Android programming method to realize the sliding effect of novel reader
- 2020-10-07 18:53:09
- OfStack
This paper illustrates the Android programming method to realize the sliding effect of novel readers. To share for your reference, the details are as follows:
Anyone who has read a novel knows that a novel reader has a variety of effects, such as simulated page turning, sliding page turning, and so on. For some reason, I suddenly want to write a simple slide page turning effect. I don't really want to write it here, but I hope you can pick 1 to 3 and write the other effects. I'm not going to draw it.
Here's the code: Just understand the onTouch event
package com.example.testscroll.view;
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 FlipperLayout extends ViewGroup {
private Scroller mScroller;
private VelocityTracker mVelocityTracker;
private int mVelocityValue = 0;
/** Agree on whether the slip is valid or not */
private int limitDistance = 0;
private int screenWidth = 0;
/** The direction of the finger */
private static final int MOVE_TO_LEFT = 0;
private static final int MOVE_TO_RIGHT = 1;
private static final int MOVE_NO_RESULT = 2;
/** The final direction of the result of touch */
private int mTouchResult = MOVE_NO_RESULT;
/** 1 Starting direction */
private int mDirection = MOVE_NO_RESULT;
/** Mode of touch */
private static final int MODE_NONE = 0;
private static final int MODE_MOVE = 1;
private int mMode = MODE_NONE;
/** The sliding view */
private View mScrollerView = null;
/** The top of the view (on the edge, not visible) */
private View currentTopView = null;
/** According to the view , displayed on the screen */
private View currentShowView = null;
/** At the bottom of the view (Not visible) */
private View currentBottomView = null;
public FlipperLayout(Context context) {
super(context);
init(context);
}
public FlipperLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
public FlipperLayout(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
private void init(Context context) {
mScroller = new Scroller(context);
screenWidth = context.getResources().getDisplayMetrics().widthPixels;
limitDistance = screenWidth / 3;
}
/***
*
* @param listener
* @param currentBottomView
* At the bottom of the view You can't see the initial state
* @param currentShowView
* In display View
* @param currentTopView
* The top of the View , slides off the screen when initialized
*/
public void initFlipperViews(TouchListener listener, View currentBottomView, View currentShowView, View currentTopView) {
this.currentBottomView = currentBottomView;
this.currentShowView = currentShowView;
this.currentTopView = currentTopView;
setTouchResultListener(listener);
addView(currentBottomView);
addView(currentShowView);
addView(currentTopView);
/** Default will be uppermost view Slide edge (used to view on 1 Page) */
currentTopView.scrollTo(-screenWidth, 0);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
for (int i = 0; i < getChildCount(); i++) {
View child = getChildAt(i);
int height = child.getMeasuredHeight();
int width = child.getMeasuredWidth();
child.layout(0, 0, width, height);
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
setMeasuredDimension(width, height);
for (int i = 0; i < getChildCount(); i++) {
getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
}
}
private int startX = 0;
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
if (!mScroller.isFinished()) {
break;
}
startX = (int) ev.getX();
break;
}
return super.dispatchTouchEvent(ev);
}
@SuppressWarnings("deprecation")
@Override
public boolean onTouchEvent(MotionEvent event) {
obtainVelocityTracker(event);
switch (event.getAction()) {
case MotionEvent.ACTION_MOVE:
if (!mScroller.isFinished()) {
return super.onTouchEvent(event);
}
if (startX == 0) {
startX = (int) event.getX();
}
final int distance = startX - (int) event.getX();
if (mDirection == MOVE_NO_RESULT) {
if (mListener.whetherHasNextPage() && distance > 0) {
mDirection = MOVE_TO_LEFT;
} else if (mListener.whetherHasPreviousPage() && distance < 0) {
mDirection = MOVE_TO_RIGHT;
}
}
if (mMode == MODE_NONE
&& ((mDirection == MOVE_TO_LEFT && mListener.whetherHasNextPage()) || (mDirection == MOVE_TO_RIGHT && mListener
.whetherHasPreviousPage()))) {
mMode = MODE_MOVE;
}
if (mMode == MODE_MOVE) {
if ((mDirection == MOVE_TO_LEFT && distance <= 0) || (mDirection == MOVE_TO_RIGHT && distance >= 0)) {
mMode = MODE_NONE;
}
}
if (mDirection != MOVE_NO_RESULT) {
if (mDirection == MOVE_TO_LEFT) {
if (mScrollerView != currentShowView) {
mScrollerView = currentShowView;
}
} else {
if (mScrollerView != currentTopView) {
mScrollerView = currentTopView;
}
}
if (mMode == MODE_MOVE) {
mVelocityTracker.computeCurrentVelocity(1000, ViewConfiguration.getMaximumFlingVelocity());
if (mDirection == MOVE_TO_LEFT) {
mScrollerView.scrollTo(distance, 0);
} else {
mScrollerView.scrollTo(screenWidth + distance, 0);
}
} else {
