[!!!][FEATURE] Add automatic image scaling for structure elements

In templates bootstrap columns can now be created with the view
helper `pp.render.bootstrap.column` or wrapped with the
`pp:structure.wrap.column` view helper allowing to propagate
information regarding the available content with.

CORRECTIVE ACTION: On sites using extension to structure the
content area (e.g. `pp_gridelements` or `flux_elements`) the
field `Image scaling` (register `Image` from content element)
needs to be reviewed. In most cases it can be set to its default
value since the scaling is now automatically calculated.

Classes/Utility/StructureMultiplierUtility.php

@@ -0,0 +1,92 @@
+<?php
+
+
+namespace Buepro\Pizpalue\Utility;
+
+use TYPO3\CMS\Core\Utility\GeneralUtility;
+
+/**
+ * Used to calculate the structure multiplier.
+ */
+class StructureMultiplierUtility
+{
+    private static $defaultMultiplier = [
+        'extrasmall' => 1,
+        'small' => 1,
+        'medium' => 1,
+        'large' => 1,
+        'default' => 1
+    ];
+
+    private static $breakpointMap = [
+        'extrasmall' => '',
+        'small' => 'sm',
+        'medium' => 'md',
+        'large' => 'lg',
+        'default' => 'xl'
+    ];
+
+    /**
+     * Calculates the factor for a breakpoint based on the css items used to define the column and the column count
+     * from the row.
+     *
+     * @param array $items CSS items defining the column (e.g. ['col', 'col-md', 'col-lg-4'])
+     * @param int $count
+     * @param string $breakpoint
+     * @return bool|float|int
+     */
+    private static function getColumnFactorForBreakpoint(array $items, int $count, string $breakpoint) {
+        $factor = false;
+        foreach ($items as $item) {
+            $parts = GeneralUtility::trimExplode('-', $item, true);
+            if ($parts[0] !== 'col') {
+                continue;
+            }
+            // CSS definition `col`
+            if (count($parts) === 1 && $breakpoint === 'extrasmall') {
+                $factor = 1 / $count;
+            }
+            // CSS definition `col-3`
+            if (count($parts) === 2 && (int) $parts[1] > 0 && $breakpoint === 'extrasmall') {
+                $factor = ((int) $parts[1]) / 12;
+            }
+            // CSS definition `col-md`
+            if (count($parts) === 2 && $parts[1] === self::$breakpointMap[$breakpoint]) {
+                $factor = 1 / $count;
+            }
+            // CSS definition `col-md-3`
+            if (count($parts) === 3 && $parts[1] === self::$breakpointMap[$breakpoint]) {
+                $factor = ((int) $parts[2]) / 12;
+            }
+        }
+        return $factor;
+    }
+
+    /**
+     * Calculates a new multiplier based on the current one, the column css and the column count
+     *
+     * @param array $currentMultiplier
+     * @param string $class CSS classes used to define the column
+     * @param int $count Columns count in row
+     * @return array
+     */
+    public static function getMultiplierForColumn(array $currentMultiplier = [], string $class = '', int $count = 1): array {
+        // Set initial multiplier
+        $multiplier = array_merge(self::$defaultMultiplier, $currentMultiplier);
+        $multiplier = array_intersect_key($multiplier, self::$defaultMultiplier);
+        // Calculate new multipliers
+        $items = GeneralUtility::trimExplode(' ', $class, true);
+        $previousFactor = 1.0;
+        foreach ($multiplier as $breakpoint => $value) {
+            $factor = self::getColumnFactorForBreakpoint($items, $count, $breakpoint);
+            if (false === $factor) {
+                // No column definition was present hence column width remains as for previous break point
+                $multiplier[$breakpoint] = $previousFactor * $value;
+            } else {
+                $multiplier[$breakpoint] = $factor * $value;
+                $previousFactor = $factor;
+            }
+        }
+        return $multiplier;
+    }
+}

