我正在开发具有主屏幕的应用程序。此主屏幕的行为应类似于 android 主屏幕，您可以通过将手指放在触摸屏上来在多个 View 之间切换。
解决方法很简单。我有 3 个 View 实例、右、左和当前 View 。我从之前初始化的 viewflipper 中获得了这些实例。因为我有一台 HTC G1，所以我的屏幕宽度为 320 像素，高度为 480 像素。
想象一下，当您触摸屏幕时，您捕获了一个向下 Action 事件的向下值。然后你移动你的手指，屏幕应该以完全相同的方式移动，所以你必须重新计算 View 的位置。到目前为止它对我有用，但我面临一个奇怪的问题。当您在不移动手指但将其在屏幕上停留不到一秒钟的情况下触摸右 View 时， View 会消失并显示左 View 。
这是我的代码:
public class MainActivity extends Activity implements OnTouchListener{
private ViewFlipper vf;
private float downXValue;
private View view1, view2, view3;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
this.vf = (ViewFlipper) findViewById(R.id.flipper);
if(this.vf != null){
this.view1 = vf.getChildAt(0);
this.view2 = vf.getChildAt(1);
this.view3 = vf.getChildAt(2);
vf.setDisplayedChild(0);
}
LinearLayout layMain = (LinearLayout) findViewById(R.id.layout_main);
layMain.setOnTouchListener((OnTouchListener) this);
}
public boolean onTouch(View v, MotionEvent arg1) {
final View currentView = vf.getCurrentView();
final View leftView, rightView;
if(currentView == view1){
leftView = view3;
rightView = view2;
}else if(currentView == view2){
leftView = view1;
rightView = view3;
}else if(currentView == view3){
leftView = view2;
rightView = view1;
}else{
leftView = null;
rightView = null;
}
switch (arg1.getAction()){
case MotionEvent.ACTION_DOWN:{
this.downXValue = arg1.getX();
break;
}
case MotionEvent.ACTION_UP:{
float currentX = arg1.getX();
if ((downXValue < currentX)){
if(currentView != view3){
float t3 = (320-(currentX-downXValue))/320;
this.vf.setInAnimation(AnimationHelper.inFromLeftAnimation(t3));
this.vf.setOutAnimation(AnimationHelper.outToRightAnimation(t3));
this.vf.showPrevious(); }
}
if ((downXValue > currentX)){
if(currentView != view2){
float t = (320-(downXValue-currentX))/320;
this.vf.setInAnimation(AnimationHelper.inFromRightAnimation(t));
this.vf.setOutAnimation(AnimationHelper.outToLeftAnimation(t));
this.vf.showNext();}
}
}
break;
case MotionEvent.ACTION_MOVE:{
leftView.setVisibility(View.VISIBLE);
rightView.setVisibility(View.VISIBLE);
float currentX = arg1.getX();
if(downXValue > currentX){
if(currentView != view2){
currentView.layout((int) (currentX - downXValue),
currentView.getTop(),
(int) (currentX - downXValue) + 320,
currentView.getBottom());
}
}
if(downXValue < currentX){
if(currentView != view3){
currentView.layout((int) (currentX - downXValue),
currentView.getTop(),
(int) (currentX - downXValue) + 320,
currentView.getBottom());
}
}
leftView.layout(currentView.getLeft()-320, leftView.getTop(),
currentView.getLeft(), leftView.getBottom());
rightView.layout(currentView.getRight(), rightView.getTop(),
currentView.getRight() + 320, rightView.getBottom());
}
}
return true;
}
public static class AnimationHelper {
public static Animation inFromRightAnimation(float param) {
Animation inFromRight = new TranslateAnimation(
Animation.RELATIVE_TO_PARENT, +param,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f);
inFromRight.setDuration(250);
inFromRight.setInterpolator(new AccelerateInterpolator());
return inFromRight;
}
public static Animation outToLeftAnimation(float param) {
Animation outtoLeft = new TranslateAnimation(
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, -param,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f);
outtoLeft.setDuration(250);
outtoLeft.setInterpolator(new AccelerateInterpolator());
return outtoLeft;
}
// for the next movement
public static Animation inFromLeftAnimation(float param) {
Animation inFromLeft = new TranslateAnimation(
Animation.RELATIVE_TO_PARENT, -param,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f);
inFromLeft.setDuration(250);
inFromLeft.setInterpolator(new AccelerateInterpolator());
return inFromLeft;
}
public static Animation outToRightAnimation(float param) {
Animation outtoRight = new TranslateAnimation(
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, +param,
Animation.RELATIVE_TO_PARENT, 0.0f,
Animation.RELATIVE_TO_PARENT, 0.0f);
outtoRight.setDuration(250);
outtoRight.setInterpolator(new AccelerateInterpolator());
return outtoRight;
}
}
}
我认为这样的主屏幕是一个有趣的 UI 元素。
有什么想法吗？
最佳答案
编辑(2012 年 7 月 3 日):
由于似乎仍然有很多关于这个答案的观点和评论，我想我应该添加一个注释，即对于较新的 SDK，您现在应该使用 ViewPager而是具有相同的功能。该类也包含在Android Support library 中。因此您也可以使用它在早期的 Android 设备上运行。
编辑(2013 年 3 月 4 日):
既然还有人来这里，我也想说我把 ViewPager 放在一起，背景以较慢的速度移动，以产生视差效果。代码是here .
