I have a main activity that contains a frame layout and 4 tab buttons, and there are in total 4 fragments, each fragment relates to a tab button, depending on which tab button is clicked, the corresponding fragment will be swapped into the frame layout to replace the old one. Now in each of the fragment there's a webview that loads different URL when the fragment is created. My question is how to prevent from the webview to reload every time when fragments swap? Below are the code how I swap my fragment:
FragmentMainPage fragment = new FragmentMainPage();
android.support.v4.app.FragmentManager fm = getSupportFragmentManager();
FragmentTransaction transaction = fm.beginTransaction();
transaction.replace(R.id.frameLayout, fragment);
transaction.commit();
currentPage = VT_Constants.HOME_PAGE;
Calling replace is destructive: it tears down the fragment's view hierarchy, so when you add it back later, the views have to be rebuilt, which explains the behavior you are seeing.
Try show and hide instead. These maintain the fragment's views, so they can be re-attached to your activity when the user clicks on that fragment's tab. Something like this (although I'm not sure how you want to get the reference to the current fragment):
FragmentMainPage fragment = new FragmentMainPage();
android.support.v4.app.FragmentManager fm = getSupportFragmentManager();
Fragment oldFragment = fm.findFragmentByTag(...); // somehow get the current fragment showing
FragmentTransaction transaction = fm.beginTransaction();
transaction.hide(oldFragment);
transaction.show(fragment);
transaction.commit();
You can set page limit.
viewPager.setOffscreenPageLimit(4);
Webviews won't reload anymore.
I was also facing the same problem. Tried changing the webView Settings and none worked for me. This is not the problem with the webview.
The actual problem here is your fragment is a part of ViewPager. By default viewPager will have setOffscreenPageLimit as 1.
For one immediate tab switch, you will not see any refresh of the fragment. Post that you will face this issue.
You have to simply add this one line to your view pager if you don't want to refresh fragments
mViewPager.setOffscreenPageLimit(numOfTabs);
for ex:
mViewPager.setOffscreenPageLimit(10); //if you have 10 tabs
Hope this helps.
Related
Is there a way to detect which node is being rendered when the user selects a link within the pages detail app and only the iframe changes? If just the the iframe is changing I need a mechanism that can call the parent page and send the path of the node that is being rendered in the iframe. We run Magnolia EE 5.6.11.
My issue is that I have a ValueChangeListener in a ComboBox that I use as a versionSelector in a PageBar extension in the pages detail app.
// Create a selection component;
private ComboBox versionSelector = new ComboBox();
private Listener listener;
private boolean isSettingValue;
public VersionSelectorViewImpl(){
construct();
}
private void construct() {
versionSelector.setVisible(false);
versionSelector.setSizeUndefined();
versionSelector.setImmediate(true);
versionSelector.setNullSelectionAllowed(false);
versionSelector.setTextInputAllowed(false);
//setup listener for the selected item
versionSelector.addValueChangeListener(new Property.ValueChangeListener() {
#Override
public void valueChange(Property.ValueChangeEvent event) {
if (listener != null) {
listener.versionSelected((Object) event.getProperty().getValue());
}
}
});
}
The implementation is similar to the LanguageSelector or VariantSelector. When someone activates a hyperlink in the page template the iframe changes and the valueChange method retrieves the wrong value (ie. the event is from the previous page).
When someone activates a link, the PagesEditorSubApp#updateNodePath calls the updateLocationDependentComponents which calls the PageBar.onLocationUpdate. This calls in our case the VersionSelector#setCurrentVersion method. At this point I would need to reload the page detail subapp so that the listener is correctly set to the new page. I tried using the pageEditorPresenter.refresh() method in the setCurrentVersion method but it didn't do it.
In Magnolia 5.x you need to fire ContentChangeEvent to trigger the refresh (and hope that subapp you want to refresh listens to it, which in case of page detail subapp shouldn't be a problem).
Or, since you mention LanguageSelector, you can indeed try to call PageEditorPresenter directly as it does from info.magnolia.pages.app.editor.pagebar.languageselector.LanguageSelector#languageSelected, tho unless you need to modify something in the presenter (eg. locale in the example above), it seems rather unnecessary coupling of the code.
Once you are migrating your code to Magnolia 6.x and new UI framework, you have more convenient way of triggering notification of datasource change which all the views consuming data from given source listen to and facilitating refresh that way (as is shown eg in PasteComponentAction here.
I'm trying to understand how to preserve fragment view state when fragments are used within navigation tabs. In my efforts, I've come across two problems that I cannot find any proper solutions to.
I have two tabs, Tab1 and Tab2. Tab1's layout is defined by FragmentA and Tab2's layout is defined by FragmentB.
I've followed the approach given here (edit: documentation has changed since this question was asked).
