[Sommaire] [Imprimer]

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  27  <HR NOSHADE>
  28  <H2><A NAME="8_15">8.15 Using background images</A></H2>
  29  <P> Instead of having a single color background you can easily have an
  30   arbitrary image as the background. The image may be in either PNG, JPG
  31   or GIF format depending on what your installation supports.</P>
  32  <P></P>
  33  <HR> <SMALL>
  34  <P><STRONG> A note on GD:</STRONG> If you are using GD 2.xx you must
  35   make sure that the define USE_TRUECOLOR is set to true. This is also
  36   the default. Failure to do so in combination with GD 2.xx will make the
  37   background image just look like a solid black square.</P>
  38  </SMALL>
  39  <HR>
  40  <P> To use a specific image as the background you just have to use the
  41   method <A href="../ref/Graph.html#_GRAPH_SETBACKGROUNDIMAGE">
  42   Graph::SetBackgroundImage()</A> The arguments specify file-name, how
  43   the image should be positioned in the graph and finally the format of
  44   the image (if it is in JPG, PNG or GIF) format. If the format is
  45   specified as &quot;auto&quot; (the default) then the appropriate image format
  46   will be determined from the extension of the image file.</P>
  47  <P> The file name is of course obvious but the second argument might not
  48   be. This arguments determine how the image should be copied onto the
  49   graph image. You can specify three different variants here</P>
  50  <OL>
  51  <LI> BGIMG_ COPY This will just copy the image unchanged onto the graph
  52   from the top left corner.</LI>
  53  <LI> BGIMG_CENTER This will just copy the image unchanged onto the graph
  54   but it will center the image in the graph.</LI>
  55  <LI> BGIMG_FILLFRAME This will scale the image to exactly fit the whole
  56   graph image.</LI>
  57  <LI> BGIMG_FILLPLOT This will scale the image to exactly fit just the
  58   plot area of the graph.</LI>
  59  </OL>
  60  <P></P>
  61  <P></P>
  62  <HR><STRONG> The following section only applies to palette based images.
  63   True color images can NOT be manipulated this way. Applying the
  64   following sections to true-color images will have no affect.</STRONG>
  65  <HR>
  66  <P> You might often find yourself wanting to use a background image as a
  67   &quot;waterstamp&quot;. This usually means taking the original image, import it
  68   to some image editing program and then &quot;bleaching&quot; the color
  69   saturation, reducing the contrast and so on. Finally you save the
  70   modified image which you then use as a background image.</P>
  71  <P> This whole process can be automatically accomplished in JpGraph by
  72   using the method <A href="../ref/Graph.html#_GRAPH_ADJBACKGROUNDIMAGE">
  73   Graph::AdjBackgroundImage()</A> which allow you to adjust color
  74   saturation, brightness and contrast of the background image.</P>
  75  <P><DIV class="phpscript"><CODE><FONT color="#000000"> <FONT color="#0000BB">
  76  &nbsp;$graph</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
  77  AdjBackgroundImage</FONT><FONT color="#007700">(...)</FONT><FONT color="#0000BB">
  78  </FONT></FONT></CODE></DIV></P>
  79  <P></P>
  80  <P> to achieve the &quot;watercolor&quot; effect to avoid the image being too
  81   intrusive in the graph.<DIV class="example">
  82  <BR> <A href="exframes/frame_backgroundex03.html" target="blank"><IMG border="0"
  83  HEIGHT="200"  src="img/backgroundex03.png" WIDTH="400"></A>
  84  <BR><B>Figure 89:</B> Example on using a watermark type background image
  85   <A href="exframes/frame_backgroundex03.html" target="blank">[src]</A>&nbsp;
  86  <P></P>
  87  </DIV></P>
  88  <P><DIV class="note"><B>Note:</B> The background image depicts a 1998
  89   Triumph Tiger. This bike is a 900cc off-road bike.</DIV></P>
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