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<?php |
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namespace Afonso\Plotta; |
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use \RuntimeException; |
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class PlotBuilder |
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{ |
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const PLOT_MARGIN = 10; |
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const TITLE_FONT_SIZE = 5; |
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const AXIS_VALUE_FONT_SIZE = 2; |
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const INTER_ELEMENT_SPACING = 10; |
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const N_TICKS_Y_AXIS = 10; |
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const COLORS = [ |
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[0x00, 0x00, 0xff], |
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[0xff, 0x00, 0x00], |
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[0x00, 0xff, 0x00], |
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]; |
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/** |
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* @var int |
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*/ |
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private $width; |
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/** |
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* @var int |
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*/ |
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private $height; |
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/** |
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* @var string |
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*/ |
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private $title; |
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/** |
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* @var \Afonso\Plotta\XAxisConfig |
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*/ |
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private $xAxisConfig; |
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/** |
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* @var \Afonso\Plotta\YAxisConfig |
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*/ |
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private $yAxisConfig; |
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/** |
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* @var array |
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*/ |
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private $data = []; |
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/** |
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* Set the dimensions of the chart, in pixels. |
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* |
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* @param int $width |
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* @param int $height |
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* @return self |
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*/ |
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public function withDimensions(int $width, int $height): PlotBuilder |
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{ |
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$this->width = $width; |
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$this->height = $height; |
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return $this; |
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} |
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/** |
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* Set the title of the chart. |
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* |
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* @param string $title |
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* @return self |
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*/ |
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public function withTitle(string $title): PlotBuilder |
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{ |
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$this->title = $title; |
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return $this; |
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} |
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/** |
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* Set the configuration of the X axis. |
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* |
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* @param \Afonso\Plotta\XAxisConfig $xAxisConfig |
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* @return self |
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*/ |
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public function withXAxis(XAxisConfig $xAxisConfig): PlotBuilder |
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{ |
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$this->xAxisConfig = $xAxisConfig; |
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return $this; |
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} |
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/** |
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* Set the configuration of the Y axis. |
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* |
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* @param \Afonso\Plotta\YAxisConfig $yAxisConfig |
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* @return self |
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*/ |
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public function withYAxis(YAxisConfig $yAxisConfig): PlotBuilder |
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{ |
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$this->yAxisConfig = $yAxisConfig; |
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return $this; |
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} |
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/** |
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* Add a time series to the data to be plotted. |
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* |
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* @param array $data |
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* @return self |
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*/ |
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public function withData(array $data): PlotBuilder |
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{ |
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$this->data[] = $data; |
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return $this; |
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} |
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/** |
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* Generate the chart and save it as a PNG to the specified location. |
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* |
