/jpgraph/src/jpgraph_gradient.php

<?php
/*=======================================================================
 // File:        JPGRAPH_GRADIENT.PHP
 // Description: Create a color gradient
 // Created:     2003-02-01
 // Ver:         $Id: jpgraph_gradient.php 1301 2009-06-15 07:03:27Z ljp $
 //
 // Copyright (c) Aditus Consulting. All rights reserved.
 //========================================================================
 */

// Styles for gradient color fill
define("GRAD_VER",1);
define("GRAD_VERT",1);
define("GRAD_HOR",2);
define("GRAD_MIDHOR",3);
define("GRAD_MIDVER",4);
define("GRAD_CENTER",5);
define("GRAD_WIDE_MIDVER",6);
define("GRAD_WIDE_MIDHOR",7);
define("GRAD_LEFT_REFLECTION",8);
define("GRAD_RIGHT_REFLECTION",9);
define("GRAD_RAISED_PANEL",10);
define("GRAD_DIAGONAL",11);

//===================================================
// CLASS Gradient
// Description: Handles gradient fills. This is to be
// considered a "friend" class of Class Image.
//===================================================
class Gradient {
    private $img=null, $numcolors=100;
    //---------------
    // CONSTRUCTOR
    function __construct(&$img) {
        $this->img = $img;
    }


    function SetNumColors($aNum) {
        $this->numcolors=$aNum;
    }
    //---------------
    // PUBLIC METHODS
    // Produce a gradient filled rectangle with a smooth transition between
    // two colors.
    // ($xl,$yt)  Top left corner
    // ($xr,$yb) Bottom right
    // $from_color Starting color in gradient
    // $to_color End color in the gradient
    // $style  Which way is the gradient oriented?
    function FilledRectangle($xl,$yt,$xr,$yb,$from_color,$to_color,$style=1) {

        switch( $style ) {
            case GRAD_VER:
                $steps = ceil(abs($xr-$xl)+1);
                $delta = $xr>=$xl ? 1 : -1;
                $this->GetColArray($from_color,$to_color,$steps,$colors,$this->numcolors);
                for( $i=0, $x=$xl; $i < $steps; ++$i ) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($x,$yt,$x,$yb);
                    $x += $delta;
                }
                break;

            case GRAD_HOR:
                $steps = ceil(abs($yb-$yt)+1);
                $delta = $yb>=$yt ? 1 : -1;
                $this->GetColArray($from_color,$to_color,$steps,$colors,$this->numcolors);
                for($i=0,$y=$yt; $i < $steps; ++$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($xl,$y,$xr,$y);
                    $y += $delta;
                }
                break;

            case GRAD_MIDHOR:
                $steps = ceil(abs($yb-$yt)/2);
                $delta = $yb >= $yt ? 1 : -1;
                $this->GetColArray($from_color,$to_color,$steps,$colors,$this->numcolors);
                for($y=$yt, $i=0; $i < $steps;  ++$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($xl,$y,$xr,$y);
                    $y += $delta;
                }
                --$i;
                if( abs($yb-$yt) % 2 == 1 ) {
                    --$steps;
                }
                for($j=0; $j < $steps; ++$j, --$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($xl,$y,$xr,$y);
                    $y += $delta;
                }
                $this->img->Line($xl,$y,$xr,$y);
                break;

            case GRAD_MIDVER:
                $steps = ceil(abs($xr-$xl)/2);
                $delta = $xr>=$xl ? 1 : -1;
                $this->GetColArray($from_color,$to_color,$steps,$colors,$this->numcolors);
                for($x=$xl, $i=0; $i < $steps; ++$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }
                --$i;
                if( abs($xr-$xl) % 2 == 1 ) {
                    --$steps;
                }
                for($j=0; $j < $steps; ++$j, --$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }
                $this->img->Line($x,$yb,$x,$yt);
                break;

