PHP Cookbook

15.1. Drawing Lines, Rectangles, and Polygons

Problem

You want to draw a line, rectangle, or polygon. You also want to be able to control if the rectangle or polygon is open or filled in. For example, you want to be able to draw bar charts or create graphs of stock quotes.

Solution

To draw a line, use ImageLine( ):

ImageLine($image, $x1, $y1, $x2, $y2, $color);

To draw an open rectangle, use ImageRectangle( ):

ImageRectangle($image, $x1, $y1, $x2, $y2, $color);

To draw a solid rectangle, use ImageFilledRectangle( ) :

ImageFilledRectangle($image, $x1, $y1, $x2, $y2, $color);

To draw an open polygon, use ImagePolygon( ):

$points = array($x1, $y1, $x2, $y2, $x3, $y3);
ImagePolygon($image, $points, count($points)/2, $color);

To draw a filled polygon, use ImageFilledPolygon( ):

$points = array($x1, $y1, $x2, $y2, $x3, $y3);
ImageFilledPolygon($image, $points, count($points)/2, $color);

Discussion

The prototypes for all five functions in the Solution are similar. The first parameter is the canvas to draw on. The next set of parameters are the x and y coordinates to specify where GD should draw the shape. In ImageLine( ) , the four coordinates are the end points of the line, and in ImageRectangle( ) , they’re the opposite corners of the rectangle. For example, ImageLine($image, 0, 0, 100, 100, $color) produces a diagonal line. Passing the same parameters to ImageRectangle( ) produces a rectangle with corners at (0,0), (100,0), (0,100), and (100,100). Both shapes are shown in Figure 15-2 ...