Mercurial > hg > digilib
annotate common/doc/Scaler.html @ 1231:21441a3f5208
trying to fix problem with scaled image size being off from dw and dh.
changed calculation of scaling factor to double precision.
(still issues with sizes though)
| author | robcast |
|---|---|
| date | Tue, 22 Oct 2013 15:46:47 +0200 |
| parents | 53dd7e189155 |
| children |
| rev | line source |
|---|---|
| 179 | 1 <!doctype html public "-//w3c//dtd html 4.0 transitional//en"> |
| 2 <html> | |
| 3 <head> | |
| 323 | 4 <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> |
| 5 <title>Scaler servlet</title> | |
| 179 | 6 </head> |
| 323 | 7 <body> |
| 8 <h1>Scaler</h1> | |
| 1 | 9 |
| 323 | 10 <p>A Servlet for scaling images. (Version 1.5.2)</p> |
| 76 | 11 |
| 12 <h2>Web API</h2> | |
| 1 | 13 |
| 76 | 14 <p>The Scaler servlet takes parameters in the http request format: |
| 323 | 15 <code>Scaler/request_path/?param1=value1&param2=value2&...</code> |
| 76 | 16 Unknown parameters will be silently ignored.</p> |
| 1 | 17 |
| 179 | 18 <p>Recognised parameters:</p> |
| 1 | 19 <ul> |
| 76 | 20 <li><b>request_path</b> path to file or directory.</li> |
| 1 | 21 |
| 76 | 22 <li><b>fn</b> path to file or directory below <code>/docuserver/images</code> |
| 23 (or other configured image directory). | |
| 1 | 24 This path will be added to the <code>request_path</code> behind the servlet name. |
| 76 | 25 Either parameter can be empty.</li> |
| 1 | 26 |
| 27 <li><b>pn</b> page number. Index into the (alphabetically sorted) directory | |
| 28 given by the path. Starts with 1. Ignored if the path points to a file. | |
| 76 | 29 Default: 1.</li> |
| 1 | 30 |
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31 <li><b>dw</b> destination image width (pixels). If omitted the image is scaled to fit |
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32 dh.</li> |
| 76 | 33 |
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34 <li><b>dh</b> destination image height (pixels). If omitted the image is scaled to fit |
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35 dw.</li> |
| 1 | 36 |
| 37 <li><b>wx</b> relative x offset of the image area to be sent (0 <= wx <= 1). | |
| 76 | 38 Default: 0.</li> |
| 39 | |
| 40 <li><b>wy</b> relative y offset of the image area to be sent (0 <= wy <= 1). | |
| 41 Default: 0.</li> | |
| 42 | |
| 43 <li><b>ww</b> relative width of the image area to be sent (0 <= ww <= 1). | |
| 44 Default: 1.</li> | |
| 45 | |
| 46 <li><b>wh</b> relative height of the image area to be sent (0 <= wh <= 1). | |
| 47 Default: 1.</li> | |
| 1 | 48 |
| 49 <li><b>ws</b> additional scaling factor. The resulting image will have the size | |
| 76 | 50 <code>[ws*dw,ws*dh]</code>. Default: 1.</li> |
| 1 | 51 |
| 105 | 52 <li><b>mo</b> flags for the mode of operation separated by ",". |
| 1 | 53 <ul> |
| 76 | 54 <li><b>fit</b>: always scale the image to fit |
| 323 | 55 <code>[dw,dh]</code> (default).<br> |
| 56 | |
| 57 <b>clip</b>: send the file in its | |
| 58 original resolution, cropped to fit <code>[dw,dh]</code>. | |
| 59 <br> | |
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60 |
| 323 | 61 <b>osize</b>: scale to original size based on the image resolution |
| 62 (from the image metadata) and display resolution (from parameter | |
| 63 <code>ddpi</code>). Fails if either resolution is unknown. | |
| 64 </li> | |
| 65 | |
| 66 <li> | |
| 105 | 67 <b>file</b>: send the file as-is (may |
| 76 | 68 be very large and all sorts of image types!). If configuration |
| 69 doesn't allow sending files | |
| 70 (<code>sendfile-allowed=false</code>) revert to | |
| 105 | 71 <code>clip</code>.<br> |
| 178 | 72 |
| 73 <b>rawfile</b>: send the file as-is with a mime-type of | |
| 74 <code>application/octet-stream</code> so it can be downloaded with | |
| 323 | 75 the browser. |
| 127 | 76 </li> |
| 76 | 77 |
