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Volume Number: | 3 | |
Issue Number: | 9 | |
Column Tag: | C Workshop |
CDEV Extends Control Panel
By Jan Eugenides, Assembly Corner, Maynard, MA
The new control panel that comes with System 4.1 is extensible. You can write a code resource called a ‘cdev’ to add functions to the control panel. The process is not difficult, and it offers a number of interesting possibilities.
What I had in mind for this project was to write a fairly simple cdev, just to test the waters. Having just acquired a Macintosh II, I also wanted to explore some of the sound generation capabilities. The result is Monkey, an amusing addition to the control panel. Although this particular cdev will only work on a Macintosh II (because it calls the Mac II’s sound routines), the techniques shown here will work for more generalized cdevs as well.
The Control Panel
Figure 1 shows the new Control Panel with the General panel displayed. The panel allows choosing the Desktop pattern, setting the rate of insertion point blinking, setting the time, and more. Some other standard panels allow setting keyboard options, sound options, and display options.
By writing your own cdev, you can add a new icon to the scrollable list that appears on the left edge of the Control Panel. In Figure 1, you can see the icon for the Monkey cdev at the bottom. Clicking on an icon selects it, and the Control Panel displays various controls, depending on the item list contained in the corresponding cdev. Figure 2 shows how the Control Panel appears when Monkey is selected. Clicking on the picture of a monkey causes the Macintosh II to generate the a monkey screech sound.
How It Works
When the user opens the Control Panel, it scans the System Folder for all resource files of type ‘cdev’. When it finds one, it loads the icon and the file’s name and adds it to the icon list. After all the cdevs are loaded, the General icon is selected and the standard controls are displayed. The Control Panel then calls the cdev with various event messages, indicating which items the user has clicked or dragged, enabling the cdev to track its controls.
A cdev file must contain eight resources:
• cdev - a code resource
• mach - some data that indicates which machines the cdev is compatible with
• DITL - a standard Dialog item list
• nrct - some data that defines the number of rectangles needed for the cdev’s display, and their sizes.
• ICN# - a standard icon with mask
• BNDL - a standard bundle resource
• FREF - a standard file reference resource
• An owner resource, that must be a unique four-character identifier, just like the ones used for applications. The Monkey cdev uses the type ‘mOnk’.
With the exception of the owner resource, all the resources should have the same ID number, -4064. The owner resource ID depends on how the BNDL is structured, and is usually zero.
Fig. 1 Adding our own control functions
The nrct and mach Resources
These two resources are unique to cdevs, and require some more detailed explanation. The nrct type is a list of rectangles. The first word of the resource is the number of rectangles in the list. It is followed by eight bytes for each rectangle, which describe the top, left, bottom, and right boundaries. For each rectangle defined in the nrct, the Control Panel clears out some white space in its window, and draws a frame around it. The nrct, along with the DITL, define the look of the cdev panel.
The mach resource type consists of two words. The first is called the Softmask, and is compared to the global variable ROM85 to determine which toolbox features are available (such as Color Quickdraw). The second word is called the Hardmask, and it is used to determine which hardware features are available. The values of these masks determines on which machines the cdev will appear. Table 1 shows some possible settings.
The cdev code
Listing 1 shows the code used in the Monkey cdev, written in LightspeedC. The main function is declared as:
pascal Handle main(message,item,numItems,CPanelID,ep,cdevStorage, CPDialog) intmessage,item,numItems,CPanelID; EventRecord *ep; Handle cdevStorage; DialogPtr CPDialog;
Message is a number that tells the cdev what event just took place. Monkey only responds to three types of messages: initDev, which means “do your initialization”; closeDev, which means “dispose of any allocated storage and close up shop”; and hitDev, which means “the user clicked on an item”.
For initDev, Monkey just allocates 16 bytes of storage, and returns the handle in cdevStorage. Monkey does not use this storage, but the Control Panel wants to see a valid handle. For closeDev, Monkey releases the 16 bytes of storage, and clears the cdevStorage variable. For hitDev, Monkey loads the ‘snd ’ resource with ID# 4 (the monkey screech),and then calls the Macintosh II Sound Manager routine SndPlay to generate the sound. Since there is only one item, the DoHit routine does not have to determine which item was clicked on. If there were more items, the DoHit routine would have to subtract numItems from item to determine which item in its DITL was clicked. This is because the cdev’s DITL is appended to the Control Panel’s DITL.
Fig. 2 Our Monkey Squeek!
