Page 554 - Beginning PHP 5.3

Part III: Using PHP in Practice
complete ellipse). The zero - degree position is at the far right - hand side of the ellipse — the 3 o ’ clock
position on a clock face — as shown in Figure 17 - 10. The degrees progress in a clockwise direction:

270 degrees

Arc height x, y 0 degrees

Arc width
Figure 17-10

Here ’ s an example of using the imagearc() function to draw a partial ellipse:

imagearc( $myImage, 90, 60, 160, 50, 45, 200, $myBlack );

The first argument, $myImage , identifies the image in which you ’ re drawing. The next two arguments
(90 and 60) specify the center point of the ellipse that the arc should follow. The width and height
arguments, 160 and 50 , are the same as in the ellipse example earlier. The next two arguments really
create the arc: 45 tells the function to start the arc at the 45 - degree position (at 4:30 if it was a clock) and
200 is the position in degrees where the arc is to end. Remember, 200 degrees is the end point, not the
number of degrees to rotate around the ellipse. Figure 17 - 11 shows the arc drawn from 45 to 200 degrees.

Figure 17-11

The arc in the figure may look strange, but remember that the arc is drawn along the ellipse described
by the width and height you provide. Compare this arc with the ellipse you drew earlier (see Figure 17 - 8)
using the same width and height parameters.

Drawing Polygons
A polygon is a shape that has three or more corners. To draw a polygon, you use the imagepolygon()
function. Besides passing the image resource to the function, you also need to pass an array of points
that define the corners of your polygon. You also need to tell the function how many points there are in
the polygon. Finally, as with the other drawing functions, you pass in the color you would like to use.

Take a look at the following code:

$myPoints = array( 20, 20, 185, 55, 70, 80 );

imagepolygon( $myImage, $myPoints, 3, $myBlack );
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