Turbo C Graphics - linerel function

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line , lineto and linerel function are used to draw a line in the graphics screen. It uses the color and style set by the setcolor and setlinestyle functions. line function will take 4 arguments - begx, begy and endx, endx. whereas lineto function will take only two argument endx, endy.

 

linerel function takes the end coordinates (offsetx, offsety) in relative term. The begin position (begx, begy) is last position set by either moveto or lineto function. The end position is calculated by internally by,

 

endx = begx + offsetx;

endy = endx + offsety;

 

Here is the sample code with using moverel and linerel for drawing a rectangle. Note that all the coordinates specfied by moverel and linerel functions are relative values. To use the absolue coordinates, refer to the functions moveto and lineto. The following code draws 50 pixels square starting from left + 20, to + 20.

 

//another inner square drawn with the use of moverel and linerel functions

      setcolor(WHITE);

      moveto(left, top);

      moverel(20, 20);

      linerel(50, 0);

      linerel(0, 50);

      linerel(-50, 0);

      linerel(0, -50);

 

 

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Source Code

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#include <graphics.h>

#include <stdio.h>

#include <math.h>

#include <conio.h>

#include <dos.h>

#include <stdlib.h>

 

int InitGraphics()

{

      int grd, grm;

      int gresult;

      // Detect the graphics driver and mode

      detectgraph(&grd,&grm);

      // initialize the graphics mode with initgraph

      initgraph(&grd, &grm, "");

 

      gresult = graphresult();

      if(gresult != grOk)

      {

            printf(grapherrormsg(gresult));

            getch();

            return -1;

      }

 

      // set the background color

      setbkcolor(RED);

      // set the foreground color

      setcolor(WHITE);

      // draw a white color border with rectangle

      rectangle(0,0,getmaxx(),getmaxy());

      return 1;

}

 

void main()

{

      int i, x, y, w;

      int left,top,right,bottom;

      int margin, width, height;

      int cx, cy;

      char msg[512];

      unsigned char patternbuffer[8];

      unsigned char upattern_solid[8] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };

      unsigned char upattern[8] = {  0xAA, 0x55, 0xAA, 0x55, 0xAA, 0x55, 0xAA, 0x55 };

      struct fillsettingstype fstype;

      struct linesettingstype lstype;

 

      if(InitGraphics() == -1)

            return;

 

      margin = 100; // 100 pixel margin

      left = margin;

      top = margin;

      bottom = getmaxy() - margin;

      right = getmaxx() - margin;

 

      // draw a bar with user defined solid fill on blue color

      // use rectangle to have a white color border

      setfillstyle(SOLID_FILL, WHITE);

      setfillpattern(upattern_solid, BLUE);

      getfillpattern(patternbuffer);

      getfillsettings(&fstype);

      sprintf(msg, "pattern id: %d color: %d buffer: %d", fstype.pattern, fstype.color, patternbuffer[0]);

      bar(left, top, right, bottom);

      rectangle(left, top, right, bottom);

 

      //another inner rectangle drawn with the use of moveto and lineto functions

      setcolor(YELLOW);

      moveto(left + 5, top + 5);

      lineto(right - 5, top + 5);

      lineto(right - 5, bottom - 5);

      lineto(left + 5, bottom - 5);

      lineto(left + 5, top + 5);

 

      //another inner square drawn with the use of moverel and linerel functions

      setcolor(WHITE);

      moveto(left, top);

      moverel(20, 20);

      linerel(50, 0);

      linerel(0, 50);

      linerel(-50, 0);

      linerel(0, -50);

 

      // draw two lines by crossing above square

      // SOLID_LINE, DOTTED_LINE, CENTER_LINE, DASHED_LINE, USERBIT_LINE

      setlinestyle(DASHED_LINE, 1, 1);

      line(left + 20, top + 20, left + 70, top + 70);

      setlinestyle(DOTTED_LINE, 1, 3);

      line(left + 70, top + 20, left + 20, top + 70);

      getlinesettings(&lstype);

 

      // find the text width and text height

      width = textwidth(msg);

      height = textheight(msg);

      // calculate the right and bottom with margin and getmaxx and getmaxy function

 

      // change the text foreground color to yellow

      setcolor(YELLOW);

      cx = (right + left - width) / 2;

      cy = (bottom + top - height) / 2;

      settextstyle(DEFAULT_FONT, HORIZ_DIR, 1);

      outtextxy(cx,cy,msg);

 

      setcolor(WHITE);

      moveto(100, 100);

      sprintf(msg, "linestyle: %d thickness: %d getx : %d, gety: %d", lstype.linestyle, lstype.thickness, getx(), gety());

      width = textwidth(msg);

      cx = (right + left - width) / 2;

      cy += textheight(msg) + 10;;

 

      // use moveto and outtext function instead of outtextxy

      moveto(cx, cy);

      outtext(msg);

 

      getch();

      closegraph();

}

 

Output

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