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* @param string $path |
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*/ |
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public function render(string $path): void |
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{ |
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// Check that everything is okay before proceeding |
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$this->checkOrFail(); |
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// Determine the minimum and maximum values of the data series |
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$minValue = $this->yAxisConfig->min ?? $this->getMinValue($this->data); |
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$maxValue = $this->yAxisConfig->max ?? $this->getMaxValue($this->data); |
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// Calculate the key coordinates for the chart components |
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$coords = $this->calculateCoordinates(); |
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// Initialize chart |
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$img = $this->initChart($this->width, $this->height); |
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// Title |
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$this->drawTitle($img, $coords, $this->title); |
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// Y Axis |
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$this->drawYAxis($img, $coords, $this->yAxisConfig, $minValue, $maxValue); |
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// X Axis |
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$this->drawXAxis($img, $coords, $this->xAxisConfig); |
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// Data |
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$this->drawData($img, $coords, $this->data, $minValue, $maxValue); |
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// Write to file |
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imagepng($img, $path); |
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} |
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private function checkOrFail(): void |
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{ |
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// Check that the number of data points and labels are the same |
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$maxDataPoints = max(array_map('count', $this->data)); |
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$minDataPoints = min(array_map('count', $this->data)); |
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$nLabels = count($this->xAxisConfig->labels); |
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if ($maxDataPoints != $minDataPoints) { |
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throw new RuntimeException("Data series do not have the same number of items. Min: ${minDataPoints}, max: ${maxDataPoints}"); |
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} elseif ($maxDataPoints != $nLabels) { |
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throw new RuntimeException("Number of X axis labels does not match the number of data items. Data points: ${maxDataPoints}, labels: ${nLabels}"); |
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} |
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} |
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/** |
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* Return the min and max values across all data series. |
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* |
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* @param float[][] $series |
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* @return float[] |
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*/ |
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private function getMinAndMaxValues(array $series): array |
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{ |
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return [$this->getMinValue($series), $this->getMaxValue($series)]; |
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} |
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/** |
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* Return the min value across all data series. |
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* |
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* @param float[][] $series |
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* @return float |
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*/ |
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private function getMinValue(array $series): float |
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{ |
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return min(array_map('min', $series)); |
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} |
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/** |
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* Return the max values across all data series. |
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* |
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* @param float[][] $series |
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* @return float |
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*/ |
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private function getMaxValue(array $series): float |
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{ |
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return max(array_map('max', $series)); |
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} |
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private function interpolateYCoord( |
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int $areaTopY, |
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int $areaBottomY, |
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int $value, |
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int $maxValue, |
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int $minValue |
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): int { |
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$pct = 1 - ($value - $minValue) / ($maxValue - $minValue); |
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return $areaTopY + ($areaBottomY - $areaTopY) * $pct; |
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} |
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private function calculateCoordinates(): array |
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{ |
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$coords = []; |
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$coords['title_top_left'] = [ |
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'x' => $this->width / 2 - imagefontwidth(self::TITLE_FONT_SIZE) * strlen($this->title) / 2, |
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'y' => self::PLOT_MARGIN |
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]; |
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$coords['y_axis_top_left'] = [ |
