Related Info: Color Quickdraw

Working With Color

By Dave Mark, MacTech Magazine Regular Contributing Author

This month’s column combines two of my favorite activities: working with color and rewriting Primer, Volume II code (bringing it from the Pliocene era to full PowerPC squishiness). This month’s program is a floor to ceiling rewrite of ColorTutor. ColorTutor is a hands-on color blending environment. You specify the foreground and background colors and patterns, then select a Color Quickdraw drawing mode. ColorTutor uses CopyBits() to mix the foreground and background colors. Figure 1 shows a sample.

Figure 1. The ColorTutor window.

ColorTutor first copies the Background image to the lower-right rectangle, then copies the Source image on top of the Background using the current Mode and OpColor. Since this program is so large, we’ll get into the details in next month’s column. For now, we’ll focus on putting the project together and getting ColorTutor up and running.

The ColorTutor Resources

ColorTutor uses six different resource types: an ALRT, a CNTL, a DITL, an MBAR, a MENU, and a WIND. Start by creating a folder named ColorTutor in your Projects folder. Next, fire up ResEdit or Resorcerer and create a new file named ColorTutor.Π.rsrc in the ColorTutor folder.

Create an ALRT resource with an ID of 128, a top of 40, left of 40, bottom of 156 and right of 332. Make sure the DITL ID is set to 128.

Next, create a DITL with an ID of 128. Figure 2 shows the specifications for item 1, the OK button, and Figure 3 shows the specs for item 2, the static text field. The alert you just created is used to display an error message.

Figure 2. Specifications for the OK button.

Figure 3. Specifications for item 2, the static text field.

Next, you’ll create a CNTL resource with an ID of 128. The CNTL will be used to implement the OpColor button in the lower-left corner of the ColorTutor window. The ProcID of 0 specifies a pushButtonProc control.

Figure 4. Specifications for the CNTL resource.

Now create an MBAR resource with an ID of 128. Add the menu IDs 128, 129, and 130 (the •, File, and Edit menus) to the MBAR. Though we’ll be creating 5 menus, don’t be fooled. Only the first three will be added to the menu bar.

Next, you’ll create five MENU resources. The first four are shown in Figure 5, and the fifth in Figure 6. MENUs 128, 129, and 130 will be used to create the menu bar. The last two implement the ColorTutor popup menus. Note that the popup menus don’t have titles. Note also that MENU 132 has 17 items including the separator line (the 9th item).

Figure 5. Specifications for the first four MENUs.

Figure 6. Specifications for the two popup MENUs.

The last resource is a WIND with a resource ID of 128. Figure 7 shows the ResEdit WIND editing screen for my WIND. This WIND implements the main ColorTutor window.

Figure 7. Specifications for the WIND resource.

Finally, save your changes and quit your resource editor.

The ColorTutor Project

Next, pick your development environment and create a new project. From now on, I’ll test all my source code to make sure it compiles in both THINK C and CodeWarrior, so it shouldn’t matter which environment you pick. Create your new project with the name ColorTutor.Π inside the ColorTutor folder.

Next, add MacTraps to the project if you are using THINK C, or MacOS.lib if you are using CodeWarrior.

Finally, create a new source code file, save it as ColorTutor.c, and add it to the project. Here’s the source code:

/* 1 */
#include <Picker.h>
#include <GestaltEqu.h>


#define kBaseResID 128
#define kErrorALRTid 128
#define kNullFilterProc   NULL
#define kMoveToFront (WindowPtr)-1L
#define kNotNormalMenu    -1
#define kSleep   60L

#define mApple   kBaseResID
#define iAbout   1

#define mFile    kBaseResID+1
#define iQuit    1

#define mColorsPopup kBaseResID+3
#define iBlackPattern1
#define iGrayPattern 2
#define iColorRamp 4
#define iGrayRamp5
#define iSingleColor 6

#define mModePopup kBaseResID+4

Globals
Boolean gDone;

Rect    gSrcRect, gBackRect, gDestRect, gSrcMenuRect,
 gBackMenuRect, gModeMenuRect, gOpColorRect;
 
intgSrcPattern, gBackPattern, gCopyMode, gSrcType,
 gBackType;

RGBColorgSrcColor, gBackColor, gOpColor;

MenuHandlegSrcMenu, gBackMenu, gModeMenu;

