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| <document> |
| <header> |
| <title>HPSF THUMBNAIL HOW-TO</title> |
| <authors> |
| <person name="Drew Varner" email="Drew.Varner@-deleteThis-sc.edu" /> |
| </authors> |
| </header> |
| <body> |
| <section><title>The VT_CF Format</title> |
| |
| <p>Thumbnail information is stored as a VT_CF, or Thumbnail Variant. The |
| Thumbnail Variant is used to store various types of information in a |
| clipboard. The VT_CF can store information in formats for the Macintosh or |
| Windows clipboard.</p> |
| |
| <p>There are many types of data that can be copied to the clipboard, but the |
| only types of information needed for thumbnail manipulation are the image |
| formats.</p> |
| |
| <p>The <code>VT_CF</code> structure looks like this:</p> |
| |
| <table> |
| <tr> |
| <th>Element:</th> |
| <td>Clipboard Size</td> |
| <td>Clipboard Format Tag</td> |
| <td>Clipboard Data</td> |
| </tr> |
| <tr> |
| <th>Size:</th> |
| <td>32 bit unsigned integer (DWord)</td> |
| <td>32 bit signed integer (DWord)</td> |
| <td>variable length (byte array)</td> |
| </tr> |
| </table> |
| |
| <p>The Clipboard Size refers to the size (in bytes) of Clipboard Data |
| (variable size) plus the Clipboard Format (four bytes).</p> |
| |
| <p>Clipboard Format Tag has four possible values:</p> |
| |
| <table> |
| <tr> |
| <th>Value</th> |
| <th>Identifier</th> |
| <th>Description</th> |
| </tr> |
| <tr> |
| <td><code>-1L</code></td> |
| <td><code>CFTAG_WINDOWS</code></td> |
| <td>a built-in Windows© clipboard format value</td> |
| </tr> |
| <tr> |
| <td><code>-2L</code></td> |
| <td><code>CFTAG_MACINTOSH</code></td> |
| <td>a Macintosh clipboard format value</td> |
| </tr> |
| <tr> |
| <td><code>-3L</code></td> |
| <td><code>CFTAG_FMTID</code></td> |
| <td>a format identifier (FMTID) This is rarely used.</td> |
| </tr> |
| <tr> |
| <td><code>0L</code></td> |
| <td><code>CFTAG_NODATA</code></td> |
| <td>No data This is rarely used.</td> |
| </tr> |
| </table> |
| </section> |
| |
| |
| |
| <section><title>Windows Clipboard Data</title> |
| |
| <p>Windows clipboard data has four image formats for thumbnails:</p> |
| |
| <table> |
| <tr> |
| <th>Value</th> |
| <th>Identifier</th> |
| <th>Description</th> |
| </tr> |
| <tr> |
| <td>3</td> |
| <td><code>CF_METAFILEPICT</code></td> |
| <td>Windows metafile format - recommended</td> |
| </tr> |
| <tr> |
| <td>8</td> |
| <td><code>CF_DIB</code></td> |
| <td>Device Independent Bitmap</td> |
| </tr> |
| <tr> |
| <td>14</td> |
| <td><code>CF_ENHMETAFILE</code></td> |
| <td>Enhanced Windows metafile format</td> |
| </tr> |
| <tr> |
| <td>2</td> |
| <td><code>CF_BITMAP</code></td> |
| <td>Bitmap - Obsolete - Use <code>CF_DIB</code> instead</td> |
| </tr> |
| </table> |
| </section> |
| |
| <section><title>Windows Metafile Format</title> |
| |
| <p>The most common format for thumbnails on the Windows platform is the |
| Windows metafile format. The Clipboard places and extra header in front of |
| a the standard Windows Metafile Format data.</p> |
| |
| <p>The Clipboard Data byte array looks like this when an image is stored in |
| Windows' Clipboard WMF format.</p> |
| |
| <table> |
| <tr> |
| <th>Identifier</th> |
| <td>CF_METAFILEPICT</td> |
| <td>mm</td> |
| <td>width</td> |
| <td>height</td> |
| <td>handle</td> |
| <td>WMF data</td> |
| </tr> |
| <tr> |
| <th>Size</th> |
| <td>32 bit unsigned int</td> |
| <td>16 bit unsigned(?) int</td> |
| <td>16 bit unsigned(?) int</td> |
| <td>16 bit unsigned(?) int</td> |
| <td>16 bit unsigned(?) int</td> |
| <td>byte array - variable length</td> |
| </tr> |
| <tr> |
| <th>Description</th> |
| <td>Clipboard WMF</td> |
| <td>Mapping Mode</td> |
| <td>Image Width</td> |
| <td>Image Height</td> |
| <td>handle to the WMF data array in memory, or 0</td> |
| <td>standard WMF byte stream</td> |
| </tr> |
| </table> |
| </section> |
| |
| |
| <section><title>Device Independent Bitmap</title> |
| <p><strong>FIXME:</strong> Describe the Device Independent Bitmap |
| format!</p> |
| </section> |
| |
| |
| |
| <section><title>Macintosh Clipboard Data</title> |
| <p><strong>FIXME:</strong> Describe the Macintosh clipboard formats!</p> |
| </section> |
| |
| </body> |
| </document> |
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