Fetch binary chunk and draw on canvas

web/src/harmonie/draw/bitmask.ts

@@ -0,0 +1,34 @@
+import { u8ToBits } from '../../helpers/u8ToBits.js'
+import { MeteoGrid } from '../interfaces.js'
+
+export function applyBitmask(
+    grid: MeteoGrid,
+    buffer: Uint8Array,
+    bitmask: Uint8Array,
+    bytesPerPoint: number,
+): Uint8Array {
+    const newBuffer = new Uint8Array(grid.rows * grid.cols * bytesPerPoint)
+
+    let i=0, bufferI=0
+    for (; i<bitmask.length; i++) {
+        const bits = u8ToBits(bitmask[i])
+        for (let bitI=0; bitI<bits.length; bitI++) {
+            const newI = (i*8 + bitI) * bytesPerPoint
+            if (newI >= newBuffer.length) {
+                break;
+            }
+            if (bits[bitI]) {
+                newBuffer[newI] = buffer[bufferI]
+                newBuffer[newI+1] = buffer[bufferI+1]
+                newBuffer[newI+2] = buffer[bufferI+2]
+                bufferI += bytesPerPoint
+            } else {
+                newBuffer[newI] = 255
+                newBuffer[newI+1] = 255
+                newBuffer[newI+2] = 255
+            }
+        }
+    }
+
+    return newBuffer
+}