            case GRAD_WIDE_MIDVER:
                $diff = ceil(abs($xr-$xl));
                $steps = floor(abs($diff)/3);
                $firststep = $diff - 2*$steps ;
                $delta = $xr >= $xl ? 1 : -1;
                $this->GetColArray($from_color,$to_color,$firststep,$colors,$this->numcolors);
                for($x=$xl, $i=0; $i < $firststep; ++$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }
                --$i;
                $this->img->current_color = $colors[$i];
                for($j=0; $j< $steps; ++$j) {
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }

                for($j=0; $j < $steps; ++$j, --$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }
                break;

            case GRAD_WIDE_MIDHOR:
                $diff = ceil(abs($yb-$yt));
                $steps = floor(abs($diff)/3);
                $firststep = $diff - 2*$steps ;
                $delta = $yb >= $yt? 1 : -1;
                $this->GetColArray($from_color,$to_color,$firststep,$colors,$this->numcolors);
                for($y=$yt, $i=0; $i < $firststep;  ++$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($xl,$y,$xr,$y);
                    $y += $delta;
                }
                --$i;
                $this->img->current_color = $colors[$i];
                for($j=0; $j < $steps; ++$j) {
                    $this->img->Line($xl,$y,$xr,$y);
                    $y += $delta;
                }
                for($j=0; $j < $steps; ++$j, --$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($xl,$y,$xr,$y);
                    $y += $delta;
                }
                break;

            case GRAD_LEFT_REFLECTION:
                $steps1 = ceil(0.3*abs($xr-$xl));
                $delta = $xr>=$xl ? 1 : -1;

                $from_color = $this->img->rgb->Color($from_color);
                $adj = 1.4;
                $m = ($adj-1.0)*(255-min(255,min($from_color[0],min($from_color[1],$from_color[2]))));
                $from_color2 = array(min(255,$from_color[0]+$m),
                min(255,$from_color[1]+$m), min(255,$from_color[2]+$m));

                $this->GetColArray($from_color2,$to_color,$steps1,$colors,$this->numcolors);
                $n = count($colors);
                for($x=$xl, $i=0; $i < $steps1 && $i < $n; ++$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }
                $steps2 = max(1,ceil(0.08*abs($xr-$xl)));
                $this->img->SetColor($to_color);
                for($j=0; $j< $steps2; ++$j) {
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }
                $steps = abs($xr-$xl)-$steps1-$steps2;
                $this->GetColArray($to_color,$from_color,$steps,$colors,$this->numcolors);
                $n = count($colors);
                for($i=0; $i < $steps && $i < $n; ++$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }
                break;

            case GRAD_RIGHT_REFLECTION:
                $steps1 = ceil(0.7*abs($xr-$xl));
                $delta = $xr>=$xl ? 1 : -1;

                $this->GetColArray($from_color,$to_color,$steps1,$colors,$this->numcolors);
                $n = count($colors);
                for($x=$xl, $i=0; $i < $steps1 && $i < $n; ++$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }
                $steps2 = max(1,ceil(0.08*abs($xr-$xl)));
                $this->img->SetColor($to_color);
                for($j=0; $j< $steps2; ++$j) {
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }

                $from_color = $this->img->rgb->Color($from_color);
                $adj = 1.4;
                $m = ($adj-1.0)*(255-min(255,min($from_color[0],min($from_color[1],$from_color[2]))));
                $from_color = array(min(255,$from_color[0]+$m),
                min(255,$from_color[1]+$m), min(255,$from_color[2]+$m));

