在Android应用中,一般TabActivity和若干个Tab选项卡(TabWidget)。如果选项卡的数量超过了5个,就不适合放到一个屏幕中,这样可以让这些选项卡滑动起来。
滑动的选项卡的实现有好几种方式,在这些方式中,最简单也是我最满意的还是在原生的TabActivity上修改,将上面的选项卡改为可滑动的状态。这样既有新的滑动的效果,也保留了原有TabActivity的各项功能。
实现Tab可滑动基本的思路就是把上面的TabWidget放到一个HorizontalScrollView中,让TabWidget滑动起来。不过如果仅仅修改XML还是会产生问题,就是没有办法控制每个选项卡的宽度。所以还是需要在程序中设置每个选项卡的宽度。例如:
[java] view
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- // 设置窗口的宽度
- DisplayMetrics dm = new DisplayMetrics();
- getWindowManager().getDefaultDisplay().getMetrics(dm);
- int screenWidth = dm.widthPixels;
- if (count < 4) {
- for (int i = 0; i < count; i++) {
- // 设置每个选项卡的宽度
- tabWidget.getChildTabViewAt(i).setMinimumWidth(screenWidth / 4);
- }
- }
自定义TabActivity主界面的XML:
[html] view
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- <?xml version="1.0" encoding="utf-8"?>
- <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
- android:orientation="vertical" android:layout_width="fill_parent"
- android:layout_height="fill_parent">
- <TabHost android:id="@android:id/tabhost" android:layout_width="fill_parent"
- android:layout_height="fill_parent">
- <LinearLayout android:orientation="vertical"
- android:layout_width="fill_parent" android:layout_height="fill_parent">
- <HorizontalScrollView android:layout_height="wrap_content"
- android:layout_width="fill_parent" android:scrollbars="none">
- <TabWidget android:id="@android:id/tabs"
- android:layout_width="fill_parent" android:layout_height="60dp" />
- </HorizontalScrollView>
- <FrameLayout android:id="@android:id/tabcontent"
- android:layout_width="fill_parent" android:layout_height="wrap_content"
- android:layout_weight="1" />
- </LinearLayout>
- </TabHost>
- </LinearLayout>
效果图如下
上面的tab是可以滑动的,屏幕左右滑动,tab也会切换
[java] view
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- package com.xu81.testflip;
- import java.util.Vector;
- import android.content.Context;
- import android.util.AttributeSet;
- import android.view.MotionEvent;
- import android.view.VelocityTracker;
- import android.view.View;
- import android.view.ViewConfiguration;
- import android.view.ViewGroup;
- import android.widget.Scroller;
- public class ScrollLayout extends ViewGroup {
- private Scroller mScroller;
- private VelocityTracker mVelocityTracker;
- private int mCurScreen;
- private int mDefaultScreen = 0;
- private static final int TOUCH_STATE_REST = 0;
- private static final int TOUCH_STATE_SCROLLING = 1;
- private static final int SNAP_VELOCITY = 500;
- private int mTouchState = TOUCH_STATE_REST;
- private int mTouchSlop;
- private float mLastMotionX;
- private int sensitivity = 30;
- private boolean spring;
- private Vector<LayoutChangeListener> listeners;
- public ScrollLayout(Context context, AttributeSet attrs) {
- super(context, attrs);
- // TODO Auto-generated constructor stub
- mScroller = new Scroller(context);
- mCurScreen = mDefaultScreen;
- mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
- listeners = new Vector<LayoutChangeListener>();
- }
- public void addChangeListener(LayoutChangeListener listener) {
- listeners.add(listener);
- }
- @Override
- protected void onLayout(boolean changed, int l, int t, int r, int b) {
- // TODO Auto-generated method stub
- int childLeft = 0;
- final int childCount = getChildCount();
- for (int i = 0; i < childCount; i++) {
- final View childView = getChildAt(i);
- if (childView.getVisibility() != View.GONE) {
- final int childWidth = childView.getMeasuredWidth();
- childView.layout(childLeft, 0, childLeft + childWidth,
- childView.getMeasuredHeight());
- childLeft += childWidth;
- }
- }
- }
- @Override
- protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
- super.onMeasure(widthMeasureSpec, heightMeasureSpec);
- final int width = MeasureSpec.getSize(widthMeasureSpec);
- final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
- if (widthMode != MeasureSpec.EXACTLY) {
- throw new IllegalStateException(
- "ScrollLayout only canmCurScreen run at EXACTLY mode!");
- }
- final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
- if (heightMode != MeasureSpec.EXACTLY) {
