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June 20, 2015 23:16
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Bar chart in PHP using the GD library
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<?php | |
/* | |
* Chart data | |
*/ | |
$data = [ | |
'Jan' => 103, | |
'Feb' => 24, | |
'Mar' => 44, | |
'Apr' => 14, | |
'May' => 89, | |
'Jun' => 147, | |
'Jul' => 181, | |
'Aug' => 172, | |
'Sep' => 52, | |
'Oct' => 106, | |
'Nov' => 121, | |
'Dec' => 76, | |
]; | |
/* | |
* Chart settings and create image | |
*/ | |
// Image dimensions | |
$imageWidth = 700; | |
$imageHeight = 400; | |
// Grid dimensions and placement within image | |
$gridTop = 40; | |
$gridLeft = 50; | |
$gridBottom = 340; | |
$gridRight = 650; | |
$gridHeight = $gridBottom - $gridTop; | |
$gridWidth = $gridRight - $gridLeft; | |
// Bar and line width | |
$lineWidth = 1; | |
$barWidth = 20; | |
// Font settings | |
$font = 'OpenSans-Regular.ttf'; | |
$fontSize = 10; | |
// Margin between label and axis | |
$labelMargin = 8; | |
// Max value on y-axis | |
$yMaxValue = 200; | |
// Distance between grid lines on y-axis | |
$yLabelSpan = 40; | |
// Init image | |
$chart = imagecreate($imageWidth, $imageHeight); | |
// Setup colors | |
$backgroundColor = imagecolorallocate($chart, 255, 255, 255); | |
$axisColor = imagecolorallocate($chart, 85, 85, 85); | |
$labelColor = $axisColor; | |
$gridColor = imagecolorallocate($chart, 212, 212, 212); | |
$barColor = imagecolorallocate($chart, 47, 133, 217); | |
imagefill($chart, 0, 0, $backgroundColor); | |
imagesetthickness($chart, $lineWidth); | |
/* | |
* Print grid lines bottom up | |
*/ | |
for($i = 0; $i <= $yMaxValue; $i += $yLabelSpan) { | |
$y = $gridBottom - $i * $gridHeight / $yMaxValue; | |
// draw the line | |
imageline($chart, $gridLeft, $y, $gridRight, $y, $gridColor); | |
// draw right aligned label | |
$labelBox = imagettfbbox($fontSize, 0, $font, strval($i)); | |
$labelWidth = $labelBox[4] - $labelBox[0]; | |
$labelX = $gridLeft - $labelWidth - $labelMargin; | |
$labelY = $y + $fontSize / 2; | |
imagettftext($chart, $fontSize, 0, $labelX, $labelY, $labelColor, $font, strval($i)); | |
} | |
/* | |
* Draw x- and y-axis | |
*/ | |
imageline($chart, $gridLeft, $gridTop, $gridLeft, $gridBottom, $axisColor); | |
imageline($chart, $gridLeft, $gridBottom, $gridRight, $gridBottom, $axisColor); | |
/* | |
* Draw the bars with labels | |
*/ | |
$barSpacing = $gridWidth / count($data); | |
$itemX = $gridLeft + $barSpacing / 2; | |
foreach($data as $key => $value) { | |
// Draw the bar | |
$x1 = $itemX - $barWidth / 2; | |
$y1 = $gridBottom - $value / $yMaxValue * $gridHeight; | |
$x2 = $itemX + $barWidth / 2; | |
$y2 = $gridBottom - 1; | |
imagefilledrectangle($chart, $x1, $y1, $x2, $y2, $barColor); | |
// Draw the label | |
$labelBox = imagettfbbox($fontSize, 0, $font, $key); | |
$labelWidth = $labelBox[4] - $labelBox[0]; | |
$labelX = $itemX - $labelWidth / 2; | |
$labelY = $gridBottom + $labelMargin + $fontSize; | |
imagettftext($chart, $fontSize, 0, $labelX, $labelY, $labelColor, $font, $key); | |
$itemX += $barSpacing; | |
} | |
/* | |
* Output image to browser | |
*/ | |
header('Content-Type: image/png'); | |
imagepng($chart); |
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Note, if labels are not seen, examine https://www.php.net/manual/en/function.imagettftext.php for a possible solution, specifically in the fontfile section.
Try adding the following to the end of the // Font settings section.
Note, this may be specific to only some PHP/GD installations.