改造SwipeRefreshLayout，实现折叠效果
2017-03-02 本文已影响220人
浩运
123.gif
要实现如上图的效果，红色区域是筛选条件的区域，随着想向上滚动并且停留在顶部。
第一感觉是想用CoordinatorLayout.Behavior 来实现，将Toolbar+图片区域+红色筛选区域作为折叠的头部。但是这样SwipeRefreshLayout的下拉圈圈就不是从Toolbar下面下拉出来的。
我尝试过自己用CoordinatorLayout.Behavior来实现这这个效果，而且上下滚动的效果已经实现了，但是写到下拉刷新处的时候，我暂时放弃了，我想到了另外一个方法，就是仿CoordinatorLayout.Behavior 来拦截SwipeRefreshLayout 的nestedscroll事件，因为SwipeRefreshLayout也继承了NestedScrollingParent。
public class MySwipeRefreshLayout extends SwipeRefreshLayout {
private static final String TAG = "MySwipeRefreshLayout";
private static int HEADER_EXPEND_HEIGTH =0;
private View rootScrollLayout;
private View mScrollUpChild;
private int curentTranslationY;
public MySwipeRefreshLayout(Context context) {
this(context, null);
}
public MySwipeRefreshLayout(Context context, AttributeSet attrs) {
super(context, attrs);
HEADER_EXPEND_HEIGTH = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 200, context.getResources().getDisplayMetrics());
curentTranslationY = HEADER_EXPEND_HEIGTH;
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
rootScrollLayout = findViewById(R.id.rootScrollLayout);
Log.i(TAG, "MySwipeRefreshLayout: rootScrollLayout=" + rootScrollLayout);
rootScrollLayout.setTranslationY(curentTranslationY);
}
@Override
public boolean canChildScrollUp() {
if (mScrollUpChild != null) {
return ViewCompat.canScrollVertically(mScrollUpChild, -1);
}
return super.canChildScrollUp();
}
public void setScrollUpChild(View view) {
mScrollUpChild = view;
}
@Override
public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {
Log.i(TAG, "onStartNestedScroll: child="+child);
//接收垂直方向的滚动事件，SwipeRefreshLayout默认是，只要正在刷新，父控件就不接受嵌套事件，由scrollview自己内部消耗
return isEnabled() && (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0;
// return super.onStartNestedScroll(child, target, nestedScrollAxes);
}
@Override
public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) {
if (dy > 0) {//向上滚动
if (curentTranslationY>=0) {//可以整体先向上滚动
int min = (int) Math.min(rootScrollLayout.getTranslationY(), dy);
curentTranslationY = (int) (rootScrollLayout.getTranslationY() - min);
rootScrollLayout.setTranslationY(curentTranslationY);
consumed[1] = min;
}
}
super.onNestedPreScroll(target, dx, dy, consumed);
Log.i(TAG, "onNestedPreScroll: ");
}
@Override
public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) {
int max = 0;
if (dyConsumed <= 0 && dyUnconsumed < 0) {//向下滚动
if (curentTranslationY<HEADER_EXPEND_HEIGTH) {//可以整体先向下滚动
max = (int) Math.max(rootScrollLayout.getTranslationY()-HEADER_EXPEND_HEIGTH, dyUnconsumed);
curentTranslationY = (int) (rootScrollLayout.getTranslationY() - max);
rootScrollLayout.setTranslationY(curentTranslationY);
}
if (isRefreshing()) {//如果正在更新，则不显示让SwipeRefreshLayout处理，否则会二度下拉正在更新
return;
}
}
//如果还有多余的需要SwipeRefreshLayout 处理，比如再下拉显示正在更新
super.onNestedScroll(target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed-max);
Log.i(TAG, "onNestedScroll: ");
}
@Override
protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
Log.i(TAG, "drawChild: child=" + child);
return super.drawChild(canvas, child, drawingTime);
}
}
onlayout
主要处理红色筛选区与scrollview所在区域的setTranslationY偏移，以露出imageView，实现滑动遮盖的效果
由于滚动后系统有可能会调用onlayout方法，所以要记录当前的curentTranslationY，在onlayout的时候设置他的偏移
onStartNestedScroll
只要是垂直方向的滚动就都要处理，SwipeRefreshLayout默认的是在Refreshing状态就不接收子view的nested事件。而这里正在刷新的时候，整体还要能向上滚动，所以重写了此处。
onNestedPreScroll
当开始向上滚动的时候，先整体向上移动SwipeRefreshLayout的内部控件，剩余的再给子view去内部消耗
向下滚动的时候，先由子view内部消耗。
onNestedScroll
当子view 滚动完毕后，如果是向下滚动，先整体向下移动SwipeRefreshLayout的内部控件，还有多余的就给SwipeRefreshLayout自己处理，比如显示下拉进度条。而如果正在刷新的时候，是不应该二次显示下拉进度条的，这也是为啥isRefreshing 为true的时候，直接return的原因，否则你会看到下拉进度条再次被下拉下来。
布局文件如下：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main"
