android - 添加选项时 decodeResource 返回 null

Question

您好，我正在使用以下方法将位图设置为 ImageView:

        o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        o.inDither = false;
        o.inPurgeable = true;
        o.inInputShareable = true;

        b = BitmapFactory.decodeResource(getApplicationContext()
                .getResources(), resourceId);
                     //Note the Options parameter is ignored
        ivWallpaper = (ImageView) findViewById(R.id.ivWallpaper);
        ivWallpaper.setImageBitmap(b);
        ivWallpaper.setOnClickListener(Wallpapers.this);

效果很好，但是当我添加选项参数时:

        o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        o.inDither = false;
        o.inPurgeable = true;
        o.inInputShareable = true;

        b = BitmapFactory.decodeResource(getApplicationContext()
                .getResources(), resourceId, o);
        ivWallpaper = (ImageView) findViewById(R.id.ivWallpaper);
        ivWallpaper.setImageBitmap(b);
        ivWallpaper.setOnClickListener(Wallpapers.this);

它在以下位置给了我一个 nullPointerException: ivWallpaper.setImageBitmap(b);

请帮帮我。几个小时以来一直在努力解决这个问题

Answer 1

http://developer.android.com/reference/android/graphics/BitmapFactory.Options.html

公共(public) bool 值 inJustDecodeBounds

如果设置为 true，解码器将返回 null(无位图)，但 out... 字段仍将被设置，允许调用者查询位图而无需为其像素分配内存。