TweetFollow Us on Twitter

All About The Palette Manager

ALL ABOUT THE PALETTE MANAGER

DAVID VAN BRINK

One of the goals of QuickDraw is to isolate the application from the specific graphic display devices it is running on. The Palette Manager lets multiple applications share screen space and color allocation in a fair and orderly fashion.

The Palette Manager has been enhanced in 32-Bit QuickDraw to support new color usages. When applications use the Palette Manager to establish and maintain a specific color environment, the Palette Manager juggles numerous factors in honoring a request. It must consider, for example, the limits of the available display hardware and the presence of other applications requesting color environments. On a multiple-screen system, the Palette Manager will keep track of the colors for each screen. Also, the Palette Manager provides an extra level of indirection in drawing colors, which serves as a color naming or numbering system.

UNDERSTANDING THE PALETTE MANAGER

A palette is a data structure attached to a window using the SetPalette system call or other means. The palette, which contains a list of colors, each with a usage value and a tolerance value, lets the system know what colors that window needs. When colors are changed, the Palette Manager makes sure that windows, the menu bar, and the desktop are redrawn as needed with the new colors.

The Palette Manager calls should be used any time you might be tempted to call the Color Manager routines SetEntries or RestoreEntries. These calls modify the color environment directly, without letting the system decide which colors would be best to change. Also, they operate on a single screen. SetEntries or RestoreEntries should only be called by programs that have no intention of sharing the screen--programs like lava-lamp screen-savers and programs that will never, ever run under MultiFinder. Most commercial software does not fall in this category and absolutely should not call SetEntries and RestoreEntries. Use the Palette Manager to modify the color environment to get a better application with less work.

Suppose we are writing a program to display PICTs on a four or more bit-depth screen. The built-in color table for four bits ('clut' ;ID 4, in ROM resources) contains a smattering of different colors. If the PICT we wish to display contains only shades of red, we'd want to have as many shades of red as possible (14 on a four-bit screen) in the screen's 'clut'. There are actually 16 different colors available, but 2 of them, black and white, are never changed. This guarantees that menus, windows, and other such things that are always black on the Macintosh will be visible in their intended colors.

To get some shades of red on the screen, we create a palette with 14 entries, each with a different shade of red in it. We set the usage of each entry to pmTolerant. When the palette's window is activated, the Palette Manager will look for shades of red that are within a certain range, or within tolerance, of each palette entry. If an index in the screen's 'clut' is already within range of one of the entries, then the Palette Manager will use that index. If not, the Palette Manager will steal an index in the order specified by its color arbitration rules and change it to the requested color.

Here is how we generate the sample palette:

   FUNCTION Make14RedPalette: PaletteHandle;
    VAR
        i:  LONGINT;
        ph: PaletteHandle;
        c:  RGBColor;
                
    BEGIN
        ph := NewPalette(14,NIL,pmTolerant,4000);
(* should check for NIL result *)
        c.green := 0;
        c.blue := 0;
        FOR i:=0 TO 13
        DO
        BEGIN
(* range red component from 1/14 to 14/14 *)
(* i is a longint, and so can safely be multiplied by 65535 *)
            c.red := (i+1)*65535 DIV 14;
            SetEntryColor(ph,i,c);
        END;
        Make14RedPalette := ph;
    END;
Next, we might attach it to our window:
myPalette := Make14RedPalette;
SetPalette(myWindow,myPalette);

Whenever this window is brought to the front, the Palette Manager will attempt to provide 14 shades of red, ranging from RGB(4681,0,0) to RGB(65535,0,0). We might consider RGB(0,0,0), black, which is always available, to be a 15th shade of red. To draw in these colors, we just make the normal Color QuickDraw calls (like RGBForeColor), and we'll automatically get the closest shade of red available. If, after setting up this palette, we try to draw in nonred colors, the results will not be pretty. With black, white, and 14 shades of red, the available options for a good match to green, for example, are severely limited.

In the preceding example, we assumed the PICT uses shades of red. This is generally hard to determine, unless we generate the PICT in the first place. Since the PICT is in reds, we might want to load the palette from a resource with GetNewPalette rather than compute it in code. Or, we might happen to have a color table with the colors we need. In that case, we could have passed it to NewPalette, instead of nil in the example, or to CTab2Palette, if we already had a palette allocated.

We've just described how a program can ensure that a set of colors is available for a specific graphic display. The well-mannered programmer may be thinking, "Gee, that's swell, but how do I give those colors back when I'm done?" The answer is, don't even try. Any other window that needs colors to look good will have its own palette attached, and therefore get the colors it needs. Also, each time a program quits, the Palette Manager restores the color environment to a well-balanced state in terms of color distribution.

