Additional Properties for Trendlines (#3028)

Fix #3011. Some properties for Trendlines were omitted in the original request for this feature. Also, the trendlines sample spreadsheet included two charts. The rendering script 35_Chart_render handles this, but overlays the first output file with the second. It is changed to produce files with different names.

samples/Chart/33_Chart_create_scatter5_trendlines.php

@@ -193,7 +193,7 @@ $dataSeriesValues = [
 // 3- moving Avg (period=2) single-arrow trendline, w=1.5, same color as marker fill; no dispRSqr, no dispEq
 $trendLines = [
     new TrendLine(TrendLine::TRENDLINE_LINEAR, null, null, false, false),
-    new TrendLine(TrendLine::TRENDLINE_POLYNOMIAL, 3, null, true, true),
+    new TrendLine(TrendLine::TRENDLINE_POLYNOMIAL, 3, null, true, true, 20.0, 28.0, 44104.5, 'metric3 polynomial fit'),
     new TrendLine(TrendLine::TRENDLINE_MOVING_AVG, null, 2, true),
 ];
 $dataSeriesValues[0]->setTrendLines($trendLines);

samples/Chart/35_Chart_render.php

@@ -73,6 +73,9 @@ foreach ($inputFileNames as $inputFileName) {
                 $helper->log('    ' . $chartName . ' - ' . $caption);
 
                 $jpegFile = $helper->getFilename('35-' . $inputFileNameShort, 'png');
+                if ($i !== 0) {
+                    $jpegFile = substr($jpegFile, 0, -3) . "$i.png";
+                }
                 if (file_exists($jpegFile)) {
                     unlink($jpegFile);
                 }

src/PhpSpreadsheet/Chart/TrendLine.php

@@ -34,13 +34,44 @@ class TrendLine extends Properties
     /** @var bool */
     private $dispEq = false;
 
+    /** @var string */
+    private $name = '';
+
+    /** @var float */
+    private $backward = 0.0;
+
+    /** @var float */
+    private $forward = 0.0;
+
+    /** @var float */
+    private $intercept = 0.0;
+
     /**
      * Create a new TrendLine object.
      */
-    public function __construct(string $trendLineType = '', ?int $order = null, ?int $period = null, bool $dispRSqr = false, bool $dispEq = false)
+    public function __construct(
-    {
+        string $trendLineType = '',
+        ?int $order = null,
+        ?int $period = null,
+        bool $dispRSqr = false,
+        bool $dispEq = false,
+        ?float $backward = null,
+        ?float $forward = null,
+        ?float $intercept = null,
+        ?string $name = null
+    ) {
         parent::__construct();
-        $this->setTrendLineProperties($trendLineType, $order, $period, $dispRSqr, $dispEq);
+        $this->setTrendLineProperties(
+            $trendLineType,
+            $order,
+            $period,
+            $dispRSqr,
+            $dispEq,
+            $backward,
+            $forward,
+            $intercept,
+            $name
+        );
     }
 
     public function getTrendLineType(): string
@@ -103,8 +134,65 @@ class TrendLine extends Properties
         return $this;
     }
 
-    public function setTrendLineProperties(?string $trendLineType = null, ?int $order = 0, ?int $period = 0, ?bool $dispRSqr = false, ?bool $dispEq = false): self
+    public function getName(): string
     {
+        return $this->name;
+    }
+
+    public function setName(string $name): self
+    {
+        $this->name = $name;
+
+        return $this;
+    }
+
+    public function getBackward(): float
+    {
+        return $this->backward;
+    }
+
+    public function setBackward(float $backward): self
+    {
+        $this->backward = $backward;
+
+        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,
+        ?float $backward = null,
+        ?float $forward = null,
+        ?float $intercept = null,
+        ?string $name = null
+    ): self {
         if (!empty($trendLineType)) {
             $this->setTrendLineType($trendLineType);
         }
@@ -120,6 +208,18 @@ class TrendLine extends Properties
         if ($dispEq !== null) {
             $this->setDispEq($dispEq);
         }
+        if ($backward !== null) {
+            $this->setBackward($backward);
+        }
+        if ($forward !== null) {
+            $this->setForward($forward);
+        }
+        if ($intercept !== null) {
+            $this->setIntercept($intercept);
+        }
+        if ($name !== null) {
+            $this->setName($name);
+        }
 
         return $this;
     }

src/PhpSpreadsheet/Reader/Xlsx/Chart.php

@@ -531,7 +531,25 @@ class Chart
                                 $order = self::getAttribute($seriesDetail->order, 'val', 'integer');
                                 /** @var ?int */
                                 $period = self::getAttribute($seriesDetail->period, 'val', 'integer');
-                                $trendLine->setTrendLineProperties($trendLineType, $order, $period, $dispRSqr, $dispEq);
+                                /** @var ?float */
+                                $forward = self::getAttribute($seriesDetail->forward, 'val', 'float');
+                                /** @var ?float */
+                                $backward = self::getAttribute($seriesDetail->backward, 'val', 'float');
+                                /** @var ?float */
+                                $intercept = self::getAttribute($seriesDetail->intercept, 'val', 'float');
+                                /** @var ?string */
+                                $name = (string) $seriesDetail->name;
+                                $trendLine->setTrendLineProperties(
+                                    $trendLineType,
+                                    $order,
+                                    $period,
+                                    $dispRSqr,
+                                    $dispEq,
+                                    $backward,
+                                    $forward,
+                                    $intercept,
+                                    $name
+                                );
                                 $trendLines[] = $trendLine;
 
