psGraphLineDelta()
Delta Line Graph
Description:
A simple delta line graph that doesnt require any special libraries.
Uses tick marks in X and Y, and a simple title.
Segments swinging up over 0 have a green color, down below 0 have red
Usage:
$imagePointer = psGraphLineDelta($width,$height,$dataSet,$yTicks,$xTicks[,$title][,$maxY]);
Dont forget to use ob_start(); and ob_end_clean(), so as to avoid any data (blank lines)
fronm being introduced into the output from included files.
Example:
ob_start();
include("../inc/phpsalt.php");
ob_end_clean();
header("Content-type: image/jpeg");
$w = 800;
$h = 200;
$yTicks[1500] = "1500";
$yTicks[1000] = "1000";
$yTicks[500] = "500";
$yTicks[200] = "200";
$yTicks[100] = "-100";
$xTicks[5] = "5"; // 5th item
$xTicks[10] = "10"; // 10th item
$xTicks[15] = "15"; // 15th item
$dataSet = array( 424,145,176,223,-32,416,1500,-40,-20,-5,-60,134,122,152,500,100,120);
$title = "Graph of data example";
$im = psGraphLineDelta($w,$h,$dataSet,$yTicks,$xTicks,$title);
imagejpeg($im);
Code:
function psGraphLineDelta($width,$height,$dataSet,$yTicks,$xTicks,$title="",$maxY=0)
{
$im = imagecreatetruecolor($width,$height);
$white = imagecolorallocate($im, 255,255,255);
$black = imagecolorallocate($im, 0,0,0);
$grey = imagecolorallocate($im, 127,127,127);
$greyLt = imagecolorallocate($im, 192,192,192);
$red = imagecolorallocate($im, 255,0,0);
$blue = imagecolorallocate($im, 0,0,255);
$green = imagecolorallocate($im, 0, 255, 0);
// start of graph area
$fontHeight = 12;
$fontWidth = 5;
$tickSize = 7;
$gPad = 5;
$gSX = 70;
$gSY = $gPad;
$gEY = $height - 45;
$gEX = $width - $gPad;
$gWidth = $gEX - $gSX;
$gHeight = $gEY - $gSY;
// number of data points
$pointCnt = count($dataSet);
// some backgrounds and borders
imagesetthickness($im,1);
imagefill($im, 0, 0, $white); // background
imagerectangle($im,0,0,$width-1,$height-1,$black); // outline
$oW = ($width/2) - (strlen($title) / 2);
imagestring($im,2,$oW,$height-$fontHeight-$gPad,$title,$black); // draw title
$incX = $gWidth / ($pointCnt-1); // X space between data points
// lets loop through data and find min and max values
$min = min($dataSet);
$max = max($dataSet);
if ($maxY > 0) { $max = $maxY; }
$max = $max * 1.05; // adds 5% padding to highest value
$factY = $gHeight / ($max - $min);
$floorY = $min * $factY; // adjust Y values to match floor
// imagestring ( resource $image , int $font , int $x , int $y , string $string , int $color )
// draw the Y ticks
imagesetthickness($im,1);
foreach ($yTicks as $key=>$val)
{
if ($min <= $key && $key <= $max)
{
$tX = $gPad;
$tY = $gEY - ($key * $factY) + $floorY;
//print "x:$tX y:$tY str:$val\r\n";
$oW = (strlen($val) * $fontWidth) + $tickSize + $gPad;
imagestring($im,2,$gSX-$oW,$tY-7,$val,$blue); // draw the string
imageline($im,$gSX - $tickSize,$tY,$gSX-4,$tY,$grey); // tick
if ($key == 0 ) { imageline($im,$gSX,$tY-1,$gEX,$tY-1,$blue); } // double for 0
imageline($im,$gSX,$tY,$gEX,$tY,$greyLt); // line
if ($key == 0 ) { imageline($im,$gSX,$tY+1,$gEX,$tY+1,$blue); } // double for 0
}
}
// draw the X ticks
imagesetthickness($im,1);
foreach ($xTicks as $key=>$val)
{
$tX = $gSX + ($key * $incX);
$tY = $gEY + $gPad;
$oW = (strlen($val) * $fontWidth);
imagestring($im,2,$tX-($oW),$tY+$tickSize,$val,$blue); // draw the string
imageline($im,$tX,$gEY+3,$tX,$gEY+$tickSize,$grey); // tick
imageline($im,$tX,$gSY,$tX,$gEY,$greyLt); // line
}
// outline graph area
imagesetthickness($im,1);
imagerectangle($im,$gSX-1,$gSY,$gEX,$gEY,$blue); // outline graph area
// draw the graph
imagesetthickness($im,2);
$x1 = $gSX;
$x2 = $gSX;
$y1 = $gEY - ($dataSet[0] * $factY) + $floorY;;
foreach ($dataSet as $val)
{
$y2 = $gEY - ($val * $factY) + $floorY;
if ($val >= 0 )
{
imageline($im,$x1,$y1,$x2,$y2,$green);
}
else
{
imageline($im,$x1,$y1,$x2,$y2,$red);
}
$x1 = $x2; $y1 = $y2;
$x2 += $incX;
}
return $im;
}
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