如何在ScrollView内强制线性布局到屏幕底部？

Question

I found a little difficult to force layout (that is inside a SrollView) to be on the bottom of the screen.

Well, it would be easy if I detached this Bottom layout off the ScrollView and create it's own layout on the very bottom using Gravity, but when someone expands some of the layouts (or rotate to landscape) the app is going to start using the ScrollView. At this moment I want the bottom part to roll up and down with all the stuff and my "Stretching layout" should be only about 8dp (similar to upper dark-blue line) this time.

Here is my structure: (it is not so complicated how it might seems to be) :)

<ScrollView
    android:id="@+id/lt_bcnbldmenu_scroll"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_alignParentBottom="true"
    android:layout_below="@+id/lt_FillScrl"
    android:scrollbars="vertical" >

    <LinearLayout //HELPER LAYOUT
        android:id="@+id/lt_ScrollingPart"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_gravity="top"
        android:gravity="bottom"
        android:orientation="vertical" >

        <LinearLayout //only to make some space (upper dark-blue line)
            android:id="@+id/lt_Fill1"
            android:layout_width="fill_parent"
            android:layout_height="6dp"
            android:background="#70000000"
            android:orientation="vertical" >
        </LinearLayout>

        <LinearLayout //blue background layout
            android:id="@+id/lt_bgLine"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_alignParentLeft="true"
            android:layout_alignParentRight="true"
            android:layout_below="@+id/lt_Fill1"
            android:background="@drawable/bg_line"
            android:orientation="vertical" >

            <LinearLayout //MENU LAYOUT
                android:id="@+id/lt_Menu"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="8dp"
                android:layout_marginLeft="16dp"
                android:layout_marginRight="16dp"
                android:layout_marginTop="8dp"
                android:background="@drawable/bg_main"
                android:orientation="vertical" >

                <LinearLayout //Stuff (first layout)
                    android:id="@+id/lt_pic"
                    android:layout_width="fill_parent"
                    android:layout_height="wrap_content"
                    android:gravity="top|fill_horizontal"
                    android:orientation="horizontal" >

                    <ImageButton
                        android:id="@+id/img_bcnbldmenu_pic"
                        android:layout_width="100dp"
                        android:layout_height="100dp"
                        android:background="@drawable/bg_main_rd"
                        android:padding="16dp"
                        android:scaleType="fitXY"
                        android:src="@drawable/lighthouse" />

                    <EditText
                        android:id="@+id/edt_bcnbldmenu_adress"
                        android:layout_width="fill_parent"
                        android:layout_height="fill_parent"
                        android:layout_gravity="right"
                        android:layout_weight="1"
                        android:background="@drawable/bg_main_d"
                        android:ems="10"
                        android:gravity="start"
                        android:hint="Beacon Adress..."
                        android:inputType="textMultiLine"
                        android:padding="16dp"
                        android:textColor="#222222"
                        android:textColorHint="#777777"
                        android:textSize="14sp" />

                </LinearLayout>

                <LinearLayout //Stuff (second layout)
                    android:id="@+id/lt_group"
                    android:layout_width="fill_parent"
                    android:layout_height="wrap_content"
                    android:background="@drawable/bg_main_ud"
                    android:orientation="horizontal" >

                    <EditText
                        android:id="@+id/edt_bcnbldmenu_group"
                        android:layout_width="fill_parent"
                        android:layout_height="100dp"
                        android:layout_centerHorizontal="true"
                        android:layout_gravity="left"
                        android:layout_weight="1"
                        android:background="#00000000"
                        android:ems="10"
                        android:gravity="center"
                        android:hint="Group..."
                        android:inputType="textPersonName"
                        android:minHeight="100dp"
                        android:textColor="#222222"
                        android:textColorHint="#777777" />

                    <Button
                        android:id="@+id/btn_bcnbldmenu_list"
                        android:layout_width="68dp"
                        android:layout_height="fill_parent"
                        android:layout_gravity="bottom|right"
                        android:layout_margin="16dp"
                        android:background="@drawable/btn_list"
                        android:gravity="center_vertical|center_horizontal"
                        android:textOff="@string/nothing"
                        android:textOn="@string/nothing" />

