I can't scroll my customized view

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_height="fill_parent"
        android:layout_width="fill_parent"
        android:orientation="vertica开发者_JAVA技巧l">

    <ScrollView android:id="@+id/scroll"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent" android:fillViewport="true">

        <adam.music.testfont.NwcDrawingArea android:id="@+id/NwcDrawingArea"
              android:layout_height="2000dp"
              android:layout_width="2000dp"
           />
           </ScrollView>
   </LinearLayout>

I created Android Project and edited main.xml as above. And then I customized view to draw image. To see the effect of scrolling customized view I set width and height as above. Now I can see the image in a customized view but it doesn't scroll. Could you help me what the problem is? Should I add something more?

There's an interplay between ScrollView and its contents. For example, if, instead of your NwcDrawingArea widget, you inserted this TextView into your ScrollView:

<TextView android:text="8This is a lot of text 7This is a lot of text 6This is a lot of text 5This is a lot of text 4This is a lot of text 3This is a lot of text 2This is a lot of text 1This is a lot of text"
android:layout_width="10dp"
android:layout_height="2000dp"
android:background="#FF00FF00"
/>

You'll see a skinny green vertical TextView whose text is longer than the screen, and the ScrollView shows scrollbars that let you see the hidden part of the TextView to the extent of the text. Now, change the TextView layout_width="2000dp". The TextView becomes a full-screen green area that has a single line of text that runs off the right side of the screen. ScrollView, of course, shows no horizontal scroll bars. However, ScrollView shows no vertical scroll bars either, even though we sized the TextView to be much longer than the screen. ScrollView is attempting to determine the visually interesting portion of its contents, so you need to understand the behavior for whatever widget you are subclassing.

For example, ScrollView respects the layout sizes of LinearLayout and RelativeLayout in the way that you expected it to behave with TextView. In fact, it is common to make a LinearLayout or RelativeLayout -- rather than a view such as TextView -- the child of a ScrollView. Drop your TextView in a fixed-height LinearLayout and you should get the behavior that you expected.