204 lines
9.8 KiB
Plaintext
204 lines
9.8 KiB
Plaintext
//////////////////////////////////////////////////////////////
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/// phpThumb() by James Heinrich <info@silisoftware.com> //
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// available at http://phpthumb.sourceforge.net ///
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//////////////////////////////////////////////////////////////
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/// //
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// Frequently Asked Questions (FAQ) about phpThumb() //
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// ///
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//////////////////////////////////////////////////////////////
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Q: My question isn't answered here and I can't find any
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forums, how do I get support?
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A: Please email me directly at info@silisoftware.com with
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any questions, suggestions, donations, etc.
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Q: What is the GPL? Can I use this for commercial sites?
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A: See the GPL FAQ: http://www.gnu.org/licenses/gpl-faq.html
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In general, if you just want to call phpThumb.php in the
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standard <img src="phpThumb.php?src=pic.jpg&w=100"> manner
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then there is no problem, you're free to do this no matter
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if you site is commercial or not, or what license your code
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is released under.
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If you're calling phpThumb() as an object then you will
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probably run into license issues, so consult the above FAQ
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and the GPL itself.
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No matter if you use phpThumb() commercially or not, no
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payment is required. However, donations are always welcome
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and can be made at http://phpthumb.sourceforge.net
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Q: Some images generate thumbnails, but some fail (the original
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non-resized image is output instead).
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A: Your PHP installation does not have a high enough memory_limit
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and ImageMagick is not installed on the server. The PHP memory
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required is 5 times the number of pixels in the image.
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For example:
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640x480x5 = 1.5MB
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1600x1200x5 = 9.2MB
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You can adjust the PHP memory limit in php.ini (if you have
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permission on your server to do so), or (better yet) install
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ImageMagick on the server and that will bypass the memory limit
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issue. If you can't do either of the above, you can resize the
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images manually (with your favourite image editor) to a size
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that your memory_limit setting can handle, and/or you can
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re-save the images with an image editor that can embed an EXIF
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thumbnail (Photoshop for example) which phpThumb can use as an
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image source (lower image quality, but perhaps better than
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nothing).
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Q: I'm getting is this error message:
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Failed: RenderToFile(<filename>) failed because
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!is_resource($this->gdimg_output)
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A: You missed the call to GenerateThumbnail() before
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RenderToFile() or OutputThumbnail.
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See /demo/phpThumb.demo.object.php for an example.
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Q: I'm trying to save a phpThumb-generated image in Internet
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Explorer and it saves in BMP format, why?
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A: This is not phpThumb's fault, it is an IE issue:
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http://support.microsoft.com/default.aspx?scid=kb;en-us;810978
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http://support.microsoft.com/default.aspx?scid=kb;en-us;260650
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Q: PNG images with transparent areas show up with gray background
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in the areas that are supposed to be transparent.
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A: Internet Explorer has had a broken PNG alpha-channel display
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implementation for a decade, so it may never get fixed. Other
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major browsers generally handle alpha-transparent PNGs fine.
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See http://www.silisoftware.com/png_transparency/
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For an alpha-channel PNG display in IE hack, see this page:
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http://www.koivi.com/ie-png-transparency/
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Q: I'm getting "<filename> does not exist" when I know the
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file does exist
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A: Check these two values are present and properly configured
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in phpThumb.config.php (introduced in v1.6.0):
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$PHPTHUMB_CONFIG['allow_src_above_docroot'] (default=false)
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$PHPTHUMB_CONFIG['allow_src_above_phpthumb'] (default=true)
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If your images are outside DOCUMENT_ROOT then you will have
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to configure 'allow_src_above_docroot' to true.
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Q: Should I use phpThumb.php, or use phpThumb() as an object?
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A: phpThumb.php is easier to use (less coding) for basic uses.
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phpThumb.php handles all caching; your own object will need
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to have its own caching code. If you just want to display a
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thumbnailed version of an existing image, use phpThumb.php
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If you want to render one (or more) thumbnails to static
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files (during upload, for example), that's an appropriate
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use for the object mode. Also, phpThumb.config.php is only
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used by phpThumb.php, so if you instantiate your own object
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you need to manually set all configuration options because
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phpThumb.config.php has NO effect. So, to repeat:
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**always use phpThumb.php unless you NEED to have an object**
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Q: Are there any front-end GUI interfaces to phpThumb()?
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A: See /demo/readme.demo.txt
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Q: Are there / have there been any security issues in phpThumb?
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A: http://secunia.com/product/5199/
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Q: Why can't Flash work with images output from phpThumb()?
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A: Flash doesn't like progressive JPEG. Set:
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$PHPTHUMB_CONFIG['output_interlace'] = false;
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Q: Image quality is not very good - why?
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A: If you're using GD v1.x, no way around it. Upgrade to GD v2.x
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Q: Image quality is very bad, very pixelated -- why?
