I have a VBox who dynamically adds and removes children programatically. The height is set to 100% and verticalScrollPolicy=auto.
When a user wants to add another child to that Vbox, I want it to autoscroll to the bottom of the VBox since that is where the child is added.
I've tried every solution I could find online, but no matter what, the verticalScrollPosition and maxVerticalScrollPosition are both ALWAYS equal to 0. Even if I manually scroll to the bottom of the VBox and press a button that alerts these numbers.(Even after 'validateNow()' as well).
The only time I can get these numbers to change programmaticaly is when the VBox height is set in pixels, which I don't want since the children all have varying heights.
Plllease tell me that it's possible to set verticalScrollPosition without hard coding the height in pixels? Am I missing something totally obvious here?
You might not be scrolling the VBox, actually; there's a good chance that if your VBox is contained by another container, like a Canvas or the like, and you're adding items to the VBox as you say you are, it's the Canvas that's doing the scrolling, not the VBox -- in which case the VBox would indeed return 0 for its scroll position.
One way or another, you're right -- you have to set the component's height; even constraint-layout settings (e.g., "bottom='10'", etc.) won't work. But if you can manage to set the height of the VBox, either by binding its dimensions somehow to another control or by setting them explicitly as part of a child's appending/creation process, you should be able to accomplish what you're after.
Here's an example of an AIR app I've mocked up to illustrate the example. Basically it just adds randomly sized boxes to a VBox, and scrolls to the bottom of the VBox after each child gets created.
<?xml version="1.0" encoding="utf-8"?>
<mx:WindowedApplication xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" verticalScrollPolicy="off" horizontalScrollPolicy="off" width="250">
<mx:Script>
<![CDATA[
import mx.core.Application;
import mx.containers.Box;
import mx.events.FlexEvent;
private function addItem(h:Number):void
{
var b:Box = new Box();
b.width = 200;
b.setStyle("backgroundColor", 0xFFFFFF);
b.height = h;
// Wait for the component to complete its creation, so you can measure and scroll accordingly later
b.addEventListener(FlexEvent.CREATION_COMPLETE, b_creationComplete);
vb.addChild(b);
}
private function b_creationComplete(event:FlexEvent):void
{
event.currentTarget.removeEventListener(FlexEvent.CREATION_COMPLETE, b_creationComplete);
vb.verticalScrollPosition = vb.getChildAt(vb.numChildren - 1).y;
}
]]>
</mx:Script>
<mx:VBox id="vb" top="10" right="10" left="10" height="{Application.application.height - 80}" verticalScrollPolicy="on" />
<mx:Button label="Add Item" click="addItem(Math.random() * 100)" bottom="10" left="10" />
</mx:WindowedApplication>
In this case, the height of the VBox is being bound to the height of its containing component (here, just the Application). Everything else should be pretty self-explanatory.
Hope that helps! Post back if you have any questions.
Related
We have a list of variable height items that we display in a Spark List control. When the user clicks and drags the vertical scrollbar the list scrolls smoothly. When the up/down arrows are used it moves in small and discrete steps. When the mouse wheel is used the list scrolls in very large discrete steps that is problematic for the user.
We would like to enable smooth scrolling for the mouse wheel. The height of our items vary significantly and it is easy to get lost when you scroll with the moouse due to the discrete scrolling.
Our implementation is fairly simple:
<s:List id="chartList"
dataProvider="{pm.charts}"
itemRenderer="charts.ChartItemRenderer"
horizontalScrollPolicy="off"
verticalScrollPolicy="on"
useVirtualLayout="false"
cachePolicy="auto">
</s:List>
<?xml version="1.0" encoding="utf-8"?>
<s:ItemRenderer xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx"
autoDrawBackground="false"
xmlns:charts="charts.*"
>
<fx:Script>
<![CDATA[
private var _canvas:BitmapData;
public function set canvas(value:BitmapData):void
{
_canvas = value;
}
[Bindable]
public function get canvas():BitmapData
{
return _canvas;
}
public function render(x:int,y:int, data:int):void
{
_canvas.draw(this);
}
]]>
</fx:Script>
<charts:DefaultChartContainer
chart="{data}"
cachePolicy="on"/>
</s:ItemRenderer>
There does not appear to be an out of the box method for implementing smooth scrolling in a Spark List. How would one go about implementing smooth scrolling in a spark list for variable height items?
Edit:
Here is another way to do this:
http://forums.adobe.com/message/3844410#3844410
Ok, so this wont be easy, but it is doable.