| 1 | 78 <li><b>errtxt</b>: send error response as HTML.<br> |
| 76 | 79 <b>errimg</b>: response as image (default).</li> |
| 1 | 80 |
| 81 <li><b>q0</b>-<b>q2</b>: quality of interpolation in scaling | |
| 76 | 82 (<code>q0</code>: worst, default).</li> |
| 1 | 83 |
| 84 <li><b>lores</b>: try to use scaled image (default)<br> | |
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85 |
| 76 | 86 <b>hires</b>: always use unscaled image.<br> |
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87 |
| 323 | 88 If the image is zoomed (ww, wh < 1) the use of the scaled |
| 89 image files depends on the requested resolution.</li> | |
| 76 | 90 |
| 91 <li><b>vmir</b>: mirror image vertically.<br> | |
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92 |
| 76 | 93 <b>hmir</b>: mirror image horizontally.</li> |
| 323 | 94 |
| 95 <li><b>jpg</b>: the resulting image is always sent as JPEG | |
| 96 (otherwise TIFF and PNG images are sent as PNG). | |
| 97 </li> | |
| 1 | 98 </ul> |
| 76 | 99 </li> |
| 1 | 100 |
| 76 | 101 <li><b>cont</b>: change contrast of the image. Negative value |
| 102 reduces contrast, positive value enhances contrast. Pixel value is | |
| 77 | 103 multiplied by 2^cont. Default: 0</li> |
| 76 | 104 |
| 105 <li><b>brgt</b>: change brightness of image. Negative value reduces | |
| 105 | 106 brightness, positive value enhances brightness. The value brgt is |
| 107 added to the pixel value. Default: 0</li> | |
| 76 | 108 |
| 105 | 109 <li><b>rot</b>: rotate image. Rotation angle is given in |
| 110 degrees. Default: 0</li> | |
| 111 | |
| 112 <li><b>rgbm</b>: modify color by multiplication. The contrast of the | |
| 113 red green and blue components of the image can be reduced or | |
| 114 enhanced similar to the <code>cont</code> parameter. The factors for | |
| 115 red, green and blue are separated by slashes (for example | |
| 116 0.86/0/-0.5). Default: 0/0/0</li> | |
| 117 | |
| 118 <li><b>rgba</b>: modify color by addition. The brightness of the red | |
| 119 green and blue components of the image can be reduced or enhanced | |
| 120 similar to the <code>brgt</code> parameter. The factors for red, | |
| 121 green and blue are separated by slashes (for example | |
| 122 100/0/25). Default: 0/0/0</li> | |
| 76 | 123 |
| 127 | 124 <li><b>ddpi</b>: resolution of client display for <code>osize</code> mode. |
| 125 Either <code>ddpi</code> or <code>ddpix</code> and <code>ddpiy</code> must | |
| 126 be set to use <code>osize</code> mode.</li> | |
| 127 | |
| 128 <li><b>ddpix</b>: resolution of client display in x direction for | |
| 129 <code>osize</code> mode.</li> | |
| 130 | |
| 131 <li><b>ddpiy</b>: resolution of client display in y direction for | |
| 132 <code>osize</code> mode.</li> | |
| 133 | |
| 1 | 134 </ul> |
| 179 | 135 |
| 136 <p>The image to be loaded can be specified by the | |
| 137 <code>request_path</code> (deprecated) or the <code>fn</code> | |
| 138 (preferred) parameter and the optional index <code>pn</code></p> | |
| 139 <ul> | |
| 140 <li> if <code>fn</code> points to a directory then the file with | |
| 141 the index <code>pn</code> (in alphabetical order according to | |
| 142 ASCII) will be loaded</li> | |
| 143 | |
| 144 <li>if <code>fn</code> points to a file (with or without | |
| 145 extension) then this file will be loaded</li> | |
| 146 </ul> | |
| 147 | |
| 148 <p>The image will be scaled equally in horizontal and vertical | |
| 149 direction such that the resulting image does not exceed the rectangle | |
| 150 <code>[dw,dh]</code>. If only either height or width is given the | |
| 151 image is scaled to match only the given parameter. The size of the | |
| 152 resulting image in the other parameter is determined by the aspect | |
| 153 ratio of the image. | |
| 154 </p> | |
| 1 | 155 |
| 323 | 156 </body> |
| 179 | 157 </html> |