                $steps = abs($xr-$xl)-$steps1-$steps2;
                $this->GetColArray($to_color,$from_color,$steps,$colors,$this->numcolors);
                $n = count($colors);
                for($i=0; $i < $steps && $i < $n; ++$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }
                break;

            case GRAD_CENTER:
                $steps = ceil(min(($yb-$yt)+1,($xr-$xl)+1)/2);
                $this->GetColArray($from_color,$to_color,$steps,$colors,$this->numcolors);
                $dx = ($xr-$xl)/2;
                $dy = ($yb-$yt)/2;
                $x=$xl;$y=$yt;$x2=$xr;$y2=$yb;
                $n = count($colors);
                for($x=$xl, $i=0; $x < $xl+$dx && $y < $yt+$dy && $i < $n; ++$x, ++$y, --$x2, --$y2, ++$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Rectangle($x,$y,$x2,$y2);
                }
                $this->img->Line($x,$y,$x2,$y2);
                break;

            case GRAD_RAISED_PANEL:
                // right to left
                $steps1 = $xr-$xl;
                $delta = $xr>=$xl ? 1 : -1;
                $this->GetColArray($to_color,$from_color,$steps1,$colors,$this->numcolors);
                $n = count($colors);
                for($x=$xl, $i=0; $i < $steps1 && $i < $n; ++$i) {
                    $this->img->current_color = $colors[$i];
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }

                // left to right
                $xr -= 3;
                $xl += 3;
                $yb -= 3;
                $yt += 3;
                $steps2 = $xr-$xl;
                $delta = $xr>=$xl ? 1 : -1;
                for($x=$xl, $j=$steps2; $j >= 0; --$j) {
                    $this->img->current_color = $colors[$j];
                    $this->img->Line($x,$yb,$x,$yt);
                    $x += $delta;
                }
                break;

            case GRAD_DIAGONAL:
                // use the longer dimension to determine the required number of steps.
                // first loop draws from one corner to the mid-diagonal and the second
                // loop draws from the mid-diagonal to the opposing corner.
                if($xr-$xl > $yb - $yt) {
                    // width is greater than height -> use x-dimension for steps
                    $steps = $xr-$xl;
                    $delta = $xr>=$xl ? 1 : -1;
                    $this->GetColArray($from_color,$to_color,$steps*2,$colors,$this->numcolors);
                    $n = count($colors);

                    for($x=$xl, $i=0; $i < $steps && $i < $n; ++$i) {
                        $this->img->current_color = $colors[$i];
                        $y = $yt+($i/$steps)*($yb-$yt)*$delta;
                        $this->img->Line($x,$yt,$xl,$y);
                        $x += $delta;
                    }

                    for($x=$xl, $i = 0; $i < $steps && $i < $n; ++$i) {
                        $this->img->current_color = $colors[$steps+$i];
                        $y = $yt+($i/$steps)*($yb-$yt)*$delta;
                        $this->img->Line($x,$yb,$xr,$y);
                        $x += $delta;
                    }
                } else {
                    // height is greater than width -> use y-dimension for steps
                    $steps = $yb-$yt;
                    $delta = $yb>=$yt ? 1 : -1;
                    $this->GetColArray($from_color,$to_color,$steps*2,$colors,$this->numcolors);
                    $n = count($colors);

                    for($y=$yt, $i=0; $i < $steps && $i < $n; ++$i) {
                        $this->img->current_color = $colors[$i];
                        $x = $xl+($i/$steps)*($xr-$xl)*$delta;
                        $this->img->Line($x,$yt,$xl,$y);
                        $y += $delta;
                    }

                    for($y=$yt, $i = 0; $i < $steps && $i < $n; ++$i) {
                        $this->img->current_color = $colors[$steps+$i];
                        $x = $xl+($i/$steps)*($xr-$xl)*$delta;
                        $this->img->Line($x,$yb,$xr,$y);
                        $x += $delta;
                    }

                }
                break;

            default:
                JpGraphError::RaiseL(7001,$style);
                //("Unknown gradient style (=$style).");
                break;
        }
    }

    // Fill a special case of a polygon with a flat bottom
    // with a gradient. Can be used for filled line plots.
    // Please note that this is NOT a generic gradient polygon fill
    // routine. It assumes that the bottom is flat (like a drawing
    // of a mountain)
    function FilledFlatPolygon($pts,$from_color,$to_color) {
        if( count($pts) == 0 ) return;