SELECTING THE RIGHT COLOR SET

Different types of screens often require different color sets to best display the same image. Grayscale screens default to having a range of gray tones from black to white, which is an excellent range for drawing most images. A grayscale screen should usually be left with its default color table. Here is the sample routine modified to provide 14 shades of red on a four-bit color screen, 254 shades on an eight-bit color screen, and no color requests at all on two-bit or grayscale screens:
FUNCTION MakeRedPalette: PaletteHandle;
    VAR
        i:  LONGINT;
        ph: PaletteHandle;
        c:  RGBColor;
                
    BEGIN
        ph := NewPalette(14+254,NIL,0,0);
(* should check for NIL result *)
        c.green := 0;
        c.blue := 0;
(*  Make fourteen reds that are inhibited on all *)
(*  screens except four-bit color *)
        FOR i:=0 TO 13
        DO
        BEGIN
(* range red component from 1/14 to 14/14 *)
(* i is a longint, and so can safely be multiplied by 65535 *)
            c.red := (i+1)*65535 DIV 14;
            SetEntryColor(ph,i,c);
            SetEntryUsage(ph,i,pmTolerant+pmInhibitC2+
                    pmInhibitG2+pmInhibitG4+
                    pmInhibitC8+pmInhibitG8,4000);
        END;
(*  Make 254 reds that are inhibited on all *)
(*  screens except eight-bit color *)
        FOR i:=0 TO 253
        DO
        BEGIN
(* range red component from 1/254 to 254/254 *)
(* i is a longint, and so can safely be multiplied by 65535 *)
            c.red := (i+1)*65535 DIV 254;
            SetEntryColor(ph,14+i,c);
            SetEntryUsage(ph,14+i,pmTolerant+pmInhibitC2+
                    pmInhibitG2+pmInhibitG4+
                    pmInhibitC4+pmInhibitG8,0);
        END;
        MakeRedPalette := ph;
    END;

MORE WAYS OF REQUESTING COLOR

So far, we've seen how to request a set of colors from the Palette Manager. The examples use colors with usage combinations of pmTolerant, and various inhibit bits. Other ways to request colors are explained in Inside Macintosh, volume V, page 154. In addition, combinations of pmExplicit and pmTolerant or pmAnimated are now supported. Here are some examples of different usages.
SetEntryUsage(ph,1,pmCourteous,0);

The color is courteous, activating the palette will never cause a change in a screen's color table. This is useful only for "naming" the color, in this case to 1. PmForeColor(1) and PmBackColor(1) are two ways to use this color.

SetEntryUsage(ph,2,pmTolerant,10000);

The color is tolerant, activating the palette will ensure that some index in the screen's color table is within 10000 in each RGB component from palette entry 2.

SetEntryUsage(ph,3,pmAnimated,0);

The color is animated, activating the palette will reserve an index from the screen's color table to be owned by this palette (if the screen is indexed). If the color is changed with AnimateEntry then any previous drawing done with that entry will change.

SetEntryUsage(ph,4,pmExplicit,0);

The color is explicit, any drawing done with this entry will draw in device index 4, because this entry is the 4th color in the palette. This is mostly useful for monitoring the color environment.

SetEntryUsage(ph,5,pmExplicit+pmTolerant,0);

The color is both explicit and tolerant. Activating the palette will ensure that device index 5 exactly matches the palette's color 5 (because the tolerance here is 0).

SetEntryUsage(ph,6,pmExplicit+pmAnimated,0);

The color is both explicit and animated. Activating the palette will reserve screen index 6 for this palette's use. The color may be modified with AnimateEntry and AnimatePalette.

SetEntryUsage(ph,7,pmAnimated+pmInhibitC8+pmInhibitG8,0);

The color is animated on any screen other than an 8-bit color or an 8-bit gray- scale device. On those devices, the color behaves as a courteous color.

DRAWING WITH PALETTE COLORS

After the palette has been set up, there are several ways to draw with the colors in the palette. In addition to PmForeColor and PmBackColor, a pixMap or pixPat color table may be specified to point to palette entries. To do this, set bit 14 in the ctFlags field of the color table (ctFlags is called transindex in older equate files). Then set the desired palette entry numbers in the value field of each colorSpec. The color table is then assumed to be sequential, as device tables are (colorSpec 0 refers to pixel value 0 in the pixMap or pixPat; color value 1 refers to pixel value 1, and so on).

This code retrieves a copy of the desktop pattern (system resource 'ppat' 16) and modifies its fields to refer to sequential palette entries.

myPP:  PixPatHandle;
myCT:   CTabHandle;
myPP := GetPixPat(16);  
(* Gets the system color desktop pattern    *)
myCT := myPP^^.patMap^^.pmTable
    FOR j := 0 TO myCT^^.ctSize 
    (* Set .value field equal to position for each element *)
    DO
        myCT^^.ctTable[j].value := j;
    myCT^^.ctFlags := BitOr(myCT^^.ctFlags,$4000);  
    (* .ctFlags aka .transindex *)

Drawing the unmodified ppat 16 would produce it exactly as it appears on the desktop. After the modification, drawing with myPP would produce the same pattern with the colors replaced by palette colors.

