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. *
 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Audio Hijack 3.2.0 - Record and enhance...
Audio Hijack (was Audio Hijack Pro) drastically changes the way you use audio on your computer, giving you the freedom to listen to audio when you want and how you want. Record and enhance any audio... Read more
FontExplorer X Pro 5.0.1 - Font manageme...
FontExplorer X Pro is optimized for professional use; it's the solution that gives you the power you need to manage all your fonts. Now you can more easily manage, activate and organize your... Read more
Calcbot 1.0.2 - Intelligent calculator a...
Calcbot is an intelligent calculator and unit converter for the rest of us. Featuring an easy-to-read history tape, expression view, intuitive conversion, and much more! Features History Tape -... Read more
MTR 5.0.0.1 - The Mac's oldest and...
MTR (was MacTheRipper)--the Mac's oldest and smartest DVD-backup app--is now updated to version 5.001 MTR -- the complete toolbox, not a one-trick, point-and-click extractor. MTR is intended for... Read more
LibreOffice 4.4.5.2 - Free, open-source...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
Adobe Lightroom 6.1.1 - Import, develop,...
Adobe Lightroom is available as part of Adobe Creative Cloud for as little as $9.99/month bundled with Photoshop CC as part of the photography package. Lightroom 6 is also available for purchase as a... Read more
File Juicer 4.41 - Extract images, video...
File Juicer is a drag-and-drop can opener and data archaeologist. Its specialty is to find and extract images, video, audio, or text from files which are hard to open in other ways. It finds and... Read more
A Better Finder Rename 9.52 - File, phot...
A Better Finder Rename is the most complete renaming solution available on the market today. That's why, since 1996, tens of thousands of hobbyists, professionals and businesses depend on A Better... Read more
OmniFocus 2.2.3 - GTD task manager with...
OmniFocus helps you manage your tasks the way that you want, freeing you to focus your attention on the things that matter to you most. Capturing tasks and ideas is always a keyboard shortcut away in... Read more
TinkerTool 5.4 - Expanded preference set...
TinkerTool is an application that gives you access to additional preference settings Apple has built into Mac OS X. This allows to activate hidden features in the operating system and in some of the... Read more

Cosmonautica (Games)
Cosmonautica 1.1 Device: iOS Universal Category: Games Price: $6.99, Version: 1.1 (iTunes) Description: Cast off! Are you ready for some hilarious adventures in outer space? | Read more »
Rescue humanity from a Demon horde in An...
Angel Stone is Fincon's follow up to the massively successful Hello Hero and is out now on iOS and Android. You play as a member of The Resistance, a group of mighty human warriors who have risen up in defiance of the Demon horde threatening to... | Read more »
Gallery Doctor (Photography)
Gallery Doctor 1.0 Device: iOS iPhone Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Free up valuable iCloud and iPhone storage with Gallery Doctor, the only iPhone cleaner that automatically identifies the... | Read more »
You Against Me (Games)
You Against Me 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: A simple game… You. Me. Claim, steal, lock, score, win! | Read more »
Yep, it's True - Angry Birds 2 is O...
The not exactly rumors were true and the birds are back. Angry Birds 2 has come to the App Store and the world will... well I suppose it'll still be the same, but now we have more bird-flinging options! [Read more] | Read more »
You Could Design Your Own Card for Chain...
If you've ever wanted to create your own item, weapon, trap, or even monster for Chainsaw Warrior: Lords of the Night, this is your chance. Auroch Digital is currently holding a contest so that fans can fight to the death (not really) to see which... | Read more »
Bitcoin Billionaire is Going Back in Tim...
If you thought you managed to buy everything there is to buy in Bitcoin Billionaire and make all the money, well you though wrong. Those of you who made it far enough might remember investing in time travel - and it looks like that investment is... | Read more »
Domino Drop (Games)
Domino Drop 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Domino Drop is a delightful new puzzle game with dominos and gravity!Learn how to play it in a minute, master it day by day.Your... | Read more »
OPERATION DRACULA (Games)
OPERATION DRACULA 1.0.1 Device: iOS Universal Category: Games Price: $5.99, Version: 1.0.1 (iTunes) Description: 25% off launch sale!!! 'Could prove to be one of the most accurate representations of the Japanese bullet hell shmup... | Read more »
Race The Sun (Games)
Race The Sun 1.01 Device: iOS iPhone Category: Games Price: $4.99, Version: 1.01 (iTunes) Description: You are a solar craft. The sun is your death timer. Hurtle towards the sunset at breakneck speed in a futile race against time.... | Read more »

Price Scanner via MacPrices.net

Sale! 13-inch MacBook Pros on sale for $100 o...
B&H Photo has 13″ MacBook Pros on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.5GHz/500GB MacBook Pro: $999.99 save $100 - 13″ 2.7GHz/128GB Retina... Read more
Sale! Save $100 on 13-inch MacBook Airs this...
B&H Photo has the 13″ 1.6GHz/128GB MacBook Air on sale for $899.99 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price available for this model.... Read more
Worldwide Tablet Market Decline Continues, Ap...
The worldwide tablet market declined -7.0% year-over-year in the second quarter of 2015 (2Q15) with shipments totaling 44.7 million units according to preliminary data from the International Data... Read more
TP-LINK TL-PA8030P KIT Powerline Featuring Ho...
Consumer and business networking products provider TP-LINK is now shipping its TL-PA8030P KIT AV1200 3-Port Gigabit Passthrough Powerline Starter Kit that expands your home’s network over its... Read more
Apple refurbished iPad Air 2s available for u...
The Apple Store has Apple Certified Refurbished iPad Air 2s available for up to $140 off the price of new models. Apple’s one-year warranty is included with each model, and shipping is free: - 128GB... Read more
Updated Apple iPad Price Trackers
We’ve updated our iPad Air Price Tracker and our iPad mini Price Tracker with the latest information on prices and availability from Apple and other resellers. Read more
Apple refurbished 2014 13-inch 128GB MacBook...
The Apple Store has Apple Certified Refurbished 2014 13″ MacBook Airs available starting at $759. An Apple one-year warranty is included with each MacBook, and shipping is free: - 13″ 1.4GHz/128GB... Read more
Apple’s Education discount saves up to $300 o...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
Save up to $600 with Apple refurbished Mac Pr...
The Apple Store has Apple Certified Refurbished Mac Pros available 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
Mac Pros on sale for up to $260 off MSRP
B&H Photo has Mac Pros on sale for up to $260 off MSRP. Shipping is free, and B&H charges sales tax in NY only: - 3.7GHz 4-core Mac Pro: $2799, $200 off MSRP - 3.5GHz 6-core Mac Pro: $3719.99... Read more

Jobs Board

*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
*Apple* Online Store UAT Lead - Apple (Unite...
**Job Summary** The Apple Online Store is a fast paced and ever evolving business environment. The User Acceptance Testing (UAT) lead in this organization is able to Read more
*Apple* MAC Support Services Subject Matter...
Title: Apple MAC Support Services Subject Matter Expert Location: Pleasanton, CA Type of position: Temporary Contract for approximately 6 weeks Tasks The tasks for the Read more
Lead Infrastructure Engineer - *Apple* /Mac P...
…of a team * Requires proven problem solving skills Preferred Additional: * Apple Certified System Administrator (ACSA) * Apple Certified Technical Coordinator (ACTC) 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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.