[Sommaire] [Imprimer]

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  28  <H2><A NAME="11_3">11.3 Adding lines and rectangles to a canvas</A></H2>
  29  <P> A canvas also makes a good background for using standard graphic
  30   primitives, for example circles and lines. What you first have to
  31   remember is that you are (so far) working with absolute screen
  32   coordinates and secondly all drawing primitives are found in the <A href="../ref/Image.html#_C_IMAGE">
  33   Image Class</A> accessible as a property of the Graph class. So for
  34   example to draw a line between coordinate (0,0) and (100,100) you would
  35   have to add the line<DIV class="phpscript"><CODE><FONT color="#000000">
  36   <FONT color="#0000BB">&nbsp;$graph</FONT><FONT color="#007700">-&gt;</FONT><FONT
  37  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
  38  Line</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">0</FONT><FONT
  39  color="#007700">,</FONT><FONT color="#0000BB">0</FONT><FONT color="#007700">
  40  ,</FONT><FONT color="#0000BB">100</FONT><FONT color="#007700">,</FONT><FONT
  41  color="#0000BB">100</FONT><FONT color="#007700">);</FONT><FONT color="#0000BB">
  42  </FONT></FONT></CODE></DIV></P>
  43  <P></P>
  44  <P> To your code. The following example shows some of the graphic
  45   primitives you have access to in the Image class<DIV class="phpscript">
  46  (File: canvasex02.php)
  47  <BR><CODE><FONT color="#000000"> <FONT color="#0000BB">&lt;?php
  48  <BR></FONT><FONT color="#FF8000">
  49  //&nbsp;$Id:&nbsp;canvasex02.php,v&nbsp;1.1&nbsp;2002/08/27&nbsp;20:08:57&nbsp;aditus&nbsp;Exp&nbsp;$
  50  <BR></FONT><FONT color="#007700">include&nbsp;</FONT><FONT color="#DD0000">
  51  &quot;../jpgraph.php&quot;</FONT><FONT color="#007700">;
  52  <BR>include&nbsp;</FONT><FONT color="#DD0000">&quot;../jpgraph_canvas.php&quot;</FONT><FONT
  53  color="#007700">;
  54  <BR>
  55  <BR></FONT><FONT color="#FF8000">//&nbsp;Setup&nbsp;a&nbsp;basic&nbsp;canvas&nbsp;we&nbsp;can&nbsp;work&nbsp;
  56  <BR></FONT><FONT color="#0000BB">$g&nbsp;</FONT><FONT color="#007700">=&nbsp;new&nbsp;</FONT><FONT
  57  color="#0000BB">CanvasGraph</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">
  58  400</FONT><FONT color="#007700">,</FONT><FONT color="#0000BB">200</FONT><FONT
  59  color="#007700">,</FONT><FONT color="#DD0000">'auto'</FONT><FONT color="#007700">
  60  );
  61  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
  62  color="#0000BB">SetMargin</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">
  63  5</FONT><FONT color="#007700">,</FONT><FONT color="#0000BB">11</FONT><FONT
  64  color="#007700">,</FONT><FONT color="#0000BB">6</FONT><FONT color="#007700">
  65  ,</FONT><FONT color="#0000BB">11</FONT><FONT color="#007700">);
  66  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
  67  color="#0000BB">SetShadow</FONT><FONT color="#007700">();
  68  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
  69  color="#0000BB">SetMarginColor</FONT><FONT color="#007700">(</FONT><FONT color="#DD0000">
  70  &quot;teal&quot;</FONT><FONT color="#007700">);
  71  <BR>
  72  <BR></FONT><FONT color="#FF8000">
  73  //&nbsp;We&nbsp;need&nbsp;to&nbsp;stroke&nbsp;the&nbsp;plotarea&nbsp;and&nbsp;margin&nbsp;before&nbsp;we&nbsp;add&nbsp;the
  74  <BR>//&nbsp;text&nbsp;since&nbsp;we&nbsp;otherwise&nbsp;would&nbsp;overwrite&nbsp;the&nbsp;text.
