This application decompresses "ZIP" files. A ZIP file may hold a number of other files inside it, in compressed form. Generally, ZIP files are created on computers other than the Macintosh. This version of UnZip features a command which lets you say what application each unzipped file should be associated with. Here is a description of each command:
The "About UnZip..." command in the Apple menu shows some of the credits.
The "Open ZIP File..." command lets you select the ZIP file you want to process. A file select dialog will appear, which will let you choose any kind of file. Usually, the names of ZIP files end with the extension ".ZIP". The file you choose is examined. If it is not a ZIP file you will get a warning message and a chance to pick again. If it is a ZIP file, a window will appear that lists all the files which are inside.
The "Quit" command will exit the application.
The "Extract Files..." command will cause the files in the ZIP file you opened to be decompressed and placed on your disk. This command is dimmed if you haven't opened a ZIP file yet.
The "Strip LF's From TEXT Files" command toggles a checkmark next to the menu item. Normally, this checkmark is there, which means that Linefeed characters are removed from text files after they are expanded. This is the default condition because on the Macintosh, there is only a Return character between lines of text, while on most computers that generate ZIP files, there is both a Return and Linefeed character between lines. If necessary, you can remove the checkmark and the Linefeeds will remain. To indicate the non-default condition, "*Strip LF off*" will appear in the menu bar.
The "Extract .GIF and TEXT Only" command also toggles a checkmark. Normally, the checkmark os off, meaning that when you give the Extract Files command, all the files inside the ZIP file will be created. With the checkmark on, all text files will still be created, but only the binary files which have ".GIF" in their names will be created. Any others will be skipped. This can be useful if you expand many ZIP files with GIF files in them (some ZIPs may include a text document and a picture in several formats including GIF - this filters out the less interesting formats). To indicate the non-default condition, "*.GIF & TEXT filter*" will appear in the menu bar.
The "Set File Codes..." command will allow you to tell the UnZip application what application each unzipped file should be associated with - in other words, what icon each file should have on the desktop. Normally, each file inside a ZIP file includes an extension in the name which indicates the file type. For example, ".TXT" for a text file, ".GIF" for a GIF file, ".MID" for a MIDI file, and so on.
To associate a file on the Macintosh with an application and to determine what icon the file should have on the desktop, each file is given "type" and "creator" codes of four letters each. The type can be 'TEXT', 'GIFf', 'Midi', or 'DATA' for example (there are infinite varieties). The creator is a signature of the application. Every application on the Mac has a unique signature. For example for MacWrite it is 'MACA', for Microsoft Word it is 'MSWD', for MacPaint it is 'PNTG' and so on.
When you choose the Set File Codes command, a dialog appears. It includes entries for eight different types of files. The first six entries have three fields: "Extension", "Type", and "Creator", and an icon. The last two entries, labeled "Text" and "Binary", don't have "Extension" fields.
When UnZip expands a file, it looks at the file name, and searches through all the extension fields in this dialog. If it finds one of the extension fields in the file name, it gives that file the associated "Type" and "Creator".
If UnZip does not find an extension that matches, it will check to see if the file is text or binary (by looking in the ZIP directory displayed by the "Open ZIP File" command). If the file is binary, it will use the binary type/creator in the dialog. If the file is text, it checks to see how the "Strip LF's From TEXT Files" is set. If it has a checkmark, the expanded file is given the text type/creator. If there is no checkmark, it is given the binary type/creator. This is because on the Macintosh, text files should not include Linefeed characters.
Although you can type the "Type" and "Creator" fields directly, it is difficult to figure out what codes to use for the application you want. UnZip makes it easy, by allowing you to click on the icon next to the type/creator.
As an example, suppose you want MIDI (music) files to be expanded such that when you double click on them, the "Performer" application (a music sequencer application that can read MIDI files) will start.
First, enter ".MID" in the extension field of the dialog. Next, to set the type and creator, click on the icon on the line with the ".MID" extension. A file selection dialog will appear. Choose the "Performer" application. Since Performer knows how to handle several different types of files, UnZip shows a second dialog that displays all the file types and icons inside Performer. One of the icons says "Midi" under it. Click on that icon, and the dialog disappears and the selected icon, along with the type and creator codes for it, will appear in the fields.
Performer has several different icons for its files, but other applications have only one, or none at all. If you pick an application which only uses one type of icon, it is selected automatically without the second dialog. If you pick an application which uses no specific icon, the generic blank document and a "????" type is automatically selected
Note that since there is a general "text" entry and a general "binary" entry, you probably don't have to set up every possible extension you know about. If you always want MacWrite to open all text documents, set up MacWrite in the general text entry and you don't have to set up extensions for ".TXT", ".DOC" and all the other possible text extensions.
If you know the type and creator codes already and type directly into the type/creator fields, the icon will revert to the dotted "unknown" icon. This does not necessarily mean your files will not have the proper icon for the type/creator you selected. It only means UnZip does not know exactly what the icon will look like.
If you select an application through the icon, but do not have the application on the disk to which you expand the ZIP file, the expanded file will have the right type/creator but it might have the generic document icon. When placed on a disk with the proper application, the icon will appear.
In the default settings supplied, the default binary setting is a 'TEXT' type. This is because even though binary data will be placed in the file, it might need to be mislabeled as 'TEXT' for various utilities which use such files. Some utilities assume binary files are type 'TEXT' because some communications programs use that type when they download binary files.