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'x' => self::PLOT_MARGIN, |
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'y' => self::PLOT_MARGIN + imagefontheight(self::TITLE_FONT_SIZE) + self::INTER_ELEMENT_SPACING |
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]; |
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$coords['y_axis_bottom_right'] = [ |
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'x' => self::PLOT_MARGIN + 75, |
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'y' => $this->height - self::PLOT_MARGIN - (imagefontheight(self::AXIS_VALUE_FONT_SIZE) + self::INTER_ELEMENT_SPACING) * 2 |
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]; |
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$coords['x_axis_top_left'] = [ |
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'x' => $coords['y_axis_bottom_right']['x'], |
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'y' => $coords['y_axis_bottom_right']['y'] |
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]; |
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$coords['x_axis_bottom_right'] = [ |
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'x' => $this->width - self::PLOT_MARGIN, |
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'y' => $this->height - self::PLOT_MARGIN, |
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]; |
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$coords['chart_area_top_left'] = [ |
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'x' => $coords['y_axis_bottom_right']['x'], |
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'y' => $coords['y_axis_top_left']['y'] |
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]; |
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$coords['chart_area_bottom_right'] = [ |
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'x' => $coords['x_axis_bottom_right']['x'], |
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'y' => $coords['x_axis_top_left']['y'] |
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]; |
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return $coords; |
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} |
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private function initChart(int $width, int $height) |
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{ |
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$img = imagecreatetruecolor($this->width, $this->height); |
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imageantialias($img, true); |
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// White background fill |
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imagefill( |
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$img, |
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0, |
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0, |
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imagecolorallocate($img, 0xff, 0xff, 0xff) |
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); |
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return $img; |
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} |
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private function drawTitle(&$img, array $coords, string $title): void |
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{ |
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imagestring( |
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$img, |
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self::TITLE_FONT_SIZE, |
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$coords['title_top_left']['x'], |
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$coords['title_top_left']['y'], |
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$this->title, |
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imagecolorallocate($img, 0x00, 0x00, 0x00) |
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); |
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} |
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private function drawYAxis(&$img, array $coords, YAxisConfig $yAxisConfig, float $minValue, float $maxValue): void |
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{ |
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// Main Y axis line |
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imageline( |
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$img, |
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$coords['chart_area_top_left']['x'], |
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$coords['chart_area_top_left']['y'], |
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$coords['chart_area_top_left']['x'], |
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$coords['chart_area_bottom_right']['y'], |
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imagecolorallocate($img, 0x00, 0x00, 0x00) |
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); |
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// Ticks and values |
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$tickSpacing = ($coords['y_axis_bottom_right']['y'] - $coords['y_axis_top_left']['y']) / self::N_TICKS_Y_AXIS; |
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$valueInterval = ($maxValue - $minValue) / self::N_TICKS_Y_AXIS; |
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$valueYOffset = imagefontheight(self::AXIS_VALUE_FONT_SIZE) / 2; |
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for ($i = 0; $i < self::N_TICKS_Y_AXIS; $i++) { |
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$y = $coords['y_axis_top_left']['y'] + $i * $tickSpacing; |
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imageline( |
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$img, |
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$coords['y_axis_bottom_right']['x'] - 1, |
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$y, |
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$coords['y_axis_bottom_right']['x'] + 1, |
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$y, |
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imagecolorallocate($img, 0x00, 0x00, 0x00) |
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); |
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$label = $maxValue - $i * $valueInterval; |
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imagestring( |
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$img, |
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self::AXIS_VALUE_FONT_SIZE, |
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$coords['y_axis_bottom_right']['x'] - imagefontwidth(self::AXIS_VALUE_FONT_SIZE) * strlen($label) - self::INTER_ELEMENT_SPACING, |
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$y - $valueYOffset, |
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$label, |
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imagecolorallocate($img, 0x00, 0x00, 0x00) |
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); |
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} |
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// Name |