final int scrollX = mScrollerView.getScrollX();
if (mDirection == MOVE_TO_LEFT && scrollX != 0 && mListener.whetherHasNextPage()) {
mScrollerView.scrollTo(0, 0);
} else if (mDirection == MOVE_TO_RIGHT && mListener.whetherHasPreviousPage() && screenWidth != Math.abs(scrollX)) {
mScrollerView.scrollTo(-screenWidth, 0);
}
}
}
break;
case MotionEvent.ACTION_UP:
if (mScrollerView == null) {
return super.onTouchEvent(event);
}
final int scrollX = mScrollerView.getScrollX();
mVelocityValue = (int) mVelocityTracker.getXVelocity();
// scroll Positive left, negative right (),(startX + dx) If the value of 0 , the reset
/*
* android.widget.Scroller.startScroll( int startX, int startY, int
* dx, int dy, int duration )
*/
int time = 500;
if (mMode == MODE_MOVE && mDirection == MOVE_TO_LEFT) {
if (scrollX > limitDistance || mVelocityValue < -time) {
// By moving your finger to the left, you can flip the screen
mTouchResult = MOVE_TO_LEFT;
if (mVelocityValue < -time) {
time = 200;
}
mScroller.startScroll(scrollX, 0, screenWidth - scrollX, 0, time);
} else {
mTouchResult = MOVE_NO_RESULT;
mScroller.startScroll(scrollX, 0, -scrollX, 0, time);
}
} else if (mMode == MODE_MOVE && mDirection == MOVE_TO_RIGHT) {
if ((screenWidth - scrollX) > limitDistance || mVelocityValue > time) {
// Move your finger to the right to flip the screen
mTouchResult = MOVE_TO_RIGHT;
if (mVelocityValue > time) {
time = 250;
}
mScroller.startScroll(scrollX, 0, -scrollX, 0, time);
} else {
mTouchResult = MOVE_NO_RESULT;
mScroller.startScroll(scrollX, 0, screenWidth - scrollX, 0, time);
}
}
resetVariables();
postInvalidate();
break;
}
return true;
}
private void resetVariables() {
mDirection = MOVE_NO_RESULT;
mMode = MODE_NONE;
startX = 0;
releaseVelocityTracker();
}
private TouchListener mListener;
private void setTouchResultListener(TouchListener listener) {
this.mListener = listener;
}
@Override
public void computeScroll() {
super.computeScroll();
if (mScroller.computeScrollOffset()) {
mScrollerView.scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
postInvalidate();
} else if (mScroller.isFinished() && mListener != null && mTouchResult != MOVE_NO_RESULT) {
if (mTouchResult == MOVE_TO_LEFT) {
if (currentTopView != null) {
removeView(currentTopView);
}
currentTopView = mScrollerView;
currentShowView = currentBottomView;
if (mListener.currentIsLastPage()) {
final View newView = mListener.createView(mTouchResult);
currentBottomView = newView;
addView(newView, 0);
} else {
currentBottomView = new View(getContext());
currentBottomView.setVisibility(View.GONE);
addView(currentBottomView, 0);
}
} else {
if (currentBottomView != null) {
removeView(currentBottomView);
}
currentBottomView = currentShowView;
currentShowView = mScrollerView;
if (mListener.currentIsFirstPage()) {
final View newView = mListener.createView(mTouchResult);
currentTopView = newView;
currentTopView.scrollTo(-screenWidth, 0);
addView(currentTopView);
} else {
currentTopView = new View(getContext());
currentTopView.scrollTo(-screenWidth, 0);
currentTopView.setVisibility(View.GONE);
addView(currentTopView);
}
}
mTouchResult = MOVE_NO_RESULT;
}
}
private void obtainVelocityTracker(MotionEvent event) {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(event);
}
private void releaseVelocityTracker() {
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
/***
* Used for real-time callback of touch event callbacks
*
* @author freeson
*/
public interface TouchListener {
/** Slide your finger to the left to check 1 chapter */
final int MOVE_TO_LEFT = 0;
/** Swipe to the right to view up 1 chapter */
final int MOVE_TO_RIGHT = 1;
/**
* create 1 A bearing Text the View
*
* @param direction
* {@link MOVE_TO_LEFT,MOVE_TO_RIGHT}
* @return
*/
public View createView(final int direction);
/***
* Is the current page the first 1 page
*
* @return
*/
public boolean currentIsFirstPage();
/***
* Is the current page last 1 page
*
* @return
*/
public boolean currentIsLastPage();
/**
* Is the current page on 1 Page (to determine slidability)
*
* @return
*/
public boolean whetherHasPreviousPage();
/***
* Whether the current page is under 1 Page (to determine slidability)
*
* @return
*/
public boolean whetherHasNextPage();
}
}
Activity test file:
package com.example.testscroll;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import android.app.Activity;
import android.content.res.AssetManager;
import android.os.Bundle;
import android.os.Handler;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;
import com.example.testscroll.view.FlipperLayout;
import com.example.testscroll.view.FlipperLayout.TouchListener;
import com.example.testscrollactivity.R;
public class MainActivity extends Activity implements OnClickListener, TouchListener {
private String text = "";
private int textLenght = 0;
private static final int COUNT = 400;
private int currentTopEndIndex = 0;
private int currentShowEndIndex = 0;
private int currentBottomEndIndex = 0;