android:layout_width="match_parent" android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.tospur.exmind.testswiperefresh.MainActivity">
<android.support.v7.widget.Toolbar
android:id="@+id/toolBar"
android:layout_width="match_parent"
android:layout_height="wrap_content"></android.support.v7.widget.Toolbar>
<com.tospur.exmind.testswiperefresh.MySwipeRefreshLayout
android:id="@+id/mySwipeRefreshLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/mImgView"
android:layout_width="match_parent"
android:layout_height="200dp"
android:src="@mipmap/test"
/>
<LinearLayout
android:id="@+id/rootScrollLayout"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:id="@+id/mFilterView"
android:orientation="vertical"
android:layout_width="match_parent"
android:background="#f0f"
android:layout_height="72dp"></LinearLayout>
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:background="#ff0"
android:layout_width="match_parent"
android:layout_height="match_parent"></android.support.v7.widget.RecyclerView>
</LinearLayout>
</FrameLayout>
</com.tospur.exmind.testswiperefresh.MySwipeRefreshLayout>
</LinearLayout>
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setSupportActionBar((Toolbar) findViewById(R.id.toolBar));
MySwipeRefreshLayout mySwipeRefreshLayout = (MySwipeRefreshLayout) findViewById(R.id.mySwipeRefreshLayout);
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(new MAdapter());
mySwipeRefreshLayout.setScrollUpChild(recyclerView);
}
private class MAdapter extends RecyclerView.Adapter<MHolder> {
@Override
public MHolder onCreateViewHolder(ViewGroup parent, int viewType) {
TextView textView = new TextView(parent.getContext());
return new MHolder(textView);
}
@Override
public void onBindViewHolder(MHolder holder, int position) {
holder.textView.setText("A "+position);
}
@Override
public int getItemCount() {
return 50;
}
}
private class MHolder extends RecyclerView.ViewHolder {
TextView textView;
public MHolder(View itemView) {
super(itemView);
textView = (TextView) itemView;
}
}
}
如果要实现平滑滚动，就是imageview随着一起向上滚动，只需要做个简单的调整
123.gif
public class MySwipeRefreshLayout2 extends SwipeRefreshLayout {
private static final String TAG = "MySwipeRefreshLayout";
private static int HEADER_MAX_TOP_OFFSET =0;
private View rootScrollLayout;
private View mScrollUpChild;
private int curentTranslationY;
public MySwipeRefreshLayout2(Context context) {
this(context, null);
}
public MySwipeRefreshLayout2(Context context, AttributeSet attrs) {
super(context, attrs);
HEADER_MAX_TOP_OFFSET = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 200, context.getResources().getDisplayMetrics());
curentTranslationY = 0;
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
rootScrollLayout = findViewById(R.id.rootScrollLayout);
Log.i(TAG, "onMeasure: getMeasuredHeight="+rootScrollLayout.getMeasuredHeight()+" getMeasuredWidth="+rootScrollLayout.getMeasuredWidth());
Log.i(TAG, "onMeasure: parent.getMeasuredHeight="+getMeasuredHeight());
int w = View.MeasureSpec.makeMeasureSpec(rootScrollLayout.getMeasuredWidth(),View.MeasureSpec.EXACTLY);
int h = View.MeasureSpec.makeMeasureSpec(getMeasuredHeight()+HEADER_MAX_TOP_OFFSET,View.MeasureSpec.EXACTLY);
rootScrollLayout.measure(w,h);//让rootScrollLayout的子view知道，重新测量让子view铺满rootScrollLayout
//扩大rootScrollLayout在SwipeRefreshLayout中的显示区域
rootScrollLayout.layout(rootScrollLayout.getLeft(), rootScrollLayout.getTop(), rootScrollLayout.getRight(), rootScrollLayout.getBottom() + HEADER_MAX_TOP_OFFSET);
rootScrollLayout.setTranslationY(curentTranslationY);
}
@Override
public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
//这里的measure没有效果
/*rootScrollLayout = findViewById(R.id.rootScrollLayout);
