56 lines
2.6 KiB
Plaintext
56 lines
2.6 KiB
Plaintext
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Many different types of programs can be enhanced by the use of graphical
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information. Often, this graphical information can take the form of
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horizontal bar graphs.
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An easy way to draw horizontal bars in door programs written with
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OpenDoors, is to use the od_repeat() function. Not only does od_repeat()
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allow you to easily form a bar by repeating a particular character the
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specified number of times, but it is also a very efficient way to do so.
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od_repeat() will take advantage of terminal emulation optimizations,
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when available. For instance, a character can be repeated any number of
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times with AVATAR by sending a short 3-byte sequence that specifies the
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character and number of times to repeat.
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How do you calculate the number of character to use to form a bar in
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your graph? The DrawHorizontalBar() function, which is provided below,
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will do this calculation for you. Simply provide the value to be
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represented by this bar, the minimum and maximum possible values, and
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the maximum number of character to use to draw the bar. For example, if
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you are graphing percentages (which could range from 0% to 100%), and
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wanted the graph to fit in a space of 40 columns, you would use:
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DrawHorizontalBar(nPercent, 0, 100, 40);
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The included tip1.c is a complete program which demonstrates the
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DrawHorizontalBar() function as called from another function that will
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create complete horizontal bar graphs. This second function,
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DrawGraphOfPercentages(), takes an array of titles, and array of values
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corresponding to each title, and draws a complete bar graph from this
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information.
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/* Function to draw a horizontal bar, given a value, the minimum and maximum */
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/* possible values, and the number of characters the horizontal bar should */
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/* extended for the maximum value. */
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void DrawHorizontalBar(int nValue, int nMinValue, int nMaxValue,
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int nMaxChars)
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{
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/* Determine lenght of bar */
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int nBarChars = ((nValue - nMinValue) * nMaxChars) / nMaxValue;
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if(od_control.user_ansi || od_control.user_avatar)
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{
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/* If ANSI or AVATAR graphics are available, assume that IBM extended */
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/* ASCII is also available. This function uses character 220 to form */
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/* bars that are 1/2 the height of the line. You might also want to */
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/* try character 119, which will form bars that are the entire height */
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/* of the line. */
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od_repeat(220, nBarChars);
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}
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else
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{
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/* In ASCII mode, the bar is formed by the '=' character. */
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od_repeat('=', nBarChars);
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}
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}
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