                                 break;

src/PhpSpreadsheet/Writer/Xlsx/Chart.php

@@ -1158,10 +1158,19 @@ class Chart extends WriterPart
                     $period = $trendLine->getPeriod();
                     $dispRSqr = $trendLine->getDispRSqr();
                     $dispEq = $trendLine->getDispEq();
+                    $forward = $trendLine->getForward();
+                    $backward = $trendLine->getBackward();
+                    $intercept = $trendLine->getIntercept();
+                    $name = $trendLine->getName();
                     $trendLineColor = $trendLine->getLineColor(); // ChartColor
                     $trendLineWidth = $trendLine->getLineStyleProperty('width');
 
                     $objWriter->startElement('c:trendline'); // N.B. lowercase 'ell'
+                    if ($name !== '') {
+                        $objWriter->startElement('c:name');
+                        $objWriter->writeRawData($name);
+                        $objWriter->endElement(); // c:name
+                    }
                     $objWriter->startElement('c:spPr');
 
                     if (!$trendLineColor->isUsable()) {
@@ -1181,6 +1190,21 @@ class Chart extends WriterPart
                     $objWriter->startElement('c:trendlineType'); // N.B lowercase 'ell'
                     $objWriter->writeAttribute('val', $trendLineType);
                     $objWriter->endElement(); // trendlineType
+                    if ($backward !== 0.0) {
+                        $objWriter->startElement('c:backward');
+                        $objWriter->writeAttribute('val', "$backward");
+                        $objWriter->endElement(); // c:backward
+                    }
+                    if ($forward !== 0.0) {
+                        $objWriter->startElement('c:forward');
+                        $objWriter->writeAttribute('val', "$forward");
+                        $objWriter->endElement(); // c:forward
+                    }
+                    if ($intercept !== 0.0) {
+                        $objWriter->startElement('c:intercept');
+                        $objWriter->writeAttribute('val', "$intercept");
+                        $objWriter->endElement(); // c:intercept
+                    }
                     if ($trendLineType == TrendLine::TRENDLINE_POLYNOMIAL) {
                         $objWriter->startElement('c:order');
                         $objWriter->writeAttribute('val', $order);

tests/PhpSpreadsheetTests/Chart/TrendLineTest.php

@@ -73,6 +73,10 @@ class TrendLineTest extends AbstractFunctional
         self::assertSame('accent4', $lineColor->getValue());
         self::assertSame('stealth', $trendLine->getLineStyleProperty(['arrow', 'head', 'type']));
         self::assertEquals(0.5, $trendLine->getLineStyleProperty('width'));
+        self::assertSame('', $trendLine->getName());
+        self::assertSame(0.0, $trendLine->getBackward());
+        self::assertSame(0.0, $trendLine->getForward());
+        self::assertSame(0.0, $trendLine->getIntercept());
 
         $trendLine = $trendLines[1];
         self::assertSame('poly', $trendLine->getTrendLineType());
@@ -82,6 +86,10 @@ class TrendLineTest extends AbstractFunctional
         self::assertSame('accent3', $lineColor->getValue());
         self::assertNull($trendLine->getLineStyleProperty(['arrow', 'head', 'type']));
         self::assertEquals(1.25, $trendLine->getLineStyleProperty('width'));
+        self::assertSame('metric3 polynomial', $trendLine->getName());
+        self::assertSame(20.0, $trendLine->getBackward());
+        self::assertSame(28.0, $trendLine->getForward());
+        self::assertSame(14400.5, $trendLine->getIntercept());
 
         $trendLine = $trendLines[2];
         self::assertSame('movingAvg', $trendLine->getTrendLineType());
@@ -91,6 +99,10 @@ class TrendLineTest extends AbstractFunctional
         self::assertSame('accent2', $lineColor->getValue());
         self::assertNull($trendLine->getLineStyleProperty(['arrow', 'head', 'type']));
         self::assertEquals(1.5, $trendLine->getLineStyleProperty('width'));
+        self::assertSame('', $trendLine->getName());
+        self::assertSame(0.0, $trendLine->getBackward());
+        self::assertSame(0.0, $trendLine->getForward());
+        self::assertSame(0.0, $trendLine->getIntercept());
 
         $reloadedSpreadsheet->disconnectWorksheets();
     }