                </LinearLayout>

                <EditText //Stuff (third layout - actually only a textbox)
                    android:id="@+id/edt_BcnBldMenu_Description"
                    android:layout_width="fill_parent"
                    android:layout_height="wrap_content"
                    android:background="#00000000"
                    android:ems="10"
                    android:gravity="top|left"
                    android:hint="Description..."
                    android:inputType="textMultiLine"
                    android:minHeight="100dp"
                    android:padding="16dp"
                    android:textColor="#222222"
                    android:textColorHint="#777777"
                    android:textSize="16sp" />

            </LinearLayout>

        </LinearLayout>

        <LinearLayout //STRETCHING LAYOUT (lower dark-blue line)
            android:id="@+id/lt_Fill2"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:background="#70000000"
            android:minHeight="32dp"
            android:orientation="vertical" >
        </LinearLayout>

        <LinearLayout //BOTTOM LAYOUT
            android:id="@+id/lt_BottomMenu"
            android:layout_width="fill_parent"
            android:layout_height="62dp"
            android:layout_weight="1"
            android:background="@drawable/bg_line"
            android:gravity="bottom"
            android:orientation="horizontal" >

            <ImageButton
                android:id="@+id/imageButton1"
                android:layout_width="100dp"
                android:layout_height="fill_parent"
                android:layout_gravity="left"
                android:layout_weight="0"
                android:background="#00000000"
                android:scaleType="center"
                android:src="@drawable/uncheck_press" />

            <ImageView //empty image to make some space here
                android:id="@+id/imageView1"
                android:layout_width="wrap_content"
                android:layout_height="fill_parent"
                android:layout_gravity="center_horizontal"
                android:layout_weight="1"
                android:src="#00000000" />

            <ImageButton
                android:id="@+id/imageButton2"
                android:layout_width="100dp"
                android:layout_height="fill_parent"
                android:layout_gravity="right"
                android:layout_weight="0"
                android:background="#00000000"
                android:scaleType="center"
                android:src="@drawable/crane" />
        </LinearLayout>

    </LinearLayout>
</ScrollView>

I hope there is an easy way to figure this out, because otherwise I will have to do it programmatically somehow which I really want to avoid.

Thanks in advance! I am looking for a solution for several hours.

Answer 1

Add this property to your ScrollView in XML:

android:fillViewport="true"

This will make the "Helper layout" at least as high as the ScrollView in the case if scrolling is not necessary.

Answer 2

The easiest way in my opinion of solving your problem is to check if the helper Linearlayout has less height than the ScrollView.

Also note that the preferred xml syntax is "match_parent" and not "fill_parent", which is technically deprecated.

1. In the XML change layout_height to wrap_content for the helper Linearlayout, also remove layout_gravity and gravity, useless code for this solution. You also add an empty view into the helper LinearLayout. Your XML should look like this:

<ScrollView
    android:id="@+id/lt_bcnbldmenu_scroll"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_alignParentBottom="true"
    android:layout_below="@+id/lt_FillScrl"
    android:scrollbars="vertical" >

    <LinearLayout //HELPER LAYOUT
        android:id="@+id/lt_ScrollingPart"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

    <FrameLayout
        android:id="@+id/lt_empty"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
    />

    <LinearLayout //only to make some space (upper dark-blue line)
        android:id="@+id/lt_Fill1"
        android:layout_width="fill_parent"
        android:layout_height="6dp"
        android:background="#70000000"
        android:orientation="vertical" >
    </LinearLayout>
....

2. in the OnCreate(...) method of the respective Activity, add the following:

final ScrollView scrollView = (ScrollView)findViewById(R.id.lt_bcnbldmenu_scroll);
final LinearLayout helperLayout = (LinearLayout)findViewById(R.id.lt_ScrollingPart);
final View emptyView = findViewById(R.id.lt_empty);

// when post(...) is called all View heights have been measured by Android
helperLayout.post(new Runnable() {
    @Override
    public void run() {
        int nHeightDiff = scrollView.getHeight() - helperLayout.getHeight();
        // Does the ScrollView have more height than what it contains?
        if (nHeightDiff > 0) {
            // add padding to compensate for the missing height, you can also set the height directly via LinearLayout.LayoutParams(...)
            emptyView.setPadding(0, nHeightDiff, 0, 0);
        }
    }
});