Android - 確認ImageView的圖片是否加載成功

確認ImageView的圖片是否加載成功

 

 

 

判斷ImageView圖片是否存在，未加載成功，就顯示默認圖片。

      if (mPhotoView.getDrawable() == null) {
//            Toast.makeText(getActivity(), 圖片加載失敗, Toast.LENGTH_SHORT).show();
            mPhotoView.setImageDrawable(getResources().getDrawable(R.drawable.icon_default_user_photo));
        }

Android中Bitmap, Drawable, Byte,ID之間的轉化
1. Bitmap 轉化為 byte

ByteArrayOutputStream out = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
byte[] array= out.toByteArray();

2. byte轉化為bitmap

Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);

3. bitmap轉化為Drawable

Drawable drawable = new FastBitmapDrawable(bitmap);

4. Drawable轉化為bitmap
a. BitmapDrawable, FastBitmapDrawable直接用getBitmap
b. 其他類型的Drawable用Canvas畫到一個bitmap上

      Canvas canvas = new Canvas(bitmap)
      drawable.draw(canvas)

5.id轉化graphic.drawable

Drawable drawable = activity.getResources().getDrawable(R.drawable.icon);

6.id轉化成Bitmap

Bitmap bitmap = BitmapFactory. decodeResource (Resources   res, int id)