One use for this might be to draw a pixMap with all animated colors, and then let the user adjust color, brightness, and contrast with slider controls. The color changes would be performed with AnimatePalette calls.

ACCESSING NEW COLOR LOOK-UP TABLES

Several new 'clut's have been defined for 32-Bit QuickDraw and may be accessed with the GetCTable routine. As before, 'clut' IDs 1, 2, 4, and 8 are the standard color tables for those depths. A gray ramp for each depth can be requested using the depth plus 32. 'Clut' IDs for gray ramps with depths 1,2,4, and 8 are 33, 34, 36, and 40 respectively.

'clut's 2 and 4 are modified to include the highlight color and may be accessed as the depth plus 64.

'clut's may not exist as actual resources; the GetCTable routine may synthesize them when they are requested. If there is a 'clut' resource with the specified ID, however, GetCTable will load that resource and return a detached handle to it. So to dispose of the handle, you should call DisposCTable rather than release resource. *

David Van Brink, graphics software engineer, graduated from the University of California-Irvine in 1986 with a BSICS (you figure it out!) degree. After working in southern California for MegaGraphics, he moved north to work for Apple. Despite the fact that sleeping on the job is his professed favorite part of working here, he does seem to find time to write some awesome software. When he's not sleeping his days away at Apple, he dabbles in computer-aided music and writes his own music sequencing software. Other activities he enjoys: recreating Philip K. Dick scenarios with friends; watching Star Trek while eating Kraft® Macaroni And Cheese; and encouraging his parrot named "12" to teach his rat "X" to talk. And always remember....*

Color Arbitration; Color look-up table ('clut') displays, like the Macintosh II Video Card, have a certain number of colors available at each bit-depth. Different applications, and different documents within an application, use the colors in different ways. For example, a full-color digitized photograph isn't usually meant to be displayed in various tones of brown. If there aren't enough colors to go around, the Palette Manager arbitrates. When a window with a palette comes to the front, the Palette Manager inspects the window's palette and tries to modify the screen's color table to best satisfy the palette. (If a window without a palette comes to the front, no change occurs.) When another window is activated and comes to the front, the Palette Manager inspects its palette and modifies the colors, taking colors used by previous windows last. *
 
AAPL
$104.94
Apple Inc.
+1.95
MSFT
$45.41
Microsoft Corpora
+1.03
GOOG
$546.88
Google Inc.
+14.17

MacTech Search:
Community Search:

Software Updates via MacUpdate

Art Text 2.4.8 - Create high quality hea...
Art Text is an OS X application for creating high quality textual graphics, headings, logos, icons, Web site elements, and buttons. Thanks to multi-layer support, creating complex graphics is no... Read more
Live Interior 3D Pro 2.9.6 - Powerful an...
Live Interior 3D Pro is a powerful yet very intuitive interior designing application. View Video Tutorials It has every feature of Live Interior 3D Standard, plus some exclusive ones: Create multi... Read more
The Hit List 1.1.7 - Advanced reminder a...
The Hit List manages the daily chaos of your modern life. It's easy to learn - it's as easy as making lists. And it's powerful enough to let you plan, then forget, then act when the time is right.... Read more
jAlbum Pro 12.2.4 - Organize your digita...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code!... Read more
jAlbum 12.2.4 - Create custom photo gall...
With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly, with pro results Simply drag and drop photos into groups, choose a design... Read more
ExpanDrive 4.1.7 - Access remote files o...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
OmniOutliner Pro 4.1.3 - Pro version of...
OmniOutliner Pro is a flexible program for creating, collecting, and organizing information. Give your creativity a kick start by using an application that's actually designed to help you think. It'... Read more
Evernote 5.6.2 - Create searchable notes...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
OmniOutliner 4.1.3 - Organize your ideas...
OmniOutliner is a flexible program for creating, collecting, and organizing information. Give your creativity a kick start by using an application that's actually designed to help you think. It's... Read more
BBEdit 11.0 - Powerful text and HTML edi...
BBEdit is the leading professional HTML and text editor for the Mac. Specifically crafted in response to the needs of Web authors and software developers, this award-winning product provides a... Read more