1) Create a custom skin for your list
2) In the custom skin, replace the scroller with a custom scroller (MyScroller)
3) Create a new class that extends Scroller, called MyScroller
4) Adobe in their infinite wisdom made skin_mouseWheelHandler private - which they seem to do all over the place, so you would have to override something higher up, maybe attachSkin and detachSkin. Or you could try adding your own skin_mouseWheelHandler with a higher priority in attachSkin and prevent default on it so the default does not get called.
5) Replicate the code in skin_mouseWheelHandler, and modify it to suit your requirements.
Like #Sunil_D. suggested, listening the mousewheel event and manually adjusting the HorizontalScrollPosition is an easy way to handle this. Add the EventListener for your component
chartList.addEventListener(MouseEvent.MOUSE_WHEEL, chartList_mouseWheelHandler);
and increase/decrease the horizontalScrollPosition with, for example, multiples of event.delta
protected function chartList_mouseWheelHandler(event:MouseEvent):void
{
chartList.verticalScrollPosition -= (event.delta * SOME_CORRECT_VALUE);
}
Finding the proper SOME_CORRECT_VALUE might need some experimenting, but it shouldn't be to hard to find.
I have a collection of UIMovieClip components which reside in an s:HGroup tag. In ActionScript code I am modifying the width of a child clip in one of the UIMovieClips but these changes are not reflected by the s:HGroup.
<s:HGroup id="_buttonGroup">
<uiassets:NavigationTabButtonSWC id="_lobby" />
<uiassets:NavigationTabButtonSWC id="_achievements" />
</s:HGroup>
<fx:Script>
<![CDATA[
protected function init() : void
{
// The HGroup does not pickup this change and so my buttons
// are no longer evenly spaced out and overlap!
_lobby.getChildByName("background").width += 200;
}
]]>
</fx:Script>
Thanks!
There's a few reasons for this. Just changing one child's width doesn't mean it'll change the whole UIMovieClip's width, so you should check that first.
Second, Flex has a very specific way of doing things (called the component lifecycle), which the UIMovieClip doesn't implement so you can't manage the width yourself in the 'measure' function. I'm guessing that you just have other children in your movieclip that doesn't let you resize it all. Try changing the width of the MovieClip itself and it should work. If it doesn't, then there's another problem.
If you know Flex, you probably know what the property "includeInLayout" does. If not, this property make the parent of your component disregard the bounds (like width and height) of your component in render their own bounds.
Description in reference below:
Specifies whether this component is
included in the layout of the parent
container. If true, the object is
included in its parent container's
layout and is sized and positioned by
its parent container as per its layout
rules. If false, the object size and
position are not affected by its
parent container's layout.
http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/mx/core/UIComponent.html#includeInLayout
In Flex, for example:
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
layout="absolute"
creationComplete="application1_creationCompleteHandler(event)">
<mx:Script>
<![CDATA[
import mx.events.FlexEvent;
protected function application1_creationCompleteHandler( event:FlexEvent ):void
{
trace( container.width, container.height ); // output: 200 200
}
]]>
</mx:Script>
<mx:Canvas id="container">
<mx:Button label="Test"
width="100"
height="100" />
<mx:Button label="Test2"
width="200"
height="200" />
</mx:Canvas>
</mx:Application>
Now if I set includeInLayout="false" in second button:
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
layout="absolute"
creationComplete="application1_creationCompleteHandler(event)">
<mx:Script>
<![CDATA[
import mx.events.FlexEvent;
protected function application1_creationCompleteHandler( event:FlexEvent ):void
{
trace( container.width, container.height ); // output: 100 100
}
]]>
</mx:Script>
<mx:Canvas id="container">
<mx:Button label="Test"
width="100"
height="100" />
<mx:Button label="Test2"
width="200"
height="200"
includeInLayout="false" />
</mx:Canvas>
</mx:Application>
I know of all framework architecture involved to implement this property and know than this property is a property from Flex Framework. What I wanna is this behavior in pure actionscript. For example:
import flash.display.Shape;
var myBox:Shape = new Shape();
myBox.graphics.beginFill(0xFF0000);
myBox.graphics.drawRect(0, 0, 100, 100);
myBox.graphics.endFill();
addChild(myBox);
trace(width, height); // output: 100 100
var myAnotherBox:Shape = new Shape();
myAnotherBox.graphics.beginFill(0xFF00FF, .5);
myAnotherBox.graphics.drawRect(0, 0, 200, 200);
myAnotherBox.graphics.endFill();
addChild(myAnotherBox);
trace(width, height); // output: 200 200
Is there some equivalent implementation in pure Actionscript to reproduce this behavior on "myAnotherBox"?
I already tried:
Change transform matrix;
Change transform pixelBounds;
Change scrollRect;
Apply masks;
And no successful.
Cheers...
You are trying to compare to different things.
