精心打造的，仅支持左滑的ItemLayout
前言：
-
这个
ItemLayout出现的的初衷是为了配合ListVieworRecyclerView实现侧滑的。但是我实在是太天真了。这个ItemLayout实现侧滑当然没有问题。放在ListVieworRecyclerView里面也可以侧滑。~~但是，凡是都有个但是。~~但是，将这个ItemLayout作为Item使用的时候，无论是ListView还是RecyclerView都不好管理。也就是说，很难在ListVieworRecyclerView中，去知道哪个Item是侧滑打开的，哪个不是。然后是怎样去关闭已经打开的Item.比如：一个常见的使用场景是：当前已经有一个Item被打开了。然后，现在想去打开另外一个，就应该先去关闭上一个，再打开当前想要打开的。但是，真的太麻烦了。我能想到的一个方案就是获取所有的ItemLayout然后遍历处理。但是，如果这样做，我感觉真的已经失去了意义。如果是这样做，还不如去使用现成的开源库。最起码不会那么蹩脚。 -
但是，
凡事都有个但是啊。 -
虽然这个
SwipeItemLayout似乎没有使用场景了。可能唯一的使用场景是，一个布局里面有那么一两个Item是需要侧滑的。这时候倒是可以使用上。因为只有几个侧滑的Item控制起来比较容易。 -
看到网上的很多侧滑菜单，其实是没有考虑内边距
padding和外边距的margin。使用起来就没有办法设置这些。因为设置了也没用。于是准备自己写一个的....
后语：
-
虽然这个
ItemLayout可能是没有什么使用场景了。但是毕竟是一番心血。况且，里面对padding和margin都有很好的支持。对滑动边界的检测，对事件冲突的处理，对滑动释放的处理，个人感觉都处理的很完善。当然，一定是有不足之处的。不过就目前而言，里面的，我能想到的，需要处理的，都处理好了。 -
这个
ItemLayout算是对ViewDragHelper的一次实践吧。顺便吐槽一句：ViewDragHelper对边界处理是不算友好的。里面的边界处理计算值，我是打了好多log才慢慢找到规律，然后正确处理的。 -
add: 自己横向滑动时，不让父容器滑动。2017-05-07 22:07:55
好吧。前言后语就这些了。 顺便安利一个
log库：从Log切换到LogUtils。 这个log库满足你对log的所有幻想！
源码如下：
package com.python.cat.animatebutton.view;
import android.content.Context;
import android.support.annotation.IntRange;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.view.ViewCompat;
import android.support.v4.widget.ViewDragHelper;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import com.python.cat.animatorbutton.BuildConfig;
import java.util.ArrayList;
import java.util.List;
import static com.python.cat.animatebutton.view.SwipeItemLayout.State.Center;
import static com.python.cat.animatebutton.view.SwipeItemLayout.State.Right;
/**
* packageName: com.python.cat.animatebutton.view
* Created on 2017/5/6.
* 右边有菜单的item
*
* @author cat
*/
public class SwipeItemLayout extends FrameLayout {
@SuppressWarnings("FieldCanBeLocal")
private int mHeight;
private int mWidth;
private ViewDragHelper mDragHelper;
private List<ItemPos> mItemSet;
private OnOpenStatedListener mViewStateListener;
private DragCallback mDragCallBack;
public SwipeItemLayout(Context context) {
this(context, null);
}
public SwipeItemLayout(Context context, @Nullable AttributeSet attrs) {
this(context, attrs, 0);
}
public SwipeItemLayout(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
// setOrientation(HORIZONTAL); // 验证说明ok
initDragHelper();
}
private void initDragHelper() {
mDragCallBack = new DragCallback();
mDragHelper = ViewDragHelper.create(this, 1, mDragCallBack);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
// LogUtils.w("on measure....");
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
// LogUtils.w("on finish inflate....");
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
this.mWidth = w;
this.mHeight = h;
int touchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
// LogUtils.i("touchSlop = %d", touchSlop);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
// super.onLayout(changed, left, top, right, bottom);
layoutChildren(0, 0);
// LogUtils.w("on layout.........");
}
private void layoutChildren(int dx, int dy) {
mItemSet = new ArrayList<>();
mItemSet.clear();
int childCount = getChildCount();
int cl, ct, cr, cb;
int tempX = 0;
boolean isFirstView;
for (int i = 0; i < childCount; i++) {
isFirstView = i == 0;
View child = getChildAt(i);
MarginLayoutParams params = getChildLayoutParams(child);
cl = tempX + params.leftMargin + dx;
ct = params.topMargin + get().getPaddingTop() + dy;
if (isFirstView) {
// first view
cl += get().getPaddingLeft();
}
cr = cl + getChildWidth(child);
cb = ct + getChildHeight(child);
tempX += cr + params.rightMargin;
//noinspection unused
int bX = getChildWidth(child)
+ params.leftMargin + params.rightMargin
+ getPaddingLeft() + getPaddingRight();
// 当子View完全填充时， ax == bx
// LogUtils.w("index ---ax= " + aX + " , bx=" + bX);
// LogUtils.w("index = %d, left= %d, top= %d, right=%d, bottom=%d", cl, ct, cr, cb);
child.layout(cl, ct, cr, cb);
ItemPos it = new ItemPos(i, cl, ct, cr, cb);
mItemSet.add(it);
}
}
private class ItemPos {
int index;
int left;
int top;
int right;
int bottom;
