@allmaps/iiif-parser/dist/lib/tiles.js

Allmaps IIIF parser

export function getTileImageRequest({ width: imageWidth, height: imageHeight }, zoomLevel, column, row) {
    // See https://iiif.io/api/image/3.0/implementation/#3-tile-region-parameter-calculation
    const regionX = column * zoomLevel.originalWidth;
    const regionY = row * zoomLevel.originalHeight;
    const regionWidth = column * zoomLevel.originalWidth + zoomLevel.width * zoomLevel.scaleFactor >
        imageWidth
        ? imageWidth - column * zoomLevel.originalWidth
        : zoomLevel.width * zoomLevel.scaleFactor;
    const regionHeight = row * zoomLevel.originalHeight + zoomLevel.height * zoomLevel.scaleFactor >
        imageHeight
        ? imageHeight - row * zoomLevel.originalHeight
        : zoomLevel.height * zoomLevel.scaleFactor;
    let tileWidth = zoomLevel.width;
    let tileHeight = zoomLevel.height;
    if (regionX + zoomLevel.width * zoomLevel.scaleFactor > imageWidth) {
        tileWidth = Math.floor((imageWidth - regionX + zoomLevel.scaleFactor - 1) / zoomLevel.scaleFactor);
    }
    if (regionY + zoomLevel.height * zoomLevel.scaleFactor > imageHeight) {
        tileHeight = Math.floor((imageHeight - regionY + zoomLevel.scaleFactor - 1) /
            zoomLevel.scaleFactor);
    }
    return {
        region: {
            x: regionX,
            y: regionY,
            width: regionWidth,
            height: regionHeight
        },
        size: {
            width: tileWidth,
            height: tileHeight
        }
    };
}
function getDefaultTileset({ width: imageWidth, height: imageHeight }, tileWidth = 768) {
    const maxTilesPerSide = Math.max(imageWidth, imageHeight) / tileWidth;
    const maxExponent = Math.ceil(Math.log(maxTilesPerSide) / Math.log(2));
    // let maxTileSide
    // if (parsedImage.maxWidth) {
    //   maxTileSide = parsedImage.maxWidth
    // }
    // if (parsedImage.maxHeight) {
    //   maxTileSide = maxTileSide
    //     ? Math.min(maxTileSide, parsedImage.maxHeight)
    //     : parsedImage.maxHeight
    // }
    // if (parsedImage.maxArea) {
    //   maxTileSide = maxTileSide
    //     ? Math.min(maxTileSide, Math.sqrt(parsedImage.maxArea))
    //     : Math.sqrt(parsedImage.maxArea)
    // }
    return {
        scaleFactors: Array.from({ length: maxExponent }, (_, exponent) => 2 ** exponent),
        // .filter((scaleFactor) => {
        //   if (maxTileSide) {
        //     return tileWidth * scaleFactor <= maxTileSide
        //   } else {
        //     return true
        //   }
        // }),
        width: tileWidth
    };
}
function getTileZoomLevelFromScaleFactor({ width: imageWidth, height: imageHeight }, tileset, scaleFactor) {
    const height = tileset.height || tileset.width;
    const originalWidth = tileset.width * scaleFactor;
    const originalHeight = height * scaleFactor;
    return {
        scaleFactor,
        width: tileset.width,
        height,
        originalWidth,
        originalHeight,
        columns: Math.ceil(imageWidth / originalWidth),
        rows: Math.ceil(imageHeight / originalHeight)
    };
}
function getTileZoomLevelsFromTilesets(imageSize, tilesets) {
    return tilesets
        .map((tileset) => tileset.scaleFactors.map((scaleFactor) => getTileZoomLevelFromScaleFactor(imageSize, tileset, scaleFactor)))
        .flat();
}
function hasValidTileset(tilesets) {
    if (tilesets.some((tileset) => tileset.width && tileset.scaleFactors && tileset.scaleFactors.length)) {
        return true;
    }
    return false;
}
export function getTileZoomLevels(imageSize, tilesets, supportsAnyRegionAndSize) {
    if (!tilesets || !hasValidTileset(tilesets)) {
        if (supportsAnyRegionAndSize) {
            tilesets = [getDefaultTileset(imageSize)];
        }
        else {
            throw new Error('Image does not support tiles or custom regions and sizes.');
        }
    }
    return getTileZoomLevelsFromTilesets(imageSize, tilesets);
}