android programming pull down refresh implementation method analysis
- 2020-10-31 21:59:01
- OfStack
An example of this article describes the android programming pull-down refresh implementation. To share for your reference, the details are as follows:
At present, there are many drop-downs and refreshes in android app. Today, I will study 1 related data by myself
public class MyListView extends ListView implements OnScrollListener {
private static final String TAG = "listview";
private final static int RELEASE_To_REFRESH = 0;
private final static int PULL_To_REFRESH = 1;
private final static int REFRESHING = 2;
private final static int DONE = 3;
private final static int LOADING = 4;
// The actual padding The ratio of the distance to the offset distance on the interface
private final static int RATIO = 3;
private LayoutInflater inflater;
private LinearLayout headView;
private TextView tipsTextview;
private TextView lastUpdatedTextView;
private ImageView arrowImageView;
private ProgressBar progressBar;
private RotateAnimation animation;
private RotateAnimation reverseAnimation;
// Used to ensure startY The value of the 1 A complete touch Only recorded in the event 1 time
private boolean isRecored;
private int headContentWidth;
private int headContentHeight;
private int startY;
private int firstItemIndex;
private int state;
private boolean isBack;
private OnRefreshListener refreshListener;
private boolean isRefreshable;
public MyListView(Context context) {
super(context);
init(context);
}
public MyListView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
private void init(Context context) {
setCacheColorHint(context.getResources().getColor(R.color.transparent));
inflater = LayoutInflater.from(context);
headView = (LinearLayout) inflater.inflate(R.layout.head, null);
arrowImageView = (ImageView) headView
.findViewById(R.id.head_arrowImageView);
arrowImageView.setMinimumWidth(70);
arrowImageView.setMinimumHeight(50);
progressBar = (ProgressBar) headView
.findViewById(R.id.head_progressBar);
tipsTextview = (TextView) headView.findViewById(R.id.head_tipsTextView);
lastUpdatedTextView = (TextView) headView
.findViewById(R.id.head_lastUpdatedTextView);
measureView(headView);
headContentHeight = headView.getMeasuredHeight();
headContentWidth = headView.getMeasuredWidth();
headView.setPadding(0, -1 * headContentHeight, 0, 0);
headView.invalidate();
Log.v("size", "width:" + headContentWidth + " height:"
+ headContentHeight);
addHeaderView(headView, null, false);
setOnScrollListener(this);
animation = new RotateAnimation(0, -180,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
animation.setInterpolator(new LinearInterpolator());
animation.setDuration(250);
animation.setFillAfter(true);
reverseAnimation = new RotateAnimation(-180, 0,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
reverseAnimation.setInterpolator(new LinearInterpolator());
reverseAnimation.setDuration(200);
reverseAnimation.setFillAfter(true);
state = DONE;
isRefreshable = false;
}
public void onScroll(AbsListView arg0, int firstVisiableItem, int arg2,
int arg3) {
firstItemIndex = firstVisiableItem;
}
public void onScrollStateChanged(AbsListView arg0, int arg1) {
}
public boolean onTouchEvent(MotionEvent event) {
if (isRefreshable) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (firstItemIndex == 0 && !isRecored) {
isRecored = true;
startY = (int) event.getY();
Log.v(TAG, " in down Time record current position ' ");
}
break;
case MotionEvent.ACTION_UP:
if (state != REFRESHING && state != LOADING) {
if (state == DONE) {
// Nothing
}
if (state == PULL_To_REFRESH) {
state = DONE;
changeHeaderViewByState();
Log.v(TAG, " From the drop-down refresh state, to done state ");
}
if (state == RELEASE_To_REFRESH) {
state = REFRESHING;
changeHeaderViewByState();
onRefresh();
Log.v(TAG, " By releasing the refresh state, to done state ");
}
}
isRecored = false;
isBack = false;
break;
case MotionEvent.ACTION_MOVE:
int tempY = (int) event.getY();
if (!isRecored && firstItemIndex == 0) {
Log.v(TAG, " in move Time to record the location ");
isRecored = true;
startY = tempY;
}
if (state != REFRESHING && isRecored && state != LOADING) {
// Be sure to set padding Process of the current position 1 Straight in head Otherwise, if the list goes off the screen, it will scroll while it is being pushed up
// You can let go and refresh
if (state == RELEASE_To_REFRESH) {
setSelection(0);
// I'm pushing it up. I'm pushing it up enough to cover the screen head To the extent, but not to the extent of a total cover-up
