DIWE - Using Extensions and Image Manipulation

Diploma in Web Engineering
Module IX: Using Extensions and
Image Manipulation
Rasan Samarasinghe
ESOFT Computer Studies (pvt) Ltd.
No 68/1, Main Street, Pallegama, Embilipitiya.

Contents
1. Image Manipulation with PHP
2. GD Library
3. ImageCreate()
4. ImageColorAllocate()
5. Drawing shapes and lines
6. imageellipse()
7. imagearc()
8. imagepolygon()
9. imagerectangle()
10. imageline()
11. Creating a new image
12. Using a Color Fill
13. imagefilledellipse()
14. imagefilledarc()
15. imagefilledpolygon()
16. imagefilledrectangle()
17. Basic Pie Chart
18. 3D Pie Chart
19. Modifying Existing Images
20. imagecreatefrompng()
21. imagecolortransparent()
22. imagecopymerge()
23. Creating a new image…
24. Stacking images…
25. Imagestring()
26. Draw a string

Image Manipulation with PHP
• PHP is not limited to creating just HTML output. It can
also be used to create and manipulate image files.
• You will need to compile PHP with the GD library for
this to work.
• GD and PHP may also require other libraries,
depending on which image formats you want to work
with.

GD Library
• The GD Graphics Library is a graphics software library
by Thomas Boutell for dynamically manipulating
images.
• GD stands for "Graphics Draw".
• GD can create images composed of lines, arcs, text,
other images, and multiple colors.

Drawing a new image - ImageCreate()
Returns an image identifier representing a blank
image of specified size.
resource imagecreate (int $width, int $height)

Define a color - ImageColorAllocate()
Returns a color identifier representing the color
composed of the given RGB components.
int imagecolorallocate (resource $image ,int $red
,int $green ,int $blue)

Creating Image
$myImage = imagecreate(250, 250);
$black = imagecolorallocate($myImage, 0, 0, 0);
header("Content-type: image/png"); // Send a Raw
HTTP Header
imagepng($myImage); // Outputs a PNG image
imagedestroy($myImage); // Destroy an image

Drawing shapes and lines
• imageellipse() - Draw an ellipse
• imagearc() - Draws an arc
• imagepolygon() - Draws a polygon
• imagerectangle() - Draw a rectangle
• imageline() - Draw a line

imageellipse() - Draw an ellipse
Draws an ellipse centered at the specified
coordinates.
bool imageellipse (resource $image, int $cx, int $cy,
int $width, int $height, int $color)

imagearc() - Draws an arc
Draws an arc of circle centered at the given
coordinates.
bool imagearc (resource $image, int $cx, int $cy, int
$width, int $height, int $start, int $end, int $color)

imagepolygon() - Draws a polygon
Creates a polygon in the given image.
bool imagepolygon (resource $image, array $points,
int $num_points, int $color)

imagerectangle() - Draw a rectangle
Creates a rectangle starting at the specified
coordinates.
bool imagerectangle (resource $image, int $x1, int
$y1, int $x2, int $y2, int $color)

imageline() - Draw a line
Draws a line between the two given points.
bool imageline (resource $image, int $x1, int $y1,
int $x2, int $y2, int $color)

Creating a new image
$white = imagecolorallocate($myImage, 255, 255, 255);
$red = imagecolorallocate($myImage, 255, 0, 0);
$green = imagecolorallocate($myImage, 0, 255, 0);
$blue = imagecolorallocate($myImage, 0, 0, 255);
imagerectangle($myImage, 15, 15, 40, 55, $red);
imagerectangle($myImage, 40, 55, 165, 195, $white);
header("Content-type: image/png"); // Send a Raw HTTP Header
imagepng($myImage); // Outputs a PNG image
imagedestroy($myImage); // Destroy an image

