I am trying to drag and drop an object across the SkinnableContainer- am coming across a very strange issue
The drop occurs only at a few places- elsewhere it just shows the "X" sign and on dropping there, reverts to original position. I have used very standard commands... from function 2 to function 3, the call occurs very rarely as seen in trace statements- any guidance on why this happens?
I added the following code to SkinnableContainer: dragEnter="dragEnterHandler(event);" dragDrop="dragDropHandler(event);
(1):
private function mouseMoveHandler(event:MouseEvent):void
{
var dragInitiator:Image = Image(event.currentTarget);
var ds:DragSource = new DragSource();
ds.addData(dragInitiator,"img"); //made change here
DragManager.doDrag(dragInitiator, ds, event);
}
(2):
private function dragEnterHandler(event:DragEvent):void {
if (event.dragSource.hasFormat("img"))
{
trace("came here"); //comes here for each mouse move
DragManager.acceptDragDrop(SkinnableContainer(event.currentTarget));
}
(3):
private function dragDropHandler(event:DragEvent):void {
trace("in drag drop handler"); //doesn't come here for most places
According to the Using Flex 4 reference:
To use a container as a drop target, you must use the backgroundColor property of the container to set a color. Otherwise, the background color of the container is transparent, and the Drag and Drop Manager is unable to detect that the mouse pointer is on a possible drop target.
In the subsequent example, they use an mx container (Canvas), but I checked the AS3 reference, and spark.components.SkinnableContainer does have a style backgroundColor.
I haven't tried this myself, so please confirm whether it is the issue. From your description that only certain parts of the container are registering the dragEnter event, this seems like a consideration that would lead to such effects.
Related
If a ContextMenu has lots of items, it fills the entire screen. It seems that ContextMenu.setMaxSize has no effect whatsoever.
Is there a way to restrict the size of a ContextMenu, in a way that it is still scrollable via mouse wheel & and the up and down buttons appear?
I guess I could roll my own control with VBox & Scrollpane, but I'd like to avoid this if possible.
Unfortunately, limiting the size of popup is not supported: the Region that's responsible for showing the MenuItems is ContextMenuContent and implements its computeMaxHeight to return the screenHeight. That container is created by ContextMenuSkin and stored into a private final field, so there's no way to replace it with a custom implementation with a more intelligent implementation.
What we can do, though, is to access that region and set its maxHeight to the same value as the ContextMenu. To remain off the evil illegal reflective access to the private field, we can register a handler for the Menu.ON_SHOWING event and update the size as needed [*].
Something like
public class MaxSizedContextMenu extends ContextMenu {
public MaxSizedContextMenu() {
addEventHandler(Menu.ON_SHOWING, e -> {
Node content = getSkin().getNode();
if (content instanceof Region) {
((Region) content).setMaxHeight(getMaxHeight());
}
});
}
}
[*] update: to make this work, the ContextMenu must have a reasonable maxHeight (default is Double.MAX_VALUE), that is it must be set manually after instantiation. Furthermore, we have to use the ContextMenu's maxHeight in the eventHandler (vs. f.i. an arbitrary constant), otherwise vertical location of the popup is broken - the layout code still thinking, that it's filling the entire screen height.
ContextMenu menu = new MaxSizedContextMenu();
menu.setMaxHeight(200);
I'm writing a program using Qt 4.8 that displays a table (QTableWidget) filled with filenames and file's params. First an user adds files to the list and then clicks process. The code itself updates the contents of the table with simple progress description. I want the table by default to be scrolled automatically to show the last processed file and that code is ready.
If I want to scroll it by hand the widget is being scrolled automatically as soon as something changes moving the viewport to the last element. I want to be able to override the automated scroll if I detect that it was the user who wanted to change view.
This behavior can be seen in many terminal emulator programs. When there's a new line added the view is scrolled but when user forces the terminal to see some previous lines the terminal does not try to scroll down.
How could I do that?
Solution:
I created an object which filters event processed by my QTableWidget and QScrollBar embedded inside. If I spot the event that should turn off automatic scrolling I just set a flag and stop scrolling view if that flag is set.