Log.i(TAG, "onMeasure: getMeasuredHeight="+rootScrollLayout.getMeasuredHeight()+" getMeasuredWidth="+rootScrollLayout.getMeasuredWidth());
Log.i(TAG, "onMeasure: parent.getMeasuredHeight="+getMeasuredHeight());
int w = View.MeasureSpec.makeMeasureSpec(rootScrollLayout.getMeasuredWidth(),View.MeasureSpec.EXACTLY);
int h = View.MeasureSpec.makeMeasureSpec(getMeasuredHeight()+HEADER_MAX_TOP_OFFSET,View.MeasureSpec.EXACTLY);
rootScrollLayout.measure(w,h);*/
}
@Override
public boolean canChildScrollUp() {
if (mScrollUpChild != null) {
return ViewCompat.canScrollVertically(mScrollUpChild, -1);
}
return super.canChildScrollUp();
}
public void setScrollUpChild(View view) {
mScrollUpChild = view;
}
@Override
public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {
Log.i(TAG, "onStartNestedScroll: child="+child);
//接收垂直方向的滚动事件，SwipeRefreshLayout默认是，只要正在刷新，父控件就不接受嵌套事件，由scrollview自己内部消耗
return isEnabled() && (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0;
// return super.onStartNestedScroll(child, target, nestedScrollAxes);
}
@Override
public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) {
if (dy > 0) {//向上滚动
if (curentTranslationY<=0) {//可以整体先向上滚动
int min = (int) Math.min(rootScrollLayout.getTranslationY()+ HEADER_MAX_TOP_OFFSET, dy);
curentTranslationY = (int) (rootScrollLayout.getTranslationY() - min);
rootScrollLayout.setTranslationY(curentTranslationY);
consumed[1] = min;
}
}
super.onNestedPreScroll(target, dx, dy, consumed);
Log.i(TAG, "onNestedPreScroll: ");
}
@Override
public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) {
int max = 0;
if (dyConsumed <= 0 && dyUnconsumed < 0) {//向下滚动
if (curentTranslationY<0) {//可以整体先向下滚动
max = (int) Math.max(rootScrollLayout.getTranslationY(), dyUnconsumed);
curentTranslationY = (int) (rootScrollLayout.getTranslationY() - max);
rootScrollLayout.setTranslationY(curentTranslationY);
}
if (isRefreshing()) {//如果正在更新，则不显示让SwipeRefreshLayout处理，否则会二度下拉正在更新
return;
}
}
//如果还有多余的需要SwipeRefreshLayout 处理，比如再下拉显示正在更新
super.onNestedScroll(target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed-max);
}
@Override
protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
Log.i(TAG, "drawChild: child=" + child);
return super.drawChild(canvas, child, drawingTime);
}
}
这里要注意onlayout方法中的代码，需要调整rootScrollLayout 的高度，防止向上整体滚动时，底部空白问题
device-2017-03-02-112321.png
如上图底部。
刚开始在onMeasure中重新测量，死活出不来，然后想起CoordinatorLayout.Behavior 中也有调整位置大小的代码，于是在onLayout中重新layout，扩大显示区域，但是必须也要measure一下，否则里面的子view无法完全填充。
附布局代码
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main"
android:layout_width="match_parent" android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.tospur.exmind.testswiperefresh.MainActivity">
<android.support.v7.widget.Toolbar
android:id="@+id/toolBar"
android:layout_width="match_parent"
android:layout_height="wrap_content"></android.support.v7.widget.Toolbar>
<com.tospur.exmind.testswiperefresh.MySwipeRefreshLayout2
android:id="@+id/mySwipeRefreshLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:background="#00f"
android:id="@+id/rootScrollLayout"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/mImgView"
android:layout_width="match_parent"
android:layout_height="200dp"
android:src="@mipmap/test"
/>
<LinearLayout
android:id="@+id/mFilterView"
android:orientation="vertical"
android:layout_width="match_parent"
android:background="#f0f"
android:layout_height="72dp"></LinearLayout>
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:background="#ff0"
android:layout_width="match_parent"
android:layout_height="match_parent"></android.support.v7.widget.RecyclerView>
</LinearLayout>
</com.tospur.exmind.testswiperefresh.MySwipeRefreshLayout2>
</LinearLayout>