ItemPos(int index, int left, int top, int right, int bottom) {
this.index = index;
this.left = left;
this.top = top;
this.right = right;
this.bottom = bottom;
}
}
@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
return mDragHelper.shouldInterceptTouchEvent(event);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
mDragHelper.processTouchEvent(event);
return true;
}
private class DragCallback extends ViewDragHelper.Callback {
State mCurrentOpen = Center; // default is center
ScrollState scrollState = new ScrollState();
@IntRange(from = 0, to = 2)
private int mDragState = ViewDragHelper.STATE_IDLE; // default is idle
class ScrollState {
static final int LEFT = -1;
static final int RIGHT = 1;
int scrollDirection; // Left or Right
@Override
public String toString() {
return "ScrollState{" +
"scrollDirection=" + scrollDirection +
'}';
}
}
@Override
public int getViewHorizontalDragRange(View child) {
int dx = getMeasuredWidth() - child.getMeasuredWidth();
// LogUtils.w("dx = " + dx);
return dx;
}
@Override
public boolean tryCaptureView(View child, int pointerId) {
return true;
}
/**
* @param left 父容器的左侧，到child的左侧的距离
*/
@Override
public int clampViewPositionHorizontal(View child, int left, int dx) {
// LogUtils.w("clampH : " + left + " , " + dx + " , " + child);
getParent().requestDisallowInterceptTouchEvent(true); // 不给外层布局上下滑动
View childAt1 = getChildAt(1);
// 滑动第一个view
if (child == getChildAt(0)) {
// left [getPaddingLeft() + getChildLayoutParams(child).leftMargin,
int maxL = getPaddingLeft() + getChildLayoutParams(child).leftMargin;
if (left > maxL) {
// 向右 ok
left = maxL;
} else {
// 向左 ok
int min = mWidth - getChildWidthWithMargin(child) - getChildWidthWithMargin(childAt1);
if (left < min) {
left = min;
}
}
}
// 滑动第二个view
else if (child == getChildAt(1)) {
int max = mItemSet.get(1).left;
int min = mWidth - getChildWidthWithMargin(child) - getPaddingRight();
if (left > max) {
// 向右 ok
left = max;
} else if (left < min) {
// 向左 ok
left = min;
}
}
if (dx > 0) {
scrollState.scrollDirection = ScrollState.RIGHT;
} else if (dx < 0) {
scrollState.scrollDirection = ScrollState.LEFT;
}
return left;
}
@Override
public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {
// LogUtils.w("onViewPositionChanged : " + left + " , " + top + " , " + dx + " , " + dy);
View childAt0 = getChildAt(0);
View childAt1 = getChildAt(1);
if (changedView == childAt0) {
ItemPos it = mItemSet.get(1);
int moveX = left - mItemSet.get(0).left;
childAt1.layout(it.left + moveX, it.top, it.right + moveX, it.bottom + dy);
} else if (changedView == childAt1) {
ItemPos it = mItemSet.get(0);
int moveX = left - mItemSet.get(1).left;
childAt0.layout(it.left + moveX, it.top, it.right + moveX, it.bottom + dy);
}
}
@Override
public int clampViewPositionVertical(View child, int top, int dy) {
// 继续保持margin与padding
return getPaddingTop() + getChildLayoutParams(child).topMargin;
}
@Override
public void onViewDragStateChanged(int state) {
super.onViewDragStateChanged(state);
this.mDragState = state;
// LogUtils.e("ViewDragState == " + state);
}
@Override
public void onViewReleased(View releasedChild, float xvel, float yvel) {
View childAt0 = getChildAt(0);
View childAt1 = getChildAt(1);
int a = getPaddingLeft();
int d = getChildLayoutParams(childAt0).leftMargin;
int L = getChildAt(0).getLeft();
int k = getChildWidth(childAt1);
if (BuildConfig.DEBUG) {
int b = getWidth();
int c = getPaddingRight();
int e = getChildLayoutParams(childAt0).rightMargin;
int f = getChildWidthWithMargin(childAt0);
int g = getChildWidth(childAt0);
int h = getChildLayoutParams(childAt1).leftMargin;
int i = getChildLayoutParams(childAt1).rightMargin;
int j = getChildWidthWithMargin(childAt1);
// LogUtils.e("release: " + a + " , " + b + " , "
// + c + " , " + d + " , " + e + " , "
// + f + " , " + g + " , " + h + " , "
// + i + " , " + j + " , " + k + " , "
// + L);
// // L == -34 , d==e==26 , a==c==80 , ---> k/2 == 140
// LogUtils.e("L-d-a = " + (L - d - a) + " k/2 = " + k / 2); // 中点真难找啊..