Everything is implemented inside tableController class. Here are parts of three crucial methods.
bool tableController::eventFilter(QObject* object, QEvent* event)
{
switch (event->type())
{
case QEvent::KeyPress:
case QEvent::KeyRelease:
case QEvent::Wheel:
case QEvent::MouseButtonDblClick:
case QEvent::MouseButtonPress:
case QEvent::MouseButtonRelease:
_autoScrollEnabled = false;
default:
break;
}
return QObject::eventFilter(object, event);
}
void tableController::changeFile(int idx)
{
[...]
if (_autoScrollEnabled)
{
QTableWidgetItem* s = _table.item(_engine.getLastProcessed(), 1);
_table.scrollToItem(s);
}
[...]
}
void tableController::tableController()
{
[...]
_autoScrollEnabled = true;
_table.installEventFilter(this);
_table.verticalTableScrollbar()->installEventFilter(this);
[...]
}
Thanks for all the help. I hope somebody will find it useful :)
Subclass QTableWidget and overload its wheelEvent. You can use the parameters of the supplied QWheelEvent object in order to determine if the user scrolled up or down.
Then use a simple boolean flag which is set (or reset) in your wheelEvent override. The method which is responsible for calling scrollToBottom() should then consider this boolean flag.
You will have to find a way to figure out when to set or reset that flag, e.g. always set it when the user scrolls up and reset it when the user scrolls down and the currently displayed area is at the bottom.
connect(_table->view()->verticalScrollBar(), &QAbstractSlider::actionTriggered, this, [this](int) {
_autoScrollEnabled = false;
});
I am building an RIA application using Flex 4.6 that contains a main borderContainer (page) that can contain some other borderContainers (graphic or text elements).
I added an event listener on the page to listen to click events:
page.addEventListener(MouseEvent.CLICK, clickHandler, true);
clickHandler looks like this:
private function clickHandler(event:MouseEvent):void
{
// Remove event listeners
page.removeEventListener(MouseEvent.CLICK, clickHandler, true);
// Get click position
objX = event.localX;
objY = event.localY;
}
My problem is that although the event's currentTarget is always the page (normal), the target can either be the page or one of its children, and then localX doesn't give me the position on the page but on the child.
Is there a way to make sure the page is always the target of the event? Something like stopping the capturing phase on the page so it doesn't go deeper?
Thanks in advance for your help
Darrel
I think you may be asking the wrong question. As I understand it, you want the x/y position relative to 'page'. You can use the DisplayObject#globalToLocal() function to find this.
Just take the the global coordinates and convert them to local coordinates relative to 'page':
var coordinates:Point = new Point(event.stageX, event.stageY);
coordinates = page.globalToLocal(coordinates);
objX = coordinates.x;
objY = coordinates.y;
I have a simple list and a background refresh protocol.
When the list is scrolled down, the refresh scrolls it back to the top. I want to stop this.
I have tried catching the COLLECTION_CHANGE event and
validateNow(); // try to get the component to reset to the new data
list.ensureIndexIsVisible(previousIndex); // actually, I search for the previous data id in the IList, but that's not important
This fails because the list resets itself after the change (in DataGroup.commitProperties).
I hate to use a Timer, ENTER_FRAME, or callLater(), but I cannot seem to figure out a way.
The only other alternatives I can see is sub-classing the List so it can catch the dataProviderChanged event the DataGroup in the skin is throwing.
Any ideas?
Actually MUCH better solution to this is to extend DataGroup. You need to override this.
All the solutions here create a flicker as the scrollbar gets resetted to 0 and the it's set back to the previous value. That looks wrong. This solution works without any flicker and the best of all, you just change DataGroup to FixedDataGroup in your code and it works, no other changes in code are needed ;).
