Viewpager 的相关总结

public class FixedSpeedScroller extends Scroller {
private int mDuration = 300;

public FixedSpeedScroller(Context context) {
super(context);
}

public FixedSpeedScroller(Context context, android.view.animation.Interpolator interpolator) {
super(context, interpolator);
}

public FixedSpeedScroller(Context context, android.view.animation.Interpolator interpolator, boolean flywheel) {
super(context, interpolator, flywheel);
}

@Override
public void startScroll(int startX, int startY, int dx, int dy, int duration) {
super.startScroll(startX, startY, dx, dy, mDuration);
}

@Override
public void startScroll(int startX, int startY, int dx, int dy) {
super.startScroll(startX, startY, dx, dy, mDuration);
}
}

private void setViewPagerScrollSpeed(){
try {
Field mScroller = null;
mScroller = ViewPager.class.getDeclaredField("mScroller");
if(mScroller != null){
mScroller.setAccessible(true);
FixedSpeedScroller scroller = new FixedSpeedScroller( getContext(), new LinearInterpolator());
mScroller.set(mUserInfoViewPager, scroller);
}
}catch(NoSuchFieldException e){

}catch (IllegalArgumentException e){

}catch (IllegalAccessException e){

}
}

mUserInfoViewPager.setPageTransformer(true, new PageTransformer() {

private static final float MIN_SCALE = 0.85f;
private static final float MIN_ALPHA = 0.5f;

@Override
public void transformPage(View view, float position) {
//
int pageWidth = view.getWidth();
int pageHeight = view.getHeight();

if (position < -1)  {
view.setAlpha(0);

} else if (position <= 1) {
//a页滑动至b页 ； a页从 0.0 -1 ；b页从1 ~ 0.0
// [-1,1]
// Modify the default slide transition to shrink the page as well
float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position));
float vertMargin = pageHeight * (1 - scaleFactor) / 2;
float horzMargin = pageWidth * (1 - scaleFactor) / 2;
if (position < 0){
view.setTranslationX(horzMargin - vertMargin / 2);
} else  {
view.setTranslationX(-horzMargin + vertMargin / 2);
}

// Scale the page down (between MIN_SCALE and 1)
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);

// Fade the page relative to its size.
view.setAlpha(MIN_ALPHA + (scaleFactor - MIN_SCALE)/ (1 - MIN_SCALE) * (1 - MIN_ALPHA));

} else  { // (1,+Infinity]
// This page is way off-screen to the right.
view.setAlpha(0);
}

}
});

package com.joyodream.pingo.near.ui;

import java.lang.reflect.Field;

import android.content.Context;
import android.graphics.Camera;
import android.graphics.Matrix;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.LinearInterpolator;
import android.view.animation.Transformation;
import android.widget.Scroller;

import com.joyodream.common.util.DipPixelUtil;

/**
*
* 自定义的展示图片的控件
* 通过Camera 调整z轴距离，实现图片放大缩小
*
* 注意：
* 1、为了实现在屏幕上面看到多个Item，需要在滑动的过程中刷新父控件
* 2、另外，通过设置clipChildren = false，不去裁剪子控件的绘图区域
* 3、
*
* @author lipeilong
*
*/
public class NearViewPager extends ViewPager {

/**
* The camera class is used to 3D transformation matrix.
*/
private Camera mCamera = new Camera();

/**
* The max zoom value (Z axis).
*/
private int mMaxZoom     = -120;

private int mMaxAlpha    = 0x8f;

private OnPageChangeListener mScrollListener;

private int mScrollPosition;

private int mScrollOffset;

public int mCurPosition;

private float mDownX;

private float mDownY;

private boolean mClick;

public NearViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
//
init();
}

public NearViewPager(Context context) {
super(context);
//
init();
}

private void init() {

// Enable set transformation.
this.setStaticTransformationsEnabled(true);
// Enable set the children drawing order.
this.setChildrenDrawingOrderEnabled(true);

this.setOverScrollMode(ViewPager.OVER_SCROLL_NEVER);
super.setOnPageChangeListener(new MyOnPageChangeListener());

setViewPagerScrollSpeed();
}

private void setViewPagerScrollSpeed(){
try {
Field mScroller = null;
mScroller = ViewPager.class.getDeclaredField("mScroller");
if(mScroller != null){
mScroller.setAccessible(true);
FixedSpeedScroller scroller = new FixedSpeedScroller( getContext(), new LinearInterpolator());
mScroller.set(this, scroller);
}
}catch(NoSuchFieldException e){

}catch (IllegalArgumentException e){

}catch (IllegalAccessException e){

}
}

@Override
protected int getChildDrawingOrder(int childCount, int i) {
// Current selected index.
int selectedIndex = getCurrentItem();

if (selectedIndex < 0) {
return i;
}

if (i < selectedIndex) {
return i;
} else if (i >= selectedIndex) {
return childCount - 1 - i + selectedIndex;
} else {
return i;
}
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
}

@Override
protected boolean getChildStaticTransformation(View child, Transformation t) {
super.getChildStaticTransformation(child, t);
t.clear();
t.setTransformationType(Transformation.TYPE_MATRIX);

int index    = findViewIndex(child);
if(index != -1){
transformImageBitmap(child, t, index);
}

return true;
}

/**
*
*  找出子控件的索引
* @param child
* @return
*/
private int findViewIndex(View child){

int index = (Integer) child.getTag();

return index;
}

/**
*
*  刷新所有的子控件，通过这个来触发 getChildStaticTransformation 的调用
*
*/
private void invalidateVisibleChilds() {
for (int i = 0; i < getChildCount(); i++) {
getChildAt(i).invalidate();
}
}