}
State temp = this.mCurrentOpen;
// LogUtils.e(scrollState);
int left = L - d - a;
int change; // 释放临界值：不要放中间，放1/4处就好了
int absLeft = Math.abs(left);
if (scrollState.scrollDirection == ScrollState.LEFT) {
// 左滑
change = k / 4;
if (absLeft > change) {
// 左滑到底
openRight(childAt0, childAt1);
} else {
// 右滑到底
openCenter(childAt0, childAt1);
}
// LogUtils.e("left = " + left + " absLeft = " + absLeft + " change = " + change);
} else if (scrollState.scrollDirection == ScrollState.RIGHT) {
// 右滑
change = k * 3 / 4;
if (absLeft > change) {
// 左滑到底
openRight(childAt0, childAt1);
this.mCurrentOpen = Right;
} else {
// 右滑到底
openCenter(childAt0, childAt1);
this.mCurrentOpen = Center;
}
// LogUtils.e("left = " + left + " absLeft = " + absLeft + " change = " + change);
}
// LogUtils.e("xv = " + xvel + " , yv = " + yvel);
// xvel<0 -->右滑 >0 左滑 | 缓慢滑就 == 0
// LogUtils.e("temp = " + temp + " , state = " + mCurrentOpen);
if (mViewStateListener != null) {
mViewStateListener.onViewOpen(temp != this.mCurrentOpen, this.mCurrentOpen);
}
invalidate();
}
// ####################################
private void openCenter(View childAt0, View childAt1) {
mDragHelper.smoothSlideViewTo(childAt0, mItemSet.get(0).left, mItemSet.get(0).top);
mDragHelper.smoothSlideViewTo(childAt1, mItemSet.get(1).left, mItemSet.get(1).top);
this.mCurrentOpen = Center;
}
private void openRight(View childAt0, View childAt1) {
mDragHelper.smoothSlideViewTo(childAt0,
mItemSet.get(0).left - getChildWidthWithMargin(childAt1),
mItemSet.get(0).top);
mDragHelper.smoothSlideViewTo(childAt1,
mItemSet.get(1).left - getChildWidthWithMargin(childAt1),
mItemSet.get(1).top);
this.mCurrentOpen = Right;
}
}
@Override
public void computeScroll() {
if (mDragHelper.continueSettling(true)) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
public void setOnViewStatedChangedListener(OnOpenStatedListener listener) {
this.mViewStateListener = listener;
}
public interface OnOpenStatedListener {
@SuppressWarnings("unused")
void onViewOpen(boolean changed, State state);
}
@SuppressWarnings("unused")
public enum State {
Left, Center, Right,
}
@SuppressWarnings("unused")
public State getOpenState() {
return mDragCallBack.mCurrentOpen;
}
@SuppressWarnings("unused")
public int getDragState() {
return mDragCallBack.mDragState;
}
public State openRight() {
mDragCallBack.openRight(getChildAt(0), getChildAt(1));
return mDragCallBack.mCurrentOpen;
}
public State openCenter() {
mDragCallBack.openCenter(getChildAt(0), getChildAt(1));
return mDragCallBack.mCurrentOpen;
}
@SuppressWarnings("unused")
public State changeState() {
switch (getOpenState()) {
case Center:
openRight();
break;
case Right:
openCenter();
break;
}
return mDragCallBack.mCurrentOpen;
}
// ######################---##########################
private MarginLayoutParams getChildLayoutParams(@NonNull View child) {
ViewGroup.LayoutParams pa = child.getLayoutParams();
if (pa instanceof MarginLayoutParams) {
return (MarginLayoutParams) pa;
} else {
throw new RuntimeException(pa == null ? null : pa.toString());
}
}
private int getChildWidth(@NonNull View child) {
return child.getMeasuredWidth();
}
private int getChildHeight(@NonNull View child) {
return child.getMeasuredHeight();
}
private int getChildWidthWithMargin(@NonNull View child) {
MarginLayoutParams params = getChildLayoutParams(child);
return getChildWidth(child) + params.leftMargin + params.rightMargin;
}
@SuppressWarnings("unused")
private int getChildHeightWithMargin(@NonNull View child) {
MarginLayoutParams params = getChildLayoutParams(child);
return getChildWidth(child) + params.topMargin + params.bottomMargin;
}
private ViewGroup get() {
return this;
}
}