if (((tempY - startY) / RATIO < headContentHeight)
&& (tempY - startY) > 0) {
state = PULL_To_REFRESH;
changeHeaderViewByState();
Log.v(TAG, " Change from release refresh state to drop down refresh state ");
}
// 1 Now it was pushed to the top
else if (tempY - startY <= 0) {
state = DONE;
changeHeaderViewByState();
Log.v(TAG, " Change from release refresh state to done state ");
}
// It's pulled down, or it's not pushed up to cover the top of the screen head The point of
else {
// No special operations, just updates paddingTop And that's it
}
}
// The display has not yet reached the point of release to refresh ,DONE Or is it PULL_To_REFRESH state
if (state == PULL_To_REFRESH) {
setSelection(0);
// Drop down to enter RELEASE_TO_REFRESH The state of the
if ((tempY - startY) / RATIO >= headContentHeight) {
state = RELEASE_To_REFRESH;
isBack = true;
changeHeaderViewByState();
Log.v(TAG, " by done Or the dropdown refresh state changes to the release refresh ");
}
// We're at the top
else if (tempY - startY <= 0) {
state = DONE;
changeHeaderViewByState();
Log.v(TAG, " by DOne Or the dropdown refresh state is changed to done state ");
}
}
// done State,
if (state == DONE) {
if (tempY - startY > 0) {
state = PULL_To_REFRESH;
changeHeaderViewByState();
}
}
// update headView the size
if (state == PULL_To_REFRESH) {
headView.setPadding(0, -1 * headContentHeight
+ (tempY - startY) / RATIO, 0, 0);
}
// update headView the paddingTop
if (state == RELEASE_To_REFRESH) {
headView.setPadding(0, (tempY - startY) / RATIO
- headContentHeight, 0, 0);
}
}
break;
}
}
return super.onTouchEvent(event);
}
// This method is called to update the interface when the state changes
private void changeHeaderViewByState() {
switch (state) {
case RELEASE_To_REFRESH:
arrowImageView.setVisibility(View.VISIBLE);
progressBar.setVisibility(View.GONE);
tipsTextview.setVisibility(View.VISIBLE);
lastUpdatedTextView.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.startAnimation(animation);
tipsTextview.setText(" Loosen the refresh ");
Log.v(TAG, " Current state, release refresh ");
break;
case PULL_To_REFRESH:
progressBar.setVisibility(View.GONE);
tipsTextview.setVisibility(View.VISIBLE);
lastUpdatedTextView.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.setVisibility(View.VISIBLE);
// Is made up of RELEASE_To_REFRESH It's a state shift
if (isBack) {
isBack = false;
arrowImageView.clearAnimation();
arrowImageView.startAnimation(reverseAnimation);
tipsTextview.setText(" The drop-down refresh ");
} else {
tipsTextview.setText(" The drop-down refresh ");
}
Log.v(TAG, " Current state, pull down and refresh ");
break;
case REFRESHING:
headView.setPadding(0, 0, 0, 0);
progressBar.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.setVisibility(View.GONE);
tipsTextview.setText(" Is refreshing ...");
lastUpdatedTextView.setVisibility(View.VISIBLE);
Log.v(TAG, " The current state , Is refreshing ...");
break;
case DONE:
headView.setPadding(0, -1 * headContentHeight, 0, 0);
progressBar.setVisibility(View.GONE);
arrowImageView.clearAnimation();
arrowImageView.setImageResource(R.drawable.arrow);
tipsTextview.setText(" The drop-down refresh ");
lastUpdatedTextView.setVisibility(View.VISIBLE);
Log.v(TAG, " Current status, done");
break;
}
}
public void setonRefreshListener(OnRefreshListener refreshListener) {
this.refreshListener = refreshListener;
isRefreshable = true;
}
public interface OnRefreshListener {
public void onRefresh();
}
public void onRefreshComplete() {
state = DONE;
lastUpdatedTextView.setText(" Recent updates :" + new Date().toLocaleString());
changeHeaderViewByState();
}
private void onRefresh() {
if (refreshListener != null) {
refreshListener.onRefresh();
}
}
// This method is copied directly from the Internet 1 A drop-down refresh demo ", "estimate" headView the width As well as height
private void measureView(View child) {
ViewGroup.LayoutParams p = child.getLayoutParams();
if (p == null) {
p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
}
int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0, p.width);
int lpHeight = p.height;
int childHeightSpec;
if (lpHeight > 0) {
childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight,
MeasureSpec.EXACTLY);
} else {
childHeightSpec = MeasureSpec.makeMeasureSpec(0,
MeasureSpec.UNSPECIFIED);
}
child.measure(childWidthSpec, childHeightSpec);
}
public void setAdapter(BaseAdapter adapter) {
lastUpdatedTextView.setText(" Recent updates :" + new Date().toLocaleString());
super.setAdapter(adapter);
}
}
I hope this article has been helpful in Android programming.