Fantasy-Map-Generator/modules/activeZooming.js

window.handleZoom = function (isScaleChanged, isPositionChanged) {
  viewbox.attr("transform", `translate(${viewX} ${viewY}) scale(${scale})`);

  if (isPositionChanged) drawCoordinates();

  if (isScaleChanged) {
    invokeActiveZooming();
    drawScaleBar(scale);
  }

  // zoom image converter overlay
  if (customization === 1) {
    const canvas = document.getElementById("canvas");
    if (!canvas || canvas.style.opacity === "0") return;

    const img = document.getElementById("imageToConvert");
    if (!img) return;

    const ctx = canvas.getContext("2d");
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.setTransform(scale, 0, 0, scale, viewX, viewY);
    ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
  }
};

// active zooming feature
export function invokeActiveZooming() {
  if (coastline.select("#sea_island").size() && +coastline.select("#sea_island").attr("auto-filter")) {
    // toggle shade/blur filter for coatline on zoom
    const filter = scale > 1.5 && scale <= 2.6 ? null : scale > 2.6 ? "url(#blurFilter)" : "url(#dropShadow)";
    coastline.select("#sea_island").attr("filter", filter);
  }

  // rescale labels on zoom
  if (labels.style("display") !== "none") {
    labels.selectAll("g").each(function () {
      if (this.id === "burgLabels") return;
      const desired = +this.dataset.size;
      const relative = Math.max(rn((desired + desired / scale) / 2, 2), 1);
      if (rescaleLabels.checked) this.setAttribute("font-size", relative);

      const hidden = hideLabels.checked && (relative * scale < 6 || relative * scale > 60);
      if (hidden) this.classList.add("hidden");
      else this.classList.remove("hidden");
    });
  }

  // rescale emblems on zoom
  if (emblems.style("display") !== "none") {
    emblems.selectAll("g").each(function () {
      const size = this.getAttribute("font-size") * scale;
      const hidden = hideEmblems.checked && (size < 25 || size > 300);
      if (hidden) this.classList.add("hidden");
      else this.classList.remove("hidden");
      if (!hidden && window.COArenderer && this.children.length && !this.children[0].getAttribute("href"))
        renderGroupCOAs(this);
    });
  }

  // turn off ocean pattern if scale is big (improves performance)
  oceanPattern
    .select("rect")
    .attr("fill", scale > 10 ? "#fff" : "url(#oceanic)")
    .attr("opacity", scale > 10 ? 0.2 : null);

  // change states halo width
  if (!customization) {
    const desired = +statesHalo.attr("data-width");
    const haloSize = rn(desired / scale ** 0.8, 2);
    statesHalo.attr("stroke-width", haloSize).style("display", haloSize > 0.1 ? "block" : "none");
  }

  // rescale map markers
  +markers.attr("rescale") &&
    pack.markers?.forEach(marker => {
      const {i, x, y, size = 30, hidden} = marker;
      const el = !hidden && document.getElementById(`marker${i}`);
      if (!el) return;

      const zoomedSize = Math.max(rn(size / 5 + 24 / scale, 2), 1);
      el.setAttribute("width", zoomedSize);
      el.setAttribute("height", zoomedSize);
      el.setAttribute("x", rn(x - zoomedSize / 2, 1));
      el.setAttribute("y", rn(y - zoomedSize, 1));
    });

  // rescale rulers to have always the same size
  if (ruler.style("display") !== "none") {
    const size = rn((10 / scale ** 0.3) * 2, 2);
    ruler.selectAll("text").attr("font-size", size);
  }
}