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Microsoft OS/2 SDK PM 08-08-1988

/* -----------------------------------------------------------------*\
/*	AVIO (windowed) File Browser Demo
/*	Version 1.0
/*	Created by Microsoft Corp. 1988
/* -----------------------------------------------------------------*/

/* ------------------------------------ */
/* library includes			*/
/* ------------------------------------ */
#define INCL_BASE
#define INCL_AVIO
#include <stdlib.h>
#include <stdio.h>
#include <os2.h>
#include <string.h>
#include "browse.h"

/* ------------------------------------ */
/* global variables			*/
/* ------------------------------------ */
FILE *pFile_In;
char *apchDataLines[ NUM_DATA_LINES ];
SHORT HighestLine= -1;
SHORT HorScrollPos=0;
extern HVPS hVPS;
extern HWND hwndSkel;
extern HDC hDC;
extern USHORT Vid_Cols, Vid_Rows;

/* ================================================================ */
/*	    Functions						    */
/* ================================================================ */

SHORT Initialize(argc,argv)
int argc;
char *argv[];

/* tries to open input file and initialize global variables */
/* plus any other misc. functions			    */
{
    char *achInFile;
    VIOMODEINFO viomiMode;

    /* -------------------------- */
    /* get input file ready	  */
    /* -------------------------- */
    if (argc==1)
	pFile_In=stdin;
    else {
	achInFile=argv[1];
	if ((pFile_In=fopen(achInFile,"r"))==NULL) {
	    fprintf(stderr,"Error--could not open %s",achInFile);
	    return(-1);
	}
    }

    /* -------------------------- */
    /* read input file		  */
    /* -------------------------- */
    if (ReadFile())
	return(-1);

    /* -------------------------- */
    /* get video parameters	  */
    /* -------------------------- */
    viomiMode.cb = sizeof(viomiMode);

    GetWinCharSize();

    SetScrollPosVert( 0, HighestLine );
    SetScrollPosHorz( 0, HIGHEST_HSCROLL );
    DisplayScreen(0, TRUE);
}

/* ================================================================ */

SHORT ReadFile( void )

/* reads data lines from the file to memory.	    */
/* if an error occurs, it will abort the program    */
/* stores the lines as null-terminated ascii, with  */
/* no /n's in the strings.                          */
{   char achLine[256];

    while (fgets(achLine,128,pFile_In)) {

	/* strip LF character from end of string before storing */
	/* by converting LF to /0				*/
	if (achLine[strlen(achLine)-1]=='\n')
	    achLine[strlen(achLine)-1]=0;
	else {
	    fprintf(stderr,"Internal error in ReadFile.\n");
	    return(-1);
	}
	if (StoreLine(achLine)) {
	    fprintf(stderr,"Error while storing line in ReadFile.\n");
	    return(-1);
	}
    }

    fclose(pFile_In);
    return(0);
}

/* ================================================================ */
/*	Line-handling subsystem 				    */
/* ================================================================ */

SHORT StoreLine( pchLine )
char *pchLine;

/* store a line in memory at end of list.			*/
/* creates the line number automatically			*/
/* extensions to allow >64K data go here and in RetrieveLine	*/
{
    /* don't forget to malloc space for \0 */
    if (HighestLine==NUM_DATA_LINES ||
      (apchDataLines[++HighestLine]=malloc(strlen(pchLine)+1))==NULL )
	return(-1);
    /* copy (to, from) */
    strcpy(apchDataLines[HighestLine],pchLine);
    return(0);
}

/* ================================================================ */

SHORT RetrieveLine( ppchLine , LineNum )
char **ppchLine;
USHORT LineNum;

/* take line number and convert it to a string of data from memory  */
/* extensions to allow >64K data also incorporated here 	    */
{
    if (LineNum > HighestLine)
	return(-1);
    *ppchLine=apchDataLines[LineNum];
    return(0);
}

/* ================================================================ */
/*		Video-handling subsystem			    */
/* ================================================================ */

void ClearScreen( void )

/* self-explanitory I hope	    */
/* uses technique from qh examples  */
/* clearing=scrolldown(maxlines)    */
{
    BYTE bBlank[2];
    bBlank[0] = 0x20;                      /* space character       */
    bBlank[1] = 0x07;                      /* white attribute (EGA) */
    VioScrollUp(0,			   /* top row		    */
        0,                                 /* left column           */
        -1,                                /* bottom row            */
        -1,                                /* right column          */
        -1,                                /* number of lines       */
        bBlank,                            /* cell to write         */
	WINDOW);				/* video handle 	 */
}

/* ================================================================ */

void DisplayScreen( USHORT TopLine, BOOL force)

/* display lines from memory to video, starting at line number TopLine	*/
/* has 'smarts' to scroll+paint remainder.				*/
{
    SHORT LineDiff;
    static USHORT OldTopLine;