        $maxy=$pts[1];
        $miny=$pts[1];
        $n = count($pts) ;
        for( $i=0, $idx=0; $i < $n; $i += 2) {
            $x = round($pts[$i]);
            $y = round($pts[$i+1]);
            $miny = min($miny,$y);
            $maxy = max($maxy,$y);
        }

        $colors = array();
        $this->GetColArray($from_color,$to_color,abs($maxy-$miny)+1,$colors,$this->numcolors);
        for($i=$miny, $idx=0; $i <= $maxy; ++$i ) {
            $colmap[$i] = $colors[$idx++];
        }

        $n = count($pts)/2 ;
        $idx = 0 ;
        while( $idx < $n-1 ) {
            $p1 = array(round($pts[$idx*2]),round($pts[$idx*2+1]));
            $p2 = array(round($pts[++$idx*2]),round($pts[$idx*2+1]));

            // Find the largest rectangle we can fill
            $y = max($p1[1],$p2[1]) ;
            for($yy=$maxy; $yy > $y; --$yy) {
                $this->img->current_color = $colmap[$yy];
                $this->img->Line($p1[0],$yy,$p2[0]-1,$yy);
            }

            if( $p1[1] == $p2[1] ) {
                continue;
            }

            // Fill the rest using lines (slow...)
            $slope = ($p2[0]-$p1[0])/($p1[1]-$p2[1]);
            $x1 = $p1[0];
            $x2 = $p2[0]-1;
            $start = $y;
            if( $p1[1] > $p2[1] ) {
                while( $y >= $p2[1] ) {
                    $x1=$slope*($start-$y)+$p1[0];
                    $this->img->current_color = $colmap[$y];
                    $this->img->Line($x1,$y,$x2,$y);
                    --$y;
                }
            }
            else {
                while( $y >= $p1[1] ) {
                    $x2=$p2[0]+$slope*($start-$y);
                    $this->img->current_color = $colmap[$y];
                    $this->img->Line($x1,$y,$x2,$y);
                    --$y;
                }
            }
        }
    }

    //---------------
    // PRIVATE METHODS
    // Add to the image color map the necessary colors to do the transition
    // between the two colors using $numcolors intermediate colors
    function GetColArray($from_color,$to_color,$arr_size,&$colors,$numcols=100) {
        if( $arr_size==0 ) {
            return;
        }

        // If color is given as text get it's corresponding r,g,b values
        $from_color = $this->img->rgb->Color($from_color);
        $to_color = $this->img->rgb->Color($to_color);

        $rdelta=($to_color[0]-$from_color[0])/$numcols;
        $gdelta=($to_color[1]-$from_color[1])/$numcols;
        $bdelta=($to_color[2]-$from_color[2])/$numcols;
        $colorsperstep = $numcols/$arr_size;
        $prevcolnum = -1;
        $from_alpha = $from_color[3];
        $to_alpha = $to_color[3];
        $adelta = ( $to_alpha - $from_alpha ) / $numcols ;
        for ($i=0; $i < $arr_size; ++$i) {
            $colnum = floor($colorsperstep*$i);
            if ( $colnum == $prevcolnum ) {
                $colors[$i] = $colidx;
            }
            else {
                $r = floor($from_color[0] + $colnum*$rdelta);
                $g = floor($from_color[1] + $colnum*$gdelta);
                $b = floor($from_color[2] + $colnum*$bdelta);
                $alpha = $from_alpha + $colnum*$adelta;
                $colidx = $this->img->rgb->Allocate(sprintf("#%02x%02x%02x",$r,$g,$b),$alpha);
                $colors[$i] = $colidx;
            }
            $prevcolnum = $colnum;
        }
    }
} // Class

?>