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| 2 | <body> |
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| 3 | <h2>The Visualisation Sub project</h2> |
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| 4 | |
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| 5 | <h3>Introducion and Overview</h3> |
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| 6 | <p> |
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| 7 | We have made many afforts to draw paper tapes on computer screens. |
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| 8 | This subproject is surely one of the biggest and most complex |
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| 9 | programs in the complete paper tape project. It hasn't be |
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| 10 | simply written down in some days but has gone throught various |
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| 11 | development generations, from simply two C files up to the current |
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| 12 | bunch of a dozen C++ files. |
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| 13 | |
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| 14 | This is the structure we are targetting: |
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| 15 | </p> |
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| 16 | |
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| 17 | <ul> |
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| 18 | <li><b>LOCHSTREIFEN</b>: A small pure C library that uses the |
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| 19 | <a href="http://www.cairographics.org">cairo graphics library</a> |
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| 20 | (famous from GTK, Mozilla Firefox and other) for |
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| 21 | drawing paper tapes on any Cairo surface. This is very |
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| 22 | low level. |
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| 23 | <li><b>cli frontend</b>: A simple command line interface written in |
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| 24 | pure C |
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| 25 | to the LOCHSTREIFEN library. The frontend should be non interactive, |
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| 26 | so it's controlled via command line arguments.</li> |
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| 27 | <li><b>web-frontend</b>: Rendering paper tapes via the Web by using |
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| 28 | PHP and the cli frontend. Due to it's complexity this is an |
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| 29 | own sub project.</li> |
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| 30 | <li><b>gtkpapertape</b>: A <a href="http://www.gtkmm.org">Gtkmm</a> |
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| 31 | widget (written in C++) that wraps all features of LOCHSTREIFEN |
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| 32 | with a very powerful and flexible GUI. This is split up in many |
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| 33 | Cpp/header files, so it's almost an own library</li> |
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| 34 | <li><b>gtk-frontend</b>: A simple (almost dummy) C++ frontend |
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| 35 | that simply uses the gtkpapertape widget.</li> |
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| 36 | </ul> |
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| 37 | |
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| 38 | <h3>LOCHSTREIFEN cairo drawing routines</h3> |
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| 39 | <p>The files <i>lochstreifen.c</i> and <i>lochstreifen.h</i> implement the |
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| 40 | drawing of paper tapes by using the cairo graphics library. |
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| 41 | These routines only need cairo, so they can be compiled |
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| 42 | by using <tt>`pkg-config --cflags --libs cairo`</tt>. They do not |
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| 43 | need neither GTK nor Glib (this is a special feature! :-) ) |
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| 44 | <br/>The routines only implement the drawing routines - the |
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| 45 | cairo object (<tt>cairo_t</tt>) must be given from the implementing |
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| 46 | programs. In this way you have full freedom to choose a |
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| 47 | cairo surface -- among others PNG, SVG, PDF, ...). |
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| 48 | See <i>lochstreifen.h</i> for the structure of the object |
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| 49 | `LOCHSTREIFEN'. See <i>lochstreifen.c</i> for help with the usage |
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| 50 | of the functions. |
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| 51 | </p> |
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| 52 | |
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| 53 | <p>There are two generations of this file: The one before I |
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| 54 | learned that there's a standard for paper tapes and the one after |
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| 55 | I learned that there's such a standard, called <a |
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| 56 | href="http://www.srcf.ucam.org/~jsm28/ECMA-10/">ECMA 10</a>. When |
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| 57 | I read about this ECMA standard, I've rewritten the routines completely, |
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| 58 | cleaning the programming interface and making it more flexible and |
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| 59 | robust. The new code is stable right now.</p> |
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| 60 | |
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| 61 | <p>Features of this library:</p> |
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| 62 | <ul> |
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| 63 | <li><b>Pure C</b>: Very flexible in usage with other programming |
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| 64 | languages</li> |
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| 65 | <li><b>Standard compilant (ECMA 10)</b>: The rendered paper tape |
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| 66 | will have proper geometrical dimensions</li> |
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| 67 | <li><b>Lightweight object system</b>, e.g: |
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| 68 | <pre> |
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| 69 | LOCHSTREIFEN *papertape = lochstreifen_new(); |
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| 70 | printf( "%d", lochstreifen_get_width(papertape) ); |
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| 71 | lochstreifen_set_d(papertape, 42); |
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| 72 | int dir = lochstreifen_get_orientation(papertape); |