The first problem: Even though my views have IDs, their states are not fully restored when a fragment is re-attached (after a tab switch rotation). In particular: an EditText with an ID does indeed save its entered text, but it does not save its enabled status. Also, buttons do not save if they are enabled or disabled even though they have IDs. I've found two possible workarounds for this problem:
Use hide()/show() instead of attach()/detach() when switching tabs.
in onPause(), save the current fragment view state in a View instance variable of the fragment via getView(). In onCreateView(Bundle savedInstanceState) check if this field is non-null and if that is the case return the value of this field. This solution seems hacky, and I've been told that it might also introduce a memory leak in my app.
The second problem: Consider the following user interaction:
User starts on Tab1 and does some changes that put the view state of Tab1 in a different state than its default state (and we want the fragment to save this view state through tabswitches and device tilts).
User then goes to Tab2. User then tilts her/his device (still at Tab2).
User then swaps to Tab1 (at the new screen orientation).
Now, the problem is: when the user initially swaps from Tab1 to Tab2, the fragment is detached and thereby its view discarded (even though the fragment instance still lives). When the user then tilts the device, the activity - and thereby both FragmentA and FragmentB associated with it - are destroyed. Since FragmentA at this point does no longer have a view (remember: it was detached), we cannot save the state of its view elements (e.g., what buttons are enabled/disabled) during the call to FragmentA.onSaveInstanceState(Bundle savedInstanceState). How do you recover fragment view state in a situation like this? Is the only viable solution to save every single view element's different status flags as SharedPreferences? This seems way too complicated for such an "everyday job".
Problem 1:
Android does not save your view enabled state by default. It seems only things which are directly influenced by user actions (without additional code) are saved. For a normal View, no information is saved, and for a TextView, of which EditText is a subclass, the entered text is saved (if freezesText is set).
If you want to anything else to be saved, you will have to do it yourself. Here is an question with some answers that show how to implement custom view state saving. You can stick with attach/detach if you follow that approach.
Problem 2:
You are right in that Fragment.onSaveInstanceState(Bundle) can be called after your view has already been destroyed. However, this is not where you should be saving your view state. Android will call View.onSaveInstanceState() right before it destroys your views when detaching a fragment. It saves this state and gives it back to you when you attach the fragment again. This is exactly what happens when you flip between tabs normally with no rotations. Fragment.onSaveInstanceState(Bundle) is not called when detaching. Even if you rotate the device, the view state saved as a result of the detach will persist. If you implement View.onSaveInstanceState() as directed above, your view state will be saved and restored properly, even in the Tab1-Tab2-rotate-Tab1 scenario.
Side note:
The example code in the docs seems to have some problems when you try to rotate. The lifetime of the TabListener is the same as that of the Activity - a new one is created every time you rotate. This means it also loses its internal reference to the fragment, every time you rotate. Added fragments are recreated automatically and so there is no need for the TabListener to try to create a new instance and add it, after rotation. Instead, of the internal reference, it should just try to find the fragment with the appropriate tag in the fragment manager. After rotation it will still exist.
The other problem is with that the selected tab is not saved, but this is noted at the bottom of the example. You could save this in Activity.onSaveInstanceState(Bundle).
private ViewPager viewPager;
viewPager = (ViewPager) findViewById(R.id.pager);
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
// on changing the page
// make respected tab selected
actionBar.setSelectedNavigationItem(position);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
// on tab selected
// show respected fragment view
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
}
Setup: My Flex application is one consisting of several "subapps". Basically, the main application area is an ApplicationControlBar with buttons for each of the subapps. The rest of the area is a canvas where the subapps are displayed. Only one subapp is visible at a time. When switching between subapps, we do a canvas.removeAllChildren(), then canvas.addChild(subAppSwitchedTo). It's essentially a manual implementation of a ViewStack (the pros and cons of which are not the topic of this, so refrain from commenting on this).
Problem: In one of my subapps (let's say subapp "A"), I have a search function where results are displayed in a TitleWindow that gets popped up. Workflow is like enter search criteria, click search button, TitleWindow pops up with results (multiple selection datagrid), choose desired result(s), click OK, popup goes away (PopUpManager.removePopUp), and continue working. This all works fine. The problem is if I switch to a different subapp (say "B" -- where A gets removeAllChildren()'d and B gets added), then switch back to A and search again, when the results TitleWindow pops open, there will be TWO stacked on top of each other. If I continue to navigate away and back to A, every time I search, there will be an additional popup in the "stack" of popups (one for each time A gets addChild()'d).
Has anyone else experienced this? I'm not sure what to do about it and it's causing a serious usability bug in my application. Does this ring any bells to anyone? It's like I somehow need to flush the PopUpManager or something (even though I'm correctly calling removePopUp() to remove the TitleWindow). Please help!
