Android - 确認ImageView的圖檔是否加載成功

确認ImageView的圖檔是否加載成功

本文位址：http://blog.csdn.net/caroline_wendy

本文的合集已經編著成書，進階Android開發強化實戰，歡迎各位讀友的建議和指導。

在京東即可購買：https://item.jd.com/12385680.html

判斷ImageView圖檔是否存在，未加載成功，就顯示預設圖檔。 

if (mPhotoView.getDrawable() == null) {
//            Toast.makeText(getActivity(), "圖檔加載失敗", 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)