本文主要是介绍左右划屏，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
在网上找到了仿Launcher中的WorkSapce，可以左右滑动切换屏幕的类实现效果就比较理想了：
activity类很简单：
package com.cn;
import android.app.Activity;
import android.os.Bundle;
public class MainActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
}
自定义组件的类ScrollLayout如下：
public class ScrollLayout extends ViewGroup {
private static final String TAG = "ScrollLayout";
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 = 600;
private int mTouchState = TOUCH_STATE_REST;
private int mTouchSlop;
private float mLastMotionX;
private float mLastMotionY;
public ScrollLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
// TODO Auto-generated constructor stub
}
public ScrollLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
mScroller = new Scroller(context);
mCurScreen = mDefaultScreen;
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// TODO Auto-generated method stub
if (changed) {
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) {
Log.e(TAG, "onMeasure");
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);
}
// Log.e(TAG, "moving to screen "+mCurScreen);
scrollTo(mCurScreen * width, 0);
}
/**
*
* According to the position of current layout
*
* scroll to the destination page.
*/
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
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
}
}
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();
}
}
@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();
final float y = event.getY();
switch (action) {
case MotionEvent.ACTION_DOWN:
Log.e(TAG, "event down!");
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
mLastMotionX = x;
break;
case MotionEvent.ACTION_MOVE:
int deltaX = (int) (mLastMotionX - x);
mLastMotionX = x;
scrollBy(deltaX, 0);
break;
case MotionEvent.ACTION_UP:
Log.e(TAG, "event : up");
// if (mTouchState == TOUCH_STATE_SCROLLING) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000);
int velocityX = (int) velocityTracker.getXVelocity();
Log.e(TAG, "velocityX:" + velocityX);
if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
// Fling enough to move left
Log.e(TAG, "snap left");
snapToScreen(mCurScreen - 1);
} else if (velocityX < -SNAP_VELOCITY
&& mCurScreen < getChildCount() - 1) {
// Fling enough to move right
Log.e(TAG, "snap 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
Log.e(TAG, "onInterceptTouchEvent-slop:" + mTouchSlop);
final int action = ev.getAction();
if ((action == MotionEvent.ACTION_MOVE) &&
(mTouchState != TOUCH_STATE_REST)) {
return true;
}
final float x = ev.getX();
final float y = ev.getY();
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;
mLastMotionY = y;
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;
}
}
main.xml:
<?xml version="1.0" encoding="utf-8"?>
<com.cn.ScrollLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/ScrollLayoutTest"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
android:background="#FF00"
android:layout_width="fill_parent"
android:layout_height="fill_parent"></LinearLayout>
<FrameLayout
android:background="#F0F0"
android:layout_width="fill_parent"
android:layout_height="fill_parent"></FrameLayout>
<FrameLayout
android:background="#F00F"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
</FrameLayout>
<LinearLayout
android:background="#FF00"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button1" />
</LinearLayout>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button2" />
</LinearLayout>
</com.cn.ScrollLayout>
这篇关于左右划屏的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