Functions
void    ToolboxInit( void );
void    MenuBarInit( void );
void    CreateWindow( void );
void    SetUpGlobals( void );
void    EventLoop( void );
void    DoEvent( EventRecord *eventPtr );
void    HandleMouseDown( EventRecord *eventPtr );
void    HandleMenuChoice( long menuChoice );
void    HandleAppleChoice( short item );
void    HandleFileChoice( short item );
void    DoUpdate( WindowPtr window );
void    DrawContents( WindowPtr window );
void    DrawColorRamp( Rect *rPtr );
void    DrawGrayRamp( Rect *rPtr );
void    DrawLabel( Rect *boundsPtr, Str255 s );
void    DoContent( WindowPtr window, Point globalPoint );
void    UpdateSrcMenu( void );
void    UpdateBackMenu( void );
void    UpdateModeMenu( void );
void    DoSrcChoice( short item );
void    DoBackChoice( short item );
void    DoModeChoice( short item );
short   DoPopup( MenuHandle menu, Rect *boundsPtr );
Boolean PickColor( RGBColor *colorPtr );
Boolean HasColorQD( void );
void    DoError( Str255 errorString );

main
void  main( void )
{
 ToolboxInit();
 MenuBarInit();
 
 if ( ! HasColorQD() )
 DoError( "\pThis machine does not support Color QuickDraw!" );

 CreateWindow();
 SetUpGlobals();
 
 EventLoop();
}

ToolboxInit
void  ToolboxInit( void )
{
 InitGraf( &qd.thePort );
 InitFonts();
 InitWindows();
 InitMenus();
 TEInit();
 InitDialogs( 0L );
 InitCursor();
}

MenuBarInit
void  MenuBarInit( void )
{
 Handle menuBar;
 MenuHandle menu;
 
 menuBar = GetNewMBar( kBaseResID );
 
 if ( menuBar == NULL )
 DoError( "\pCouldn't load the MBAR resource..." );
 
 SetMenuBar( menuBar );

 menu = GetMHandle( mApple );
 AddResMenu( menu, 'DRVR' );
 
 DrawMenuBar();
}

CreateWindow
void  CreateWindow( void )
{
 WindowPtrwindow;

 window = GetNewCWindow( kBaseResID, NULL, kMoveToFront );

 GetNewControl( kBaseResID, window );

 SetPort( window );
 
 TextFont( systemFont );
}

SetUpGlobals
void  SetUpGlobals( void )
{
 SetRect( &gSrcRect, 15, 6, 95, 86 );
 SetRect( &gBackRect, 125, 6, 205, 86 );
 SetRect( &gDestRect, 125, 122, 205, 202 );
 SetRect( &gOpColorRect, 15, 122, 95, 202 );
 
 SetRect( &gSrcMenuRect, 7, 90, 103, 108 );
 SetRect( &gBackMenuRect, 117, 90, 213, 108 );
 SetRect( &gModeMenuRect, 117, 206, 213, 224 );
 
 gSrcPattern = iBlackPattern;
 gBackPattern = iBlackPattern;
 
 gCopyMode = srcCopy;
 
 gSrcColor.red = 65535;
 gSrcColor.green = gSrcColor.blue = 0;
 gSrcType = iSingleColor;
 
 gBackColor.blue = 65535;
 gBackColor.red = gBackColor.green = 0;
 gBackType = iSingleColor;
 
 gOpColor.green = 32767;
 gOpColor.red = 32767;
 gOpColor.blue = 32767;
 OpColor( &gOpColor );
 
 gSrcMenu = GetMenu( mColorsPopup );
 InsertMenu( gSrcMenu, kNotNormalMenu );
 
 gBackMenu = GetMenu( mColorsPopup );
 InsertMenu( gBackMenu, kNotNormalMenu );
 
 gModeMenu = GetMenu( mModePopup );
 InsertMenu( gModeMenu, kNotNormalMenu );
}


EventLoop
void  EventLoop( void )
{
 EventRecordevent;
 
 gDone = false;
 while ( gDone == false )
 {
 if ( WaitNextEvent( everyEvent, &event, kSleep, NULL ) )
 DoEvent( &event );
 }
}

DoEvent
void  DoEvent( EventRecord *eventPtr )
{
 char   theChar;
 
 switch( eventPtr->what )
 {
 case mouseDown: 
 HandleMouseDown( eventPtr );
 break;
 case keyDown:
 case autoKey:
 theChar = eventPtr->message & charCodeMask;
 
 if ( (eventPtr->modifiers & cmdKey) != 0 ) 
 HandleMenuChoice( MenuKey( theChar ) );
 break;
 case updateEvt:
 DoUpdate( (WindowPtr)eventPtr->message );
 break;
 }
}