private Handler handler = new Handler() {
public void handleMessage(android.os.Message msg) {
FlipperLayout rootLayout = (FlipperLayout) findViewById(R.id.container);
View recoverView = LayoutInflater.from(MainActivity.this).inflate(R.layout.view_new, null);
View view1 = LayoutInflater.from(MainActivity.this).inflate(R.layout.view_new, null);
View view2 = LayoutInflater.from(MainActivity.this).inflate(R.layout.view_new, null);
rootLayout.initFlipperViews(MainActivity.this, view2, view1, recoverView);
textLenght = text.length();
System.out.println("----textLenght----->" + textLenght);
TextView textView = (TextView) view1.findViewById(R.id.textview);
if (textLenght > COUNT) {
textView.setText(text.subSequence(0, COUNT));
textView = (TextView) view2.findViewById(R.id.textview);
if (textLenght > (COUNT << 1)) {
textView.setText(text.subSequence(COUNT, COUNT * 2));
currentShowEndIndex = COUNT;
currentBottomEndIndex = COUNT << 1;
} else {
textView.setText(text.subSequence(COUNT, textLenght));
currentShowEndIndex = textLenght;
currentBottomEndIndex = textLenght;
}
} else {
textView.setText(text.subSequence(0, textLenght));
currentShowEndIndex = textLenght;
currentBottomEndIndex = textLenght;
}
};
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new ReadingThread().start();
}
@Override
public void onClick(View v) {
}
@Override
public View createView(final int direction) {
String txt = "";
if (direction == TouchListener.MOVE_TO_LEFT) {
currentTopEndIndex = currentShowEndIndex;
final int nextIndex = currentBottomEndIndex + COUNT;
currentShowEndIndex = currentBottomEndIndex;
if (textLenght > nextIndex) {
txt = text.substring(currentBottomEndIndex, nextIndex);
currentBottomEndIndex = nextIndex;
} else {
txt = text.substring(currentBottomEndIndex, textLenght);
currentBottomEndIndex = textLenght;
}
} else {
currentBottomEndIndex = currentShowEndIndex;
currentShowEndIndex = currentTopEndIndex;
currentTopEndIndex = currentTopEndIndex - COUNT;
txt = text.substring(currentTopEndIndex - COUNT, currentTopEndIndex);
}
View view = LayoutInflater.from(this).inflate(R.layout.view_new, null);
TextView textView = (TextView) view.findViewById(R.id.textview);
textView.setText(txt);
System.out.println("-top->" + currentTopEndIndex + "-show->" + currentShowEndIndex + "--bottom-->" + currentBottomEndIndex);
return view;
}
@Override
public boolean whetherHasPreviousPage() {
return currentShowEndIndex > COUNT;
}
@Override
public boolean whetherHasNextPage() {
return currentShowEndIndex < textLenght;
}
@Override
public boolean currentIsFirstPage() {
boolean should = currentTopEndIndex > COUNT;
if (!should) {
currentBottomEndIndex = currentShowEndIndex;
currentShowEndIndex = currentTopEndIndex;
currentTopEndIndex = currentTopEndIndex - COUNT;
}
return should;
}
@Override
public boolean currentIsLastPage() {
boolean should = currentBottomEndIndex < textLenght;
if (!should) {
currentTopEndIndex = currentShowEndIndex;
final int nextIndex = currentBottomEndIndex + COUNT;
currentShowEndIndex = currentBottomEndIndex;
if (textLenght > nextIndex) {
currentBottomEndIndex = nextIndex;
} else {
currentBottomEndIndex = textLenght;
}
}
return should;
}
private class ReadingThread extends Thread {
public void run() {
AssetManager am = getAssets();
InputStream response;
try {
response = am.open("text.txt");
if (response != null) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int i = -1;
while ((i = response.read()) != -1) {
baos.write(i);
}
text = new String(baos.toByteArray(), "UTF-8");
baos.close();
response.close();
handler.sendEmptyMessage(0);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
xml layout file:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<TextView
android:id="@+id/textview"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1.0"
android:background="#666666"
android:gravity="center"
android:text=" The new View"
android:textColor="@android:color/white"
android:textSize="16sp"
android:visibility="visible" />
<View
android:layout_width="5dp"
android:layout_height="match_parent"
android:background="#FFFF00"
android:gravity="center"
android:textSize="25sp"
android:visibility="visible" />
</LinearLayout>activity layout file:
<com.example.testscroll.view.FlipperLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</com.example.testscroll.view.FlipperLayout>Note: Why add a rate calculator above? In fact, it is just to identify whether this action is a fast sliding action. Even if the distance of sliding is less than 1/3 of the screen, as long as the rate meets, it can be determined that sliding is a page-turning action.
Note: This is just one of the sliding effects, not including the chapter logic. Although a little rough, but there are still worth learning, if you have any good solutions, you can discuss 1.
Attach the demo download address and click here to download demo.
I hope this article has been helpful in Android programming.