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<title>DrawCanvas public functions</title>
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<a href="./index.htm">CONTENTS</a>
<h3>DrawCanvas public functions</h3>
<p>The applet <a href="placing.htm#DrawCanvas">DrawCanvas</a> supports the following public functions,
which can be called from JavaScript:</p>
<p><font color="800000"><b>Caution!</b></font> IE5 on the MAC platform doesn't support JavaScript to Java communication.</p>
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<b>GetImage(format)</b>
Parameters:
format - image format ("jpeg", "png", or "gif")
Returns:
The image in the specified format and extra encoded by <a href="base64.htm">method BASE64</a>.
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<b>GetImage(width, height, format)</b>
Parameters:
width - image width in pixels
height - image height in pixels
format - image format ("jpeg", "png", or "gif")
Returns:
The image scaled to the specified [width x height],
encoded in the specified format, and extra encoded by <a href="base64.htm">method BASE64</a>.
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This function is usefull if you wish to obtain the image thumbnail.
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<b>IsChanged()</b>
Returns:
<b>true</b> if the image was changed, otherwise returns <b>false</b>.
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<b>LoadImage(imageURL)</b>
Parameters:
imageURL - URL of the image to load.
The URL may be specified as absolute or relative to the HTML page.
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<b>SetImage(base64String)</b>
Parameters:
base64String - image in "jpeg", "png", or "gif" format encoded by <a href="base64.htm">method BASE64</a>.
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<b>SetClipart(base64String, x, y)</b>
Parameters:
base64String - image in "jpeg", "png", or "gif" format encoded by <a href="base64.htm">method BASE64</a>.
x - horizontal coordinate of the insertion point.
y - vertical coordinate of the insertion point.
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<b>GetSelectedImage(format)</b>
Parameters:
format - image format ("jpeg", "png", or "gif").
Returns:
Selected image in the specified format encoded with <a href="base64.htm">BASE64</a> method
or empty string if nothing is selected.
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<p><b>How to access the applet functions in JavaScript:</b></p>
<p>To access a function in JavaScript you have to specify the attribute <b>name</b> for the applet the DrawCanvas
and call the function as
<pre>
document.applets['<i>canvas_name</i>'].<i>afunc()</i>;</pre>
where <i>canvas_name</i> is the value assigned to the attribute <b>name</b>, and <i>afunc</i> is the function you call.<br>
Keep in mind the function names are case sensitive.
<p>
<p><b>Alive example:</b></p>
<p>This example makes the call <i>GetImage("png")</i> and displays the image data in the alert window.</p>
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<applet name="mycanvas" width="200" height="100" codebase="../applet"
archive="painter.jar" code="DrawCanvas.class">
</applet>
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<p>Draw something on the canvas and press the button to see the image data<br>
in PNG graphic format enocded by <a href="base64.htm">method BASE64</a> method.</p>
<form>
<input type="button" value="Show the image data" onclick="return showBase64Data()" >
</form>
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<script language="javascript">
function showBase64Data() {
var image = document.applets["mycanvas"].GetImage("png");
if (image != "") {
window.alert(image);
}
else {
window.alert("Error extracting the image.\nMay be you didn't installed the appropriate license code");
};
}
</script>
<p><b>The example's source code</b></p>
<pre>
<applet name="<b>mycanvas</b>" code="DrawCanvas.class" archive="painter.jar" width="200" height="100" >
</applet>
<form>
<input type="button" value="Show the image data" onclick="return showBase64Data()" >
</form>
<script language="javascript">
function showBase64Data() {
var image = document.applets["<b>mycanvas</b>"].GetImage("png");
window.alert(image);
}
</script>
</pre>
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