PHP Tips and Trick on Drawing

PHP has numerous basic functions provided for drawing that are easy enough to use and understand: Draw a rectangle, draw a circle, draw a line, and so on. Often you may need to do slight variations on these methods. That can be a little tricky to achieve the effect that you are going for.

The following code includes examples of some of the fancier tricks you may want to use, such as making rectangles with rounded corners or adding drop shadows. After studying these techniques you should be able to extrapolate many different features that you want to create.

Drop-Shadows, Outline, and Rounded-Corner Rectangles

<?php
// First of all, create a function that will automatically make a
// dropshadowed box. give it the coordinates of the primary box
// and the offset that you want the drop to be.  It assumes lower right.
function i_filledrectangledropshadow($g,
        $x1, $y1, $x2, $y2,
        $drop, $color, $shcolor) {
    // First draw the shadow box offset appropriately
    imagefilledrectangle($g, $x1 + $drop, $y1 + $drop,
        $x2 + $drop, $y2 + $drop, $shcolor);

    // Now the main box:
    imagefilledrectangle($g, $x1, $y1, $x2, $y2, $color);
}

// Create a function similar to above, but that creates an outline rectangle
//  with the drop shadow.  A more normal looking drop shadow box.
function i_rectangledropshadow($g,
        $x1, $y1, $x2, $y2,
        $drop, $color, $shcolor, $border) {
    // Time to cheat a bit.  First call our previous function:
    i_filledrectangledropshadow($g, $x1, $y1, $x2, $y2,
        $drop, $color, $shcolor);

    // Now draw a regular rectangle on top of it:
    imagerectangle($g, $x1, $y1, $x2, $y2, $border);
}

// A function to draw a filled rectangle with rounded corners:
// Just like drawing a rectangle, but also specify a radius for the corners.
function i_filledroundedrectangle($g, $x1, $y1, $x2, $y2, $color, $radius) {
    // We need to know the diameter too:
    $diam = $radius * 2;

    // Going to cheat slightly to accomplish this.  First draw four circles
    //  at the corners of this box:
    imagefilledellipse($g, $x1 + $radius, $y1 + $radius, $d, $d, $color);
    imagefilledellipse($g, $x2 - $radius, $y1 + $radius, $d, $d, $color);
    imagefilledellipse($g, $x1 + $radius, $y2 - $radius, $d, $d, $color);
    imagefilledellipse($g, $x2 - $radius, $y2 - $radius, $d, $d, $color);

    // Now fill in the middle, two well placed rectangles will do it.
    imagefilledrectangle($g, $x1+$radius, $y1, $x2-$radius, $y2, $color);
    imagefilledrectangle($g, $x1, $y1+$radius, $x2, $y2-$radius, $color);
}

// Now a version that will just draw an outline of a rounded rectangle
function i_roundedrectangle($g,
        $x1, $y1, $x2, $y2,
        $color, $border, $radius) {
    // This could be implemented by doing calls of imagearc and imageline
    //  similar to the previous function.  But since we have that function
    //  we can cheat:
    // Just call it twice with the inner color, and the border.
    i_filledroundedrectangle($g, $x1, $y1, $x2, $y2, $border, $radius);
    i_filledroundedrectangle($g, $x1 + 1, $y1 + 1, $x2 - 1, $y2 - 1,
        $color, $radius);
}

// We are going to call each of these to test them.
// Create a blank image to do this on.
$gfx = imagecreatetruecolor(200, 200);

// Declare a few colors we will use:
$black = imagecolorallocate($gfx, 0, 0, 0);
$gray = imagecolorallocate($gfx, 120, 120, 120);
$white = imagecolorallocate($gfx, 255, 255, 255);
$blue = imagecolorallocate($gfx, 0, 0, 255);

// Make almost entire background white.
imagefilledrectangle($gfx, 1, 1, 198, 198, $white);

// Turn on antialiasing so that curvy things look better.
imageantialias($gfx, true);

// Ok, try to make a blue box with a gray drop shadow:
i_filledrectangledropshadow($gfx, 5, 5, 50, 40, 5, $blue, $gray);

// How about a basic white box, with black outline, with a drop shadow
i_rectangledropshadow($gfx, 5, 60, 50, 100, 5, $white, $gray, $black);

// Insert a filled rounded rectangle, blue sounds good
i_filledroundedrectangle($gfx, 70, 5, 150, 50, $blue, 15);

// Now how about a rectangle with rounded corners, not filled in:
i_roundedrectangle($gfx, 70, 65, 160, 100, $white, $black, 15);

// Output our sample as a PNG
header('Content-type: image/png');
imagepng($gfx);
?>

Hope it helps.