Extract map unit functions

1 files changed, 52 insertions, 0 deletions

diff --git a/modern/src/map/mapUtil.js b/modern/src/map/mapUtil.js
new file mode 100644
index 0000000..614234b
--- /dev/null
+++ b/modern/src/map/mapUtil.js
@@ -0,0 +1,52 @@
+export const loadImage = (url) => {
+  return new Promise(imageLoaded => {
+    const image = new Image();
+    image.onload = () => imageLoaded(image);
+    image.src = url;
+  });
+};
+
+export const loadIcon = async (key, background, url) => {
+  const image = await loadImage(url);
+  const pixelRatio = window.devicePixelRatio;
+
+  const canvas = document.createElement('canvas');
+  canvas.width = background.width * pixelRatio;
+  canvas.height = background.height * pixelRatio;
+  canvas.style.width = `${background.width}px`;
+  canvas.style.height = `${background.height}px`;
+
+  const context = canvas.getContext('2d');
+  context.drawImage(background, 0, 0, canvas.width, canvas.height);
+
+  const iconRatio = 0.5;
+  const imageWidth = canvas.width * iconRatio;
+  const imageHeight = canvas.height * iconRatio;
+  context.drawImage(image, (canvas.width - imageWidth) / 2, (canvas.height - imageHeight) / 2, imageWidth, imageHeight);
+
+  return context.getImageData(0, 0, canvas.width, canvas.height);
+};
+
+export const calculateBounds = features => {
+  if (features && features.length) {
+    const first = features[0].geometry.coordinates;
+    const bounds = [[...first], [...first]];
+    for (let feature of features) {
+      const longitude = feature.geometry.coordinates[0]
+      const latitude = feature.geometry.coordinates[1]
+      if (longitude < bounds[0][0]) {
+        bounds[0][0] = longitude;
+      } else if (longitude > bounds[1][0]) {
+        bounds[1][0] = longitude;
+      }
+      if (latitude < bounds[0][1]) {
+        bounds[0][1] = latitude;
+      } else if (latitude > bounds[1][1]) {
+        bounds[1][1] = latitude;
+      }
+    }
+    return bounds;
+  } else {
+    return null;
+  }
+}