  75  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
  76  color="#0000BB">InitFrame</FONT><FONT color="#007700">();
  77  <BR>
  78  <BR></FONT><FONT color="#FF8000">//&nbsp;Add&nbsp;a&nbsp;black&nbsp;line
  79  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
  80  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
  81  SetColor</FONT><FONT color="#007700">(</FONT><FONT color="#DD0000">
  82  'black'</FONT><FONT color="#007700">);
  83  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
  84  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
  85  Line</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">0</FONT><FONT
  86  color="#007700">,</FONT><FONT color="#0000BB">0</FONT><FONT color="#007700">
  87  ,</FONT><FONT color="#0000BB">100</FONT><FONT color="#007700">,</FONT><FONT
  88  color="#0000BB">100</FONT><FONT color="#007700">);
  89  <BR>
  90  <BR></FONT><FONT color="#FF8000">//&nbsp;..&nbsp;and&nbsp;a&nbsp;circle&nbsp;(x,y,diameter)
  91  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
  92  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
  93  Circle</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">100</FONT><FONT
  94  color="#007700">,</FONT><FONT color="#0000BB">100</FONT><FONT color="#007700">
  95  ,</FONT><FONT color="#0000BB">50</FONT><FONT color="#007700">);
  96  <BR>
  97  <BR></FONT><FONT color="#FF8000">
  98  //&nbsp;..&nbsp;and&nbsp;a&nbsp;filled&nbsp;circle&nbsp;(x,y,diameter)
  99  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
 100  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
 101  SetColor</FONT><FONT color="#007700">(</FONT><FONT color="#DD0000">'red'</FONT><FONT
 102  color="#007700">);
 103  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
 104  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
 105  FilledCircle</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">
 106  200</FONT><FONT color="#007700">,</FONT><FONT color="#0000BB">100</FONT><FONT
 107  color="#007700">,</FONT><FONT color="#0000BB">50</FONT><FONT color="#007700">
 108  );
 109  <BR>
 110  <BR></FONT><FONT color="#FF8000">//&nbsp;..&nbsp;add&nbsp;a&nbsp;rectangle
 111  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
 112  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
 113  SetColor</FONT><FONT color="#007700">(</FONT><FONT color="#DD0000">
 114  'green'</FONT><FONT color="#007700">);
 115  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
 116  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
 117  FilledRectangle</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">
 118  10</FONT><FONT color="#007700">,</FONT><FONT color="#0000BB">10</FONT><FONT
 119  color="#007700">,</FONT><FONT color="#0000BB">50</FONT><FONT color="#007700">
 120  ,</FONT><FONT color="#0000BB">50</FONT><FONT color="#007700">);
 121  <BR>
 122  <BR></FONT><FONT color="#FF8000">//&nbsp;..&nbsp;add&nbsp;a&nbsp;filled&nbsp;rounded&nbsp;rectangle
 123  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
 124  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
 125  SetColor</FONT><FONT color="#007700">(</FONT><FONT color="#DD0000">
 126  'green'</FONT><FONT color="#007700">);
 127  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
 128  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
 129  FilledRoundedRectangle</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">
 130  300</FONT><FONT color="#007700">,</FONT><FONT color="#0000BB">30</FONT><FONT
 131  color="#007700">,</FONT><FONT color="#0000BB">350</FONT><FONT color="#007700">
 132  ,</FONT><FONT color="#0000BB">80</FONT><FONT color="#007700">,</FONT><FONT
 133  color="#0000BB">10</FONT><FONT color="#007700">);
 134  <BR></FONT><FONT color="#FF8000">//&nbsp;..&nbsp;with&nbsp;a&nbsp;darker&nbsp;border
 135  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
 136  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
 137  SetColor</FONT><FONT color="#007700">(</FONT><FONT color="#DD0000">
 138  'darkgreen'</FONT><FONT color="#007700">);
 139  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
 140  color="#0000BB">img</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
 141  RoundedRectangle</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">
 142  300</FONT><FONT color="#007700">,</FONT><FONT color="#0000BB">30</FONT><FONT
 143  color="#007700">,</FONT><FONT color="#0000BB">350</FONT><FONT color="#007700">
 144  ,</FONT><FONT color="#0000BB">80</FONT><FONT color="#007700">,</FONT><FONT
 145  color="#0000BB">10</FONT><FONT color="#007700">);
 146  <BR>
 147  <BR></FONT><FONT color="#FF8000">//&nbsp;Stroke&nbsp;the&nbsp;graph
 148  <BR></FONT><FONT color="#0000BB">$g</FONT><FONT color="#007700">-&gt;</FONT><FONT
 149  color="#0000BB">Stroke</FONT><FONT color="#007700">();
 150  <BR>
 151  <BR></FONT><FONT color="#0000BB">?&gt;
 152  <BR></FONT>
 153  <BR></FONT></CODE></DIV></P>
 154  <P> Pleas note the way to access these routines through the img property
 155   of the Graph class. Please also keep in mind that the coordinates are
 156   absolute.</P>
 157  <P><DIV class="example">
 158  <BR> <A href="exframes/frame_canvasex02.html" target="blank"><IMG border="0"
 159  HEIGHT="200"  src="img/canvasex02.png" WIDTH="400"></A>
 160  <BR><B>Figure 185:</B> Example of graphic primitives <A href="exframes/frame_canvasex02.html"
 161  target="blank">[src]</A>&nbsp;
 162  <P></P>
 163  </DIV></P>
 164  <P></P>
 165  <P></P>
 166  <HR> <SMALL>
 167  <P><STRONG> A note on GD</STRONG> For those of you using GD 1.xx you
 168   might notice that the large &quot;filled circle&quot; isn't completely filled.
 169   This is because in GD 1.xx there are no low level primitives to fill an
 170   ellipse or circle so JpGraph tries to make the best out of a bad
 171   situation and manually fake a filled circle. For interest of speed
 172   JpGraph does not contain a complete (for example) Bresenham-circle fill
 173   but cheats by using some existing GD routines. This is not a perfect
 174   solution and for large filled circles like this you get some
 175   moire-patterns in the circle. If you upgrade to GD 2.x JpGraph will be
 176   able to make full use of those new existing methods and the fill will
 177   be perfect.</P>
 178  </SMALL>
 179  <HR>
 180  <P> We refer you to the class reference to find out what other graphic
 181   primitives are available for use.</P>
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