OverlayImageItem (Stringlist subroutine): Difference between revisions

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{{Template:Stringlist:OverlayImageItem subtitle}}
{{Template:Stringlist:OverlayImageItem subtitle}}


OerlayImageItem is a member of the [[Stringlist class]].
This method is used to overlay a <var>stringlist</var> item with either of the following:
 
This method is used to overlay a Stringlist item with either of the following:


<ul>
<ul>
<li>The contents of a given image item.
<li>The contents of a given image item.
<li>A specified value, but at the same offset as that of a given image item in its image.
<li>A specified value, but at the same offset as that of a given image item in its image.
</ul>  
</ul>


OverlayImageItem is a subroutine that accepts three arguments, and returns no value.
<var>OverlayImageItem</var> is a subroutine that accepts three arguments, and returns no value.


==Syntax==
==Syntax==
{{Template:Stringlist:OverlayImageItem syntax}}
{{Template:Stringlist:OverlayImageItem syntax}}
===Syntax terms===
===Syntax terms===
<dl>
<table class="syntaxTable">
<dt>%sl
<tr><th>sl</th>
<dd>A Stringlist object.
<td>A <var>stringlist</var> object. </td></tr>
<dt>itemnum
<tr><th>itemNum</th>
<dd>The number of the Stringlist item that is to be updated.
<td>The number of the <var>stringlist</var> item that is to be updated. </td></tr>
<dt>imageitem
<tr><th>imageItem</th>
<dd>The image item that indicates the overlay offset and length and, if the third argument is not specified, the value to be overlayed in the Stringlist item.
<td>The image item that indicates the overlay offset and length and, if the third argument is not specified, the value to be overlayed in the <var>stringlist</var> item. </td></tr>
<dt>value
<tr><th>value</th>
<dd>The value to be placed at the image item's offset in the Stringlist item. If this optional argument is not specified, the contents of the image item specified by the '''itemnum''' argument are used to overlay the Stringlist item.  
<td>The value to be placed at the image item's offset in the <var>stringlist</var> item. If this optional argument is not specified, the contents of the image item specified by the <var class="term">itemNum</var> argument are used to overlay the <var>stringlist</var> item.</td></tr>
</dl>
</table>


==Usage notes==
==Usage notes==
<ul>
<ul>
<li>All errors in OverlayImageItem result in request cancellation.
<li>All errors in <var>OverlayImageItem</var> result in request cancellation.
<li>OverlayImageItem does not change the length of a Stringlist item. If the overlay string does not completely overlay a Stringlist item, the characters after and before the overlay string remain unchanged.
<li><var>OverlayImageItem</var> does not change the length of a <var>Stringlist</var> item. If the overlay string does not completely overlay a <var>Stringlist</var> item, the characters before and after the overlayed string remain unchanged.
<li>If the start column plus the length of the image item is greater than the current length of the Stringlist item, the request is cancelled.
<li>If the start column plus the length of the image item is greater than the current length of the <var>Stringlist</var> item, the request is cancelled.
</ul>
</ul>


==Examples==
==Examples==
OverlayImageItem is especially useful for Stringlists whose contents map to an image. In the following example, the Stringlist item associated with product code 983 has its description overlayed with a new description:
<ol><li><var>OverlayImageItem</var> is especially useful for <var>Stringlists</var> whose contents map to an image. In the following example, the <var>Stringlist</var> item associated with product code <code>983</code> has its description overlayed with a new description:


<pre>
<p class="code">image product
image product
  code is binary len 2
code is binary len 2
  desc is string len 30
desc is string len 30
end image
end image
...
...
fr products
fr products
%product:code = code
  %product:code = code
%product:desc = desc
  %product:desc = desc
%rc = %list:addImage('PRODUCT')
  %rc = %list:addImage('PRODUCT')
end for
end for
...
...
Line 52: Line 49:
%product:desc = 'Insertion widget'
%product:desc = 'Insertion widget'
%list:overlayImageItem(%num, %product:desc)
%list:overlayImageItem(%num, %product:desc)
</pre>
</p>


If a value is specified in addition to the image item, processing is performed as if the value were assigned to the image item, and then the image item is restored to its original value. Any data type conversions required between the value and the image item are performed before the overlay is performed.  
<li>If a <var class="term">value</var> is specified in addition to the <var class="term">imageItem</var>, processing is performed as if the <var class="term">value</var> were assigned to the <var class="term">imageItem</var>, before any overlaying is performed,  and then the <var class="term">imageItem</var> is restored to its original value. Any data type conversions required between the <var class="term">value</var> and the <var class="term">imageIitem</var> are performed before the overlay is performed.


That is, this method invocation:
That is, this method invocation:


<pre>
<p class="code">%list:overlayImageItem(%num, %product:code, 543)
%list:overlayImageItem(%num, %product:code, 543)
</p>
</pre>


is identical to this:
is identical to this:


<pre>
<p class="code">%temp = %product:code
%temp = %product:code
%product:code = 543
%product:code = 543
%list:overlayImageItem(%num, %product:code)
%list:overlayImageItem(%num, %product:code)
%product:code = %temp
%product:code = %temp
</pre>
</p></ol>


{{Template:Stringlist:OverlayImageItem footer}}


[[Category:Stringlist methods|OverlayImageItem subroutine]]
==See also==

Latest revision as of 22:09, 7 February 2011

Overlay part of Stringlist item with image item (Stringlist class)


This method is used to overlay a stringlist item with either of the following:

  • The contents of a given image item.
  • A specified value, but at the same offset as that of a given image item in its image.

OverlayImageItem is a subroutine that accepts three arguments, and returns no value.

Syntax

sl:OverlayImageItem( itemNum, imageItem, [value])

Syntax terms

sl A stringlist object.
itemNum The number of the stringlist item that is to be updated.
imageItem The image item that indicates the overlay offset and length and, if the third argument is not specified, the value to be overlayed in the stringlist item.
value The value to be placed at the image item's offset in the stringlist item. If this optional argument is not specified, the contents of the image item specified by the itemNum argument are used to overlay the stringlist item.

Usage notes

  • All errors in OverlayImageItem result in request cancellation.
  • OverlayImageItem does not change the length of a Stringlist item. If the overlay string does not completely overlay a Stringlist item, the characters before and after the overlayed string remain unchanged.
  • If the start column plus the length of the image item is greater than the current length of the Stringlist item, the request is cancelled.

Examples

  1. OverlayImageItem is especially useful for Stringlists whose contents map to an image. In the following example, the Stringlist item associated with product code 983 has its description overlayed with a new description:

    image product code is binary len 2 desc is string len 30 end image ... fr products %product:code = code %product:desc = desc %rc = %list:addImage('PRODUCT') end for ... %product:code = 983 %num = %list:findImageItem(%product:code) %product:desc = 'Insertion widget' %list:overlayImageItem(%num, %product:desc)

  2. If a value is specified in addition to the imageItem, processing is performed as if the value were assigned to the imageItem, before any overlaying is performed, and then the imageItem is restored to its original value. Any data type conversions required between the value and the imageIitem are performed before the overlay is performed. That is, this method invocation:

    %list:overlayImageItem(%num, %product:code, 543)

    is identical to this:

    %temp = %product:code %product:code = 543 %list:overlayImageItem(%num, %product:code) %product:code = %temp

See also

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