如果您真的想手动完成所有操作，原始答案在下面...
我想你可以在这里找到你要找的东西:http://www.anddev.org/why_do_not_these_codes_work-t4012.html
我在另一个项目中使用它来创建具有不同 View 的主屏幕。这直接来自 Android 启动器，在关注该线程后效果很好。
这是我的代码...首先是源代码
package com.matthieu.launcher;
import android.content.Context;
import android.util.Log;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewConfiguration;
import android.widget.Scroller;
public class DragableSpace extends ViewGroup {
private Scroller mScroller;
private VelocityTracker mVelocityTracker;
private int mScrollX = 0;
private int mCurrentScreen = 0;
private float mLastMotionX;
private static final String LOG_TAG = "DragableSpace";
private static final int SNAP_VELOCITY = 1000;
private final static int TOUCH_STATE_REST = 0;
private final static int TOUCH_STATE_SCROLLING = 1;
private int mTouchState = TOUCH_STATE_REST;
private int mTouchSlop = 0;
public DragableSpace(Context context) {
super(context);
mScroller = new Scroller(context);
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
this.setLayoutParams(new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.FILL_PARENT));
}
public DragableSpace(Context context, AttributeSet attrs) {
super(context, attrs);
mScroller = new Scroller(context);
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
this.setLayoutParams(new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT ,
ViewGroup.LayoutParams.FILL_PARENT));
TypedArray a=getContext().obtainStyledAttributes(attrs,R.styleable.DragableSpace);
mCurrentScreen = a.getInteger(R.styleable.DragableSpace_default_screen, 0);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
/*
* This method JUST determines whether we want to intercept the motion.
* If we return true, onTouchEvent will be called and we do the actual
* scrolling there.
*/
/*
* Shortcut the most recurring case: the user is in the dragging state
* and he is moving his finger. We want to intercept this motion.
*/
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:
/*
* mIsBeingDragged == false, otherwise the shortcut would have caught it. Check
* whether the user has moved far enough from his original down touch.
*/
/*
* Locally do absolute value. mLastMotionX is set to the y value
* of the down event.
*/
final int xDiff = (int) Math.abs(x - mLastMotionX);
boolean xMoved = xDiff > mTouchSlop;
if (xMoved) {
// Scroll if the user moved far enough along the X axis
mTouchState = TOUCH_STATE_SCROLLING;
}
break;
case MotionEvent.ACTION_DOWN:
// Remember location of down touch
mLastMotionX = x;
/*
* If being flinged and user touches the screen, initiate drag;
* otherwise don't. mScroller.isFinished should be false when
* being flinged.
*/
mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING;
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
// Release the drag
mTouchState = TOUCH_STATE_REST;
break;
}
/*
* The only time we want to intercept motion events is if we are in the
* drag mode.
*/
return mTouchState != TOUCH_STATE_REST;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
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:
Log.i(LOG_TAG, "event : down");
/*
* If being flinged and user touches, stop the fling. isFinished
* will be false if being flinged.
