Task: Bitmap_Bresenham's line algorithm





Java: import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;

public class Bresenham {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(Bresenham::run);
    }

    private static void run() {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
        f.setTitle("Bresenham");

        f.getContentPane().add(new BresenhamPanel());
        f.pack();

        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }
}

class BresenhamPanel extends JPanel {

    private final int pixelSize = 10;

    BresenhamPanel() {
        setPreferredSize(new Dimension(600, 500));
        setBackground(Color.WHITE);
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        int w = (getWidth() - 1) / pixelSize;
        int h = (getHeight() - 1) / pixelSize;
        int maxX = (w - 1) / 2;
        int maxY = (h - 1) / 2;
        int x1 = -maxX, x2 = maxX * -2 / 3, x3 = maxX * 2 / 3, x4 = maxX;
        int y1 = -maxY, y2 = maxY * -2 / 3, y3 = maxY * 2 / 3, y4 = maxY;

        drawLine(g, 0, 0, x3, y1); 
        drawLine(g, 0, 0, x4, y2); 
        drawLine(g, 0, 0, x4, y3); 
        drawLine(g, 0, 0, x3, y4); 
        drawLine(g, 0, 0, x2, y4); 
        drawLine(g, 0, 0, x1, y3); 
        drawLine(g, 0, 0, x1, y2); 
        drawLine(g, 0, 0, x2, y1); 
    }

    private void plot(Graphics g, int x, int y) {
        int w = (getWidth() - 1) / pixelSize;
        int h = (getHeight() - 1) / pixelSize;
        int maxX = (w - 1) / 2;
        int maxY = (h - 1) / 2;

        int borderX = getWidth() - ((2 * maxX + 1) * pixelSize + 1);
        int borderY = getHeight() - ((2 * maxY + 1) * pixelSize + 1);
        int left = (x + maxX) * pixelSize + borderX / 2;
        int top = (y + maxY) * pixelSize + borderY / 2;

        g.setColor(Color.black);
        g.drawOval(left, top, pixelSize, pixelSize);
    }

    private void drawLine(Graphics g, int x1, int y1, int x2, int y2) {
        
        int d = 0;

        int dx = Math.abs(x2 - x1);
        int dy = Math.abs(y2 - y1);

        int dx2 = 2 * dx; 
        int dy2 = 2 * dy; 

        int ix = x1 < x2 ? 1 : -1; 
        int iy = y1 < y2 ? 1 : -1;

        int x = x1;
        int y = y1;

        if (dx >= dy) {
            while (true) {
                plot(g, x, y);
                if (x == x2)
                    break;
                x += ix;
                d += dy2;
                if (d > dx) {
                    y += iy;
                    d -= dx2;
                }
            }
        } else {
            while (true) {
                plot(g, x, y);
                if (y == y2)
                    break;
                y += iy;
                d += dx2;
                if (d > dy) {
                    x += ix;
                    d -= dy2;
                }
            }
        }
    }
}




VB: 
	Dim map(48,40), list(10), ox, oy
	data=Array(1,8, 8,16, 16,8, 8,1, 1,8)
	For i=0 To UBound(map,1): For j=0 To UBound(map,2)
		map(i,j)="."
	Next: Next 
	points=(UBound(data)+1)/2
	For p=1 To points 
		x=data((p-1)*2)
		y=data((p-1)*2+1)
		list(p)=Array(x,y)
		If p=1 Then minX=x: maxX=x: minY=y: maxY=y
		If x<minX Then minX=x
		If x>maxX Then maxX=x
		If y<minY Then minY=y
		If y>maxY Then maxY=y
	Next 
	border=2
	minX=minX-border*2  : maxX=maxX+border*2
	minY=minY-border    : maxY=maxY+border
	ox =-minX           : oy =-minY
	wx=UBound(map,1)-ox : If maxX>wx Then maxX=wx
	wy=UBound(map,2)-oy : If maxY>wy Then maxY=wy
	For x=minX To maxX: map(x+ox,0+oy)="-": Next 
	For y=minY To maxY: map(0+ox,y+oy)="|": Next 
	map(ox,oy)="+"
	For p=1 To points-1
		draw_line list(p), list(p+1)
	Next 
	For y=maxY To minY Step -1
		line=""
		For x=minX To maxX
			line=line & map(x+ox,y+oy)
		Next 
		Wscript.Echo line
	Next 

Sub draw_line(p1, p2)
	Dim x,y,xf,yf,dx,dy,sx,sy,err,err2
    x =p1(0)     : y =p1(1)
	xf=p2(0)     : yf=p2(1)
	dx=Abs(xf-x) : dy=Abs(yf-y)
	If x<xf Then sx=+1: Else sx=-1
	If y<yf Then sy=+1: Else sy=-1
	err=dx-dy
	Do
		map(x+ox,y+oy)="X"
		If x=xf And y=yf Then Exit Do
		err2=err+err
		If err2>-dy Then err=err-dy: x=x+sx
		If err2< dx Then err=err+dx: y=y+sy
	Loop
End Sub