HandleMouseDown
void  HandleMouseDown( EventRecord *eventPtr )
{
 WindowPtrwindow;
 short  thePart;
 long   menuChoice;
 
 thePart = FindWindow( eventPtr->where, &window );
 
 switch ( thePart )
 {
 case inMenuBar:
 menuChoice = MenuSelect( eventPtr->where );
 HandleMenuChoice( menuChoice );
 break;
 case inSysWindow : 
 SystemClick( eventPtr, window );
 break;
 case inContent:
 if ( window != FrontWindow() )
 SelectWindow( window );
 else
 DoContent( window, eventPtr->where );
 break;
 case inDrag : 
 DragWindow( window, eventPtr->where, &qd.screenBits.bounds );
 break;
 }
}

HandleMenuChoice
void  HandleMenuChoice( long menuChoice )
{
 short  menu;
 short  item;
 
 if ( menuChoice != 0 )
 {
 menu = HiWord( menuChoice );
 item = LoWord( menuChoice );
 
 switch ( menu )
 {
 case mApple:
 HandleAppleChoice( item );
 break;
 case mFile:
 HandleFileChoice( item );
 break;
 }
 HiliteMenu( 0 );
 }
}

HandleAppleChoice
void  HandleAppleChoice( short item )
{
 MenuHandle appleMenu;
 Str255 accName;
 short  accNumber;
 
 switch ( item )
 {
 case iAbout:
 SysBeep( 20 );
 break;
 default:
 appleMenu = GetMHandle( mApple );
 GetItem( appleMenu, item, accName );
 accNumber = OpenDeskAcc( accName );
 break;
 }
}

HandleFileChoice
void  HandleFileChoice( short item )
{
 switch ( item )
 {
 case iQuit:
 gDone = true;
 break;
 }
}

DoUpdate
void  DoUpdate( WindowPtr window )
{
 BeginUpdate( window );
 
 DrawContents( window );
 DrawControls( window );
 
 EndUpdate( window );
}

DrawContents
void  DrawContents( WindowPtr window )
{
 RGBColor rgbBlack;
 Rect   source, dest;
 
 rgbBlack.red = rgbBlack.green = rgbBlack.blue = 0;
 
 if ( gSrcPattern == iBlackPattern )
 PenPat( &qd.black );
 else
 PenPat( &qd.gray );
 
 if ( gSrcType == iColorRamp )
 DrawColorRamp( &gSrcRect );
 else if ( gSrcType == iGrayRamp )
 DrawGrayRamp( &gSrcRect );
 else
 {
 RGBForeColor( &gSrcColor );
 PaintRect( &gSrcRect );
 }
 
 if ( gBackPattern == iBlackPattern )
 PenPat( &qd.black );
 else
 PenPat( &qd.gray );
 
 if ( gBackType == iColorRamp )
 DrawColorRamp( &gBackRect );
 else if ( gBackType == iGrayRamp )
 DrawGrayRamp( &gBackRect );
 else
 {
 RGBForeColor( &gBackColor );
 PaintRect( &gBackRect );
 }
 
 PenPat( &qd.black );
 
 RGBForeColor( &gOpColor );
 PaintRect( &gOpColorRect );
 
 RGBForeColor( &rgbBlack );
 DrawLabel( &gSrcMenuRect, "\pSource" );
 DrawLabel( &gBackMenuRect, "\pBackground" );
 DrawLabel( &gModeMenuRect, "\pMode" );
 
 PenSize( 2, 2 );
 FrameRect( &gSrcRect );
 FrameRect( &gBackRect );
 FrameRect( &gDestRect );
 FrameRect( &gOpColorRect );
 
 PenNormal();
 
 source = gBackRect;
 InsetRect( &source, 2, 2 );
 
 dest = gDestRect;
 InsetRect( &dest, 2, 2 );
 
 CopyBits( (BitMap *)&(((CGrafPtr)window)->portPixMap),
   (BitMap *)&(((CGrafPtr)window)->portPixMap),
   &source, &dest, srcCopy, NULL );
 
 source = gSrcRect;
 InsetRect( &source, 2, 2 );
 
 CopyBits( (BitMap *)&(((CGrafPtr)window)->portPixMap),
 (BitMap *)&(((CGrafPtr)window)->portPixMap),
 &source, &dest, gCopyMode, NULL );
}

