|Column Tag:||Tools of the Trade
Differs from other interface designers and toolbox extenders in its simple code writing.
By Philip Borenstein, MacTutor Regular Contributing Author
What is ViewIt?
The promotional literature that FaceWare puts out describes ViewIt as a window designer and manager. That description is accurate, but it makes ViewIt sound like yet another interface design kit. FaceWare also describes ViewIt as extensions to the Macintosh Dialog Manager and Control Manager. And thats true, too. What these descriptions dont convey is how different ViewIt is from other interface designers and toolbox extenders.
Like other interface-building tools, ViewIt lets you create windows and lay out controls in those windows. But instead of generating source code that you customize, ViewIt uses code resources that already know how to manage those windows and controls. This approach has some clear advantages and some drawbacks. Depending on the kinds of applications you write, the advantages may outweigh the drawbacks.
The main advantage is that the code that you write is remarkably simple. Most of what you do is set up a window, call the main event loop routine, and check for hits in your controls. In general, you dont need to concern yourself with the Macintosh Toolbox. The main disadvantage is that most of the behavior is locked away in code resources, so your application may be carrying around extra baggage that you dont really need.
Whats in the package?
ViewIt works with most popular Macintosh development environments. The commercial version comes with demo programs for THINK C, THINK Pascal (both of which can be used with MPW C and MPW Pascal), Absoft Fortran, Language Systems Fortran, and MacFortran. The THINK C and THINK Pascal programs come with ready-to-use projects. Two separate utilities let you use FaceWare modules with HyperCard and Prograph.
The ViewIt package consists of three parts: FaceIt, ViewIt, and UtilIt. ViewIt is the part of the system that lets you lay out controls in windows. FaceIt is the part of the system that deals with the main event loop, the menu bar, and other program-wide features. UtilIt consists of utility routines used by FaceIt, ViewIt, and by your own program.
You can use the ViewIt module without the FaceIt module to design modal dialog boxes. With FaceIt you get automatic support for modeless windows. The documentation does tell you how you can use ViewIt modeless windows in programs that have an existing event loop, but if youre starting from scratch, you may not want to go through the trouble.
All the modules that make up ViewIt live in a resource file called FaceWare. You can place this file in your System folder, so all your ViewIt-based applications can share it, or you can copy resources from the FaceWare file into your application to create stand-alone applications.
ViewIt costs $95. FaceWare distributes a shareware version that includes nearly everything that comes in the commercial package. You can use the shareware version for 30 days. After that, you either get rid of it, or you buy the commercial package.
How does it work?
Instead of customizing source code, you make calls to a dispatching routine called FaceIt() which loads the appropriate modules for program-wide behavior like cutting, pasting, and printing and for control-specific behavior. In addition the standard Macintosh control manager, which uses CDEFs and CNTLs, ViewIt uses its own control drivers (stored in FCMD resources) and control descriptions (stored in FCTL resources). These FCMDs are the code resources that do all the work.
To create windows and lay out controls, you dont use a separate application. You dont even need to use ResEdit. Instead, you lay out the controls while your application is running. Once youve created a window, you press the Command-Shift-Option keys to enter ViewIts editing mode. In this mode, you can add or delete new controls and edit existing controls. To see how theyll work, you just press the Enter key and youre back in run mode again.
Since the edit mode is part of ViewIt (its stored in the FaceWare file), you can fine tune your user interface without using your development environment. Suppose youre doing a demo for your users, and they say, This button should be red. That menu should be over there. All you have to do is go into edit mode, make the changes, and try them out. ViewIt comes with a smaller FaceWare file without the edit mode that you can use when your application is finished.
The FaceWare file with the on-line editing support takes up about 1 MB, and the file without the on-line editing support is about 440K.
This picture shows one of the dialogs used for editing a control. The Driver Help button brings up another window that contains the on-line help for buttons.
What kinds of interface elements does ViewIt handle?
In addition to the standard controls that the Macintosh Dialog Manager provides (buttons, check boxes, radio buttons, static text, and editable text) ViewIt also gives you pop-up menus, picture-based palettes, graphic buttons based on PICTs, ICONs, and SICNs, dials, and more esoteric controls like a help text viewer and a scrap viewer.
