolder();
        newView = inflater.inflate(R.layout.selfie_list_view, null);
        holder.selfieView = (ImageView) newView.findViewById(R.id.selfie_bitmap);
        holder.selfieName = (TextView) newView.findViewById(R.id.selfie_name);
        newView.setTag(holder);

    } else {
        holder = (ViewHolder) newView.getTag();
    }

    SelfieRecord curr = list.get(position);
    String selfieName = curr.getBitmapName();
    final String selfiePath = curr.getBitmapPath();
    //Bitmap selfie = setPic(newView, selfiePath);

    ViewTreeObserver vto = holder.selfieView.getViewTreeObserver();
    vto.addOnPreDrawListener(new OnPreDrawListener() {

        @Override
        public boolean onPreDraw() {
            holder.selfieView.getViewTreeObserver().removeOnPreDrawListener(this);
            int width = holder.selfieView.getMeasuredWidth();
            int height = holder.selfieView.getMeasuredHeight();
            Log.i(TAG, "view_width = " + width + " view_height =" + height);

            BitmapFactory.Options bmOptions = new BitmapFactory.Options();
            bmOptions.inJustDecodeBounds = true;
            BitmapFactory.decodeFile(selfiePath, bmOptions);
            int photoW = bmOptions.outWidth;
            int photoH = bmOptions.outHeight;
            Log.i(TAG, "photo_width = " + photoW + " view_height =" + photoH);

            // Determine how much to scale down the image
            int scaleFactor = Math.min(photoW/width, photoH/height);

            // Decode the image file into a Bitmap sized to fill the View
            bmOptions.inJustDecodeBounds = false;
            bmOptions.inSampleSize = scaleFactor;
            bmOptions.inPurgeable = true;
            Bitmap bitmap = BitmapFactory.decodeFile(selfiePath, bmOptions);

            holder.selfieView.setImageBitmap(bitmap);

            return true;
        }
    });

    holder.selfieName.setText(selfieName);

    return newView;
}