setBackgroundResource 9 patch图会影响 LinearLayout的Padding

 <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content">
            <TextView
                android:id="@+id/order_tag_1"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:background="@drawable/order_tag_select"
                android:gravity="center"
                android:paddingBottom="10dip"
                android:paddingTop="10dip"
                android:text="TAG1"
                android:textColor="#e33531"
                android:textSize="18dip"/>
            <TextView
                android:id="@+id/order_tag_2"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:background="@drawable/order_tag"
                android:gravity="center"
                android:paddingBottom="10dip"
                android:paddingTop="10dip"
                android:text="TAG2"
                android:textSize="18dip"/>
        </LinearLayout>

布局大概是这样子的。当切换tag的时候

public void setTagStyle(int position) {
		int unSelectId = position == 0 ? 1 : 0;
		mTag[position].setTextColor(Color.parseColor("#e33531"));
		mTag[position].setBackgroundResource(R.drawable.order_tag_select);
		mTag[unSelectId].setTextColor(Color.parseColor("#666666"));
		mTag[unSelectId].setBackgroundResource(R.drawable.order_tag);
	}

对tag的背景图片进行设置

setBackgroundResource

设置完以后会发现layout中设置的TextVIew的padding属性不见了

http://stackoverflow.com/questions/10095196/whered-padding-go-when-setting-background-drawable

http://stackoverflow.com/questions/2886140/does-changing-the-background-also-change-the-padding-of-a-linearlayout

This is the default behavior when changing the background Drawable on a View. According to Romain Guy, one of the Android developers, "The reason why setting an image resets the padding is because 9-patch images can encode padding." See his full answer in a similar question.

The fix is to reset the padding in code each time you change the background drawable.

What I found was adding a 9 patch as a background resource reset the padding - although interestingly if I added a color, or non-9 patch image, it didn't. The solution was to save the padding values before the background gets added, then set them again afterwards.

当设置9 patch图的时候会重置padding。其他的不会