我的 android 应用程序中有水平滚动视图，带有下一个和上一个按钮。我只想在 scollview 需要滚动时显示这些按钮。即，滚动视图内容的宽度超过显示宽度。还想在到达第一个和下一个时隐藏上一个和下一个按钮分别是最后一个项目。单击这些按钮时如何转到下一个/上一个项目？
主要的.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/mainLayout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#ffffff" >
<Button
android:id="@+id/btnPrevoius"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:text="Previous"
android:visibility="gone" />
<HorizontalScrollView
android:id="@+id/horizontalScrollView1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_marginLeft="5dip"
android:layout_marginRight="5dip"
android:layout_toLeftOf="@+id/btnNext"
android:layout_toRightOf="@+id/btnPrevoius"
android:fillViewport="true" >
<LinearLayout
android:id="@+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
</LinearLayout>
</HorizontalScrollView>
<Button
android:id="@+id/btnNext"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:text="Next"
android:visibility="gone" />
</RelativeLayout>
活动
public class SampleActivity extends Activity {
private static LinearLayout linearLayout;
private static HorizontalScrollView horizontalScrollView;
private static Button btnPrevious;
private static Button btnNext;
private static int displayWidth = 0;
private static int arrowWidth = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
horizontalScrollView = (HorizontalScrollView) findViewById(R.id.horizontalScrollView1);
linearLayout = (LinearLayout) findViewById(R.id.linearLayout1);
btnPrevious = (Button) findViewById(R.id.btnPrevoius);
btnNext = (Button) findViewById(R.id.btnNext);
for (int i = 0; i < 15; i++) {
Button button = new Button(this);
button.setTag(i);
button.setText("---");
linearLayout.addView(button);
}
ViewTreeObserver vto = linearLayout.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
ViewTreeObserver obs = linearLayout.getViewTreeObserver();
obs.removeGlobalOnLayoutListener(this);
Display display = getWindowManager().getDefaultDisplay();
displayWidth = display.getWidth();
if (linearLayout.getMeasuredWidth() > (displayWidth - 40)) {
btnPrevious.setVisibility(View.VISIBLE);
btnNext.setVisibility(View.VISIBLE);
}
}
});
btnPrevious.setOnClickListener(listnerLeftArrowButton);
horizontalScrollView.setOnTouchListener(listenerScrollViewTouch);
}
private OnTouchListener listenerScrollViewTouch = new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
showHideViews();
return false;
}
};
private OnClickListener listnerLeftArrowButton = new OnClickListener() {
@Override
public void onClick(View v) {
horizontalScrollView.onKeyDown(KeyEvent.KEYCODE_DPAD_RIGHT, new KeyEvent(0, 0));
}
};
public static void showHideViews() {
int maxScrollX = horizontalScrollView.getChildAt(0).getMeasuredWidth()- displayWidth;
Log.e("TestProjectActivity", "scroll X = " +horizontalScrollView.getScrollX() );
Log.i("TestProjectActivity", "scroll Width = " +horizontalScrollView.getMeasuredWidth() );
Log.d("TestProjectActivity", "Max scroll X = " + maxScrollX);
if (horizontalScrollView.getScrollX() == 0) {
hideLeftArrow();
} else {
showLeftArrow();
}
if (horizontalScrollView.getScrollX() == maxScrollX) {
showRightArrow();
} else {
//hideRightArrow();
}
}
private static void hideLeftArrow() {
btnPrevious.setVisibility(View.GONE);
}
private static void showLeftArrow() {
btnPrevious.setVisibility(View.VISIBLE);
}
private static void hideRightArrow() {
btnNext.setVisibility(View.GONE);
}
private static void showRightArrow() {
btnNext.setVisibility(View.VISIBLE);
}
}
这个'maxScrollX'值对我来说不正确。如何为此找到最大滚动值？
提前致谢