PHP Classes

File: readme_ExifCapture.txt

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  Classes of Ray Paseur   Exif Capture   readme_ExifCapture.txt   Download  
File: readme_ExifCapture.txt
Role: Documentation
Content type: text/plain
Description: Readme
Class: Exif Capture
Extract metadata from picture files in Exif format
Author: By
Last change:
Date: 4 years ago
Size: 2,549 bytes


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Class ExifCapture This class uses the PHP Exif extension to extract metadata from image files. Although PHP can recognize many kinds of image files, the Exif extension only seems to work well with JPG and TIF files. The Class was motivated by this need: References: Exif has a lot of "loose ends" shown here Exif data comes in multidimensional arrays. Which arrays are present in any given image? Who knows! Consult the "SectionsFound" element. In my experimentation the most useful information was contained in FILE, COMPUTED, IFD0, and EXIF arrays. Within these arrays the items are given easy-to-understand names like "FileName" and "MimeType." BTW, It's IFD zero, not IFD oh. The Class provides the following methods __construct() makes opinionated assumptions about what information will be captured, and what unuseful information will be discarded. You may want to modify these underlying assumptions. set_included_array() can be used to capture other sections of the Exif. set_required_item() can be used to limit the return to certain items. set_excluded_item() can be used to remove items from the collection. get_image_data() returns as much data as possible for a given image file, subject to the constraints of the included arrays and the excluded items. This can be quite a lot of information. get_required_data() returns only the information that has been explicitly requested by the constructor and set_required_item(). get_image_list() creates class properties that segregate files with Exif information from files that do not provide PHP-readable Exif. The properties are arrays that can be iterated with foreach(). build_exif_array() finds all of the Exif values that PHP knows about. Many (perhaps most) of these are not going to be present in your image file. Call this method, then print the object to see them. Some image files will have more Exif than others. After processing with Photoshop, some image files gain additional Exif. Some image editors can strip Exif, which may make the image file smaller so that it loads faster over the internet. Please see the demo file for examples that use the methods.