我需要示例代码来同时扩展和折叠自定义可扩展列表视图吗？
展开和折叠应该同时发生，速度相同吗？
感谢任何帮助。
先谢谢。
答案 0 :(得分：1)
public class AnimatedExpandableListView extends ExpandableListView {
@SuppressWarnings("unused")
private static final String TAG = AnimatedExpandableListAdapter.class.getSimpleName();
/**
* The duration of the expand/collapse animations
*/
private static final int ANIMATION_DURATION = 300;
private AnimatedExpandableListAdapter adapter;
public AnimatedExpandableListView(Context context) {
super(context);
}
public AnimatedExpandableListView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public AnimatedExpandableListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
/**
* @see ExpandableListView#setAdapter(ExpandableListAdapter)
*/
public void setAdapter(ExpandableListAdapter adapter) {
super.setAdapter(adapter);
// Make sure that the adapter extends AnimatedExpandableListAdapter
if(adapter instanceof AnimatedExpandableListAdapter) {
this.adapter = (AnimatedExpandableListAdapter) adapter;
this.adapter.setParent(this);
} else {
throw new ClassCastException(adapter.toString() + " must implement AnimatedExpandableListAdapter");
}
}
/**
* Expands the given group with an animation.
* @param groupPos The position of the group to expand
* @return Returns true if the group was expanded. False if the group was
* already expanded.
*/
@SuppressLint("NewApi")
public boolean expandGroupWithAnimation(int groupPos) {
boolean lastGroup = groupPos == adapter.getGroupCount() - 1;
if (lastGroup && Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
return expandGroup(groupPos, true);
}
int groupFlatPos = getFlatListPosition(getPackedPositionForGroup(groupPos));
if (groupFlatPos != -1) {
int childIndex = groupFlatPos - getFirstVisiblePosition();
if (childIndex < getChildCount()) {
// Get the view for the group is it is on screen...
View v = getChildAt(childIndex);
if (v.getBottom() >= getBottom()) {
// If the user is not going to be able to see the animation
// we just expand the group without an animation.
// This resolves the case where getChildView will not be
// called if the children of the group is not on screen
// We need to notify the adapter that the group was expanded
// without it's knowledge
adapter.notifyGroupExpanded(groupPos);
return expandGroup(groupPos);
}
}
}
// Let the adapter know that we are starting the animation...
adapter.startExpandAnimation(groupPos, 0);
// Finally call expandGroup (note that expandGroup will call
// notifyDataSetChanged so we don't need to)
return expandGroup(groupPos);
}
/**
* Collapses the given group with an animation.
* @param groupPos The position of the group to collapse
* @return Returns true if the group was collapsed. False if the group was
* already collapsed.
*/
public boolean collapseGroupWithAnimation(int groupPos) {
int groupFlatPos = getFlatListPosition(getPackedPositionForGroup(groupPos));
if (groupFlatPos != -1) {
int childIndex = groupFlatPos - getFirstVisiblePosition();
if (childIndex >= 0 && childIndex < getChildCount()) {
// Get the view for the group is it is on screen...
View v = getChildAt(childIndex);
if (v.getBottom() >= getBottom()) {
// If the user is not going to be able to see the animation
// we just collapse the group without an animation.
// This resolves the case where getChildView will not be
// called if the children of the group is not on screen
return collapseGroup(groupPos);
}
} else {
// If the group is offscreen, we can just collapse it without an
// animation...
return collapseGroup(groupPos);
}
}
// Get the position of the firstChild visible from the top of the screen
long packedPos = getExpandableListPosition(getFirstVisiblePosition());
int firstChildPos = getPackedPositionChild(packedPos);
int firstGroupPos = getPackedPositionGroup(packedPos);
// If the first visible view on the screen is a child view AND it's a
// child of the group we are trying to collapse, then set that
// as the first child position of the group... see
// {@link #startCollapseAnimation(int, int)} for why this is necessary
firstChildPos = firstChildPos == -1 || firstGroupPos != groupPos ? 0 : firstChildPos;
// Let the adapter know that we are going to start animating the
// collapse animation.
adapter.startCollapseAnimation(groupPos, firstChildPos);
// Force the listview to refresh it's views
adapter.notifyDataSetChanged();
return isGroupExpanded(groupPos);
}
private int getAnimationDuration() {
return ANIMATION_DURATION;
}
/**
* Used for holding information regarding the group.
