<doc>
  <legacy_id>1908</legacy_id>
  <name>maskData</name>
  <type>property</type>
  <syntax>
    <example>set the maskData of <i>image</i> to <i>binaryData</i></example>
  </syntax>
  <library></library>
  <objects>
    <image/>
  </objects>
  <synonyms>
  </synonyms>
  <classification>
    <category>Images &amp; Multimedia</category>
  </classification>
  <references>
    <property tag="windowShape">windowShape Property</property>
    <property tag="alphaData">alphaData Property</property>
  </references>
  <history>
    <introduced version="1.1">Added.</introduced>
  </history>
  <platforms>
    <mac/>
    <windows/>
    <linux/>
    <ios/>
    <android/>
  </platforms>
  <classes>
    <desktop/>
    <server/>
    <web/>
    <mobile/>
  </classes>
  <security>
  </security>
  <summary>Specifies which <property tag="pixels">pixels</property> of an <keyword tag="image">image</keyword> are displayed.</summary>
  <examples>
    <example>put the maskData of image "Download" into dataToAnalyze</example>
  </examples>
  <description>
    <p>Use the <b>maskData</b> <glossary tag="property">property</glossary> to change the appearance of an <keyword tag="image">image</keyword> without changing its image data, or to examine the <glossary tag="mask">mask</glossary> of the <keyword tag="image">image</keyword>.</p><p/><p><b>Value:</b></p><p>The <b>maskData</b> of an <keyword tag="image">image</keyword> consists of a sequence of <glossary tag="binary">binary</glossary> values.</p><p/><p><b>Comments:</b></p><p>Each pixel is represented by 8 bits (1 byte) of mask data, with pixels numbered from the top left corner of the image, left to right, then top to bottom.</p><p/><p>Since each pixel is represented by 8 bits (1 byte or 1 character), you can obtain the numeric value for a given pixel using the <b>charToNum</b> <control_st tag="function">function</control_st>. For example, the numeric value of the <b>maskData</b> for the tenth <glossary tag="pixel">pixel</glossary> is given by the <glossary tag="expression">expression</glossary> <code>charToNum(char 10 of the mask of <i>image</i>)</code>.</p><p/><p>A value of zero means the pixel is fully transparent; any other value means the pixel is fully opaque. Unlike the <b>alphaData</b> <glossary tag="property">property</glossary>, the <b>maskData</b> stores only complete transparency or complete opacity, and does not support partial transparency.</p>
  </description>
</doc>