Question

I am attempting to implement a layout in Adobe Flex 4.5 / MXML where I have multiple controls in an HBox that – in total – consume all available horizontal screen estate. Some use a relative with (percentage), some an absolute width (pixels) and one is supposed to consume whatever space is still left, such as:

+----------------------+-----------------------+------+
|         35%          |      fill parent      | 10px |
+----------------------+-----------------------+------+

How would I achieve this in Flex (is there something comparable to Android’s layout_width="fillparent")?

Due to the fact that there are elements that have an absolute width I cannot easily calculate the width of the filler as a percentage a priori (as it varies with the screen width).

Setting the filler’s width to 100% also does not work as this will shrink the 35% area below 35%.

Edit: Applying the updateDisplayList suggestion from http://www.Flextras.com’s answer below yields the error “Call to a possibly undefined method updateDisplayList” at the line marked in the source excerpt below:

<?xml version="1.0"?>
<mx:HBox xmlns:fx="http://ns.adobe.com/mxml/2009"
         xmlns:s="library://ns.adobe.com/flex/spark"
         xmlns:mx="library://ns.adobe.com/flex/mx"
         creationPolicy="auto"
         width="100%"
         verticalGap="0">
    [...]
    <fx:Script>
        <![CDATA[
            [...]
        override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void {
            super.updateDisplayList(unscaledWidth, unscaledHeight);
                ^^^^

            headerLinkBox1.width = unscaledWidth * 0.375;
            headerLinkBox2.width = unscaledWidth * 0.2;
            headerLinkBox3.width = unscaledWidth - headerLinkBox4.width - headerLinkBox5.width - headerLinkBox6.width;

            headerLinkBox1.x = 0;
            headerLinkBox2.x = headerLinkBox1.x + headerLinkBox2.width;
            headerLinkBox3.x = headerLinkBox2.x + headerLinkBox3.width;
            headerLinkBox4.x = headerLinkBox3.x + headerLinkBox4.width;
            headerLinkBox5.x = headerLinkBox4.x + headerLinkBox5.width;
            headerLinkBox6.x = headerLinkBox5.x + headerLinkBox6.width;
        }

        [...]

Answer 1

You make use of the Flex Component lifecycle and write your own layout code in updateDisplayList. Conceptually something like this:

override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void{
  super.updateDisplayList(unscaledWidth, unscaledHeight);
  // size the components
  comp1.width = unscaledWidth*.35
  comp2.width = unscaledWidth-10-comp1.width
  comp3.width = 10;
  // position the components
  comp1.x = 0;
  comp2.x = comp1.width;
  comp3.x = comp2.x + comp2.width;
}

You’ll probably want to set the height of each component to, possibly using the getExplicitOrMeasuredHeight() method.