You can specify the color and framing style of any control. For text-based controls, you can set the font, size, style, and text color. You can have buttons draw their text in bold, outline Palatino, or you can have right-justified check boxes with the check box on the right side of the text. Most controls have several variations. Pop-up menus, for example, come in several varieties. Some menus behave like menus in the main menu bar. Some menus check only one item at a time while others have several items checked.
Every control belongs to a view, which is kind of a meta-control, and a window can have several views. Views can be longer than the window they belong to, and its easy to add both horizontal and vertical scroll bars to them. Views let you group controls, so you can move them around as a unit. Since you can show and hide views, you can use them for dialogs that have multiple pages.
ViewIt makes a distinction between a controls appearance and its behavior. This distinction is useful for picture-based controls. For instance, you can have an icon behave like a button, so it highlights while the mouse button is pressed on it. Or you can have several icons behave like radio buttons where only one icon of a group is highlighted at a time. Of course, some combinations, like editable buttons, dont work because the CDEF or FCMD doesnt support a particular behavior, and other combinations, like check boxes that behave like radio buttons, will get you into trouble with the user interface police.
If you want to make a control behave a little (or a lot) differently, ViewIt gives you hooks that let you intercept virtually everything a control does.
In traditional dialog box programming, when you have a list of radio buttons, check boxes, or other controls, you need to set the controls values from one of your data structures. When the user dismisses the dialog, you need to get the value of each control and set your data structure accordingly. ViewIt has a nice feature called Data Linking that does this for you automatically. When you create a window, you pass ViewIt the address of a record. When you design your controls, you give the offset into the record where the value is stored. ViewIt takes care of doing all the numeric to string conversions-even for real numbers.
Of course, you dont have to use Data Linking. You can have controls report when theyve been hit. ViewIt uses a mechanism similar to menu events to tell you which control has been hit. ViewIt variables tell you which control, in which view, and in which window received the click. The ViewIt routines let you get the state of the control so you can tell whats in an editable field, whether a check box is on or off, and so forth.
This picture shows a ViewIt window with two views in editing mode. The left view is a scrolling view that shows assorted controls. The right view is a Help Control that shows text.
All of the ViewIt documentation is on-line, and its always available when youre in edit mode. When youre editing a specific control, you can click on a button to get its documentation. The documentation is right where you need it when youre working, and it doesnt clutter your desk. A printed manual, though, would have made learning ViewIt a bit easier.
With printed documentation you can flip through the pages to get a sense of what a piece of software is about, and even the manuals physical size gives you a hint about the complexity of the software. With on-line manuals a list of topics in a menu may refer to half a kilobyte of text or two half a megabyte text. Theres no way to know.
The demo programs that come with ViewIt are complete in the sense that they show off virtually every feature, but a little hand-holding would have been nice. You can copy controls from the ViewIt demos and paste them into your own application, or you can try modifying them to see how different settings work.
Who is ViewIt for?
ViewIt is ideal for in-house programmers and consultants who need to write Macintosh applications quickly. Often, these programmers need to respond quickly to requests for new features, and ViewIts edit mode makes it easy for the programmer and the user to collaborate on the user interface. In-house programmers can take advantage of the fact that many ViewIt-based programs can share the same FaceWare file. This arrangement keeps the application size small.
ViewIt is also useful for programmers who have existing programs that they need to port to the Macintosh. ViewIt is much easier to learn to use than the Macintosh Toolbox. Its certainly easier to learn ViewIt than it is to learn object-oriented programming, and for vanilla Macintosh programs, ViewIt handles most of the Macintosh housekeeping tasks.
Commercial (and shareware) software vendors may find that ViewIts overhead makes ViewIt-based applications larger than hand-rolled applications, particularly for small applications. It is possible to move only the resources your application uses from the FaceWare file. ViewIt comes with a utility program to do just that.
ViewIt is a surprisingly powerful interface-builder. Its approach to the problem is considerably different from the other tools on the market, so it may be difficult to get into it at first. For non-Macintosh programmers who need to put together a Macintosh application in a hurry, ViewIt takes care of most of the standard housekeeping chores. ViewIt doesnt require you to learn object-oriented programming or a class library.
The only way youll be able to decide whether ViewIt will work for your application is to try it. You can use the shareware version of ViewIt for 30 days, and if you like it, youre obligated to buy the full version. If not, you can wipe it off your disk, and program like you programmed before.
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