How can I display one component on the top of another one in flex without explicitly mentioning x-axis & y-axis?
Use canvas and inside canvas you can add controls that will be displayed one above another, the last one added will be the top most one and first added will stay in behind.
Something else to consider, depending on your UI:
This is still a bit 'hacky' (any solution for doing this will be), but given a container (VBox etc) with two or more components, set the includeInLayout property in the first component to false. When the container renders the second component will ignore the first and draw on top.
This also would allow you to add additional components in that same container, but obviously it depends on your UI a great deal.
Related
i need some pointers here because i don't really know what to look for.
The project is in gwt and is using gwtquery.
I have this page with some elements and when the mouse overs an element it changes showing additional infos, let's call it header. When the mouse goes out of the header (which has some buttons so it need to stay visible once shown) it returns invisible.
The problem is that when the header is made visible all the elements of the page change position because my element changes in dimension. What i wish to do is to keep the element in the same position and overlap the header over everything with z-index.
It's not about GWT at first hand. It's mostly about general concepts of elements positioning and layout building for html pages. You should start from something like http://www.w3schools.com/Css/css_positioning.asp
And then find the appropriate tools in GWT framework or in third party libraries that are available.
I'm using Dojo GFX to do some simple drawing, but having a problem with IE 7/8 (switching browsers is not an option).
If I create a div, set up a surface and draw some rects, they draw correctly relative to the div, so far so good.
However, what I want to do is create a widget, something with an embedded 'surface' that draws based on some widget-specific data. As such, I have a widget that contains a div, and I draw into this div. When I do that, the rects I create behave as if they are responding to a float:right, appearing in order they are created and ignoring the 'x' parameter.
I assume that this behaviour is something to do with CSS, but I haven't got to the bottom of it yet. Any ideas or solutions gratefully appreciated!
Updates:
I've disabled all stylesheets and I am not using style attributes. No difference to the behaviour.
I've inspected the markup that gets generated using IE8 dev tools. Apart from the different location of the containing div, the only difference I can see is that the v:roundrect elements have no child elements when created against the widget div, but they do have empty elements like stroke when created against the div referenced by ID.
Reading back through the docs, a difference I can see that might be responsible is that the postCreate method where I am doing my drawing is manipulating a div that has not been added to the dom yet, whereas drawing on a hardcoded div is done when it does exist. Maybe the difference in rendering is something to do with this? Is there a specific lifecycle function which is appropriate to draw in for widgets?
It seems that if you are going to use Dojo GFX and draw on DOM elements that are created as part of a widget in IE7/8, you must actually do the drawing in an override of the startup() method.
Drawing in the postCreate() method causes incorrect rendering resembling a float: left.
If I skin a button and use the AS3 graphice.clear() and graphics.lineTo and beginFill to create a shape, the button overlaps other items in the container.
When I use the and mxml to create the same shape, the button is neatly positioned inside the container.
Why is that?
This is probably happening because Flex is unable to calculate the size of your dynamically drawn button, while the MXML version allows the size to be calculated prior to being displayed. You may need to override the measure method to calculate the width/height. If that's not the issue, then post some code so we can take a closer look. Hope that helps.
Because the Line Object is doing a bunch of checks and extra work you aren't doing when you use the Graphics object. Look at the code for spark.primitives.Line to see what its doing that you aren't.
How can I change the z axis of components and put one in front of the other? The new layout property in Flex 4 has changed significantly & now not sure how to do it.
It works the same way that it did in Flex 3. A components Z order is defined by the order in which they are placed as child of their parent. The second child will be in front of the first child, and the third child will be in front of the first and second child and so on.
You can still use swapChildren and swapChildrenAt to change the Z-order of children.
The layout property's value will be an instance of a Layout class; which--in a simple form your measure() and updateDisplayList() methods. IT does not, specifically, relate to moving one component in front of, or behind, another.
On a Flex 4 group, you can use swapElement and swapElementsAt, although I would bet if you were to examine the code you'd find that these are just layers of abstraction over swapChildren and swapChildrenAt.
checkout the new depth property introduced in Flex 4 e.g. see http://www.tink.ws/blog/flex-4-uicomponent-depth/
Maybe this help:
container's depth
you can use depth property of flex containers to define which element can overlap other elements.
I want to create an MXML container component that has some of its own chrome -- a standard query display, et al -- and that supports the addition of child components to it. Something a lot like the existing mx:Panel class, which includes a title label, but acts like a plain mx:Box with regards to adding children.
What's the easiest way to do this?
Edit:
To be clear, I want to be able to extend the container using MXML, so the "Multiple visual children" problem is relevant.
Extend a container and add a title label. Probably the <mx:Canvas/> will work here. Make the title a public var and include a var for the styleName of the label.
Then override the addChild() method so that any child that is added is added instead to the that is your container.
Leave enough space for your title when you position your Box element (i.e., give its y property enough space. If there is no title you may want to reclaim that space.
That's the basics. Customize to your heart's content.
EDITED TO ADD: I do this creating an ActionScript class first, extending the container I am targeting, and I add the "furniture" — items the class will always use, like title in your case — by overriding createChildren and calling super.addChild(item) for those items. Calling addChild from then on, even in MXML markup, adds items to the inner container.
We do this with states.
We put the chrome for the base container in a state (in mx:AddChild elements) and then use the initialize event to switch to that state when the control is created. All the chrome is then added to the container.
That gets round the multiple sets of visual children problem.
The downsides to this approach are:
You don't see the chrome when editing descendents of the base.
You can't directly access the parent chrome controls from descendent components as they are not there at compile time (instead, you need to define properties, methods or events on the base that the descendents can access)
However, it works well for us.