Enjoy guys.
public class FixedDataGroup extends spark.components.DataGroup
{
private var _dataProviderChanged:Boolean;
private var _lastScrollPosition:Number = 0;
public function FixedDataGroup()
{
super();
}
override public function set dataProvider(value:IList):void
{
if ( this.dataProvider != null && value != this.dataProvider )
{
dataProvider.removeEventListener(CollectionEvent.COLLECTION_CHANGE, onDataProviderChanged);
}
super.dataProvider = value;
if ( value != null )
{
value.addEventListener(CollectionEvent.COLLECTION_CHANGE, onDataProviderChanged);
}
}
override protected function commitProperties():void
{
var lastScrollPosition:Number = _lastScrollPosition;
super.commitProperties();
if ( _dataProviderChanged )
{
verticalScrollPosition = lastScrollPosition;
}
}
private function onDataProviderChanged(e:CollectionEvent):void
{
_dataProviderChanged = true;
invalidateProperties();
}
override public function set verticalScrollPosition(value:Number):void
{
super.verticalScrollPosition = value;
_lastScrollPosition = value;
}
}
I ll try to explain my approach...If you are still unsure let me know and I ll give you the source code as well.
1) Create a variable to store the current scroll position of the viewport.
2) Add Event listener for Event.CHANGE and MouseEvent.MOUSE_WHEEL on the scroller and update the variable created in step 1 with the current scroll position;
3) Add a event listener on your viewport for FlexEvent.UpdateComplete and set the scroll position to the variable stored.
In a nutshell, what we are doing is to have the scroll position stored in variable every time user interacts with it and when our viewport is updated (due to dataprovider change) we just set the scroll position we have stored previously in the variable.
I have faced this problem before and solved it by using a data proxy pattern with a matcher. Write a matcher for your collection that supports your list by updating only changed objects and by updating only attributes for existing objects. The goal is to avoid creation of new objects when your data source refreshes.
When you have new data for the list (after a refresh), loop through your list of new data objects, copying attributes from these objects into the objects in the collection supporting your list. Typically you will match the objects based on id. Any objects in the new list that did not exist in the old one get added. Your scroll position will normally not change and any selections are usually kept.
Here is an example.
for each(newObject:Object in newArrayValues){
var found:Boolean = false;
for each(oldObject:Object in oldArrayValues){
if(oldObject.id == newObject.id){
found = true;
oldObject.myAttribute = newObject.myAttribute;
oldObject.myAttribute2 = newObject.myAttribute2;
}
}
if(!found){
oldArrayValues.addItem(newObject);
}
}
My solution for this problem was targeting a specific situation, but it has the advantage of being very simple so perhaps you can draw something that fits your needs from it. Since I don't know exactly what issue you're trying to solve I'll give you a description of mine:
I had a List that was progressively loading data from the server. When the user scrolled down and the next batch of items would be added to the dataprovider, the scrollposition would jump back to the start.
The solution for this was as simple as stopping the propagation of the COLLECTION_CHANGE event so that the List wouldn't catch it.
myDataProvider.addEventListener(
CollectionEvent.COLLECTION_CHANGE, preventRefresh
);
private function preventRefresh(event:CollectionEvent):void {
event.stopImmediatePropagation();
}
You have to know that this effectively prevents a redraw of the List component, hence any added items would not be shown. This was not an issue for me since the items would be added at the end of the List (outside the viewport) and when the user would scroll, the List would automatically be redrawn and the new items would be displayed. Perhaps in your situation you can force the redraw if need be.
When all items had been loaded I could then remove the event listener and return to the normal behavior of the List component.
I am creating a canvas in actionscript like :
private var cvs_preview:Canvas = null;
private function show_preview():void
{
this.cvs_preview = new Canvas();
this.cvs_preview.id = "cvs_preview_1";
this.cvs_preview.setStyle('backgroundColor', 0x000000);
this.cvs_preview.setStyle('backgroundAlpha', 1);
this.cvs_preview.setStyle('borderColor', 0x417FDD);
this.cvs_preview.setStyle('cornerRadius', 10);
this.cvs_preview.setStyle('borderStyle', 'solid');
this.cvs_preview.setStyle('dropShadowEnabled', true);
var pt:Point = image.localToGlobal(new Point(image.x, image.y));
this.cvs_preview.x = pt.x - 50;
this.cvs_preview.y = pt.y - 50;
this.cvs_preview.height = 200;
this.cvs_preview.width = 250;
//this.cvs_preview.addEventListener(FlexEvent.CREATION_COMPLETE, get_focus_on_canvas);
//this.cvs_preview.focusManager.setFocus(
//this.cvs_preview.addEventListener(MouseEvent.CLICK, end_preview_on_focus_change);
this.cvs_preview.addEventListener(FocusEvent.MOUSE_FOCUS_CHANGE, end_preview_on_focus_change);
Application.application.addChild(this.cvs_preview); //add as top-most visible container
btn_mini_preview.enabled = false;
}
So on the focus change i want to run the "end_preview_on_focus_change()"
but this is not working.