Classes/ViewHelpers/Render/Bootstrap/ColumnViewHelper.php

@@ -0,0 +1,84 @@
+<?php
+
+
+namespace Buepro\Pizpalue\ViewHelpers\Render\Bootstrap;
+
+use Buepro\Pizpalue\Utility\StructureMultiplierUtility;
+use TYPO3\CMS\Frontend\Controller\TypoScriptFrontendController;
+use TYPO3Fluid\Fluid\Core\ViewHelper\AbstractTagBasedViewHelper;
+
+/**
+ * By using this view helper to create a div-tag defining a bootstrap column the available width within
+ * the column is being registered allowing to adjust the rendering. This allows images to be created with
+ * the size that fits the column.
+ *
+ * It is achieved by calculating a multiplier and pushing it to a stack. The latest multiplier is stored to the register
+ * `structureMultiplier` from where it is available to all elements rendering images (e.g. see
+ * `Resources\Private\Layouts\ContentElements\Default.html`).
+ *
+ * ### Example:
+ *
+ * <pp:render.bootstrap.column class="col col-md-8 col-xl-6" count="2">
+ *     <v:content.render contentUids="{0: item.data.uid}" />
+ * </pp:render.bootstrap.column>
+ */
+class ColumnViewHelper extends AbstractTagBasedViewHelper
+{
+    /**
+     * @var array
+     */
+    private static $multiplierStack = [];
+
+    protected $tagName = 'div';
+
+    /**
+     * Returns last added element from $multiplierStack
+     *
+     * @return array|mixed
+     */
+    private static function getCurrentMultiplier()
+    {
+        $currentMultiplier = [];
+        if (count(self::$multiplierStack)) {
+            $currentMultiplier = array_pop(self::$multiplierStack);
+            self::$multiplierStack[] = $currentMultiplier;
+        }
+        return $currentMultiplier;
+    }
+
+    public function initializeArguments()
+    {
+        parent::initializeArguments();
+        $this->registerUniversalTagAttributes();
+        $this->registerArgument('count', 'int', 'Column count in row',false, 1);
+        $this->registerArgument('tagName', 'string', 'Tag name', false, 'div');
+    }
+
+    public function render()
+    {
+        $this->tagName = $this->arguments['tagName'];
+        if ($GLOBALS['TSFE'] instanceof TypoScriptFrontendController) {
+            // Initialize
+            $currentMultiplier = self::getCurrentMultiplier();
+
+            // Get multiplier for current structure
+            $multiplier = StructureMultiplierUtility::getMultiplierForColumn(
+                $currentMultiplier,
+                $this->arguments['class'],
+                $this->arguments['count']
+            );
+
+            // Push multiplier -> render content -> pop multiplier
+            self::$multiplierStack[] = $multiplier;
+            $GLOBALS['TSFE']->register['structureMultiplier'] = $multiplier;
+            $this->tag->setContent($this->renderChildren());
+            $content = $this->tag->render();
+            array_pop(self::$multiplierStack);
+            $GLOBALS['TSFE']->register['structureMultiplier'] = self::getCurrentMultiplier();
+            return $content;
+        } else {
+            $this->tag->setContent($this->renderChildren());
+            return $this->tag->render();
+        }
+    }
+}

Classes/ViewHelpers/Structure/Multiplier/GetForColumnViewHelper.php

@@ -0,0 +1,55 @@
+<?php
+
+
+namespace Buepro\Pizpalue\ViewHelpers\Structure\Multiplier;
+
+use Buepro\Pizpalue\Utility\StructureMultiplierUtility;
+use TYPO3Fluid\Fluid\Core\Rendering\RenderingContextInterface;
+use TYPO3Fluid\Fluid\Core\ViewHelper\AbstractViewHelper;
+use TYPO3Fluid\Fluid\Core\ViewHelper\Traits\CompileWithRenderStatic;
+
+/**
+ * Used to generate a multiplier array used for creating image variants.
+ * A start multiplier can be provided which is useful when being used in nested structures (e.g. column in column).
+ *
+ * Currently just supports css from bootstrap framework.
+ *
+ * Usage:
+ * {pp:structure.multiplier.getForColumn(as: 'multiplier', multiplier: multiplier, class: 'col-sm col-md-8 col-lg-10', count: 3)}
+ */
+class GetForColumnViewHelper extends AbstractViewHelper
+{
+    use CompileWithRenderStatic;
+
+    /**
+     * @return void
+     */
+    public function initializeArguments()
+    {
+        parent::initializeArguments();
+        $this->registerArgument('as', 'string', 'Name of variable to create.', true);
+        $this->registerArgument('multiplier', 'array', 'Initial multiplier', false);
+        $this->registerArgument('class', 'string', 'CSS classes used for defining the column', false);
+        $this->registerArgument('count', 'int', 'Column count in row', false);
+
+    }
+
+    /**
+     * @param array $arguments
+     * @param \Closure $renderChildrenClosure
+     * @param RenderingContextInterface $renderingContext
+     * @return mixed
+     */
+    public static function renderStatic(
+        array $arguments,
+        \Closure $renderChildrenClosure,
+        RenderingContextInterface $renderingContext
+    ) {
+        $multiplier = $arguments['multiplier'] ?? [];
+        $class = $arguments['class'] ?? '';
+        $count = $arguments['count'] ?? 1;
+        $multiplier = StructureMultiplierUtility::getMultiplierForColumn($multiplier, $class, $count);
+        $renderingContext->getVariableProvider()->add($arguments['as'], $multiplier);
+    }
+
+}

Classes/ViewHelpers/GetImageMultiplierViewHelper.php → Classes/ViewHelpers/Structure/Multiplier/GetFromTextViewHelper.php

@@ -1,17 +1,17 @@
 <?php
 
 
-namespace Buepro\Pizpalue\ViewHelpers;
+namespace Buepro\Pizpalue\ViewHelpers\Structure\Multiplier;
 
 use TYPO3\CMS\Core\Utility\GeneralUtility;
 use TYPO3Fluid\Fluid\Core\Rendering\RenderingContextInterface;
 use TYPO3Fluid\Fluid\Core\ViewHelper\AbstractViewHelper;
 use TYPO3Fluid\Fluid\Core\ViewHelper\Traits\CompileWithRenderStatic;
 
 /**
- * Class GetImageMultiplierViewHelper
+ * Class GetFromTextViewHelper
  */
-class GetImageMultiplierViewHelper extends AbstractViewHelper
+class GetFromTextViewHelper extends AbstractViewHelper
 {
     use CompileWithRenderStatic;