When I add items to the ItemsSource of a LongListSelector, the LongListSelector automatically scrolls to the top. Is there anyway to disable this?
I tried to use the ScrollTo function after loading, but that is not good enough since I want to stay at the exact same scroll position (meaning I don't want the LostListSelector to scroll at all, when I add a new item to its ItemsSource).
The problem was that I used a List instead of ObservableCollection as the ItemsSource for the LongListSelector and that I used the Lists set function, which implements NotifyPropertyChanged, to assign images to the LongListSelector. This NotifyPropertyChanged event causes the LongListSelector to scroll to index 0 of the ItemsSource.
So I solved it by changing the ItemsSource to an ObservableCollection and use Add instead of the setter for the ObservableCollection.
Related
I was wondering if it is possible to have the tabs in the top position rather than the bottom. I know that CTabView encapsulates a CMFCTabCtrl, but I cannot see how I can set the tabs position.
CTabView encapsulates a tab control (CMFCTabCtrl). It is exposed through the CTabView::GetTabControl member. The CMFCTabCtrl derives from CMFCBaseTabCtrl. The latter implements a CMFCBaseTabCtrl::SetLocation member, that allows to set the tab area position. The position can be either LOCATION_BOTTOM or LOCATION_TOP as documented under CMFCBaseTabCtrl::GetLocation.
To set the tab area position to the top for a CTabView instance use the following code:
MyTabView.GetTabControl().SetLocation( LOCATION_TOP );
I want to add an icon and another textblock to my data template when the item in longListSelector is tapped. Also, when another item is tapped, I want to remove this icon and textblock from previously selected item and expand new selected item. How can I achieve that?
Options 1 (Modify it through Code-Behind)
You can modify my ListBox collapse code to do what you want : ListBox Collapse. You need to change the Border to a <Grid> then loop through the .Children to hide/show the extra textblock and icon. Always save the reference to the current SelectedItem so when the SelectionChanged event fires you can hide the previous selection and then show the newer Selected Item.
Option 2: Create An ItemControl you can use as part of the Item.DataTemplate of the LongListSelector
Using this method, you want to create your own VisualState (Selected, NotSelected.. or whatever you want).
In the Selected (StoryBoard) you change the extra Textblock/Icon's Visibility to Visible.
In the NotSelected (StoryBoard) you change the extra Textblock/Icon's Visibility to Collapse.
Then when the SelectionChanged Event on the LongListSelector, loop through your ItemSources and compare it to the SelectedItem.
If the current item is the SelectedItem then VisualStateManager.GoToState(your_control, "Selected") else VisualStateManager.GoToState(your_control, "NotSelected")
This will complete the whole interaction that you want.
I need to show a popup layer on a scene, creating a semi-transparent background layer that will also prevent touch events propagation. I am using the latest cocos2d-x v. 3.0-alpha-0.
What I want to achieve is a popup layer that fully handles touches (eg. buttons, menu items, scroll views, etc.), laying on a background layer (for design purposes), that covers the current scene. All items in the scene should not respond to touches any more.
Is this achievable using the new EventDispatcher class? I've been able to disable all touches to the main scene, but all instances of MenuItem that live in the scene are still touchable and active.
How can I achieve this? And, also, how can I create a touch listener that prevents all touches to the main scene but not to the popup?
You can disable menu items by setting setDisable property of menuitems to false.
Example
_menuItem->setEnabled(false);
For Layers use setTouchEnabled property
_backGroungLayer->setTouchEnabled(false);
Make sure that popup layer is not child of layer you want to disable.
To disable all items in menus do this
Suppose _menu contain various menuitems.
CCARRAY_FOREACH(_menu->getChildren(), item)
{
item.isEnabled=NO;
}
if you want to disable selected items just give them tags.There is no need to make any list.
I had the same problem and solved it with mm. It was dirty, but it worked:
Create a button using ccui.button.
Set the button size to your screen size.
Add this button as a background to your popup layer.
This will prevent any thing behind it being clicked.
By default, all CCMenu's have a set priority (kCCMenuHandlerPriority = -128) in cocos2d 2.1. So in a class (usually a CCNode descendant) that wants to swallow everything and preempt anything i do like in this dialog sequencer example below :
- (void)onEnter {
backdrop_.visible = self.isBackDropShown;
MPLOG(#"Adding self as a swallower touch delegate, above the rest of the planet.");
[[[CCDirector sharedDirector] touchDispatcher] addTargetedDelegate:self priority:_dialogTouchPriority swallowsTouches:YES];
for (CCMenu *mn in _menus) {
mn.touchPriotity = _dialogTouchPriority -1 ;
}
[super onEnter];
}
where _dialogTouchPriority is kCCMenuHandlerPriority-1 by default. It will be served before everything 'below'. It is a bad hack (cocos2d internals could be changed and break this), i know , but bullet proof. Use carefully, make certain you only ever have one of these in your scene.