Compiling the cdev in LightspeedC
Creating the Monkey cdev is fairly straightforward in LightspeedC. First use RMaker to compile the necessary resources, as given in Listing 3. Create a new project called MonkeyCdevP, and set the project type to a code resource of type cdev. Enter Listing 2, and save it as SoundMgr.h, in the same folder with your other Macintosh header files. Add the MacTraps library to the project. Enter Listing 1, save it as MonkeyCdev.c and add it to the project. Then build the code resource (select Build Code Resource from the Project menu). Save it as Monkey. Finally, use ResEdit to set the creator type to mOnk, and set the bundle bit. Now drag the finished cdev into the System Folder, open the Control Panel, and make the monkey screech!
A Note About the Resources
I didn’t actually use RMaker to create the resources for the Monkey cdev. I created them with ResEdit, and then used a shareware resource decompiler called ResDecomp, by Robert Comer, to create the RMaker source code for publication. To save yourself some typing, you may want to create your own ICN# and PICT resources using ResEdit, rather than enter all the hex code for them. Just be sure to give them the correct ID numbers, and make them purgeable.
By the way, the monkey picture was originally taken from a clip art disk called WetPaint, put out by Dubl-Clik software. I modified it some, but I like to give credit for these things.
Table 1: Sample mach Settings
Softmask Hardmask Function
$0000 $FFFF call cdev to determine whether it should show up
$FFFF $0000 show up on all machines
$7FFF $0400 show up on machines with an Apple Desktop Bus only
$3FFF $0000 show up on the Macintosh II only
Listing 1. /* Monkey CDEV * by Jan Eugenides * 6/6/87 * * An example of adding a function to the * Control Panel, and using the Macintosh II’s * SndPlay routine */ #include <MacTypes.h> #include <pascal.h> #include <MemoryMgr.h> #include <OSUtil.h> #include <ToolboxUtil.h> #include <DialogMgr.h> #include <EventMgr.h> #include <SoundMgr.h> /*First define some needed constants*/ enum{ initDev, hitDev, closeDev, nulDev, updateDev, deActivDev, keyEvtDev, macDev }; Handle InitStorage(); /*This is main routine, entry point for the CDEV*/ pascal Handle main(message,item,numItems,CPanelID,ep,cdevStorage,CPDialog) int message,item,numItems,CPanelID; EventRecord*ep; Handle cdevStorage; DialogPtrCPDialog; { if(message == macDev)return((Handle)1); if(cdevStorage) { switch(message) { case initDev: /*Init message received, allocate some storage*/ cdevStorage = InitStorage(); if(cdevStorage)DoHit(1+numItems, numItems,CPDialog); break; case closeDev: /*Close message received, dispose of storage*/ DisposeStorage(cdevStorage); cdevStorage = (Handle)0L; break; case hitDev: /*User clicked an item, handle it*/ DoHit(item,numItems,CPDialog); break; } /*end switch*/ } /*end else if*/ return(cdevStorage); } Handle InitStorage() /*ultra-simple storage allocation*/ { /*The storage is not used in this example*/ return(NewHandle(16L)); } DisposeStorage(h) /*Release our storage area*/ Handle h; { DisposHandle(h); } DoHit(item,numItems,CPDialog)/*Handle a click on one of our items*/ int item,numItems; /*This example has one item, so it’s*/ DialogPtrCPDialog; /*very simple*/ { Handle soundH; soundH = GetResource(‘snd ‘,4);/*there is a space after snd */ if(soundH) SndPlay(0L,soundH,TRUE); /*play