DrawColorRamp
void  DrawColorRamp( Rect *rPtr )
{
 long   numColors, i;
 HSVColor hsvColor;
 RGBColor rgbColor;
 Rect   r;
 
 r = *rPtr;
 
 InsetRect( &r, 2, 2 );
 numColors = ( rPtr->right - rPtr->left - 2 ) / 2;
 hsvColor.value = hsvColor.saturation = 65535;
 
 for ( i = 0; i < numColors; i++ )
 {
 hsvColor.hue = i * 65535 / numColors;
 HSV2RGB( &hsvColor, &rgbColor );
 RGBForeColor( &rgbColor );
 
 FrameRect( &r );
 InsetRect( &r, 1, 1 );
 }
}

DrawGrayRamp
void  DrawGrayRamp( Rect *rPtr )
{
 long   numColors, i;
 RGBColor rgbColor;
 Rect   r;
 
 r = *rPtr;
 InsetRect( &r, 2, 2 );
 numColors = ( rPtr->right - rPtr->left - 2 ) / 2;
 
 for ( i = 0; i < numColors; i++ )
 {
 rgbColor.red = i * 65535 / numColors;
 rgbColor.green = rgbColor.red;
 rgbColor.blue = rgbColor.red;
 
 RGBForeColor( &rgbColor );
 
 FrameRect( &r );
 InsetRect( &r, 1, 1 );
 }
}

DrawLabel
void  DrawLabel( Rect *boundsPtr, Str255 s )
{
 Rect r;
 int    size;
 
 r = *boundsPtr;
 r.bottom -= 1;
 r.right -= 1;
 FrameRect( &r );
 
 MoveTo( r.left + 1, r.bottom );
 LineTo( r.right, r.bottom );
 LineTo( r.right, r.top + 1 );
 
 size = boundsPtr->right - boundsPtr->left - StringWidth(s);
 MoveTo( boundsPtr->left + size / 2, boundsPtr->bottom - 6);
 
 DrawString( s );
}

DoContent
void  DoContent( WindowPtr window, Point globalPoint )
{
 int    choice;
 ControlHandle control;
 RGBColor rgbColor;
 Point  p;
 
 p = globalPoint;
 GlobalToLocal( &p );
 
 if ( FindControl( p, window, &control ) )
 {
 if ( TrackControl( control, p, NULL ) )
 {
 rgbColor = gOpColor;
 
 if ( PickColor( &rgbColor ) )
 {
 gOpColor = rgbColor;
 
 InvalRect( &gOpColorRect );
 InvalRect( &gDestRect );
 
 OpColor( &gOpColor );
 }
 }
 }
 else if ( PtInRect( p, &gSrcMenuRect ) )
 {
 UpdateSrcMenu();
 
 choice = DoPopup( gSrcMenu, &gSrcMenuRect );
 
 if ( choice > 0 )
 {
 DoSrcChoice( choice );
 
 InvalRect( &gSrcRect );
 InvalRect( &gDestRect );
 }
 }
 else if ( PtInRect( p, &gBackMenuRect ) )
 {
 UpdateBackMenu();
 
 choice = DoPopup( gBackMenu, &gBackMenuRect );
 
 if ( choice > 0 )
 {
 DoBackChoice( choice );
 
 InvalRect( &gBackRect );
 InvalRect( &gDestRect );
 }
 }
 else if ( PtInRect( p, &gModeMenuRect ) )
 {
 UpdateModeMenu();
 
 choice = DoPopup( gModeMenu, &gModeMenuRect );
 
 if ( choice > 0 )
 {
 DoModeChoice( choice );
 
 InvalRect( &gDestRect );
 }
 }
}

UpdateSrcMenu
void  UpdateSrcMenu( void )
{
 int    i;
 
 for ( i = 1; i <= 6; i++ )
 CheckItem( gSrcMenu, i, false );
 
 if ( gSrcPattern == iBlackPattern )
 CheckItem( gSrcMenu, iBlackPattern, true );
 else
 CheckItem( gSrcMenu, iGrayPattern, true );
 
 if ( gSrcType == iColorRamp )
 CheckItem( gSrcMenu, iColorRamp, true );
 else if ( gSrcType == iGrayRamp )
 CheckItem( gSrcMenu, iGrayRamp, true );
 else if ( gSrcType == iSingleColor )
 CheckItem( gSrcMenu, iSingleColor, true );
}

