PHP GD

1
PHP GD MYSQL

• Image Processing
• Database Storage

2
Why Process Images

• Automatic Watermarks
• Watermark images viewed on free page
• Unmarked image on pay-for page
• Resize images on the fly
• Thumbnail / Gallery View
• Custom images for mobile devices
• Create charts and graphs on the fly with dynamic
  data

3
Process Once or at Every Request

• Blogger, Flickr, c all make thumbnails at the
  point of upload.
• For high volume operations, disk space is always
  cheaper than processor time
• Processing Requests on the fly necessary if you
  are customizing images every time they are loaded
• Charts are updated after a set duration

4
Creating Images

• imagecreatefromjpeg(path_to_file)
• Creates an image object using a preexisting image
  file
• There are functions for png, gif, bmp c
• imagecreatetruecolor(height, width)
• Creates new image object
• imagecreatefromstring(binary_data)

5
Image Properties

• imagesx(image_resource)
• Returns the width (in pixels) of an image object
• imagesy(image_resource)
• Returns the height of an image object
• Aspect Ratio x/y or w/h
• When resizing images, aspect ratio must be
  maintained

6
Outputting Images

• imagejpeg(image_resource)
• Outputs a jpeg format image to the browser
• Other functions for png, gif, bmp c
• imagejpeg(image_resource, path_to_file)
• Saves image to the server

7
A Lame Example

• (doesnt do anything we havent seen before)

http//www.rpi.edu/gillw3/websys/gd/lame.php
8
A Dorky Example
http//www.rpi.edu/gillw3/websys/gd/dorky.php
9
Image Processing

• imagecopyresampled(lotsofargs)
• Used to resize an image
• imagecopymerge(lotsofargs)
• Used to place an image on top of another
• imagefilter(lotsofargs)
• Manipulates the content of an image

10
Water Mark Example

• PHP.NET
• http//us.php.net/manual/en/image.examples.merged-
  watermark.php

11
A Graph Example
0,0
100,100
12
A Graph Example

• http//www.rpi.edu/gillw3/websys/gd/graph.php

13
In Class Work

• Improve my graph code
• Find the extreme values in the array
• Use imagesx() and imagesy() and count() to force
  the array data to fill any graph size

14
Storing Images in Databases

• Binary Data can be stored in fields with a blob
  type
• Other data to store
• File type (.jpg, png)
• File size
• Original file name
• EXIF data
• This data can be lost after GD functions are run

15
Uploading Images

• ltinput typefile namemyfilegt
• Creates that include a file input box in an html
  form
• The form must have
• method post
• enctype multipart/form-data

16
Processing the Form

• Image is stored on server in a TMP directory
• _FILES accesses files posted to the server
• _FILES'userfile''name' name of file on the
  client
• _FILES'userfile''type' file mimetype
• _FILES'userfile''size' file size
• _FILES'userfile''tmp_name' name of file on
  the server
• MORE
• http//us.php.net/features.file-upload

17
Putting Uploaded File into MYSQL

• Open the uploaded file fopen()
• Read it in to a string fread()
• Use that string in an MYSQL INSERT command

18
Getting Images Out of MYSQL

• Create a PHP image object from DB output
• Imagecreatefromstring(rowimg)
• Unlike other Imagecreate functions, it
  auto-detects the image encoding type

19
PHP GD / MYSQL

• An Example
• http//www.rpi.edu/gillw3/websys/gd/dbgd.php

20
Put an Image in a Database

• In PHPMYADMIN
• Create a table called images
• Add two fields
• id, type INT Auto-inc
• img, type BLOB
• Click the INSERT tab
• Upload an image from your desktop to your database