/**
*
* @param child
* @param t
* @param index
*/
private void transformImageBitmap(View child, Transformation t, int index) {

mCamera.save();

final Matrix imageMatrix     = t.getMatrix();
final int imageHeight         = child.getHeight();
final int imageWidth         = child.getWidth();
int        width            = getPageMargin() + imageWidth;

if(index == mScrollPosition){ // 当前项从最大变化到最小 z轴变化范围 mMaxZoom *（1 -- 0）

float dz        = mMaxZoom * ( 1- mScrollOffset * 1f / width);
int alpha        = (int) (mMaxAlpha * mScrollOffset * 1f / width);
mCamera.translate(0, 0, dz);

if(child instanceof NearImageView){
((NearImageView)child).setShadeAlpha(alpha);
}

}else if(index == mScrollPosition + 1){ // 当前项的后一项从最小变化到最大 ，z轴变化范围 mMaxZoom * (0 -- 1)

float dz         =  mMaxZoom * mScrollOffset * 1f / width;

int alpha        = (int) (mMaxAlpha * ( 1- mScrollOffset * 1f / width ));
mCamera.translate(0, 0, dz);

if(child instanceof NearImageView){
((NearImageView)child).setShadeAlpha(alpha);
}

}else { // 当前项的后2项或者前N项大小不发生变化，z轴不变
mCamera.translate(0, 0, 0);

if(child instanceof NearImageView){
((NearImageView)child).setShadeAlpha(mMaxAlpha);
}
}

mCamera.getMatrix(imageMatrix);

imageMatrix.postTranslate((imageWidth / 2), (imageHeight / 2));
imageMatrix.preTranslate(-(imageWidth / 2), -(imageHeight / 2));

mCamera.restore();
}

@Override
public void setOnPageChangeListener(OnPageChangeListener listener) {
mScrollListener = listener;
};

/**
* @author lipeilong
*
*/
private class MyOnPageChangeListener implements OnPageChangeListener {

@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
if (mScrollListener != null) {
mScrollListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
}

mScrollPosition = position;
mScrollOffset    = positionOffsetPixels;

// 刷新子控件
if(System.currentTimeMillis() % 2 == 0){

invalidateVisibleChilds();
}
}

@Override
public void onPageSelected(int position) {
mCurPosition    = position;
if (mScrollListener != null) {
mScrollListener.onPageSelected(position);
}
}

@Override
public void onPageScrollStateChanged(final int state) {

if (mScrollListener != null) {
mScrollListener.onPageScrollStateChanged(state);
}
}
}

@Override
public boolean onTouchEvent(MotionEvent ev) {
//
final float MAX_DISTANCE    = 50;
switch(ev.getAction()){
case MotionEvent.ACTION_DOWN:
mDownX    = ev.getRawX();
mDownY    = ev.getRawY();
mClick    = true;
break;
case MotionEvent.ACTION_UP:
if(mClick && Math.abs(ev.getRawX()- mDownX) < MAX_DISTANCE && Math.abs(ev.getRawY() - mDownY) < MAX_DISTANCE){
// 点击事件
performMyClick(ev);

}
break;
case MotionEvent.ACTION_MOVE:
if(Math.abs(ev.getRawX()- mDownX) > MAX_DISTANCE || Math.abs(ev.getRawY() - mDownY) > MAX_DISTANCE){
mClick = false;
}
break;
}

return super.onTouchEvent(ev);
}

private void performMyClick(MotionEvent ev){

int index    = getCurrentItem();
if(isAtLeft(ev)){
setCurrentItem(index - 1);
}else if(isAtRight(ev)){
setCurrentItem(index + 1);
}

}

private boolean isAtLeft(MotionEvent ev){
int margin    = DipPixelUtil.dip2px(getContext(), 56);
int left    = getLeft() - margin;
int right    = getRight() + margin;
int top        = getTop();
int bottom    = getBottom();

// 必须使用全局坐标，同时要减去title和通知栏高度
int x        = (int) ev.getRawX();
int y        = (int) ev.getRawY() - DipPixelUtil.dip2px(getContext(), 96);
if(y > top && y < bottom){

if(x < left){
return true;
}
}

return false;
}

private boolean isAtRight(MotionEvent ev){
int margin    = DipPixelUtil.dip2px(getContext(), 56);
int left    = getLeft() - margin;
int right    = getRight() + margin;
int top        = getTop();
int bottom    = getBottom();

int x        = (int) ev.getRawX();
int y        = (int) ev.getRawY() - DipPixelUtil.dip2px(getContext(), 96);
if(y > top && y < bottom){

if(x > right){
return true;
}
}

return false;
}

public class FixedSpeedScroller extends Scroller {
private int mDuration = 300;

public FixedSpeedScroller(Context context) {
super(context);
}

public FixedSpeedScroller(Context context, android.view.animation.Interpolator interpolator) {
super(context, interpolator);
}

public FixedSpeedScroller(Context context, android.view.animation.Interpolator interpolator, boolean flywheel) {
super(context, interpolator, flywheel);
}

@Override
public void startScroll(int startX, int startY, int dx, int dy, int duration) {
super.startScroll(startX, startY, dx, dy, mDuration);
}

@Override
public void startScroll(int startX, int startY, int dx, int dy) {
super.startScroll(startX, startY, dx, dy, mDuration);
}
}
}