ShowInitIcon.c   [plain text]

// ShowInitIcon - version 1.0.1, May 30th, 1995
// This code is intended to let INIT writers easily display an icon at startup time.
// View in Geneva 9pt, 4-space tabs

// Written by: Peter N Lewis <>, Jim Walker <>
// and Fran├žois Pottier <>, with thanks to previous ShowINIT authors.
// Send comments and bug reports to Fran├žois Pottier.

// This version features:
// - Short and readable code.
// - Correctly wraps around when more than one row of icons has been displayed.
// - works with System 6
// - Built with Universal Headers & CodeWarrior. Should work with other headers/compilers.

#include <Memory.h>
#include <Resources.h>
#include <Icons.h>
#include <OSUtils.h>
#include "ShowInitIcon.h"

// You should set SystemSixOrLater in your headers to avoid including glue for SysEnvirons.

// ---------------------------------------------------------------------------------------------------------------------
// Set this flag to 1 if you want to compile this file into a stand-alone resource (see note below).
// Set it to 0 if you want to include this source file into your INIT project.

#if 0
#define ShowInitIcon main

// ---------------------------------------------------------------------------------------------------------------------
// The ShowINIT mechanism works by having each INIT read/write data from these globals.
// The MPW C compiler doesn't accept variables declared at an absolute address, so I use these macros instead.
// Only one macro is defined per variable; there is no need to define a Set and a Get accessor like in <LowMem.h>.

#define LMVCheckSum     (*(unsigned short*) 0x928)
#define LMVCoord        (*(         short*) 0x92A)
#define LMHCoord        (*(         short*) 0x92C)
#define LMHCheckSum     (*(unsigned short*) 0x92E)

// ---------------------------------------------------------------------------------------------------------------------
// Prototypes for the subroutines. The main routine comes first; this is necessary to make THINK C's "Custom Header" option work.

static unsigned short CheckSum (short x);
static void ComputeIconRect (Rect* iconRect, Rect* screenBounds);
static void AdvanceIconPosition (Rect* iconRect);
static void DrawBWIcon (short iconID, Rect *iconRect);

// ---------------------------------------------------------------------------------------------------------------------
// Main routine.

typedef struct {
    QDGlobals qd;                                           // Storage for the QuickDraw globals
    long qdGlobalsPtr;                                          // A5 points to this place; it will contain a pointer to qd
} QDStorage;

pascal void ShowInitIcon (short iconFamilyID, Boolean advance)
    long oldA5;                                             // Original value of register A5
    QDStorage qds;                                              // Fake QD globals
    CGrafPort colorPort;
    GrafPort bwPort;
    Rect destRect;
    SysEnvRec environment;                                  // Machine configuration.

    oldA5 = SetA5((long) &qds.qdGlobalsPtr);                        // Tell A5 to point to the end of the fake QD Globals
    InitGraf(&qds.qd.thePort);                              // Initialize the fake QD Globals

    SysEnvirons(curSysEnvVers, &environment);                   // Find out what kind of machine this is

    ComputeIconRect(&destRect, &qds.qd.screenBits.bounds);          // Compute where the icon should be drawn

    if (environment.systemVersion >= 0x0700 && environment.hasColorQD) {
        PlotIconID(&destRect, atNone, ttNone, iconFamilyID);
    else {
        DrawBWIcon(iconFamilyID, &destRect);

    if (advance)
        AdvanceIconPosition (&destRect);

    SetA5(oldA5);                                           // Restore A5 to its previous value

// ---------------------------------------------------------------------------------------------------------------------
// A checksum is used to make sure that the data in there was left by another ShowINIT-aware INIT.

static unsigned short CheckSum (short x)
    return (unsigned short)(((x << 1) | (x >> 15)) ^ 0x1021);

// ---------------------------------------------------------------------------------------------------------------------
// ComputeIconRect computes where the icon should be displayed.

static void ComputeIconRect (Rect* iconRect, Rect* screenBounds)
    if (CheckSum(LMHCoord) != LMHCheckSum)                  // If we are first, we need to initialize the shared data.
        LMHCoord = 8;
    if (CheckSum(LMVCoord) != LMVCheckSum)
        LMVCoord = (short)(screenBounds->bottom - 40);

    if (LMHCoord + 34 > screenBounds->right) {                  // Check whether we must wrap
        iconRect->left = 8;
        iconRect->top = (short)(LMVCoord - 40);
    else {
        iconRect->left = LMHCoord;
        iconRect->top = LMVCoord;
    iconRect->right  = (short)(iconRect->left + 32);
    iconRect->bottom = (short)(iconRect->top  + 32);

// AdvanceIconPosition updates the shared global variables so that the next extension will draw its icon beside ours.

static void AdvanceIconPosition (Rect* iconRect)
    LMHCoord = (short)(iconRect->left + 40);                    // Update the shared data
    LMVCoord = iconRect->top;
    LMHCheckSum = CheckSum(LMHCoord);
    LMVCheckSum = CheckSum(LMVCoord);

// DrawBWIcon draws the 'ICN#' member of the icon family. It works under System 6.

static void DrawBWIcon (short iconID, Rect *iconRect)
    Handle icon;
    BitMap source, destination;
    GrafPtr port;

    icon = Get1Resource('ICN#', iconID);
    if (icon != NULL) {
        // Prepare the source and destination bitmaps.
        source.baseAddr = *icon + 128;                      // Mask address.
        source.rowBytes = 4;
        SetRect(&source.bounds, 0, 0, 32, 32);
        destination = port->portBits;
        // Transfer the mask.
        CopyBits(&source, &destination, &source.bounds, iconRect, srcBic, nil);
        // Then the icon.
        source.baseAddr = *icon;
        CopyBits(&source, &destination, &source.bounds, iconRect, srcOr, nil);

// ---------------------------------------------------------------------------------------------------------------------
// Notes

// Checking for PlotIconID:
// We (PNL) now check for system 7 and colour QD, and use colour graf ports and PlotIconID only if both are true
// Otherwise we use B&W grafport and draw using PlotBWIcon.