In the first example, the width and height are from the UIComponent class, which actually represents a "measured" value, as provided by the Flex Framework.
In the second case, the width and height are the actual size of the rendered shape, as provided by the Flash Player.
If you open the UIComponent's implementation, you will notice that it is actually hiding the original meaning of width and height into $width and $height and provide their own implementation to it.
So to answer your question, you cannot achieve what you want working directly with Shapes (pure Flash components)
Every time you draw something in a graphics context, the width and height will update accordingly.
You options:
draw the first one in one graphics, and the second one in another graphics and measure only the first shape
compute the width and height yourself. This is what actually the containers do, and just skip the includeInLayout=false child components.
If you look up in the UIComponent source code, you'll find, that flag includeInLayout is used in invalidation mechanism (exatcly in size invalidation). If includeInLayout of the component is false, then its parent's size and its size is not recalculated.
Invalidation is native flex framework mechanism, which does not exist in pure AS projects.
You need to override width and height in your container:
override public function get width() : Number {
// place your code here
return 100;
}
override public function get height() : Number {
// place your code here
return 100;
}
Do you know any collapsible flex container that can handle dynamic content that works when pre-collapsed?
I tried the CollapsiblePanel component by Arc90 for Flex, but it did not work when pre-collapsed.
If I have a VBox inside the panel, and I set the "collapsed" property of the CollapsiblePanel to true, the size of the CollapsiblePanel cannot be restored. It seems like this is what is happening:
The CollapsiblePanel's collapsed property is pre-set to true in the MXML markup.
The VBox auto-adjusts its height to 0 since the CollapsiblePanel is collapsed.
When the CollapsiblePanel's collapsed property changes to false (i.e., it is expanded by the user), the VBox does not expand itself because its parent's content area is 0.
Therefore the CollapsiblePanel remains at the same height because its content's height is 0.
Therefore...
Note: This occurs only when the CollapsiblePanel is pre-collapsed, as seen in the markup below.
I've already tried this (didn't work):
<containers:CollapsiblePanel minimize="pnl_minimize(event)"
restore="pnl_restore(event)" height="100%" width="100%" collapsed="true">
<mx:VBox width="100%" height="100%" verticalGap="0">
<mx:LinkButton id="lnkSales1" label="Sales 1" />
<mx:LinkButton id="lnkSales2" label="Sales 2" />
</mx:VBox>
</containers:CollapsiblePanel>
private function pnl_restore(event:Event):void
{
var objPanel:CollapsiblePanel = event.target as CollapsiblePanel;
var objChildArray:Array = objPanel.getChildren();
for each (var obj:Object in objChildArray)
{
obj.invalidateSize();
}
objPanel.invalidateSize();
}
Is there anyone who has succeeded in doing something like this? What component did you use?
Finally got a solution, though it's a bit of a workaround. I allow all the panels to be loaded and then collapse them programmatically instead of pre-collapsing them in the markup. This way their size is already computed and can be restored without any issues when the user restores them.
Does anyone have a better solution?
I have a HorizontalList control that uses a custom ItemRenderer to represent each item as a toggle-button. The list allows drag and drop, and I used this method to rotate the drop feedback (line) into a vertical position instead of horizontal, but with the buttons mashed together, the drop feedback is pretty subtle. I'd like to space out the buttons somehow, so that the drop feedback is more obvious.
I've looked through the properties and nothing stands out. There are padding and margin properties, but their descriptions say they affect the list control itself, not the items.
Below is the code of my ItemRenderer. I've added padding to it, but that doesn't seem to change anything. If I add padding, that affects the inside of the button, not the space between them, and the button control doesn't have margin properties.
I suppose I could base my ItemRenderer on a canvas in order to get a margin, but then I wouldn't inherit all of the functionality of a button.
<?xml version="1.0" encoding="utf-8"?>
<mx:Button
xmlns:mx="http://www.adobe.com/2006/mxml"
creationComplete="go();"
toggle="true"
>
<mx:Script>
<![CDATA[
private var _val:int = -1;
private function go():void {
this.label = data.title;
_val = data.index;
}
override protected function clickHandler(event:MouseEvent):void{
//todo: bubble an event that causes all other
//buttons in the list to un-toggle
//now do the default clickHandler
super.clickHandler(event);
}
]]>
</mx:Script>
</mx:Button>
How about writing your item renderer as a container (either Canvas or HBox) and placing the Button element inside?
Make a custom skin for your buttons that includes the spacing you need. You may need to combine it with padding styles to ensure that text or icons don't go outside the skin.
It's a bit on the hacky side, but you can also lie about your columnWidth for the actual HorizontalList object. Set it to something larger than your actual itemRenderer width.