add support for additional properties for class Trendline

[bridgeplayr]

This is:

- [ ] a bug report
- [x] a feature request
- [ ] **not** a usage question (ask them on https://stackoverflow.com/questions/tagged/phpspreadsheet or https://gitter.im/PHPOffice/PhpSpreadsheet)

What is the expected behavior?

What is the current behavior?

Missing properties

What are the steps to reproduce?

Please provide a Minimal, Complete, and Verifiable example of code that exhibits the issue without relying on an external Excel file or a web server:

<?php

require __DIR__ . '/vendor/autoload.php';

// Create new Spreadsheet object
$spreadsheet = new \PhpOffice\PhpSpreadsheet\Spreadsheet();

// add code that show the issue here...

If this is an issue with reading a specific spreadsheet file, then it may be appropriate to provide a sample file that demonstrates the problem; but please keep it as small as possible, and sanitize any confidential information before uploading.

What features do you think are causing the issue

• Reader
• Writer
• Styles
• Data Validations
• Formula Calculations
• Charts
• AutoFilter
• Form Elements

Does an issue affect all spreadsheet file formats? If not, which formats are affected?

Xlsx

Which versions of PhpSpreadsheet and PHP are affected?

1.24 7.3

[bridgeplayr]

The following properties were missing from my original Trendline request. My apologies for that. These additional properties need simple setter/getter methods: "name", "forward", "intercept", (and possibly "backward") added to the Chart/Trendline.php class. They must also be comprehended as well in Writer/Xlsx/Chart.php class.

In my experiments with Excel, when I assigned a value to the 'backward' property, it promptly reset itself - regardless of the Trend type. Therefore I am not requesting its inclusion. I mention it only for completeness. Although it seems logical that "forward" and "backward" might be appropriate for Trendtype 'moving_avg', those two properties are unavailable - "grayed out" - for that trendline type.

modify Chart/Trendline.php

    /** @var string */
    private $trendLineName = '';

    /** @var float */
    private $forward = 0;

    /** @var float */
    private $intercept = 0;

// I propose leaving the constructor as it is. Add the extra properties' setter/getter methods,
// and tack on the 3 additional properties at the end of the argument list in 'setTrendlneProperties' method.

. . .
    public function getTrendLineName(): string
    {
        return $this->trendLineName;
    }

    public function setTrendLineName(string $trendLineName): self
    {
        $this->trendLineName = $trendLineName;

        return $this;
    }

    public function getForward(): float
    {
        return $this->forward;
    }

    public function setForward(float $forward): self
    {
        $this->forward = $forward;

        return $this;
    }

    public function getIntercept(): float
    {
        return $this->intercept;
    }

    public function setIntercept(float $intercept): self
    {
        $this->intercept = $intercept;

        return $this;
    }

    public function setTrendLineProperties(?string $trendLineType = null, ?int $order = 0, ?int $period = 0, ?bool $dispRSqr = false, ?bool $dispEq = false, ?string $trendLineName = null, ?float $forward = 0, ?float $intercept = 0): self
    {
        if (!empty($trendLineType)) {
            $this->setTrendLineType($trendLineType);
        }
        if ($order !== null) {
            $this->setOrder($order);
        }
        if ($period !== null) {
            $this->setPeriod($period);
        }
        if ($dispRSqr !== null) {
            $this->setDispRSqr($dispRSqr);
        }
        if ($dispEq !== null) {
            $this->setDispEq($dispEq);
        }
        if (!empty($trendLineName)) {
            $this->setTrendLineName($trendLineName);
        }
        if ($forward !== null) {
            $this->setForward($forward);
        }
        if ($intercept !== null) {
            $this->setIntercept($intercept);
        }

        return $this;
    }

modify Writer/Xlsx/Chart.php

            // Trendlines
            if ($plotSeriesValues !== false) {
                foreach ($plotSeriesValues->getTrendLines() as $trendLine) {
                    $trendLineType = $trendLine->getTrendLineType();
                    $trendLineName = $trendLine->getTrendLineName();
                    $order = $trendLine->getOrder();
                    $period = $trendLine->getPeriod();
                    $forward= $trendLine->getForward();
                    $intercept = $trendLine->getIntercept();
                    $dispRSqr = $trendLine->getDispRSqr();
                    $dispEq = $trendLine->getDispEq();
                    $trendLineColor = $trendLine->getLineColor(); // ChartColor
                    $trendLineWidth = $trendLine->getLineStyleProperty('width');

                    $objWriter->startElement('c:trendline'); // N.B. lowercase 'ell'
                    if ($trendLineName) {
                        $objWriter->startElement('c:name');
                        $objWriter->writeRawData($trendLineName);
                        $objWriter->endElement(); // name
                    }

                    $objWriter->startElement('c:spPr');

. . .
                    $objWriter->endElement(); // trendlineType
                    if ($forward <> 0) {
                        $objWriter->startElement('c:forward');
                        $objWriter->writeAttribute('val', $forward);
                        $objWriter->endElement(); // forward
                    }
                    if ($intercept <> 0) {
                        $objWriter->startElement('c:intercept');
                        $objWriter->writeAttribute('val', $intercept);
                        $objWriter->endElement(); // intercept
                    }

Attachments:

1. sample code to produce two charts. One chart with 3 dataseries but without trendlines; the second chart displays one dataseries but adds 3 trendlines with names and intercepts. "33_Chart_create_scatter_trendlines_wNameIntercept.php"
   33_Chart_create_scatter_trendlines_wNameIntercept.php.txt

2. resultant spreadsheet

[bridgeplayr]

33_Chart_create_scatter_trendlines.xlsx