155 lines
7.5 KiB
HTML
155 lines
7.5 KiB
HTML
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<title>gview(1) - Plan 9 from User Space</title>
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<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
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<table border=0 cellpadding=0 cellspacing=0 width=100%>
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<tr height=10><td>
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<tr><td width=20><td>
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<tr><td width=20><td><b>GVIEW(1)</b><td align=right><b>GVIEW(1)</b>
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<tr><td width=20><td colspan=2>
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<br>
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<p><font size=+1><b>NAME </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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gview – interactive graph viewer<br>
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</table>
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<p><font size=+1><b>SYNOPSIS </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>gview</font></tt> [ <tt><font size=+1>−l</font></tt> <i>logfile</i> ] [ <tt><font size=+1>−m</font></tt> ] [ <i>file</i> ]<br>
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</table>
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<p><font size=+1><b>DESCRIPTION </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<i>Gview</i> reads polygonal lines or a polygonal line drawing from an
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<tt><font size=+1>ASCII</font></tt> input file (which defaults to standard input), and views
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it interactively, with commands to zoom in and out, perform simple
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editing operations, and display information about points and polylines.
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The editing commands can change the color and
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thickness of the polylines, delete (or undelete) some of them,
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and optionally rotate and move them. It is also possible to generate
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an output file that reflects these changes and is in the same
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format as the input.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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Since the <tt><font size=+1>move</font></tt> and <tt><font size=+1>rotate</font></tt> commands are undesirable when just viewing
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a graph, they are only enabled if <i>gview</i> is invoked with the <tt><font size=+1>−m</font></tt>
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option.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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Clicking on a polyline with button 1 displays the coordinates
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and a <i>t</i> value that tells how far along the polyline. <i>(t</i>=0 at the
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first vertex, <i>t</i>=1 at the first vertex, <i>t</i>=1.5 halfway between the
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second and third vertices, etc.) The <tt><font size=+1>−l</font></tt> option generates a log
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file that lists all points selected in this manner.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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The most important interactive operations are to <i>zoom in</i> by sweeping
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out a rectangle, or to <i>zoom out</i> so that everything currently being
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displayed shrinks to fit in the swept-out rectangle. Other options
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on the button 3 menu are <i>unzoom</i> which restores the coordinate
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system to the default state where everything fits on
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the screen, <i>recenter</i> which takes a point and makes it the center
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of the window, and <i>square up</i> which makes the horizontal and vertical
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scale factors equal.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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To take a graph of a function where some part is almost linear
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and see how it deviates from a straight line, select two points
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on this part of the graph (i.e., select one with button 1 and
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then select the other) and then use the <i>slant</i> command on the button
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3 menu. This slants the coordinate system so that the line
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between the two selected points appears horizontal (but vertical
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still means positive <i>y</i>). Then the <i>zoom in</i> command can be used
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to accentuate deviations from horizontal. There is also an <i>unslant</i>
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command that undoes all of this and goes back to an unslanted
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coordinate system.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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There is a <i>recolor</i> command on button 3 that lets you select a
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color and change everything to have that color, and a similar
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command on button 2 that only affects the selected polyline. The
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<i>thick</i> or <i>thin</i> command on button 2 changes the thickness of the
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selected polyline and there is also an undo command for such
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edits.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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Finally, button 3 had commands to <i>read</i> a new input file and display
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it on top of everything else, <i>restack</i> the drawing order (in case
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lines of different color are drawn on top of each other), <i>write</i>
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everything into an output file, or <i>exit</i> the program.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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Each polyline in an input or output file is a space-delimited
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<i>x y</i> coordinate pair on a line by itself, and the polyline is a
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sequence of such vertices followed by a label. The label could
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be just a blank line or it could be a string in double quotes,
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or virtually any text that does not contain spaces and is on a
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line by itself. The
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label at the end of the last polyline is optional. It is not legal
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to have two consecutive labels, since that would denote a zero-vertex
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polyline and each polyline must have at least one vertex. (One-vertex
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polylines are useful for scatter plots.)<br>
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If the label after a polyline can contains the word <tt><font size=+1>Thick</font></tt> or a
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color name <tt><font size=+1>(Red</font></tt>, <tt><font size=+1>Pink</font></tt>, <tt><font size=+1>Dkred</font></tt>, <tt><font size=+1>Orange</font></tt>, <tt><font size=+1>Yellow</font></tt>, <tt><font size=+1>Dkyellow</font></tt>, <tt><font size=+1>Green</font></tt>,
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<tt><font size=+1>Dkgreen</font></tt>, <tt><font size=+1>Cyan</font></tt>, <tt><font size=+1>Blue</font></tt>, <tt><font size=+1>Ltblue</font></tt>, <tt><font size=+1>Magenta</font></tt>, <tt><font size=+1>Violet</font></tt>, <tt><font size=+1>Gray</font></tt>, <tt><font size=+1>Black</font></tt>, <tt><font size=+1>White</font></tt>),
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whichever color name comes first will be used to color the polyline.
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</table>
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<p><font size=+1><b>EXAMPLE </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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To see a graph of the function <i>y</i>=<i>sin(</i>x<i>)/</i>x generate input with
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an awk script and pipe it into <i>gview</i>:<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>awk 'BEGIN{for(x=.1;x<500;x+=.1)print x,sin(x)/x}' | gview<br>
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</font></tt>
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</table>
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</table>
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<p><font size=+1><b>SOURCE </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>/usr/local/plan9/src/cmd/draw/gview.c<br>
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</font></tt>
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</table>
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<p><font size=+1><b>SEE ALSO </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<a href="../man1/awk.html"><i>awk</i>(1)</a><br>
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</table>
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<p><font size=+1><b>BUGS </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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The user interface for the <i>slant</i> command is counter-intuitive.
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Perhaps it would be better to have a scheme for sweeping out a
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parallelogram.<br>
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</table>
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<td width=20>
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<tr height=20><td>
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</table>
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<!-- TRAILER -->
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<table border=0 cellpadding=0 cellspacing=0 width=100%>
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<tr height=15><td width=10><td><td width=10>
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<tr><td><td>
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<center>
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<a href="../../"><img src="../../dist/spaceglenda100.png" alt="Space Glenda" border=1></a>
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</center>
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</table>
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<!-- TRAILER -->
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</body></html>
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