Using a Color Fill
• imagefilledellipse() - Draw a filled ellipse
• imagefilledarc() - Draw a partial arc and fill it
• imagefilledpolygon() - Draw a filled polygon
• imagefilledrectangle() - Draw a filled rectangle

imagefilledellipse() - Draw a filled ellipse
Draws an ellipse centered at the specified
coordinate on the given image.
bool imagefilledellipse (resource $image, int $cx, int
$cy, int $width, int $height, int $color)

imagefilledarc() - Draw a partial arc and fill it
Draws a partial arc centered at the specified
coordinate in the given image.
bool imagefilledarc (resource $image, int $cx, int
$cy, int $width, int $height, int $start, int $end, int
$color, int $style)

imagefilledpolygon() - Draw a filled polygon
Creates a filled polygon in the given image.
bool imagefilledpolygon (resource $image, array
$points, int $num_points, int $color)

imagefilledrectangle() - Draw a filled rectangle
Creates a rectangle filled with color in the given
image starting at point 1 and ending at point 2. 0, 0
is the top left corner of the image.
bool imagefilledrectangle (resource $image, int $x1,
int $y1, int $x2, int $y2, int $color)

Using a Color Fill
imagefilledrectangle($myImage, 15, 15, 40, 55, $red);
imagefilledrectangle($myImage, 40, 55, 65, 95, $white);
header("content-type: image/png");
imagepng($myImage);
imagedestroy($myImage);

Basic Pie Chart
imagefilledarc($myImage, 50, 50, 100, 100, 0, 90, $red, IMG_ARC_PIE);
imagefilledarc($myImage, 50, 50, 100, 100, 91, 180, $green, IMG_ARC_PIE);
imagefilledarc($myImage, 50, 50, 100, 100, 181, 360, $blue, IMG_ARC_PIE);
header("Content-type: image/png");
imagepng($myImage);

3D Pie Chart
$lt_red = imagecolorallocate($myImage, 255, 150, 150);
$lt_green = imagecolorallocate($myImage, 150, 255, 150);
$lt_blue = imagecolorallocate($myImage, 150, 150, 255);
for($i = 60; $i > 50; $i--){
imagefilledarc($myImage, 50, $i, 100, 50, 0, 90, $lt_red, IMG_ARC_PIE);
imagefilledarc($myImage, 50, $i, 100, 50, 91, 180, $lt_green, IMG_ARC_PIE);
imagefilledarc($myImage, 50, $i, 100, 50, 181, 360, $lt_blue, IMG_ARC_PIE);
}
imagefilledarc($myImage, 50, $i, 100, 50, 0, 90, $red, IMG_ARC_PIE);
imagefilledarc($myImage, 50, $i, 100, 50, 91, 180, $green, IMG_ARC_PIE);
imagefilledarc($myImage, 50, $i, 100, 50, 181, 360, $blue, IMG_ARC_PIE);
imagepng($myImage);

Modifying Existing Images
• imagecreatefrompng() - Create a new image from
file or URL
• imagecolortransparent() - Define a color as
transparent
• imagecopymerge() - Copy and merge part of an
image

imagecreatefrompng()
Returns an image identifier representing the image
obtained from the given filename.
resource imagecreatefrompng (string $filename)

imagecolortransparent()
Sets the transparent color in the given image.
int imagecolortransparent (resource $image [, int
$color ])

imagecopymerge()
Copy a part of src_im onto dst_im starting at the x,y
coordinates src_x, src_y with a width of src_w and a
height of src_h. The portion defined will be copied
onto the x,y coordinates, dst_x and dst_y.
bool imagecopymerge (resource $dst_im, resource
$src_im, int $dst_x, int $dst_y, int $src_x, int $src_y,
int $src_w, int $src_h, int $pct)

Creating a new image from existing image
$myImage = imagecreatefrompng("img1.png");
imagefilledellipse($myImage, 55, 170, 50, 20, $white);
imagepng($myImage);

Stacking images and making them transparent
$baseimage = imagecreatefrompng("img1.png");
for($i=2; $i<5; $i++){
$myImage = imagecreatefrompng("img".$i.".png");
$gray = imagecolorallocate($myImage, 5, 5, 5);
imagecolortransparent($myImage, $gray);
imagecopymerge($baseimage, $myImage, 10, 10, 0, 0, 250,
250, 60);
}
imagepng($baseimage);
imagedestroy($baseimage);

Imagestring() - Draw a string horizontally
Draws a string at the given coordinates.
bool imagestring (resource $image, int $font, int $x,
int $y, string $string, int $color)

Draw a string
$background = imagecolorallocate($myImage, 200, 10, 10);
$text = imagecolorallocate($myImage, 20, 200, 20);
imagestring($myImage, 5, 10, 20, "Hello World", $text);
imagepng($myImage);

The End
http://twitter.com/rasansmn

DIWE - Using Extensions and Image Manipulation

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