Detecting whether an image loaded successfully in Flex

The following example shows how you can listen for the httpStatus event on a Flex Image control to see if an image loaded successfully or not.

Full code after the jump.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/11/04/detecting-whether-an-image-loaded-successfully-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Script>
        <![CDATA[
            import mx.controls.Alert;
            import flash.events.HTTPStatusEvent;

            private function img_httpStatus(evt:HTTPStatusEvent):void {
                switch (evt.status) {
                    case 200:
                        // Valid image, do nothing.
                        break;
                    case 404:
                        // Invalid image, PANIC!
                        Alert.show("invalid image!", evt.status.toString());
                        break;
                    default:
                        Alert.show(evt.toString(), evt.status.toString());
                        break;
                }
            }

            private function button_click(evt:MouseEvent):void {
                img.source = textInput.text;
            }
        ]]>
    </mx:Script>

    <mx:ApplicationControlBar dock="true">
        <mx:HDividedBox width="100%">
            <mx:TextInput id="textInput"
                    text="http://www.helpexamples.com/flash/images/image1.jpg" />
            <mx:Button label="load image"
                    width="100"
                    minWidth="100"
                    maxWidth="100"
                    click="button_click(event);" />
            <mx:Spacer width="100%" />
        </mx:HDividedBox>
    </mx:ApplicationControlBar>

    <mx:Image id="img"
            httpStatus="img_httpStatus(event);" />

</mx:Application>

View source is enabled in the following example.

27 thoughts on “Detecting whether an image loaded successfully in Flex

  1. Steve,

    According to the documentation for the HTTPStatusEvent class’s status property (whew!), you may get a status code of 0 if Flash Player cannot get a status code from your server.

    If Flash Player cannot get a status code from the server, or if it cannot communicate with the server, the default value of 0 is passed to your ActionScript code. A value of 0 can be generated in any player (for example, if a malformed URL is requested), and a value of 0 is always generated by the Flash Player plug-in when it is run in the following browsers, which do not pass HTTP status codes to the player: Netscape, Mozilla, Safari, Opera, and Internet Explorer for the Macintosh.

    Peter

  2. Yep….switch over to IE and I’m no longer pulling the dialog box / status = 0. But doesn’t this bring us to browser-specific behavior? Isn’t madness just a little way down that road?

  3. Doesnt work ! Server returns always 0 as status code ;-( If you want to check if your image has not been downloaded use , this code by instance change the image if img.source is not available.

    Hope to help you

  4. Hey Peter!

    Thanks for the detailed description of status code 0. The documentation that came with flex 2.x does not mention it in as much detail. Is there any way around it so that I could stick to firefox as the development and deployment browser?

    Cheers!
    Harry S.

  5. I am having a problem with loading images.

    The problem is when I change the image (same name new image) on the server in flex it still look at the old image (same name old image) until I close the application and open it up then it shows the me image.

    How can I get this to show the new image without reopening the application? The user needs to see the new image loaded.

    Thanks

  6. Thank Petere for your illuminating examples.
    I do have a smaller problem than the ‘0’ being displayed that i need to tackle, I dont have an action script background but logic is a natural thing. I am trying to show an image from a node of a node of an xml list that populates a datagrid. what i want is to show the selected image. when i tried i loads just a broken link of the image. I must be missing something , any help here’s my code

    private function doScan(evt:MouseEvent):void {

    img.source = ‘resultGrid.selectedItem.imgpath’;
    }

    my xml file

    2348056441978
    BIOS ADMIN
    Onne Field
    26/04/2008
    XN403ABr
    ../bin-debug/img1.jpg

    2348034521561
    BIOS ADMIN2
    Sapele Deopt
    26/04/2008
    XN403ABw
    ../bin-debug/img2.jpg

  7. With Mozilla the status cod is always 0. IE works perfectly. Is there any other way around with which we can find if the image loading is a success??? Is Flex browser specific???

  8. Rahul,

    Unfortunately, due to browser differences (ie: what the browser provides to the Flash Player), there can be subtle differences between browsers and OSes. In this case Firefox/Mozilla may not be passing the status code to the Flash Player plugin, but IE is passing the status codes to the ActiveX plugin.

    Feel free to file a Flash Player bug at http://bugs.adobe.com/flashplayer/ and post the bug number here and a few of us can vote on the issue.

