bmp extension is problematic, since it commonly means Windows Bitmap, for which there is no registered MIME type browsers may treat the nonstandard notation image/bmp as corresponding to. png, they will treat it as a PNG image file, instead of inspecting the content of the file. They work on filename extensions, so if you name a GIF file, or a plain text file, or a binary program file so that its name ends with. (Browsers interpret the accept attribute value in rather simple way. Its purpose is to protect a normal user from making mistakes, like submitting a file of a type that will be rejected by the server-side handler. Even if they did, the attribute would not constitute a security measure of any kind (because a user could edit the form, or write a form of his own, or use a browser that ignores the accept attribute). It also says: “User agents should prevent the user from selecting files that are not accepted by one (or more) of these tokens.” This might be sensible, but browsers do not actually do that. It then describes how it could be used by a browser to provide an adequate user interface. It says that the attribute “may be specified to provide user agents with a hint of what file types will be accepted”. The intent is to say that the attribute value should be written according to what file type(s) are expected from the user it is more or less self-evident that the server-side form handler should be written so that it is capable of handling the specified type(s).
The attribute affects client-side (browser) behavior only. The reference to server-side processing may be misleading. User agents may use this information to filter out non-conforming files when prompting a user to select files to be sent to the server”. HTML 4.01 says that the accept attribute “specifies a comma-separated list of content types that a server processing this form will handle correctly. The purpose of the attribute is to help users select files of appropriate types. Browsers that support the accept attribute use it to create an initial file filter, but they do not prevent the user from changing or removing the filter and thereby selecting and submitting any file they like. Imagecopyresampled($thmb, $resource, 0, 0, 0, 0, $newWidth, $newHeight, $sourceWidth, $sourceHeight) īelow is the version info of my setup (It's MAMP Version 1.9.This is common browser behavior. $thmb = imagecreatetruecolor($newWidth, $newHeight) $newWidth = 1.0*$size/$sourceHeight*$sourceWidth $newHeight = 1.0*$size/$sourceWidth*$sourceHeight I use imagecreatetruecolor() along with imagecopyresampled() to generate the thumbnail, like this: function _resizeImageToFit($resource, $size) This image does not display in the browser, nor can it be opened by Preview (on MacOS). It actually only contains 33 bytes (with any source PNG that I've tried so far).
#Imagejpeg imagepng imagegif code#
My code works fine for JPEG and GIF, but if I upload a PNG file, the resulting thumbnail is invalid. I call the appropriate image_() function to save in the same format as the original. I am using the GD library to automatically generate a thumbnail version of an uploaded image.
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