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<H2><A NAME="9_19">9.19 Rotating the graphs</A></H2>
<P> JpGraph provide the possibility for you to rotate the generated
 graph an arbitrary angle. This will only affect the actual graph (axis,
 axis titles, labels and so on) and not fixed elements on the graph like
 title or footer.</P>
<P> Rotation is probably most used to rotate a graph 90 degrees, for
 example a bar graph to get the effect of horizontal bars.</P>
<P></P>
<HR> <SMALL>
<P><STRONG> Performance note:</STRONG> Adding a rotation transformation
 will make the graph generation slightly slower since each point of the
 graph as to go through a transformation step before being stroked on to
 the image. JpGraph optimizes this by using a pre-calculated
 transformation matric and also optimizes the special case 90 degrees.</P>
</SMALL>
<HR>
<P> By default the center of the rotation will be the center of the plot
 area, which may or may not coincide with the center of the entire
 image.</P>
<P> To control the rotation you use the two methods</P>
<UL>
<LI> <A href="../ref/RotImage.html#_ROTIMAGE_SETANGLE">
Graph::image::SetAngle()</A>, Specify rotation angle in degrees.</LI>
<LI> <A href="../ref/RotImage.html#_ROTIMAGE_SETCENTER">
Graph::image::SetCenter()</A>, Specify center of rotation in absolute
 image pixels</LI>
</UL>
<P> For example<DIV class="phpscript"><CODE><FONT color="#000000"> <FONT color="#0000BB">
&nbsp;$graph</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">image</FONT><FONT
color="#007700">-&gt;</FONT><FONT color="#0000BB">SetAngle</FONT><FONT color="#007700">
(</FONT><FONT color="#0000BB">45</FONT><FONT color="#007700">);</FONT><FONT
color="#0000BB"></FONT></FONT></CODE></DIV></P>
<P></P>
<P> There is actually a third method that you could use, adding a
 translation to the graph<STRONG> after</STRONG> the rotation. Since
 this probably a very little used method we don't discuss it further but
 refer the reader to the class reference instead <A href="../ref/RotImage.html#_ROTIMAGE_SETTRANSLATION">
 Graph:image::SetTranslation()</A></P>
<P> When you rotate an image you should be aware of that the individual
 labels on the axis are not rotated. The design decision behind this is
<BR><STRONG> a)</STRONG> Bit mapped font can't be rotated
<BR><STRONG> b)</STRONG> Maintain readability</P>
<P> Please remember that you may still rotate the labels by calling the <A
href="../ref/Axis.html#_AXIS_SETLABELANGLE"> Axis::SetLabelAngle()</A>
 method.</P>
<P> Since the anchor point for labels is by default the optimum for
 graph at 0 degree you might want to adjust the anchor point and
 alignment for the labels on the axis to get a better visual appearance
 on you rotated graph. This is accomplished by the method <A href="../ref/Axis.html#_AXIS_SETLABELALIGN">
 Axis::SetLabelAlign()</A> For a detailed discussion on how to do this
 please see the section on horizontal bar graphs, ( <A href="3030barplot.html">
Working with bar plots</A> )</P>
<P> The table below shows some examples on different kinds of rotation
 to give you an idea of how changing the angle and rotation center may
 be used to generate different effects. The top left graph is the
 original image. The point of rotation has been marked with a red-cross
 in each of the images.</P>
<P><DIV class="example">
<BR> <A href="exframes/frame_rotex0.html" target="blank"><IMG border="0" HEIGHT="170"
      src="img/img/img/img/img/img/rotex0.png" WIDTH="270"></A>
<BR><B>Figure 176:</B> Original image <A href="exframes/frame_rotex0.html"
target="blank">[src]</A>&nbsp;
<P></P>
</DIV></P>
<P><DIV class="example">
<BR> <A href="exframes/frame_rotex1.html" target="blank"><IMG border="0" HEIGHT="170"
      src="img/img/img/img/img/img/rotex1.png" WIDTH="270"></A>
<BR><B>Figure 177:</B> Rotated 45 degrees around center of plot area <A href="exframes/frame_rotex1.html"
target="blank">[src]</A>&nbsp;
<P></P>
</DIV></P>
<P><DIV class="example">
<BR> <A href="exframes/frame_rotex2.html" target="blank"><IMG border="0" HEIGHT="170"
      src="img/img/img/img/img/img/rotex2.png" WIDTH="270"></A>
<BR><B>Figure 178:</B> Rotated 90 degrees around center of plot area <A href="exframes/frame_rotex2.html"
target="blank">[src]</A>&nbsp;
<P></P>
</DIV></P>
<P><DIV class="example">
<BR> <A href="exframes/frame_rotex3.html" target="blank"><IMG border="0" HEIGHT="170"
      src="img/img/img/img/img/img/rotex3.png" WIDTH="270"></A>
<BR><B>Figure 179:</B> Rotated 45 degrees around center of the image <A href="exframes/frame_rotex3.html"
target="blank">[src]</A>&nbsp;
<P></P>
</DIV></P>
<P><DIV class="example">
<BR> <A href="exframes/frame_rotex4.html" target="blank"><IMG border="0" HEIGHT="170"
      src="img/img/img/img/img/img/rotex4.png" WIDTH="270"></A>
<BR><B>Figure 180:</B> Rotated 90 degrees around center of the image <A href="exframes/frame_rotex4.html"
target="blank">[src]</A>&nbsp;
<P></P>
</DIV></P>
<P><DIV class="example">
<BR> <A href="exframes/frame_rotex5.html" target="blank"><IMG border="0" HEIGHT="170"
      src="img/img/img/img/img/img/rotex5.png" WIDTH="270"></A>
<BR><B>Figure 181:</B> Rotated -30 degrees around the lower left point
 of the plot area <A href="exframes/frame_rotex5.html" target="blank">
[src]</A>&nbsp;
<P></P>
</DIV></P>
<P></P>
<P> As you can see from the images above if you rotate about any other
 point than the center of the plot area the plot can be placed outside
 the image after rotation.</P>
<P> Since the rotation, by design, only affects the plot area it is
 often most effective to use when the color of the margin is the same as
 the background color.</P>
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