    VioSetOrg(0, HorScrollPos, WINDOW);   /* effects horizontal shift */
    LineDiff=TopLine-OldTopLine;
    if ( (abs(LineDiff) < Vid_Rows ) && !force ) {
	/* is legal to apply scroll+paint remainder algorithm */
	/* (usually applied when user wants line up/down) */
	if (LineDiff<0) {
	    /* user scrolls back; repaint top part of screen */
	    ScrollDown( -LineDiff );
	    VidRefresh(TopLine, -LineDiff, 0);
	}
	else {
	    /* user scrolls forward; repaint bottom part */
	    ScrollUp( LineDiff );
	    VidRefresh( TopLine+Vid_Rows-LineDiff, LineDiff, Vid_Rows-LineDiff);
	}
    }
    else {
	/* repaint entire screen */
	ClearScreen();
	VidRefresh(TopLine, Vid_Rows, 0);
    }
    OldTopLine=TopLine;
}

/* ================================================================ */

void VidRefresh ( USHORT LineFrom, USHORT NumLines, USHORT VidRowStart)
/* Redisplay lines LineFrom to LineTo starting at video VidRowStart */
/* Will NOT check that you haven't given it stupid arguments        */
{
    USHORT LineOffset;
    char *pchLine;

    for (LineOffset=0; LineOffset < NumLines ; LineOffset++) {
	if (LineOffset + LineFrom > HighestLine)
	    break;
	RetrieveLine(&pchLine, LineOffset + LineFrom);
	VioSetCurPos(
	    VidRowStart+LineOffset,	/* vertical pos   */
	    0			 ,	/* horizontal pos */
	    WINDOW			/* hvio */
	);
	VioWrtTTY(
	    pchLine,		/* string to print */
	    strlen(pchLine),	/* string length */
	    WINDOW		/* hvio */
	);
    }
}

void ScrollUp(int Nlines)
{
    BYTE bBlank[2];
    bBlank[0] = 0x20;                      /* space character       */
    bBlank[1] = 0x07;                      /* white attribute (EGA) */
    VioScrollUp(0,			   /* top row		    */
        0,                                 /* left column           */
        -1,                                /* bottom row            */
        -1,                                /* right column          */
	Nlines, 			   /* number of lines	    */
        bBlank,                            /* cell to write         */
	WINDOW);				/* video handle 	 */
}

void ScrollDown(int Nlines)
{
    BYTE bBlank[2];
    bBlank[0] = 0x20;                      /* space character       */
    bBlank[1] = 0x07;                      /* white attribute (EGA) */
    VioScrollDn(0,                         /* top row               */
        0,                                 /* left column           */
        -1,                                /* bottom row            */
        -1,                                /* right column          */
	Nlines, 			   /* number of lines	    */
        bBlank,                            /* cell to write         */
	WINDOW);				/* video handle 	 */
}

/* ================================================================ */
/*	User input subsystem					    */
/* ================================================================ */

VOID ExecuteAction( CHAR ch , USHORT usSliderPos )
/* should be: Execute_User_Action()				*/
/* determine the new line number				*/
/* at top of screen						*/
/* given the movement code in ch				*/
/* returns 1 if successful					*/
/* returns 0 if unsuccessful (user wants to quit)		*/
{
    static USHORT OldLine ;
    BOOL bForce=FALSE;

#define downbound( X, A, B) ( (X) > ((B)-(A)) )? (B) : (X)+(A)
#define upbound( X, A, B) ( (X) < ((B)+(A)) )? (B) : (X)-(A)


    switch (ch) {
	case LINE_UP:
	    OldLine=upbound( OldLine, 1, 0);
	    break;
	case LINE_DOWN:
	    OldLine=downbound( OldLine, 1, MAX_START_LINE);
	    break;
	case PAGE_UP:
	    OldLine=upbound( OldLine, Vid_Rows, 0);
	    break;
	case PAGE_DOWN:
	    OldLine=downbound( OldLine, Vid_Rows, MAX_START_LINE);
	    break;
	case GOTO_TOP:
	    OldLine= 0;
	    break;
	case GOTO_BOTTOM:
	    OldLine= MAX_START_LINE;
	    break;
	case GOTO_LINE_TRACK:
	    OldLine= usSliderPos;
	    break;
	case CHAR_RIGHT:
	    HorScrollPos= downbound ( HorScrollPos, 1, HIGHEST_HSCROLL);
	    break;
	case CHAR_LEFT:
	    HorScrollPos = upbound( HorScrollPos, 1, 0);
	    break;
	case PAGE_RIGHT:
	    HorScrollPos = downbound( HorScrollPos, HSCROLL_PAGESIZE, HIGHEST_HSCROLL);
	    break;
	case PAGE_LEFT:
	    HorScrollPos = upbound( HorScrollPos, HSCROLL_PAGESIZE, 0);
	    break;
	case GOTO_HSCROLL_TRACK:
	    HorScrollPos = (SHORT) usSliderPos;
	    break;
	case NULL:
	    bForce=TRUE;
	    break;
	case GOTO_LINE, GOTO_HSCROLL:
	    break;
    }
    if ( (ch != GOTO_HSCROLL_TRACK) && (ch != GOTO_LINE_TRACK) ) {
	SetScrollPosVert ( OldLine, MAX_START_LINE );
	SetScrollPosHorz ( HorScrollPos, HIGHEST_HSCROLL );
    }
    DisplayScreen( OldLine, bForce );
}

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