UpdateBackMenu
void  UpdateBackMenu( void )
{
 int    i;
 
 for ( i = 1; i <= 6; i++ )
 CheckItem( gBackMenu, i, false );
 
 if ( gBackPattern == iBlackPattern )
 CheckItem( gBackMenu, iBlackPattern, true );
 else
 CheckItem( gBackMenu, iGrayPattern, true );
 
 if ( gBackType == iColorRamp )
 CheckItem( gBackMenu, iColorRamp, true );
 else if ( gBackType == iGrayRamp )
 CheckItem( gBackMenu, iGrayRamp, true );
 else if ( gBackType == iSingleColor )
 CheckItem( gBackMenu, iSingleColor, true );
}

UpdateModeMenu
void  UpdateModeMenu( void )
{
 int    i;
 
 for ( i = 1; i <= 17; i++ )
 CheckItem( gModeMenu, i, false );
 
 if ( ( gCopyMode >= 0 ) && ( gCopyMode <= 7 ) )
 CheckItem( gModeMenu, gCopyMode + 1, true );
 else
 CheckItem( gModeMenu, gCopyMode - 22, true );
}

DoSrcChoice
void  DoSrcChoice( short item )
{
 RGBColor rgbColor;
 
 switch ( item )
 {
 case iBlackPattern:
 case iGrayPattern:
 gSrcPattern = item;
 break;
 case iColorRamp:
 case iGrayRamp:
 gSrcType = item;
 break;
 case iSingleColor:
 gSrcType = iSingleColor;
 rgbColor = gSrcColor;
 
 if ( PickColor( &rgbColor ) )
 gSrcColor = rgbColor;
 break;
 }
}

DoBackChoice
void  DoBackChoice( short item )
{
 RGBColor rgbColor;
 
 switch ( item )
 {
 case iBlackPattern:
 case iGrayPattern:
 gBackPattern = item;
 break;
 case iColorRamp:
 case iGrayRamp:
 gBackType = item;
 break;
 case iSingleColor:
 gBackType = iSingleColor;
 rgbColor = gBackColor;
 
 if ( PickColor( &rgbColor ) )
 gBackColor = rgbColor;
 break;
 }
}

DoModeChoice
void  DoModeChoice( short item )
{
 if ( ( item >= 1 ) && ( item <= 8 ) )
 gCopyMode = item - 1;
 else
 gCopyMode = item + 22;
}

DoPopup
short DoPopup( MenuHandle menu, Rect *boundsPtr )
{
 Point  corner;
 long theChoice = 0L;
 
 corner.h = boundsPtr->left;
 corner.v = boundsPtr->bottom;
 
 LocalToGlobal( &corner );
 
 InvertRect( boundsPtr );
 
 theChoice = PopUpMenuSelect(menu,corner.v-1,corner.h+1,0);    
 InvertRect( boundsPtr );
 return( LoWord( theChoice ) );
}

PickColor
Boolean PickColor( RGBColor *colorPtr )
{
 Point  where;
 
 where.h = -1;
 where.v = -1;
 
 return( GetColor( where, "\pChoose a color...", colorPtr,
 colorPtr ) );
}

HasColorQD
Boolean HasColorQD( void )
{
 unsigned char version[ 4 ];
 OSErr  err;
 
 err = Gestalt( gestaltQuickdrawVersion, (long *)version );
 
 if ( version[ 2 ] > 0 )
 return( true );
 else
 return( false );
}

DoError
void  DoError( Str255 errorString )
{
 ParamText( errorString, "\p", "\p", "\p" );
 StopAlert( kErrorALRTid, kNullFilterProc );
 ExitToShell();
}

Running ColorTutor

Save your code, and run ColorTutor. The ColorTutor window will appear, as shown in Figure 8.

Figure 8. The ColorTutor WIndow.

The Source and Background menus are identical, as shown in Figure 9. Play with these selections till you get the source and background that you want.

Figure 9. The Source and Background menus.

The real fun comes when you play with the Mode popup (Figure 10). Basically, the mode is passed as the fifth parameter to the CopyBits() call that copies the source rectangles over the destination rectangle which had been previously copied to the lower right corner of the ColorTutor window. Some of the modes take an OpColor, which you can set using the OpColor button.

Figure 10. The Mode popup menu.

Till Next Month

Confused? Experiment! We’ll get into all the hows and whys next month. Till then, read up on the Color Quickdraw transfer modes in THINK Reference and Inside Macintosh.