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  28  <H3><A NAME="8_2_9">8.2.9 Using gradient fill for bar graphs</A></H3>
  29  <P> It is possible to use color gradient fill for the individual bars in
  30   the bar graph.</P>
  31  <P> Color gradient fill fills a rectangle with a smooth transition
  32   between two colors. In what direction the transition goes (from left to
  33   right, down and up, from the middle and out etc) is determined by the
  34   style of the gradient fill. JpGraph currently supports 8 different
  35   styles. All supported styles are displayed in the figure below.<DIV class="example">
  36  <BR> <A href="exframes/frame_bargradsmallex1.html" target="blank"><IMG border="0"
  37  HEIGHT="150"  src="img/bargradsmallex1.png" WIDTH="200"></A>
  38  <BR><B>Figure 44:</B> <A href="exframes/frame_bargradsmallex1.html" target="blank">
  39  [src]</A>&nbsp;
  40  <P></P>
  41  </DIV></P>
  42  <P><DIV class="example">
  43  <BR> <A href="exframes/frame_bargradsmallex2.html" target="blank"><IMG border="0"
  44  HEIGHT="150"  src="img/bargradsmallex2.png" WIDTH="200"></A>
  45  <BR><B>Figure 45:</B> <A href="exframes/frame_bargradsmallex2.html" target="blank">
  46  [src]</A>&nbsp;
  47  <P></P>
  48  </DIV></P>
  49  <P><DIV class="example">
  50  <BR> <A href="exframes/frame_bargradsmallex3.html" target="blank"><IMG border="0"
  51  HEIGHT="150"  src="img/bargradsmallex3.png" WIDTH="200"></A>
  52  <BR><B>Figure 46:</B> <A href="exframes/frame_bargradsmallex3.html" target="blank">
  53  [src]</A>&nbsp;
  54  <P></P>
  55  </DIV></P>
  56  <P><DIV class="example">
  57  <BR> <A href="exframes/frame_bargradsmallex4.html" target="blank"><IMG border="0"
  58  HEIGHT="150"  src="img/bargradsmallex4.png" WIDTH="200"></A>
  59  <BR><B>Figure 47:</B> <A href="exframes/frame_bargradsmallex4.html" target="blank">
  60  [src]</A>&nbsp;
  61  <P></P>
  62  </DIV></P>
  63  <P><DIV class="example">
  64  <BR> <A href="exframes/frame_bargradsmallex5.html" target="blank"><IMG border="0"
  65  HEIGHT="150"  src="img/bargradsmallex5.png" WIDTH="200"></A>
  66  <BR><B>Figure 48:</B> <A href="exframes/frame_bargradsmallex5.html" target="blank">
  67  [src]</A>&nbsp;
  68  <P></P>
  69  </DIV></P>
  70  <P><DIV class="example">
  71  <BR> <A href="exframes/frame_bargradsmallex6.html" target="blank"><IMG border="0"
  72  HEIGHT="150"  src="img/bargradsmallex6.png" WIDTH="200"></A>
  73  <BR><B>Figure 49:</B> <A href="exframes/frame_bargradsmallex6.html" target="blank">
  74  [src]</A>&nbsp;
  75  <P></P>
  76  </DIV></P>
  77  <P><DIV class="example">
  78  <BR> <A href="exframes/frame_bargradsmallex7.html" target="blank"><IMG border="0"
  79  HEIGHT="150"  src="img/bargradsmallex7.png" WIDTH="200"></A>
  80  <BR><B>Figure 50:</B> <A href="exframes/frame_bargradsmallex7.html" target="blank">
  81  [src]</A>&nbsp;
  82  <P></P>
  83  </DIV></P>
  84  <P><DIV class="example">
  85  <BR> <A href="exframes/frame_bargradsmallex8.html" target="blank"><IMG border="0"
  86  HEIGHT="150"  src="img/bargradsmallex8.png" WIDTH="200"></A>
  87  <BR><B>Figure 51:</B> <A href="exframes/frame_bargradsmallex8.html" target="blank">
  88  [src]</A>&nbsp;
  89  <P></P>
  90  </DIV></P>
  91  <P></P>
  92  <P> To specify a gradient fill for the bar plots you make use of the
  93   method <A href="../ref/BarPlot.html#_BARPLOT_SETFILLGRADIENT">
  94   BarPlot::SetFillGradient()</A> . See the class reference for details of
  95   this function.</P>
  96  <P> When using gradient fills there are a couple of caveats you should
  97   be aware of:</P>
  98  <UL>
  99  <LI>gradient filling is computational expensive. Large plots with
 100   gradient fill will take in the order of 6 times longer to fill then for
 101   a normal one-color fill. This might to some extent be helped by making
 102   use of the cache feature of JpGraph so that the graph is only generated
 103   a few times.</LI>
 104  <LI>gradient filling will make use of much more colors (by definition)
 105   this will make the color palette for the image bigger and hence make
 106   the overall image larger. It might also have some severe effect on
 107   using anti-aliased line in the same image as color gradient filling
 108   since anti-aliased lines also have the possibility to make use of many
 109   colors. Hence the color palette might not be big enough for all the
 110   colors you need. So if you use gradient fills you should also be using
 111   a true-color image since you otherwise run out of colors.
 112  <BR> This problem is often seen as that for no apparent reason some
 113   color you have specified in the image does appear as another color.
 114   (This is not a bug in JpGraph!) This is something to especially watch
 115   out for when enabling anti-aliasing since that also uses a lot of
 116   colors. Since the numbers of colors used with anti-aliasing depends on
 117   the angle on the lines it is impossible to foresee the number of colors
 118   used for this.</LI>
 119  </UL>
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