EDIT
Flex SDK = 4.5.1
// Subapp "A"
if (!certificateSearchTitleWindow)
{
certificateSearchTitleWindow = new CertificateSearchTitleWindow;
certificateSearchTitleWindow.addEventListener("searchAccept", searchOKPopupHandler);
certificateSearchTitleWindow.addEventListener("searchCancel", searchClosePopupHandler);
}
PopUpManager.addPopUp(certificateSearchTitleWindow, this, true);
My guess is that the popup is removed from the main display list when you remove its parent (this in the PopUpManager.addPopup() method), but not from its parent display list. Why don't you listen, in your subapps, to the Event.REMOVED event, and then remove your popup ? That would be :
private var pp:CertificateSearchTitleWindow;
private function onCreationComplete():void
{
addEventListener(Event.REMOVED, onRemovede);
}
private function addPopUp():void
{
if (!pp) {
pp = new CertificateSearchTitleWindow();
PopUpManager.addPopUp(pp, this, true);
}
}
private function onRemoved(event:Event):void
{
if (pp) {
PopupManager.removePopUp(pp);
pp = null;
}
}
Thank you to those who gave suggestions. It turned out I was re-registering an eventListener over and over.
I am using a singleton to act as "shared memory" between the subapps. I was setting singleton.addEventListener(someType, listener) in subapp A's creationComplete callback. So everytime I navigated back to A, the creationComplete was running and re-adding this listener. After the search, the listener method (that opened the popup) was being called multiple times, i.e., as many times as the event had been added.
xref: http://forums.adobe.com/message/3941163
For some unknown reason I cannot push a view, I will try to explain the best I can but i have alot of complicated views going on, And it would be a nightmare to explain but say I have the following method.
-(void)showDetailView{
DetailViewController *detailView = [[DetailViewController alloc] initWithNibName:#"DetailViewController" bundle:nil];
[self.navigationController pushViewController:detailView animated:YES];
[detailView release];
}
Which works and would push the detail view onto the stack, this is on my main view and my main thread.
So in the table view i have a cell with a Subview that then takes its view from another view controller. In that view controller I have more subviews, and say when a user clicks a subview a method is called. Which in turn will call this method on the mainView.
So one would believe that then a new view should get pushed. And the code runs, no errors occur but the view is not changed/switched.
I have tried various method of pushing a view inside the view controller that is it called from. and then just calling a method which is directly connected to the navigation controller to push the views.
A few things to add.
1. I have a IBAaction button that pushes a view (that works fine)
2. I assume its because im through so many views but I'm assuming that if you call push view controller it will push whatever view you pass it.
3. I have checked when the method is called from the main view self.navigationcontroller does not = null.
But if the navigation controller is called through the method call it = null.
So is there anyway to restore the null value of a navigation controller?
Im a little confused on why i cant simply call a method to push a view
Thanks
Its ok I have sorted it now
In terms of how i solved accessing the superior superview to my view is
An ID tag to the views superview which is the cell that my subview is in
id CellController = [self.view.superview.superview nextResponder];
[CellController performSelector:#selector(showDetailView:) withObject:Link];
Then calling a method in my cell which then in turn access its superview
id mainController = [self.view.superview.superview nextResponder];
[mainController performSelector:#selector(showDetailView:) withObject:Link];
Which then the main still retains its navigation controller and then in the show detail method in the main passes the link and pushes the new view.
Basically the total superview of a subview can be no higher then wherever it was created. So the subview in my cell could never access and run anything through my mainView properly, i could stuff but it never performed how it should be. So accessing its highest level superview and then getting that to access its superview as the cell is in my main view then I could run methods correctly.
Hope this makes sense only getting my head around it all.
Thanks to -> How does one access a super's view controller?
For the Id tag bit, not used Id in this way so another things learnt
I just had nearly the same problem today. If the navigation bar is hidden when you push a view, you may have a nil navigation controller. I resolve the problem like this :
self.navigationController.navigationBarHidden = NO; // So the navigation controller is not nil
[self.navigationController pushViewController:articleInfoController animated:YES];
I currently have a tab bar controller set up with a navigationcontroller on one of the tabs, then I have a UITableView nib set up for that Navigationcontrollers view. All of this has been set up through IB and I want to keep it that way. Kind of like this tutorial http://twilloapp.blogspot.com/2009/05/how-to-embed-navigation-controller.html
now the view loads perfectly when ViewDidLoad is called. But when I then load further views via code IE
MyApp_AppDelegate *delegate = [[UIApplication sharedApplication] delegate];
UINavigationController *nav = (UINavigationController *)delegate.controller.selectedViewController;
newViewController = [[newViewController alloc] initWithNibName:#"newView" bundle:nil];
[nav pushViewController:newViewController animated:YES];
//At this point the view works! and loads
If I try to go back with the navigation toolbar it goes back to my previous view fine
Now I need to refresh the tableview when I go back but calling viewDidAppear does not work.
I tried adding UINavigationDelegate to the same ViewController Class as the tableview and then calling - (void)navigationController:(UINavigationController *)navigationController didShowViewController:
But that did not work. I also tried adding the same delegate as the tab bar controller and adding the same navigationController didShowViewController: there but that also failed.
How do I get this table to refresh every time the view loads?
You should not have to call viewDidAppear from your code. Cocoa Touch should do that for you.
Call the table view's reloadData method to get it to refresh its contents.
Found I was missing the Delegate declaration in the Interface file. doh! also I tried that in lots of places it only ended up working when I added it to the NavigationControllers first view (my table view)