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A: You may be trying to resize images larger than the available
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PHP memory, so phpThumb is simply extracting and using the
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EXIF thumbnail as the image source, which is usually about
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160x120 (so if you resize it to 640x480 it will look very bad).
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To calculate the required size for memory_limit in php.ini,
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calculate the number of pixels in the image and multiply by 5:
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For example, 1600x1200 = 1600 * 1200 * 5 = 9600000 = 10M
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Q: Can I save the generated thumbnail to a file?
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A: Yes, there are several ways to do so; the best way is to call
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phpThumb as an object and call RenderToFile() to save the
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thumbnail to whatever filename you want.
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See /demo/phpThumb.demo.object.php for an example.
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The other way is to use the 'file' parameter (see
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/docs/phpthumb.readme.txt) but this parameter is deprecated
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and may not exist in future versions of phpThumb().
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Q: "Off-server thumbnailing is not allowed" -- how do I enable it?
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A: By default, phpThumb() only makes thumbnails for the same domain
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that it is running on. To allow it to make thumbnails for a limited
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number of other domains, add them (in phpThumb.config.php) like this:
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$PHPTHUMB_CONFIG['nohotlink_valid_domains'] = array(
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@$_SERVER['HTTP_HOST'], 'example.com', 'www.example.com',
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'subdomain.example.net', 'example.org');
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To disable off-server thumbnail blocking, just set:
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$PHPTHUMB_CONFIG['nohotlink_enabled'] = false;
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Q: Is it possible to set the parameters (like w/h/fltr[]) in the config,
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so that they can't be changed over the URL?
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A: Take a look at $PHPTHUMB_DEFAULTS at the bottom of phpThumb.config.php
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You'll want to set $PHPTHUMB_DEFAULTS_GETSTRINGOVERRIDE=false,
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possibly also $PHPTHUMB_DEFAULTS_DISABLEGETPARAMS=true.
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You may also want to investigate $PHPTHUMB_CONFIG['high_security_enabled']
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(see the example at the bottom of phpThumb.config.php for how to call
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images in HighSecurity mode.
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Q: Is there a way to use phpThumb() object to create thumbnails without the
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parameters in the URL showing the location of the image etc?
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A: There is a demo in /demo/phpThumb.demo.object.php. You could modify this
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into your own file, but there still remains the problem of passing
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parameters to the file, whether it's phpThumb.php or your own instantiation
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of a phpThumb() object. I would suggest is putting as many of the common
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parameters into phpThumb.config.php as possible under $PHPTHUMB_DEFAULTS,
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so you then don't have to pass them for each image. If you don't want people
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modifying the parameters, turn on $PHPTHUMB_CONFIG['high_security_enabled']
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and set a password (you'll need to generate the <img> tags with phpThumbURL()
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provided at the bottom of phpThumb.config.php). If you don't want people
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accessing your source images at all, you can place them outside DOCUMENT_ROOT
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on your server (as long as phpThumb/PHP has read access to the directory).
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The other option is to put your source images in a MySQL database and set
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$PHPTHUMB_CONFIG['mysql_query'] and related parameters in phpThumb.config.php
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to pull your source images from the database. That way it's impossible to
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retrieve the images except through phpThumb.php, and if high_security is enabled,
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then nobody can modify the parameters to view anything except what you want to show.
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So, yes, it's possible to use your own object, but it's probably better to use
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phpThumb.php if possible -- one notable issue is that phpThumb.php handles all
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the caching, so you're on your own to deal with that if you create your own object.
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Q: phpThumb runs slowly, as if the images aren't cached, when I use HTTP source
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images (not on my server). How can I make it go faster?
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A: $PHPTHUMB_CONFIG['cache_source_filemtime_ignore_remote'] = true;
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// if true, remote source images will not be checked for modification date and
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// cached image will be used if available, even if source image is changed or removed
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Q: What does the "cache_default_only_suffix" configuration option do?
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A: Cache files are normally created with big ugly names like
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"phpThumb_cache_www.example.com_src1a482c2c760463795ff18faf073b389f_par3e099041c2f4a73041a7f5d7e7fc481a_dat1119952152.jpeg"
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but if cache_default_only_suffix is enabled, cache filenames are simplified to
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"pic_thumb.jpg" (for example). The problem is that only one version of that
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thumbnail is possible, and you can never call it again with a different size,
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or different filters, etc. Generally you don't want that enabled, but it's
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there because some people asked for it.
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Q: Why is the visual size of rotated images smaller than the unrotated images?
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A: phpThumb fits the rotated image into the 'w' and 'h' dimensions.
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Try not specifying a 'w' parameter: phpThumb.php?src=file.png&ra=15
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That should leave the image the apparent same size as the unrotated image
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(in actual fact the canvas size is enlarged to fit the rotated image in it).
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