*/
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
// Remember where the motion event started
mLastMotionX = x;
break;
case MotionEvent.ACTION_MOVE:
// Log.i(LOG_TAG,"event : move");
// if (mTouchState == TOUCH_STATE_SCROLLING) {
// Scroll to follow the motion event
final int deltaX = (int) (mLastMotionX - x);
mLastMotionX = x;
//Log.i(LOG_TAG, "event : move, deltaX " + deltaX + ", mScrollX " + mScrollX);
if (deltaX < 0) {
if (mScrollX > 0) {
scrollBy(Math.max(-mScrollX, deltaX), 0);
}
} else if (deltaX > 0) {
final int availableToScroll = getChildAt(getChildCount() - 1)
.getRight()
- mScrollX - getWidth();
if (availableToScroll > 0) {
scrollBy(Math.min(availableToScroll, deltaX), 0);
}
}
// }
break;
case MotionEvent.ACTION_UP:
Log.i(LOG_TAG, "event : up");
// if (mTouchState == TOUCH_STATE_SCROLLING) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000);
int velocityX = (int) velocityTracker.getXVelocity();
if (velocityX > SNAP_VELOCITY && mCurrentScreen > 0) {
// Fling hard enough to move left
snapToScreen(mCurrentScreen - 1);
} else if (velocityX < -SNAP_VELOCITY
&& mCurrentScreen < getChildCount() - 1) {
// Fling hard enough to move right
snapToScreen(mCurrentScreen + 1);
} else {
snapToDestination();
}
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
// }
mTouchState = TOUCH_STATE_REST;
break;
case MotionEvent.ACTION_CANCEL:
Log.i(LOG_TAG, "event : cancel");
mTouchState = TOUCH_STATE_REST;
}
mScrollX = this.getScrollX();
return true;
}
private void snapToDestination() {
final int screenWidth = getWidth();
final int whichScreen = (mScrollX + (screenWidth / 2)) / screenWidth;
Log.i(LOG_TAG, "from des");
snapToScreen(whichScreen);
}
public void snapToScreen(int whichScreen) {
Log.i(LOG_TAG, "snap To Screen " + whichScreen);
mCurrentScreen = whichScreen;
final int newX = whichScreen * getWidth();
final int delta = newX - mScrollX;
mScroller.startScroll(mScrollX, 0, delta, 0, Math.abs(delta) * 2);
invalidate();
}
public void setToScreen(int whichScreen) {
Log.i(LOG_TAG, "set To Screen " + whichScreen);
mCurrentScreen = whichScreen;
final int newX = whichScreen * getWidth();
mScroller.startScroll(newX, 0, 0, 0, 10);
invalidate();
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int childLeft = 0;
final int count = getChildCount();
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (child.getVisibility() != View.GONE) {
final int childWidth = child.getMeasuredWidth();
child.layout(childLeft, 0, childLeft + childWidth, child
.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("error mode.");
}
final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (heightMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("error mode.");
}
// The children are given the same width and height as the workspace
final int count = getChildCount();
for (int i = 0; i < count; i++) {
getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
}
Log.i(LOG_TAG, "moving to screen "+mCurrentScreen);
scrollTo(mCurrentScreen * width, 0);
}
@Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
mScrollX = mScroller.getCurrX();
scrollTo(mScrollX, 0);
postInvalidate();
}
}
}
还有布局文件:
<?xml version="1.0" encoding="utf-8"?>
<com.matthieu.launcher.DragableSpace xmlns:app="http://schemas.android.com/apk/res/com.matthieu.launcher"
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/space"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
app:default_screen="1"
>
<include android:id="@+id/left" layout="@layout/left_screen" />
<include android:id="@+id/center" layout="@layout/initial_screen" />
<include android:id="@+id/right" layout="@layout/right_screen" />
</com.matthieu.launcher.DragableSpace>
为了能够在 xml 文件中拥有额外的属性，您希望将其保存在 res/values/attrs.xml 中
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="DragableSpace">
<attr name="default_screen" format="integer"/>
</declare-styleable>
</resources>
关于android - 开发 Android 主屏幕，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/3467461/