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