*/
private static class GroupInfo {
boolean animating = false;
boolean expanding = false;
int firstChildPosition;
/**
* This variable contains the last known height value of the dummy view.
* We save this information so that if the user collapses a group
* before it fully expands, the collapse animation will start from the
* CURRENT height of the dummy view and not from the full expanded
* height.
*/
int dummyHeight = -1;
}
/**
* A specialized adapter for use with the AnimatedExpandableListView. All
* adapters used with AnimatedExpandableListView MUST extend this class.
*/
public static abstract class AnimatedExpandableListAdapter extends BaseExpandableListAdapter {
private SparseArray<GroupInfo> groupInfo = new SparseArray<GroupInfo>();
private AnimatedExpandableListView parent;
private static final int STATE_IDLE = 0;
private static final int STATE_EXPANDING = 1;
private static final int STATE_COLLAPSING = 2;
private void setParent(AnimatedExpandableListView parent) {
this.parent = parent;
}
public int getRealChildType(int groupPosition, int childPosition) {
return 0;
}
public int getRealChildTypeCount() {
return 1;
}
public abstract View getRealChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent);
public abstract int getRealChildrenCount(int groupPosition);
private GroupInfo getGroupInfo(int groupPosition) {
GroupInfo info = groupInfo.get(groupPosition);
if (info == null) {
info = new GroupInfo();
groupInfo.put(groupPosition, info);
}
return info;
}
public void notifyGroupExpanded(int groupPosition) {
GroupInfo info = getGroupInfo(groupPosition);
info.dummyHeight = -1;
}
private void startExpandAnimation(int groupPosition, int firstChildPosition) {
GroupInfo info = getGroupInfo(groupPosition);
info.animating = true;
info.firstChildPosition = firstChildPosition;
info.expanding = true;
}
private void startCollapseAnimation(int groupPosition, int firstChildPosition) {
GroupInfo info = getGroupInfo(groupPosition);
info.animating = true;
info.firstChildPosition = firstChildPosition;
info.expanding = false;
}
private void stopAnimation(int groupPosition) {
GroupInfo info = getGroupInfo(groupPosition);
info.animating = false;
}
/**
* Override {@link #getRealChildType(int, int)} instead.
*/
@Override
public final int getChildType(int groupPosition, int childPosition) {
GroupInfo info = getGroupInfo(groupPosition);
if (info.animating) {
// If we are animating this group, then all of it's children
// are going to be dummy views which we will say is type 0.
return 0;
} else {
// If we are not animating this group, then we will add 1 to
// the type it has so that no type id conflicts will occur
// unless getRealChildType() returns MAX_INT
return getRealChildType(groupPosition, childPosition) + 1;
}
}
/**
* Override {@link #getRealChildTypeCount()} instead.
*/
@Override
public final int getChildTypeCount() {
// Return 1 more than the childTypeCount to account for DummyView
return getRealChildTypeCount() + 1;
}
protected ViewGroup.LayoutParams generateDefaultLayoutParams() {
return new AbsListView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT, 0);
}
/**
* Override {@link #getChildView(int, int, boolean, View, ViewGroup)} instead.
