Adobe Extending Dreamweaver CS4 Manual do Utilizador descarregar pdf (Página 238)

232

EXTENDING DREAMWEAVER CS4

Floating panels

function selectionChanged(){

/* get the selected node */

var theDOM = dw.getDocumentDOM();

var theNode = theDOM.getSelectedNode();

/* check to see if the node is a script marker */

if (theNode.nodeType == Node.ELEMENT_NODE && ¬

theNode.tagName == "SCRIPT"){

document.layers['blanklayer'].visibility = 'hidden';

document.layers['scriptlayer'].visibility = 'visible';}

else{

document.layers['scriptlayer'].visibility = 'hidden';

document.layers['blanklayer'].visibility = 'visible';

}

About performance

Declaring the selectionChanged() or documentEdited() function in your custom floating panels can impact

Dreamweaver performance adversely. Consider that the

documentEdited() and selectionChanged() functions are

called after every keystroke and mouse click when Dreamweaver is idle for more than one-tenth of a second. It’s

important to use different scenarios to test your floating panel, using large documents (100 KB or more of HTML)

whenever possible, to test performance impact.

To help avoid performance penalties, use the setTimeout() function. As in the browsers, the setTimeout() function

takes two arguments: the JavaScript to be called and the amount of time in milliseconds to wait before calling it.

The setTimeout() method lets you build pauses into your processing. These pauses let the user continue interacting

with the application. You must build in these pauses explicitly because the screen freezes while scripts process, which

prevents the user from performing further edits. The pauses also prevent you from updating the interface or the

floating panel.

The following example is from a floating panel that displays information about every AP element in the document. It

uses the

setTimeout() method to pause for half a second after processing each AP element.

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Adobe Extending Dreamweaver CS4 Manual do Utilizador Página 238