Latest Forum Discussions

See All

Puzzle to the Center of the Earth Review
Puzzle to the Center of the Earth Review By Campbell Bird on October 23rd, 2014 Our Rating: :: SPELUNKING PUZZLESUniversal App - Designed for iPhone and iPad Do some puzzles to make some platforms in this smart and fun free-to-play... | Read more »
Sleep Attack TD Review
Sleep Attack TD Review By Jennifer Allen on October 23rd, 2014 Our Rating: :: A TRUE TWISTUniversal App - Designed for iPhone and iPad Sleep Attack TD is a tower defense game with a difference – you can rotate the layout – and it’s... | Read more »
Mecanic (Education)
Mecanic 1.0 Device: iOS Universal Category: Education Price: $1.99, Version: 1.0 (iTunes) Description: Plates, screws, wheels ... Everything you need to achieve whatever you want... MECHANICWith 'MECANIC' kids will have fun... | Read more »
Earn Your Master Camper Badge in Camp Po...
Earn Your Master Camper Badge in Camp Pokemon Posted by Jessica Fisher on October 23rd, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Garruk Gets His Revenge in a New Magic 2...
Garruk Gets His Revenge in a New Magic 2015 Expansion, Coming This November Posted by Jessica Fisher on October 23rd, 2014 [ permalink ] | Read more »
Sentinels of the Multiverse Review
Sentinels of the Multiverse Review By Rob Thomas on October 23rd, 2014 Our Rating: :: SENTINELS ASSEMBLEiPad Only App - Designed for the iPad Greater Than Games’ tabletop classic, Sentinels of the Multiverse swoops in to save the... | Read more »
Build Your Own Fantasy Football Dynasty...
Build Your Own Fantasy Football Dynasty with Draft Day Posted by Jessica Fisher on October 23rd, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Cars: Fast as Lightning – Tips, Tricks,...
Hey there, Stickers: Want to know all about how impressed we were with Radiator Springs? Check out our Cars: Fast as Lightning review! Cars: Fast as Lightning is a cute and fun app that combines racing and town-building with the charisma and... | Read more »
Jam Messenger Review
Jam Messenger Review By Jennifer Allen on October 23rd, 2014 Our Rating: :: SIMPLE MESSAGINGiPhone App - Designed for the iPhone, compatible with the iPad Want a very quick way to send push-based messages? Jam Messenger is basic... | Read more »
Felllice (Games)
Felllice 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: EXCLUSIVE PRICE DROP! 50% OFF FOR A LIMITED TIME! EAT EAT EAT AND GROW ! | Read more »

Price Scanner via MacPrices.net

Save up to $125 on Retina MacBook Pros
B&H Photo has the new 2014 13″ and 15″ Retina MacBook Pros on sale for up to $125 off MSRP. Shipping is free, and B&H charges NY sales tax only. They’ll also include free copies of Parallels... Read more
Apple refurbished Time Capsules available sta...
The Apple Store has certified refurbished Time Capsules available for up to $60 off MSRP. Apple’s one-year warranty is included with each Time Capsule, and shipping is free: - 2TB Time Capsule: $255... Read more
Textilus New Word, Notes and PDF Processor fo...
Textilus is new word-crunching, notes, and PDF processor designed exclusively for the iPad. I haven’t had time to thoroughly check it out yet, but it looks great and early reviews are positive.... Read more
WD My Passport Pro Bus-Powered Thunderbolt RA...
WD’s My Passport Pro RAID solution is powered by an integrated Thunderbolt cable for true portability and speeds as high as 233 MB/s. HighlightsOverviewSpecifications Transfer, Back Up And Edit In... Read more
Save with Best Buy’s College Student Deals
Take an additional $50 off all MacBooks and iMacs at Best Buy Online with their College Students Deals Savings, valid through November 1st. Anyone with a valid .EDU email address can take advantage... Read more
iPad Air 2 & iPad mini 3 Best Tablets Yet...
The new iPads turned out to be pretty much everything I’d been hoping for and more than I’d expected.”More” particularly in terms of a drinking-from-a-firehose choice of models and configurations,... Read more
Drafts 4 Reinvents iOS Productivity App
N Richland Hills, Texas based Agile Tortoise has announced the release of Drafts 4 for iPhone and iPad. Drafts is a quick capture note taking app with flexible output actions. Drafts 4 scales from... Read more
AT&T accepting preorders for new iPads fo...
AT&T Wireless is accepting preorders for the new iPad Air 2 and iPad mini 3, cellular models, for $100 off MSRP with a 2-year service agreement: - 16GB iPad Air 2 WiFi + Cellular: $529.99 - 64GB... Read more
Apple offering refurbished Mac Pros for up to...
The Apple Store is offering Apple Certified Refurbished 2013 Mac Pros for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The... Read more
Select MacBook Airs $100 off MSRP, free shipp...
B&H Photo has 2014 a couple of MacBook Airs on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only. They also include free copies of Parallels Desktop and LoJack for... Read more

Jobs Board

Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
*Apple* Retail - Multiple Positions (US) - A...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Position Opening at *Apple* - Apple (United...
…customers purchase our products, you're the one who helps them get more out of their new Apple technology. Your day in the Apple Store is filled with a range of Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.