/* Movie Crawl
 * started on August 11th 2022
 * Copyright Michael Juneau, 1Bit Fever Dreams
 */


#define DELAY 5

typedef struct
	{
	TMTask atmTask;
	long tmRefCon;
	} TMInfo;
	
typedef TMInfo *TMInfoPtr;

typedef struct
	{
	StringHandle str;
	short index;
	short initIndex;
	Boolean firstTime;
	} aTextLine;
	
typedef aTextLine *aTextLinePtr;

short size = 28; //biggest font size at the bottom
short index = 342; //loop control variable
Boolean firstTime = true;
Boolean resumeLoop = false;
aTextLinePtr myText;

TMInfo myTMInfo;
	

void InstallTMTask(void);
pascal TMInfoPtr GetTMInfo(void);	
pascal void MyTask(void);
void doCrawl(int whichLine);
int findSize(int i);
void loadMyText(void);


void installTMTask() //Prepping the task record and installing it for the first time
	{
	myTMInfo.atmTask.tmAddr = MyTask;
	myTMInfo.atmTask.tmWakeUp = 0;
	myTMInfo.atmTask.tmReserved = 0;
	myTMInfo.tmRefCon = SetCurrentA5();
	
	InsTime((QElemPtr) &myTMInfo);
	PrimeTime((QElemPtr) &myTMInfo, DELAY);
	
	}
pascal TMInfoPtr GetTMInfo(void) //equivalent to MOVE.L A1,(SP)
	= 0x2E89;
	
pascal void MyTask() //the task's only purpose is to greenlight the movie crawl update to proceed by setting this global flag
	{
	long oldA5;
	TMInfoPtr recPtr;
	
	recPtr = GetTMInfo();
	oldA5 = SetA5(recPtr->tmRefCon);
	
	if(resumeLoop == false) resumeLoop = true;
	
	oldA5 = SetA5(oldA5);
	
	PrimeTime((QElemPtr) recPtr, DELAY);
	}


int findSize(int i) //used to figure out the font size, bigger in the bottom, smaller on top
	{
	return size-(342-i)/17;
	}
	
void doCrawl(int whichLine) //manage the movie crawl graphics, heart of this program
	{
	short predictWidth;
if(myText[whichLine].index <= 342) //only bother displaying if onscreen
{	
	if(myText[whichLine].index != 342) //erase the previous position
		{
		TextSize(findSize(myText[whichLine].index+1));
		predictWidth = StringWidth(*(myText[whichLine].str));
		MoveTo((512-predictWidth)/2,myText[whichLine].index+1);
		DrawString(*(myText[whichLine].str));
		}
	if(myText[whichLine].index == 342 && myText[whichLine].firstTime == false) //erase topmost position if restarting at the bottom
		{
		TextSize(findSize(size));
		predictWidth = StringWidth(*(myText[whichLine].str));
		MoveTo((512-predictWidth)/2,size);
		DrawString(*(myText[whichLine].str));
		}
	TextSize(findSize(myText[whichLine].index));
	predictWidth = StringWidth(*(myText[whichLine].str));
	MoveTo((512-predictWidth)/2,myText[whichLine].index);
	DrawString(*(myText[whichLine].str));
	myText[whichLine].firstTime = false;
}	
	myText[whichLine].index--;
	if(myText[whichLine].index < size) myText[whichLine].index=342; //loop back once the top position has been passed

	}

void loadMyText()
	{
	myText = (aTextLinePtr)NewPtr(3*sizeof(aTextLine));
	myText[0].str = NewString("\pLong live Eric Helgeson's Mac C Club!");
	myText[1].str = NewString("\pCoding in Macintosh THINK C is the best.");
	myText[2].str = NewString("\pVisit 1Bit Fever Dreams on YouTube.");
	
	myText[0].index = myText[0].initIndex = 342;
	myText[1].index = myText[1].initIndex = 342 + 28;
	myText[2].index = myText[2].initIndex = 342 + 56;
	
	myText[0].firstTime = true;
	myText[1].firstTime = true;
	myText[2].firstTime = true;
	
	
	}	
void main()
	{
	int loop;
		
	InitMacStuff(); //init Mac toolbox managers
	HideMyMenuBar(); //get rid of the menu bar, defined in Misc.c
	MacPlusArea(white, black, false); //Get a centered compact Mac sized active screen, works on compact macs as well
	
	loadMyText();
	
	TextMode(srcXor); //inverts pixels, works for erasing and for writing but gotta call both times
	installTMTask(); //installs the timing delay for the first time, it will call itself on and on
	
	while(!Button())
		{
		if(resumeLoop) 
			{
			for(loop = 0; loop < 3; loop++) doCrawl(loop); //if greenlit by the timing delay, then do the graphics
				resumeLoop = false; //prevent returning to this loop until the timer says it's greenlit
			}
		}
	
	ShowMyMenuBar(); //restore the menu, defined in Misc.c
	RmvTime((QElemPtr) &myTMInfo); //good practice to remove our timing procedure.
	}