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rod-php at thecomplex dot com
01-Oct-2002 10:32


function pdf_arrow ($pdfobj, $x1, $y1, $x2, $y2, $dashed) {

// This function will draw, stroke, and fill a line

// from (x1,y1) to (x2,y2) with an arrowhead defined

// by $headangle (in degrees) and $arrowlength.

// If $dashed is nonzero, a dashed line is drawn.

// REQUIRES: find_angle

        $headangle = 20;

        $arrowlength = 20;



        list ($angle, $slope) = find_angle($x1, $y1, $x2, $y2);



        pdf_moveto($pdfobj, $x2, $y2);



        // Find the two other points of the arrowhead

        // using $headangle and $arrowlength.

        $xarrow1 = $x2+cos(deg2rad(180+$angle+$headangle/2))*$arrowlength;

        $yarrow1 = $y2+sin(deg2rad(180+$angle+$headangle/2))*$arrowlength;

        $xarrow2 = $x2+cos(deg2rad(180+$angle-$headangle/2))*$arrowlength;

        $yarrow2 = $y2+sin(deg2rad(180+$angle-$headangle/2))*$arrowlength;

        // Draw two legs of the arrowhead, close and fill

        pdf_lineto($pdfobj, $xarrow1, $yarrow1);

        pdf_lineto($pdfobj, $xarrow2, $yarrow2);

        pdf_closepath($pdfobj);

        pdf_fill($pdfobj);



        // Find the point bisecting the short side

        // of the arrowhead. This is necessary so

        // the end of the line doesn't poke out the

        // beyond the arrow point.

        $x2line = ($xarrow1+$xarrow2)/2;

        $y2line = ($yarrow1+$yarrow2)/2;



        // Now draw the "body" line of the arrow

        if ($dashed != 0) {

                pdf_setdash($pdfobj,5,5);

        }

        pdf_moveto($pdfobj, $x1, $y1);

        pdf_lineto($pdfobj, $x2line, $y2line);

        pdf_stroke($pdfobj);

}

rod-php at thecomplex dot com
01-Oct-2002 10:20


function find_angle ($x1, $y1, $x2, $y2) {

// This function takes two points (x1,y1) and (x2,y2)

// as inputs and finds the slope and angle of a line

// between those two points.  It returns the angle

// and slope in an array. I can't figure out how to

// return a NULL value, so if the two input points

// are in a vertical line, the function returns

// $angle = 90 and $slope = 0. I know this is wrong.

        if (($x2-$x1) != 0) {

                $slope = ($y2-$y1)/($x2-$x1);

                // Get rotation angle by finding the arctangent of the slope

                $angle = rad2deg(atan($slope));

                if ($x1 > $x2) {

                        $angle = 180+$angle;

                } elseif ($y1 > $y2) {

                        $angle = 360+$angle;

                }

        } else {

                // Vertical line has no slope, 90deg angle

                $angle = 90;

#               unset ($slope);

                $slope = 0;

        }

        return array ($angle, $slope);

}

rod-php at thecomplex dot com
01-Oct-2002 10:18


function find_length ($x1, $y1, $x2, $y2) {

// Find distance between two points (x1,y1) and (x2,y2)

// Also useful to find length of a line.

        return sqrt( pow($x2-$x1,2) + pow($y2-$y1,2) );

}

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