supports img smaller than tile size

src/image.ts

@@ -20,15 +20,76 @@ export default class Image {
     x2: number,
     y2: number
   ) {
-    for (let j = y1; j < y2; j++) {
-      for (let i = x1; i < x2; i++) {
-        let index = (y + j - y1) * this.width * 4 + (x + i - x1) * 4;
-        let imageIndex = j * image.width * 4 + i * 4;
-        this.data[index] = image.data[imageIndex];
-        this.data[index + 1] = image.data[imageIndex + 1];
-        this.data[index + 2] = image.data[imageIndex + 2];
-        this.data[index + 3] = image.data[imageIndex + 3];
-      }
+    const width = x2 - x1;
+    for (let j = 0; j < y2 - y1; j++) {
+      const destIndex = (y + j) * this.width * 4 + x * 4;
+      const srcIndex = (y1 + j) * image.width * 4 + x1 * 4;
+      this.data.set(
+        image.data.subarray(srcIndex, srcIndex + width * 4),
+        destIndex
+      );
     }
   }
+  padToTileSize(tileSize: number) {
+    let newWidth = this.width;
+    let newHeight = this.height;
+    if (this.width < tileSize) {
+      newWidth = tileSize;
+    }
+    if (this.height < tileSize) {
+      newHeight = tileSize;
+    }
+    if (newWidth === this.width && newHeight === this.height) {
+      return;
+    }
+    const newData = new Uint8Array(newWidth * newHeight * 4);
+    for (let y = 0; y < this.height; y++) {
+      const srcStart = y * this.width * 4;
+      const destStart = y * newWidth * 4;
+      newData.set(
+        this.data.subarray(srcStart, srcStart + this.width * 4),
+        destStart
+      );
+    }
+    if (newWidth > this.width) {
+      const rightColumnIndex = (this.width - 1) * 4;
+      for (let y = 0; y < this.height; y++) {
+        const destRowStart = y * newWidth * 4;
+        const srcPixelIndex = y * this.width * 4 + rightColumnIndex;
+        const padPixel = this.data.subarray(srcPixelIndex, srcPixelIndex + 4);
+        for (let x = this.width; x < newWidth; x++) {
+          const destPixelIndex = destRowStart + x * 4;
+          newData.set(padPixel, destPixelIndex);
+        }
+      }
+    }
+    if (newHeight > this.height) {
+      const bottomRowStart = (this.height - 1) * newWidth * 4;
+      const bottomRow = newData.subarray(
+        bottomRowStart,
+        bottomRowStart + newWidth * 4
+      );
+      for (let y = this.height; y < newHeight; y++) {
+        const destRowStart = y * newWidth * 4;
+        newData.set(bottomRow, destRowStart);
+      }
+    }
+    this.width = newWidth;
+    this.height = newHeight;
+    this.data = newData;
+  }
+  cropToOriginalSize(width: number, height: number) {
+    const newData = new Uint8Array(width * height * 4);
+    for (let y = 0; y < height; y++) {
+      const srcStart = y * this.width * 4;
+      const destStart = y * width * 4;
+      newData.set(
+        this.data.subarray(srcStart, srcStart + width * 4),
+        destStart
+      );
+    }
+    this.width = width;
+    this.height = height;
+    this.data = newData;
+  }
 }

src/worker.js

@@ -37,6 +37,13 @@ self.addEventListener("message", async (e) => {
     return;
   }
   const input = new Img(data.width, data.height, new Uint8Array(data.input));
+  const width_ori = input.width;
+  const height_ori = input.height;
+  input.padToTileSize(data?.tile_size || 64);
+  let withPadding = false;
+  if (input.width !== width_ori || input.height !== height_ori) {
+    withPadding = true;
+  }
   let hasAlpha = data.hasAlpha;
   function sendprogress(progress) {
     if (hasAlpha) {
@@ -223,6 +230,9 @@ self.addEventListener("message", async (e) => {
   } catch (e) {
     postMessage({ alertmsg: e.toString() });
   }
+  if (withPadding) {
+    output.cropToOriginalSize(width_ori * factor, height_ori * factor);
+  }
   const end = Date.now();
   console.log("Time:", end - start);
   await new Promise((resolve) => setTimeout(resolve, 10));