I am building a Flex 4 application which uses a <s:Scroller> component to vertically scroll overflown content. Let me explain what happens before I ask my question:
The body of the page is loaded from a database
Once the information has loaded, the "body" of the application (in this case the list of items you see below) is constructed
Once the list is constructed, the entire encapsulating component is transitioned into view using TweenMax, like so:
myComponent.visible = true;
TweenMax.to(myComponent, 1, {
alpha : 1,
y -= 20 //Slides the component up 20px from its original location
});
Below is the result. Notice how the scrollbar is scrolled the whole way down, but you can see the tips of a few white letters that were cut off at the very bottom.
Using my custom menu, I can navigate away from the page, and come back to it, and Flex will correctly recalculate the range of the scroller so I can scroll down and see all of the desired content. This issue only happens if the initial URL that the user enters is a longer page like this one.
Any ideas on how I can force Flex to recalculate the range of the scroller?
Thank you for your time.
Ok, after many hours of researching, piecing together, and trial and error here is what I came up with.
What I was doing wrong:
When I first posted this question, the "component" that I had mentioned was already added as a child element of the <s:Scroller>, but collapsed and hidden away, like this:
<comp:MyComp alpha="0" height="0" visible="false"/>
When the data would be loaded and the component's visual appearance would be restored and transitioned into place, like this:
myComp.visible = true;
myComp.height = NaN;
myComp.invalidateSize();
myComp.height = myComp.measuredHeight;
TweenMax.to(myComp, 1, {
alpha : 1,
y -= 20 //Slides the component up 20px from its original location
});
This method of approach didn't force the <s:Scroller> to recalculate its proper size until later, sometimes not until myComp was transitioned away and another component was transitioned into place using the same method. Even then, the size of the scroller would fit the size of the previous component, not the one that is currently displaying.
Now, what I am doing correctly:
My research showed me that anytime the addElement() method is called, either directly within the <s:Scroller> itself or by any of its children, the scroller's measure() method is called, and properly re-sizes the scroller.
Instead of placing the components inside of the scroller and simply hiding them until I need them, I dynamically created them in ActionScript, set their properties, and added and removed them as needed using the addElement() and removeElement() methods respectively. Now, as old elements are transitioned away and new ones take their place, the scroller re-sizes itself correctly.
There was one final problem that I was faced with. If the very first page the user was viewing (i.e. there was no previous component that was transitioned away and destroyed) required a scroller, it wouldn't show up.
I corrected this final issue by adding an event listener that listened for when the new component had finished transitioning into place. Inside of the event handler, I explicitly set the height of the component using this code:
newComp.height = NaN;
newComp.invalidateSize();
newComp.height = newComp.measuredHeight;
Now that the component has an explicit height, the scroller now appears, even if it is the first page.
The scroller now works as expected in all cases, and does not cut off any content or disappear when it shouldn't.
I hope that it is helpful to someone.
I'd like to conditionally hide a tab in a TabNavigator. It seems that setting visible doesn't work properly (presumably because this is how the TabNavigator hides the tabs that aren't currently selected).
What's the right way to do this?
You can do this by making use of TabNavigator's getTabAt() method which returns the Button that makes up the visual tab. You can then set that Button's visible property. It's a little tricky to get this setup with a bindings, but it's doable.
You could also consider just disabling the tab instead, which you can do by setting enabled on the corresponding TabNavigator child (for which visible didn't work).
What do you mean by hide? If you actually mean remove, then just take your array that's bound to the data in the TabNavigator, and remove the applicable element from it.
If you want to just have them removed temporarily, create a component of your own that encapsulates the TabNavigator and has an array of removed tabs and an array of actual tabs. Then handle this as you see fit.
You might want to check out the flexlib project. They have a component called SuperTabNavigator that adds a lot of functionality to the base Flex TabNavigator, including hiding tabs (I think).
If you do have to create your own component, though, it's a bit more tricky. The thing to know is that "tabs" are actually specially styled buttons, contained within a TabBar component (the TabBar is then contained within the TabNavigator). What you'll have to do then, is subclass TabNavigator and have some property on your views (i.e. the canvases, etc. that are added to the TabNavigator) that is bound to the visible and includeInLayout properties of the TabBar buttons.
In essence, what you'll have is something like:
BindingUtils.bindProperty( tabButton, "visible", view, "someProperty" );
BindingUtils.bindProperty( tabButton, "includeInLayout", view, "someProperty" );
I don't know about TabNavigator, but in other containers, you can set the includeInLayout property to false and it will be ignored. You probably still need to combine it with visible.
var secondTab = tabNavigator.removeChildAt(0);