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| 73 | lochstreifen_draw(papertape, cairo_context); |
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| 74 | // ... |
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| 75 | </pre> |
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| 76 | <li>Everything is <b>configurable</b> -- e.g. any colors/surfaces, |
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| 77 | rotation/translation matrix, margins, paddings, etc.: |
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| 78 | <ul> |
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| 79 | <li>Papertape can easily be rotated and flipped horizontically |
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| 80 | or vertically. Even affine matrices can be defined -- |
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| 81 | you can use the full power of cairo.</li> |
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| 82 | <li>All colors can be set directly, all objects can be |
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| 83 | said to be skipped in the painting process. |
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| 84 | </ul> |
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| 85 | <li>The paper tape data can be served (input) in a simple byte |
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| 86 | array or read from a file. The LOCHSTREIFEN structure will |
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| 87 | not own or manage the data, so you're completely free where |
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| 88 | to store your data.</li> |
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| 89 | <li><b>Highlighting of bytes</b>: Ranges (regions) of bytes |
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| 90 | (data rows) can be highlighted in various manner: There are |
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| 91 | three highlight modes: |
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| 92 | <ol> |
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| 93 | <li>Region highlight: Rows are highlighted from a user defined |
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| 94 | start row to an end row</li> |
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| 95 | <li>Row highlight: Only one user defined row is highlighted</li> |
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| 96 | <li>Bit highlight: One bit (defined via row/track) is highlighted</li> |
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| 97 | </ol> |
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| 98 | All modes can be used concurrently. |
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| 99 | <li>There are powerful functions to transform coordinates to bytes |
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| 100 | and vice versa for GUI support</li> |
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| 101 | <li>The painting process can actually skip bytes and therefore |
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| 102 | only paint areas, which is also good for GUI support |
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| 103 | <li>There's even <b>callback</b> support that can be called at |
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| 104 | each row iteration for individual settings</li> |
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| 105 | <li>Thanks to cairo and C all painting operations are handled |
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| 106 | <i>very fast</i> and the output is always high quality</li> |
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| 107 | </ul> |
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| 108 | |
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| 109 | <h3>Command line and web frontend</h3> |
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| 110 | <p>The file <tt>cli.c</tt> uses the <i>LOCHSTREIFEN</i> structure |
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| 111 | directly. It only depends on the two <tt>lochstreifen.c/h</tt> files. |
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| 112 | For argument parsing, it uses the <tt>argp.h</tt>, from the |
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| 113 | <a href="http://www.gnu.org/software/libc/">GNU C library</a>. |
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| 114 | Unfortunately <tt>argp.h</tt> doesn't seem to be present in other |
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| 115 | c librarys, that's still an issue. Apart from that the CLI |
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| 116 | program is complete platform independent and only has to be |
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| 117 | linked against libcairo: <tt>gcc |
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| 118 | cli.c lochstreifen.c `pkg-config --cflags --libs cairo`</tt>. |
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| 119 | </p> |
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| 120 | <p>Features of the command line frontend:</p> |
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| 121 | <ul> |
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| 122 | <li>Powerful parameter set to control the result in every |
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| 123 | detail – thus you can use LOCHSTREIFEN from any other |
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| 124 | application</li> |
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| 125 | <li>Verbose help on every argument: <tt>./cli --help</tt></li> |
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| 126 | <li>Unix phiosophy: Simple usage, can read in (any) |
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| 127 | data from stdin, can put out result (SVG/PNG binary) on |
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| 128 | stdout</li> |
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| 129 | </ul> |
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| 130 | <p> |
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| 131 | We actually have developed a web frontend in PHP which uses |
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| 132 | the command line interface to generate the results. It |
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| 133 | recieves the user input by an huge HTML form. Using a lot |
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| 134 | of AJAX magic, it even caches already created images and |
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| 135 | creates reports which contain the input data and all |
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| 136 | settings and which are finally available for the client. |
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| 137 | To avoid denial of service attacks (DoS), the PHP frontend |
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| 138 | will deny creating paper tapes if the input file exceeds |
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| 139 | some MB because the resulting file will be very big |
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| 140 | (most web browsers reject rendering such big files which are, |