*/
@Override
public final View getChildView(final int groupPosition, int childPosition, boolean isLastChild, View convertView, final ViewGroup parent) {
final GroupInfo info = getGroupInfo(groupPosition);
if (info.animating) {
// If this group is animating, return the a DummyView...
if (convertView instanceof DummyView == false) {
convertView = new DummyView(parent.getContext());
convertView.setLayoutParams(new AbsListView.LayoutParams(LayoutParams.MATCH_PARENT, 0));
}
if (childPosition < info.firstChildPosition) {
convertView.getLayoutParams().height = 0;
return convertView;
}
final ExpandableListView listView = (ExpandableListView) parent;
final DummyView dummyView = (DummyView) convertView;
// Clear the views that the dummy view draws.
dummyView.clearViews();
// Set the style of the divider
dummyView.setDivider(listView.getDivider(), parent.getMeasuredWidth(), listView.getDividerHeight());
// Make measure specs to measure child views
final int measureSpecW = MeasureSpec.makeMeasureSpec(parent.getWidth(), MeasureSpec.EXACTLY);
final int measureSpecH = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
int totalHeight = 0;
int clipHeight = parent.getHeight();
final int len = getRealChildrenCount(groupPosition);
for (int i = info.firstChildPosition; i < len; i++) {
View childView = getRealChildView(groupPosition, i, (i == len - 1), null, parent);
LayoutParams p = (LayoutParams) childView.getLayoutParams();
if (p == null) {
p = (AbsListView.LayoutParams) generateDefaultLayoutParams();
childView.setLayoutParams(p);
}
int lpHeight = p.height;
int childHeightSpec;
if (lpHeight > 0) {
childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY);
} else {
childHeightSpec = measureSpecH;
}
childView.measure(measureSpecW, childHeightSpec);
totalHeight += childView.getMeasuredHeight();
if (totalHeight < clipHeight) {
// we only need to draw enough views to fool the user...
dummyView.addFakeView(childView);
} else {
dummyView.addFakeView(childView);
// if this group has too many views, we don't want to
// calculate the height of everything... just do a light
// approximation and break
int averageHeight = totalHeight / (i + 1);
totalHeight += (len - i - 1) * averageHeight;
break;
}
}
Object o;
int state = (o = dummyView.getTag()) == null ? STATE_IDLE : (Integer) o;
if (info.expanding && state != STATE_EXPANDING) {
ExpandAnimation ani = new ExpandAnimation(dummyView, 0, totalHeight, info);
ani.setDuration(this.parent.getAnimationDuration());
ani.setAnimationListener(new AnimationListener() {
@Override
public void onAnimationEnd(Animation animation) {
stopAnimation(groupPosition);
notifyDataSetChanged();
dummyView.setTag(STATE_IDLE);
}
@Override
public void onAnimationRepeat(Animation animation) {}
@Override
public void onAnimationStart(Animation animation) {}
});
dummyView.startAnimation(ani);
dummyView.setTag(STATE_EXPANDING);
} else if (!info.expanding && state != STATE_COLLAPSING) {
if (info.dummyHeight == -1) {
info.dummyHeight = totalHeight;
}
ExpandAnimation ani = new ExpandAnimation(dummyView, info.dummyHeight, 0, info);
ani.setDuration(this.parent.getAnimationDuration());
ani.setAnimationListener(new AnimationListener() {
@Override
public void onAnimationEnd(Animation animation) {
stopAnimation(groupPosition);
listView.collapseGroup(groupPosition);
notifyDataSetChanged();
info.dummyHeight = -1;
dummyView.setTag(STATE_IDLE);
}
@Override
public void onAnimationRepeat(Animation animation) {}
@Override
public void onAnimationStart(Animation animation) {}
});
dummyView.startAnimation(ani);
dummyView.setTag(STATE_COLLAPSING);
}
return convertView;
} else {
return getRealChildView(groupPosition, childPosition, isLastChild, convertView, parent);
}
}
@Override
public final int getChildrenCount(int groupPosition) {
GroupInfo info = getGroupInfo(groupPosition);
if (info.animating) {
return info.firstChildPosition + 1;
} else {
return getRealChildrenCount(groupPosition);
}
}
}
private static class DummyView extends View {
private List<View> views = new ArrayList<View>();
private Drawable divider;
private int dividerWidth;
private int dividerHeight;
public DummyView(Context context) {
super(context);
}
public void setDivider(Drawable divider, int dividerWidth, int dividerHeight) {
if(divider != null) {
this.divider = divider;
this.dividerWidth = dividerWidth;
this.dividerHeight = dividerHeight;
divider.setBounds(0, 0, dividerWidth, dividerHeight);
}
}
/**
* Add a view for the DummyView to draw.