- throw new IllegalStateException(
- "ScrollLayout only can run at EXACTLY mode!");
- }
- // The children are given the same width and height as the scrollLayout
- final int count = getChildCount();
- for (int i = 0; i < count; i++) {
- getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
- }
- scrollTo(mCurScreen * width, 0);
- }
- public void snapToDestination() {
- final int screenWidth = getWidth();
- final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth;
- snapToScreen(destScreen);
- }
- public void snapToScreen(int whichScreen) {
- // get the valid layout page
- int lastIndex = mCurScreen;
- whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
- if (getScrollX() != (whichScreen * getWidth())) {
- final int delta = whichScreen * getWidth() - getScrollX();
- mScroller.startScroll(getScrollX(), 0, delta, 0,
- Math.abs(delta) * 2);
- mCurScreen = whichScreen;
- invalidate(); // Redraw the layout
- }
- for (LayoutChangeListener listener : listeners)
- listener.doChange(lastIndex, whichScreen);
- }
- public void setToScreen(int whichScreen) {
- whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
- mCurScreen = whichScreen;
- scrollTo(whichScreen * getWidth(), 0);
- }
- public int getCurScreen() {
- return mCurScreen;
- }
- @Override
- public void computeScroll() {
- // TODO Auto-generated method stub
- if (mScroller.computeScrollOffset()) {
- scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
- postInvalidate();
- }
- }
- public boolean isSpring() {
- return spring;
- }
- public void setSpring(boolean spring) {
- this.spring = spring;
- }
- @Override
- public boolean onTouchEvent(MotionEvent event) {
- // TODO Auto-generated method stub
- if (mVelocityTracker == null)
- mVelocityTracker = VelocityTracker.obtain();
- mVelocityTracker.addMovement(event);
- final int action = event.getAction();
- final float x = event.getX();
- switch (action) {
- case MotionEvent.ACTION_DOWN:
- if (!mScroller.isFinished())
- mScroller.abortAnimation();
- mLastMotionX = x;
- break;
- case MotionEvent.ACTION_MOVE:
- int deltaX = (int) (mLastMotionX - x);
- if (Math.abs(deltaX) > sensitivity) {
- // 左滑动为正数、右为负数
- if (spring) {
- scrollBy(deltaX, 0);
- mLastMotionX = x;
- } else {
- final int childCount = getChildCount();
- boolean max = mCurScreen < childCount - 1;
- boolean min = mCurScreen > 0;
- boolean canMove = deltaX > 0 ? (max ? true : false)
- : (min ? true : false);
- if (canMove) {
- scrollBy(deltaX, 0);
- mLastMotionX = x;
- }
- }
- }
- break;
- case MotionEvent.ACTION_UP:
- final VelocityTracker velocityTracker = mVelocityTracker;
- velocityTracker.computeCurrentVelocity(1000);
- int velocityX = (int) velocityTracker.getXVelocity();
- if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
- // Fling enough to move left
- snapToScreen(mCurScreen - 1);
- } else if (velocityX < -SNAP_VELOCITY
- && mCurScreen < getChildCount() - 1) {
- // Fling enough to move right
- snapToScreen(mCurScreen + 1);
- } else {
- snapToDestination();
- }
- if (mVelocityTracker != null) {
- mVelocityTracker.recycle();
- mVelocityTracker = null;
- }
- mTouchState = TOUCH_STATE_REST;
- break;
- case MotionEvent.ACTION_CANCEL:
- mTouchState = TOUCH_STATE_REST;
- break;
- }
- return true;
- }
- @Override
- public boolean onInterceptTouchEvent(MotionEvent ev) {
- // TODO Auto-generated method stub
- final int action = ev.getAction();
- if ((action == MotionEvent.ACTION_MOVE)
- && (mTouchState != TOUCH_STATE_REST))
- return true;
- final float x = ev.getX();
- switch (action) {
- case MotionEvent.ACTION_MOVE:
- final int xDiff = (int) Math.abs(mLastMotionX - x);
- if (xDiff > mTouchSlop)
- mTouchState = TOUCH_STATE_SCROLLING;
- break;
- case MotionEvent.ACTION_DOWN:
- mLastMotionX = x;
- mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST
- : TOUCH_STATE_SCROLLING;
- break;
- case MotionEvent.ACTION_CANCEL:
- case MotionEvent.ACTION_UP:
- mTouchState = TOUCH_STATE_REST;
- break;
- }
- return mTouchState != TOUCH_STATE_REST;
- }
- }
这是模仿qq的滑动实现,和tab不是一个思路,也比较美观实用可以借鉴
源码下载
时间: 2024-10-22 22:17:48