As per my understanding, i think the canvas not getting any focus in the first place. I was trying to use focusManager.setFocus to do that after the canvas's creation complete. but even that is giving me an error.
the code i was trying on Creation.Complete is :
private function get_focus_on_canvas(e:FlexEvent)
{
focusManager.setFocus(e.target);
//Alert.show("testing img complete");
}
this is giving me an error "1118: Implicit coercion of a value with static type Object to a possibly unrelated type mx.managers:IFocusManagerComponent."
basically i just want to use the focus out event of the canvas.
Can someone help me with this...
I have been on this issue since a long time.
Regards
Zeeshan
The error is correct. You have an object of type Object which you are trying to use as an IFocusManagerComponent. This will not work. To accomplish that line of code, you need to do something like
focusManager.setFocus( IFocusManagerComponent( e.target ) );
This, of course, assumes that the target implements IFocusManagerComponent. It will give you an error otherwise (and likely will in this case because Canvas is not listed as an IFocusManagerComponent). The good news is that Canvas does have a drawFocus method which will accomplish the same thing.
As to your MOUSE_FOCUS_CHANGE event, that will only be fired if an object already HAS focus and then loses it. I think you are better off using FlexEvent.CREATION_COMPLETE. This will ensure that the component has registered itself with all of the appropriate classes in the Flex SDK so that the FocusManager can even be aware of the new object. Whatever you do, do not try to set focus on something which has not been added to the stage (ie: Event.ADDED has been called).
As another piece of advice -- Event.ADDED bubbles, make sure that event.currentTarget == event.target to make sure that you are listening to the correct object. Otherwise, you might be calling the same function multiple times erroneously.
Only a few classes implement IFocusManagerComponent as others mentioned and Canvas is not one of them. If you really must call FocusManager.setFocus() you will have to extend the canvas class to implement this interface and use that class instead. You don't have to write any methods to implement this interface, all methods have already been implemented by UIComponent itself
//FocusableCanvas.as (include appropriate package and import statements)
public class FocusableCanvas extends Canvas implements IFocusManagerComponent
{
public function FocusableCanvas()
{
super();
}
}
//Now use this class instead of Canvas
this.cvs_preview = new FocusableCanvas();
//setFocus in creation complete handler
FocusManager.setFocus(IFocusManagerComponent(e.target));
But if all you want to do is to set focus on the canvas upon it's creation, you can call canvas.setFocus() from the creationComplete handler instead.
private function get_focus_on_canvas(e:FlexEvent)
{
Canvas(e.currentTarget).setFocus();
trace("done");
}
I see two problems, and no perfect solutions. With any luck, this can help you out.
First of all, e.target returns an object typecast with type Object. This explains your implict coercion error, because Object does not implement IFocusManagerComponent.
Second, iFocusManagerComponent is only implemented by Accordion, AdvancedListBase, Button, ButtonBar, ChartBase, ComboBase, DateChooser, DateField, HTML, ListBase, MenuBar, NumericStepper, TabNavigator, TextArea, TextInput, UIMovieClip as per this entry in the Flex 3.4 AS3 Reference.
This leads me to believe that a Canvas element cannot take focus and has simply inherited access to the FocusManager through inheritance of UIComponent.
The only solutions I can see are to utilize something other than Canvas to handle your focus related concerns, or subclass Canvas and implement iFocusManagerComponent, though that looks fairly complex.
Edit
Apologies for missing drawFocus in the above solution.
Please try;
private function get_focus_on_canvas(e:FlexEvent)
{
this.cvs_preview.setFocus();
}