* @param childView View to draw
*/
public void addFakeView(View childView) {
childView.layout(0, 0, getWidth(), childView.getMeasuredHeight());
views.add(childView);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
final int len = views.size();
for(int i = 0; i < len; i++) {
View v = views.get(i);
v.layout(left, top, left + v.getMeasuredWidth(), top + v.getMeasuredHeight());
}
}
public void clearViews() {
views.clear();
}
@Override
public void dispatchDraw(Canvas canvas) {
canvas.save();
if(divider != null) {
divider.setBounds(0, 0, dividerWidth, dividerHeight);
}
final int len = views.size();
for(int i = 0; i < len; i++) {
View v = views.get(i);
canvas.save();
canvas.clipRect(0, 0, getWidth(), v.getMeasuredHeight());
v.draw(canvas);
canvas.restore();
if(divider != null) {
divider.draw(canvas);
canvas.translate(0, dividerHeight);
}
canvas.translate(0, v.getMeasuredHeight());
}
canvas.restore();
}
}
private static class ExpandAnimation extends Animation {
private int baseHeight;
private int delta;
private View view;
private GroupInfo groupInfo;
private ExpandAnimation(View v, int startHeight, int endHeight, GroupInfo info) {
baseHeight = startHeight;
delta = endHeight - startHeight;
view = v;
groupInfo = info;
view.getLayoutParams().height = startHeight;
view.requestLayout();
}
@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
super.applyTransformation(interpolatedTime, t);
if (interpolatedTime < 1.0f) {
int val = baseHeight + (int) (delta * interpolatedTime);
view.getLayoutParams().height = val;
groupInfo.dummyHeight = val;
view.requestLayout();
} else {
int val = baseHeight + delta;
view.getLayoutParams().height = val;
groupInfo.dummyHeight = val;
view.requestLayout();
}
}
}}
有关此课程如何运作的详细说明：
为ExpandableListView设置动画并非易事。这样的方式 class是通过利用ExpandableListView的工作方式来实现的。
通常在{@link ExpandableListView＃collapseGroup（int）}或 调用{@link ExpandableListView #expansionGroup（int）}，视图切换 组的标志并调用notifyDataSetChanged以导致ListView 刷新所有的视图。但这次，取决于是否 组被展开或折叠，某些childView将被忽略 或添加到列表中。
了解这一点，我们可以想出一种动画观点的方法。对于 组扩展的实例，我们告诉适配器动画 特定群体的孩子。然后我们扩大了导致这一组的小组 ExpandableListView刷新屏幕上的所有视图。的方式 ExpandableListView通过调用适配器中的getView（）来实现这一点。
然而，由于适配器知道我们正在为某个组制作动画，
而不是为该组的孩子返回真实的观点
动画，它将返回一个假的虚拟视图。然后，这个虚拟视图将是
在其dispatchDraw函数中绘制真实的子视图。原因
我们这样做是因为我们可以通过简单的方式为所有孩子制作动画
动画虚拟视图。完成动画后，我们告诉你
适配器停止动画组并调用notifyDataSetChanged。现在
除了这个外，ExpandableListView被迫再次刷新它的视图
时间，它将获得扩展组的真实观点。
因此，当{@link #expandGroupWithAnimation（int）}为
时，列出全部内容
称为以下情况：
从我们开始，为了让群体崩溃变得有点困难 不能从一开始就调用collapseGroup，因为它会忽略它 儿童用品，放弃没有机会做任何动画。代替 我们要做的是先播放动画并调用collapseGroup 动画完成后。
所以，当{@link #collapseGroupWithAnimation（int）}为时，要全部列出 称为以下情况：