    Peter

  9. Hey Peter,

    Not sure if we can file a Flash player bug as the problem might reside in the browser itself. Since, it works perfectly with IE. How to figure out the culprit here?
    Is it Browser or the Flash Player..

    Rahul

  10. Rahul,

    I would file the bug against Flash Player and if they determine the issue is with Firefox/Mozilla, they will either mark the bug as “External” and they may file a bug in the Mozilla bug base for you.

    Peter

  11. Hi, peterd. Can you also use this technique to see if the image loaded successfully?

    try {
      myImage.load("myimage.jpg");
    catch (ex:IOException) {
      // handle the error.
    }
    

    Probably not the best way according to OOP practices, though.

  12. One caveat that I just discovered: On many browsers, the default HTTP status code of 0 is returned. From the LiveDocs for Flex 3 (http://livedocs.adobe.com/flex/3/langref/flash/events/HTTPStatusEvent.html):

    If Flash Player or AIR cannot get a status code from the server, or if it cannot communicate with the server, the default value of 0 is passed to your code. A value of 0 can be generated in any player (for example, if a malformed URL is requested), and a value of 0 is always generated by the Flash Player plug-in when it is run in the following browsers, which do not pass HTTP status codes to the player: Netscape, Mozilla, Safari, Opera, and Internet Explorer for the Macintosh.

    I’ve been testing on Firefox, which is a Mozilla browser. It’s returning 0 for the status always. Any workarounds for this?

  13. Still no answer for detecting if an image is not loaded properly on other browsers??

    Can’t believe I have to depend on users using Internet Explorer only!!!

    Is ther a workaround?

  14. I’ve found that the ioError Event is launched if there is a problem loading the image.
    That’s enough for me to know that I need to change the image for a “Not available photo” image, and it work in Firefox, so I suppose it is not browser dependant.

    Hope that helps someone with a similar problem.

  15. I’m using <mx:Image id="myImg" source="x" ioError="myImg.source = null"/> and it seems to work fine in both IE and Firefox

  16. Hi Peter,

    How can I send a message to the user when the connection to the internet drops?

    1. @Daniel,

      You could try using a timer that runs every X seconds and does an HTTP get of a small file on your server. If the server connection fails, it is likely that the server or the internet connection is down and you could possibly display an alert/dialog.

      Peter

  17. Hi.,
    I am using

    iconField is using class name as menuIcon is url image file.. how to load url image file to icon field.,

    Any one help me..

    Ling’s

  18. Hi.,
    I am using mx:MenuBar id=”testmenu” labelField=”menuLabel” iconField=”menuIcon” dataProvider=”{Datamenu}” width=”100%” itemClick=”ClickMenuItem(event);” click=”Select_MenuBar(event);”

    iconField is using class name as menuIcon is url image file.. how to load url image file to icon field.,

    Any one help me..

    Ling’s

  19. Hi, i’m using this procedure to check if image loaded correctly, but I’m having problem on setting a default image when an error occurs. I would like to switch back to a default embedded image when server is returning other than 200 code.

  20. Detecting if an image loaded successfully is as easy as 1.. 2.. 3.. 4……

    This seems to be what is needed to get a reliable cross-browser load/fail for swfloader… what a PITA…

    1. complete + init events. and compare bytes to make sure you have everything. See http://numiko.com/labs/?p=268

    2. ioError

    3. Wrap your .load call with a try/catch to make sure you get any security errors, and then fire the load fail event manually if you do.

    4. Manual timeout. You need to write something that will track how long a load() has been active and timeout at some reasonable time for your app. You then need to cancel the SWFLoader so that it doesn’t eventually fire a complete/error down the road. Looks like SWFLoader.unloadAndStop can so this, though I’m not 100%.

    Since swfloader doesn’t seem to have a timeout, it will wait as long as the remote server keeps your connection open and waiting (and your browser doesn’t kill it).

    In theory, a web server could send one byte at a time and keep swfloader waiting indefinitely.

    One example: In FF, I was contacting IIS for a site that has been stopped, it seems to take 1-2 minutes before the connection finally stops and flash hits an ioError event.

    In the meantime, flash fires no events that I can see, ioError or otherwise. So for that entire time, your user will just be waiting, wondering what is going on.

  21. For who is looking for an answer, test if the content is Bitmap, e.g.:

    var image:Image;
    //load image

    trace(image.content is Bitmap); // true if its is loaded

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