Question

I just add a scrollview like this and after the screen loads a black background appears.

This black area is positioned on the left and upper most corner of a surrounding RelativeLayout. While the scroll view is positioned with android:layout_marginLeft="20dp"
android:layout_marginTop="40dp" So the left 20dp and the top 40dp are black, while the remaining grey background is undisturbed.

Here the xml part with the scrollView:

  <View
            android:id="@+id/emptyView"
            android:layout_width="match_parent"
            android:layout_height="2dp"
            android:layout_below="@+id/right1" />

        <RelativeLayout
            android:id="@+id/right2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/emptyView" >

            <RelativeLayout
                android:id="@+id/right22"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/emptyView" >

                <ImageView
                    android:id="@+id/emptyView2"
                    android:layout_width="match_parent"
                    android:layout_height="2dp"
                    android:contentDescription="@string/anyStringValue" />

                <HorizontalScrollView
                    android:id="@+id/scrollView"
                    android:layout_width="fill_parent"
                    android:layout_height="520dp"
                    android:layout_marginLeft="20dp"
                    android:layout_marginTop="40dp"
                    android:background="#0000FF" >

                    <TextView
                        android:id="@+id/infoTxt"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:background="#FF0000"
                        android:padding="10dp"
                        android:text="@string/Settings_infoTxt"
                        android:textColor="#000000"
                        android:textSize="20dp" />
                </HorizontalScrollView>
            </RelativeLayout>
        </RelativeLayout>

I already tried to add an emptyView on top of the scroll view as well as 2 RelativeLayouts. But the black area keeps appearing no matter what. (with/without RelativeLayouts and empty views on top)

Since the backgroud of the complete page is grey, this black area distorts the complete screen.

I used scroll views many times before but never had a problem like this. I have no idea what is causing this.

How can I get rid of the black area caused by the scroll view?

many thanks!

Answer 1

I got pretty much the same problem, some black areas appeared on loading the scroll view, those disappeared on touch.
I solved it by dont setting the background color of the scroll view. It should be enough to set the background color of the conten views.

      //outer layout, where black shapes appear
    LinearLayout outer = new LinearLayout(context);
    outer.setBackgroundColor(Color.MAGENTA);

    ScrollView list = new ScrollView(context);
    list.setLayoutParams(new LayoutParams(100, 300));

    //        do not set the background color here, this causes the blak shapes
    //        list.setBackgroundColor(Color.CYAN);
    //        add an inner layout to the scrollView and set the background of the innerlayout
    LinearLayout linearLayout = new LinearLayout(context);
    linearLayout.setBackgroundColor(Color.CYAN);
    linearLayout.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT));

    list.addView(linearLayout);
    outer.addView(list);