Tag Archives: Flex 4

Using DataRenderer to add custom states to a spark List renderer

ItemRenderer has logic built in that changes between some standard states like normal, hovered, selected, etc. You can supplement this logic by overriding ItemRenderer.getCurrentRendererState(), or do away with the built in states altogether by subclassing DataRenderer instead of ItemRenderer.
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Custom focus skin for spark components in Flex 4

In spark components, the focusSkin is treated differently from the normal skin. Unlike the skin of a spark component, the focusSkin is not automatically sized or positioned by the component. Instead, it is added as the first child of the component. In addition, if the focusSkin has a property called target, target is set to point to the parent component.
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Caching images loaded from a spark item renderer

I recently created a form in Flex that required using multiple DropDownLists with a custom item renderer that loads in preview images of each item. This was really easy to do initially, but I noticed a couple performance issues that bothered me. I decided to improve the performance by implementing a simple caching strategy.
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Disable selection on some items in a spark List

The spark List component in Flex 4 treats every item equally with regards to selection. Sometimes I find it useful to customize this behavior so certain items cannot be selected. You can simulate this behavior by customizing the item renderer to make the selected state visually identical to the normal state, but to get more accurate functionality you will need to subclass List.
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Multiple selection in a spark List without the control key

The spark List component in Flex 4 allows you to select multiple items when you set allowMultipleSelection to true. With this flag set you can select multiple items by using the control/command key.

If you want to have a List that allows multiple selection, but does not require the user to hold down the control key when selecting items you can subclass List and override the item_mouseDownHandler() method.
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