the monkey screech*/ } * Resources for Monkey cdev MonkeyCdevP.rsrc \00\00\00\00\00\00\00\00 Type ICN# = GNRL ,-4064 (32) ;; attributes -> Purgeable .H 00000000 0000FE00 0003FF80 000F01E0 0F9C007F 1FF9C7BF 3AF7FFDA 7FEE3C6F 6AEC992E 7FCDDBB7 6ACD99B6 7FCC0037 6AC60066 3FC4FF27 3BC1FF87 1FE3D7CF 0F67FFED 00363C78 003C003D 001DFFB0 000DC3B5 000C4230 00077E75 001F00E0 003DFFD5 0078FF08 00F57555 01E2B000 03D57555 07E8F080 0DF5F555 1FFFB000 00000000 0000FE00 0003FF80 000FFFE0 0F9FFFFF 1FFFFFFF 3FFFFFFE 7FFFFFFF 7FFFFFFE 7FFFFFFF 7FFFFFFE 7FFFFFFF 7FFFFFFE 3FFFFFFF 3FFFFFFF 1FFFFFFF 0F7FFFFD 003FFFF8 003FFFFD 001FFFF0 000FFFF5 000FFFF0 0007FFF5 001FFFE0 003FFFD5 007FFF08 00FFF555 01FFF000 03FFF555 07FFF080 0FFFF555 1FFFB000 Type FREF ,-4064 (32) ;; attributes -> Purgeable cdev 0 Type BNDL ,-4064 (32) ;; attributes -> Purgeable mOnk 0 ICN# 0 -4064 FREF 0 -4064 Type DITL ,-4064 (32) ;; attributes -> Purgeable 2 PicItem 1 128 76 194 -4064 StatText Disabled 77 133 93 206 Click Me! Type PICT = GNRL ,-4064 (32) ;; attributes -> Purgeable .H 03850000 0000004B 00421101 01000A00 00000000 4B004298 000A0031 0066007C 00A80031 0066007C 00A80000 0000004B 00420000 08FC0002 01FFF0FF 0008FC00 0203FFFC FF0008FC 000206AA AAFF0008 FC00020F F7F7FF00 08FC0002 0AAAABFF 0008FC00 020FFFFF FF0008FC 00040BFF AA800008 FC000406 00FF8000 06FA0002 2A800006 FA00023F 800006FA 00021AC0 000A0200 00FEFD00 0217C000 0B030003 FF80FE00 021AC000 0B03000F 01E0FE00 021FC000 0B090F9C 007FC000 001AC000 0B091FF9 C7BFF000 001F4000 0B093AF7 FFDAB800 001AC000 0B097FEE 3C6FFC00 001FC000 0B096AEC 992EAC00 001AC000 0B097FCD DBB7FC00 0017C000 0B096ACD 99B6AC00 001AC000 0B097FCC 0037FC00 001FC000 0B096AC6 0066B800 001AC000 0B093FC4 FF27F800 001F4000 0B093BC1 FF87FFC0 001AC000 0B091FE3 D7CFFFF8 001FC000 0B090F67 FFED557F 001AC000 0B090036 3C78080F C0178000 0B09003C 003D5555 F01A8000 0B09001D FFB00000 7C3F8000 0B09000D C3B55555 5E2A8000 0B09000C 42308080 87BF8000 0B030007 7E75FE55 02EA8000 0B03001F 00E0FE00 02FF8000 0B03003D FFD5FE55 027A8000 0A020078 FFFD0802 3F80000A 0200F575 FD55025A 80000A02 01E2B0FD 00021F80 000A0203 D575FD55 025E8000 0A0207E8 F0FD8002 8F80000A 020DF5F5 FD55025F 00000A02 1FFFB0FD 00020700 000A023A AF35FD55 02570000 0A027FFE 78FD0802 0F00000A 02777C75 FD550257 00000A02 FFF860FD 00020300 000A02EA B075FD55 02570000 0B09FFE0 6080FE80 80830000 0B09DDC0 7557FFD5 55570000 0B09FF80 C0073BC0 00030000 0B09EF00 D55E35F5 55570000 0B097E00 C81C38F8 080B0000 0B073800 D558357D 5557FF00 0B070000 C03032BC 0003FF00 0B070001 D570755D 5557FF00 0B070001 80E0688E 8083FF00 0B070001 D560755F 5557FF00 0B070003 80C06A3B 0003FF00 0B070003 D5C0D55B 5557FF00 0B070003 0980C8B1 880BFF00 0B070007 5580D571 D557FF00 0B070006 0300E2E0 C003FF00 0B070007 5700D560 D557FF00 0B07000E 860188C0 6083FF00 0B07000F 5601D5C0 7556FF00 0B07001C 0C01AB80 3006FF00 0B07001F FC01FF80 1FFEFF00 0B07003F F803FF00 1FFEFF00 0B090077 78037700 0F760000 0B0901FF F807FF00 0FFE0000 0B097FEA B9FEAB0F FEAE0000 0B09FFFF FBFFFF1F FFFE0000 0B09DDDD FBDDDF1D DDDE0000 0B09FFFF F3FFFF1F FFFE0000 0B097FFF E1FFFE0F FFFC0000 FF Type mOnk = GNRL ,-4064 (32) ;; attributes -> Purgeable .H 1C4D6F6E 6B657920 63646576 20627920 4A616E20 45756765 6E696465 73 Type nrct = GNRL ,-4064 .H 0001FFFF 00570066 00CE Type mach = GNRL ,-4064 (32) ;; attributes -> Purgeable .H 3FFF0000
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