PHP Graphics

From Pigbert Wiki

Include

• <image src='script.php' />
• <image src='script.php?<?php echo time(); ?>' />

(each time the page is accessed, the src for the <img> tag will be different, thus forcing the browser to get the latest version of the image.

Creating/ReadIn Image

• image <= imagecreate(int width, int height) //256 color palette
• image <= imagecreatetruecolor(int width, int height)
• imagecreatefromjpeg/png/gif/wbmp/xbm/xpm/gd/gd2(string filename)
• imagecreatefromstring(string filename)
• imagecreatefromgd2part(string filename, int startX, int startY, int width, int height)

Save/Send Image

To specify an output quality, but not save the image to disk, the filename should be set to NULL.

To send an image, send the header header('Content-type: image/png(jpeg)') first

• imagejpeg($image[,string filename|NULL [,int(0-95|default=75) quality]])
• imagepng($image[, string filename])
• imagewbmp($image[, string filename [,$foregroundColour]])

Colour

• int <= imagecolorallocate(image,int red, int green, int blue)

colours needed to be allocated to an image before it can be used.

the first allocated colour is used as the background of the image.

• imagecolorclosest($image, int r, int g, int b)

returns the colour identifier of the color closest to the RGB value passed in.

Retrieving Image Information

• imagesx($image) returns the width of the image
• imagesy($image) returns the height of the image
• getimagesize(imageFilePath) => resultArray:
  • resultArray[0] = int width;
  • resultArray[1] = int height;
  • resultArray[2] = int type; (1=GIF, 2=JPG, 3=PNG, 4=SWF, 5=PSD, 6=BMP, ...
  • resultArray[3] = string that can be used in <img> tag (e.g. width="413" height="271")
  • resultArray[bits] = int colorDepth; (e.g. 8)
  • resultArray[channels] = int numberOfColorChannel; (e.g. 1)
  • resultArray[mime] = string mimeHeader; (e.g. image/jpeg)

Drawing Functions

• imagerectangle($image, int startX, int startY, int endX, int endY, $colour)
• imagesetpixel($image, int x, int y, $colour)
• imageline($image, int startX, int startY, int endX, int endY, $colour)
• imagearc($image, int centerX, int centerY, int width, int height, int start, int end, $colour)
• imageellipse($image, int centerX, int centerY, int width, int height, $colour)
• imagepolygon($image, array[] points, int numPoints, $colour)
• imagefilledarc($image, int centerX, int centerY, int width, int height, int start, int end, $colour, $int style)
• imagefilledellipse($image, int centerX, int centerY, int width, int height, $colour)
• imagefilledrectangle($image, int startX, int startY, int endX, int endY, $colour)
• imagefilledpolygon($image, array[] points, int numPoints, $colour)

buffering

$buffer = join('',file("art.jpg"));
header("Content-type: image/jpeg");
echo $buffer;

destroy

imagedestroy($image)