Knowledge Base

iiif_get_canvases()

Description

Get an array of all the canvases for the identifier ready for JSON encoding

Parameters

Column	Type	Default	Description
$identifier	integer		IIIF identifier (this associates resources via the metadata field set as $iiif_identifier_field
$iiif_results	array		Array of ResourceSpace search results that match the $identifier, sorted
$sequencekeys	boolean	false	Get the array with each key matching the value set in the metadata field $iiif_sequence_field. By default the array will be sorted but have a 0 based index

Return

array

Location

include/iiif_functions.php lines 1318 to 1391

Definition

 
function iiif_get_canvases($identifier, $iiif_results,$sequencekeys=false)
    {
    global $rooturl,$iiif_sequence_field;   

    $canvases = array();
    foreach ($iiif_results as $index=>$iiif_result)
        {
        $useimage = $iiif_result;
        if ((int)$iiif_result['has_image'] === 0)
            {
            // If configured, try and use a preview from a related resource
            debug("IIIF: No image for IIIF request - check for related resources");
            $pullresource = related_resource_pull($iiif_result);
            if($pullresource !== false)
                {
                $useimage = $pullresource;
                }
            }
        $size = is_jpeg_extension($useimage["file_extension"] ?? "") ? "" : "hpr";
        $img_path = get_resource_path($useimage["ref"],true,$size,false);
        if(!file_exists($img_path))
            {
            continue;
            }
        $sequenceid = $iiif_result["iiif_position"];
        $sequence_field = get_resource_type_field($iiif_sequence_field);
        $sequence_prefix = "";
        if (isset($GLOBALS["iiif_sequence_prefix"]))
            {
            $sequence_prefix  = $GLOBALS["iiif_sequence_prefix"] === "" ? $sequence_field["title"] . " " : $GLOBALS["iiif_sequence_prefix"];
            }

        $canvases[$index]["@id"] = $rooturl . $identifier . "/canvas/" . $index;
        $canvases[$index]["@type"] = "sc:Canvas";
        $canvases[$index]["label"] = $sequence_prefix . $sequenceid;

        // Get the size of the images
        $image_size = get_original_imagesize($useimage["ref"],$img_path);
        $canvases[$index]["height"] = intval($image_size[2]);
        $canvases[$index]["width"] = intval($image_size[1]);

        // "If the largest image's dimensions are less than 1200 pixels on either edge, then the canvas dimensions 
        // should be double those of the image." - From http://iiif.io/api/presentation/2.1/#canvas
        if($image_size[1] < 1200 || $image_size[2] < 1200)
            {
            $image_size[1] = $image_size[1] * 2;
            $image_size[2] = $image_size[2] * 2;
            }

        $canvases[$index]["thumbnail"] = iiif_get_thumbnail($useimage["ref"]);

        // Add image (only 1 per canvas currently supported)
        $canvases[$index]["images"] = array();
        $size_info = array(
            'identifier' => $size,
            'return_height_width' => false,
        );
        $canvases[$index]["images"][] = iiif_get_image($identifier, $useimage["ref"], $index, $size_info);
        }

    if($sequencekeys)
        {
        // keep the sequence identifiers as keys so a required canvas can be accessed by sequence id
        return $canvases;
        }

    ksort($canvases);   
    $return=array();
    foreach($canvases as $canvas)
        {
        $return[] = $canvas;
        }
    return $return;
    }


This article was last updated 25th April 2024 21:35 Europe/London time based on the source file dated 3rd April 2024 13:55 Europe/London time.