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| 141 | for example, 400.000px in width). |
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| 142 | <br/>This progam is an own sub project, see |
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| 143 | <a href="../web-frontend/">../web-frontend/</a> for the |
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| 144 | sources and it's documentation.</p> |
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| 145 | |
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| 146 | <h3>GtkPaperTape</h3> |
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| 147 | <p>The library GtkPaperTape is a typical and unexpected result of |
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| 148 | the growth of the complete program. Whereas the GTK visualisatoin |
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| 149 | frontend initlally consisted of only one C file (corresponding to |
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| 150 | <tt>cli.c</tt>), <tt>gtk.c</tt>, it rapidly got very big and |
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| 151 | confusing so I decided to write divide the sourcecode into a |
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| 152 | Gtk+ widget, called <i>GtkPaperTape</i> and the program around it, |
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| 153 | still called <i>gtk.c</i>. Well, I developed this widget, and it |
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| 154 | got even much bigger than the former <tt>gtk.c</tt> program |
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| 155 | (about 1200 lines pure C and Glib code). There occured |
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| 156 | quite some problems (the sourcecode was badly maintainable and |
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| 157 | confusing, and there wer some drawing bugs that I could not |
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| 158 | solve), but the program was working quite fine. |
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| 159 | </p> |
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| 160 | <p>Well, there was the issue about the Windows version and the |
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| 161 | implementation of punching/reading features. This made the |
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| 162 | things much more complex, as it requires more features from |
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| 163 | both <i>LOCHSTREIFEN</i> and <i>GtkPaperTape</i>. I therefore |
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| 164 | decided to learn C++ and Gtkmm to produce a new program from |
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| 165 | the scratch with a cleaner interface and a better documentation. |
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| 166 | As was only to be expected, the sourcecode is now much more |
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| 167 | bulky, we have now more than a dozen Cpp/header files with |
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| 168 | more than 2400 lines of code (still growing). The third generation |
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| 169 | of the <i>GtkPaperTape</i> is still supposed to be called |
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| 170 | <i>GtkPaperTape</i>, but uses the gtkmm namespace <i>Gtk</i>, |
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| 171 | so it's actually <i>Gtk::PaperTape</i>. |
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| 172 | <br/>There's a meta header file, <tt>gtkpapertape.h</tt>. Include |
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| 173 | this file when you want to use the GtkPaperTape widget.</p> |
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| 174 | |
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| 175 | <p>This is an overview of the features of the current generation of |
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| 176 | <i>GtkPaperTape</i>:</p> |
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| 177 | <ul> |
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| 178 | <li><b>Gtkmm</b> widget, clean object oriented interface</li> |
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| 179 | <li>Very big files can be displayed very perfomant, because |
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| 180 | only the neccessary regions of the paper tapes have to |
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| 181 | be redrawn (very big = many MB or even GB, only limited |
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| 182 | by the size of your RAM ;-) )</li> |
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| 183 | <li>The widget implements a complete <b>Hex editor</b> with |
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| 184 | all features like copying, moving, deleting, inserting |
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| 185 | bytes and toggling bits</li> |
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| 186 | <li>The widget was programed in a model/view/controller |
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| 187 | fashion. There's an optional statusbar, as well as |
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| 188 | a complete menu, scrolling, help, mouse interaction, etc.</li> |
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| 189 | <li>The widget even can generate files and fonts/labels by |
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| 190 | interacting with the <a href="../schriften/">schriften</a> |
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| 191 | subproject.</li> |
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| 192 | <li>Powerful <b>export</b> of picture of the displayed |
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| 193 | papertape with the current settings to a SVG or PNG file.</li> |
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| 194 | <li>Zoom, Rotating or directly editing the display matrix is |
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| 195 | possible</li> |
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| 196 | <li>All colors can be changed interactively, all components |
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| 197 | can be switched off and on as you want</li> |
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| 198 | </ul> |
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| 199 | <p>There is still a bug while scrolling over really big paper tapes, |
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| 200 | but I've managed to get solved who's the guilty library: It's a |
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| 201 | Gtk+ bug, commited on <a href="http://bugzilla.gnome.org/show_bug.cgi?id=552672">the GNOME |
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| 202 | bugzilla</a> by me.</p> |
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| 203 | <p>Compared to the widget, there's a quite trivial and simple |
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| 204 | frontend programm called <tt>gtk.cc</tt> that replaces the old |
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| 205 | <tt>gtk.c</tt>.</p> |
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