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imagestringup( |
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$img, |
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self::AXIS_VALUE_FONT_SIZE, |
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$coords['y_axis_top_left']['x'], |
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$coords['y_axis_top_left']['y'] |
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+ ($coords['y_axis_bottom_right']['y'] - $coords['y_axis_top_left']['y']) / 2 |
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+ (imagefontwidth(self::AXIS_VALUE_FONT_SIZE) * strlen($yAxisConfig->name)) / 2, |
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$yAxisConfig->name, |
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imagecolorallocate($img, 0x00, 0x00, 0x00) |
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); |
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} |
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private function drawXAxis(&$img, array $coords, XAxisConfig $xAxisConfig): void |
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{ |
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// Main X axis line |
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imageline( |
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$img, |
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$coords['chart_area_top_left']['x'], |
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$coords['chart_area_bottom_right']['y'], |
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$coords['chart_area_bottom_right']['x'], |
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$coords['chart_area_bottom_right']['y'], |
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imagecolorallocate($img, 0x00, 0x00, 0x00) |
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); |
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// ================ |
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// Ticks and labels |
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// ================ |
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// The total amount of labels |
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$nLabels = count($xAxisConfig->labels); |
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// The total number of ticks and labels that we'll print. The higher |
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// the number of labels, the fewer of them we'll print so that we don't |
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// clutter the axis. |
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// Right now this is a function of the order of magnitude of the number |
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// of labels. From 1 to 9 elements, we skip none. From 10 to 100, we |
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// pick one every ten. From 101 to 1000, we pick one every one hundred, |
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// but this is clearly not ideal. We should probably factor in the |
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// chart's width, the length of the labels, etc. |
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$nTicks = floor($nLabels / (10 ** (floor(log10($nLabels)) - 1))); |
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// The number of ticks and labels we skip in between, so that all items |
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// that will be printed are evenly distributed across the axis. |
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$tickOffset = floor($nLabels / ($nTicks - 1)); |
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// The space in pixels between each tick. |
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$tickSpacing = floor(($coords['x_axis_bottom_right']['x'] - $coords['x_axis_top_left']['x']) / ($nTicks - 1)); |
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for ($i = 0; $i < $nTicks; $i++) { |
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|
$x = $coords['x_axis_top_left']['x'] + $i * $tickSpacing; |
359
|
|
|
imageline( |
360
|
|
|
$img, |
361
|
|
|
$x, |
|
|
|
|
362
|
|
|
$coords['x_axis_top_left']['y'] - 1, |
363
|
|
|
$x, |
|
|
|
|
364
|
|
|
$coords['x_axis_top_left']['y'] + 1, |
365
|
|
|
imagecolorallocate($img, 0x00, 0x00, 0x00) |
366
|
|
|
); |
367
|
|
|
|
368
|
|
|
// If the X axis configuration specifies a date format, apply it. |
369
|
|
|
// Otherwise use the label as-is. |
370
|
|
|
$label = $xAxisConfig->labels[$i * $tickOffset]; |
371
|
|
|
if ($xAxisConfig->dateFormat !== null) { |
372
|
|
|
$label = date($xAxisConfig->dateFormat, $label); |
373
|
|
|
} |
374
|
|
|
imagestring( |
375
|
|
|
$img, |
376
|
|
|
self::AXIS_VALUE_FONT_SIZE, |
377
|
|
|
$x - imagefontwidth(self::AXIS_VALUE_FONT_SIZE) * strlen($label) / 2, |
|
|
|
|
378
|
|
|
$coords['x_axis_top_left']['y'] + self::INTER_ELEMENT_SPACING, |
379
|
|
|
$label, |
380
|
|
|
imagecolorallocate($img, 0x00, 0x00, 0x00) |
381
|
|
|
); |
382
|
|
|
} |
383
|
|
|
|
384
|
|
|
// Name |
385
|
|
|
imagestring( |
386
|
|
|
$img, |
387
|
|
|
self::AXIS_VALUE_FONT_SIZE, |
388
|
|
|
$coords['x_axis_top_left']['x'] |
389
|
|
|
+ ($coords['x_axis_bottom_right']['x'] - $coords['x_axis_top_left']['x']) / 2 |
390
|
|
|
- imagefontwidth(self::AXIS_VALUE_FONT_SIZE) * strlen($xAxisConfig->name) / 2, |
391
|
|
|
$coords['x_axis_top_left']['y'] + imagefontheight(self::AXIS_VALUE_FONT_SIZE) + self::INTER_ELEMENT_SPACING * 2, |
392
|
|
|
$xAxisConfig->name, |
393
|
|
|
imagecolorallocate($img, 0x00, 0x00, 0x00) |
394
|
|
|
); |
395
|
|
|
} |
396
|
|
|
|
397
|
|
|
private function drawData(&$img, array $coords, array $data, int $minValue, int $maxValue): void |
398
|
|
|
{ |
399
|
|
|
$plotAreaTopY = $coords['chart_area_top_left']['y']; |
400
|
|
|
$plotAreaBottomY = $coords['chart_area_bottom_right']['y']; |
401
|
|
|
$nPoints = max(array_map('count', $this->data)); |
402
|
|
|
$segmentWidth = ($coords['chart_area_bottom_right']['x'] - $coords['chart_area_top_left']['x']) / ($nPoints - 1); |
403
|
|
|
foreach ($data as $idx => $series) { |
404
|
|
|
[$r, $g, $b] = self::COLORS[$idx % count(self::COLORS)]; |
405
|
|
|
$lineColor = imagecolorallocate($img, $r, $g, $b); |
406
|
|
|
|
407
|
|
|
$fromX = $fromY = null; |
408
|
|
|
for ($i = 1; $i < count($series); $i++) { |
|
|
|
|
409
|
|
|
$fromValue = $series[$i - 1]; |
410
|
|
|
$toValue = $series[$i]; |
411
|
|
|
|
412
|
|
|
if ($fromX === null) { |
413
|
|
|
$fromX = $coords['chart_area_top_left']['x'] + ($i - 1) * $segmentWidth; |
414
|
|
|
$fromY = $this->interpolateYCoord($plotAreaTopY, $plotAreaBottomY, $fromValue, $maxValue, $minValue); |
415
|
|
|
} |
416
|
|
|
|
417
|
|
|
$toX = $coords['chart_area_top_left']['x'] + $i * $segmentWidth; |
418
|
|
|
$toY = $this->interpolateYCoord($plotAreaTopY, $plotAreaBottomY, $toValue, $maxValue, $minValue); |
419
|
|
|
|
420
|
|
|
imageline($img, $fromX, $fromY, $toX, $toY, $lineColor); |
421
|
|
|
|
422
|
|
|
$fromX = $toX; |
423
|
|
|
$fromY = $toY; |
424
|
|
|
} |
425
|
|
|
} |
426
|
|
|
} |
427
|
|
|
} |
428
|
|
|
|