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Thread: Javascript dynamic adding areas to an image map

  1. #1
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    Javascript dynamic adding areas to an image map

    Hi all,

    Maybe you can help me.
    What I would like to do is to dynamically build an image map.

    Initially I have a image and a map like the following:
    <IMG id= "Img1" style="Z-INDEX: 101; LEFT: 7px; WIDTH: 410px; POSITION: absolute; TOP: 7px; HEIGHT: 405px"
    height="405" src="picture.png" width="410" usemap="#pictureMap">
    <map name="pictureMap" id="pictureMap">
    <area id='base1' shape='RECT' coords='0,0,200,200' onmouseover="LoadTooltips( 'base1' )">
    <area id='base2' shape='RECT' coords='200,0,400,200' onmouseover="LoadTooltips( 'base2' )">
    <area id='base3' shape='RECT' coords='0,200,200,400' onmouseover="LoadTooltips( 'base3' )">
    <area id='base4' shape='RECT' coords='200,200,400,400' onmouseover="LoadTooltips( 'base4' )">
    </map>

    The function LoadTooptips removes the selected area and adds other areas.
    the following is done to add the areas:

    var maps = document.getElementById( 'pictureMap' );
    var element = document.createElement( "AREA" );
    element.shape = shape;
    element.coords = coords;
    maps.areas.add( element );

    Problem is that the new areas are not added to the map.
    When one area is removed, only one area is added. The rest is "forgotten".

    Does anybody know a sollution?

    thanks in advance,
    Mark

  2. #2
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    Why not change the shape/coords of an existing area?

  3. #3
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    Hello Fang,

    Thanks for your quick reply. Changing the coordinates would work, but I want to dynamically add areas. So replace one area by, for example 100 area's.

    The question is therefore how can I achieve this, because my code doesn't seem to work.

  4. #4
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    Use the appendChild replaceChild or insertBefore methods not add

  5. #5
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    Fang, again thanks.

    I have tried the method and it works fine! Great!

    Now I have just one problem with the creation of areas and the onmouseover handler.

    The information for the to be created areas is retrieved from the server. I would like set different handlers to the areas. For example, i have an area for an apple and a car. The onmouseover of the apple should be OnApple( <parameters> ) and for the car it should be OnCar( <parameters> ).

    What the function, including parameters is, will be defined by the server in a string variabele called mouseOverFunction. So for the apple the variable will be "OnApple( 'apple1', 'green apple' ) " --> ( mouseOverFunction = "OnApple( 'apple1', 'green apple' )" )


    Just setting the variable to the onmouseover, doesn't seam to work ( onmouseover = mouseOverFunction )

    Any ideas???

  6. #6
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    Use an anonymous function:
    Code:
    obj.onmouseover=function(){OnApple( 'apple1', 'green apple' );};

  7. #7
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    Hi Fang,

    Thanks again for your reply, but this is not exacly what I needed. I have put my code below

    Code:
    function AddArea( maps, shape, coords, shref, action, tooltip )
    {
    	var element = document.createElement( "AREA" );
    	element.shape = shape;
    	element.coords = coords;
    	element.href=  shref;
    	var obj = maps.appendChild( element );
    	obj.onmouseover = action;
    }
    The action variable contains the function that should be executed by a mouseover event. This can be for example alert( 'hallo' );
    So how can this be achieved? I have tried the anonymous function , but it doens't seem to work. What am I doing wrong?

  8. #8
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    Code:
    element.onmouseover=function(){action;};

  9. #9
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    Hi Fang,

    What you mentioed was what I thought but I forgot the extra semicolun.
    Hoever it didn;t work. But I have now found the solution:

    Code:
    function AddArea( maps, shape, coords, shref, action, tooltip )
    {
    	var element = document.createElement( "AREA" );
    	element.shape = shape;
    	element.coords = coords;
    	element.href=  shref;
    	element.onmouseover = function() { eval( action ); };
    	maps.appendChild( element );
    }
    Apparently the eval() is needed to execute the function in action.

    Many thanks to you Fang!

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