add possible Canvas.toBlob for canvasToFile function

Author: Donaldcwl

lib/utils.js

@@ -139,11 +139,14 @@ export async function drawFileInCanvas (file) {
  */
 export async function canvasToFile (canvas, fileType, fileName, fileLastModified, quality = 1) {
   let file
-  if (typeof OffscreenCanvas === 'function' && canvas instanceof OffscreenCanvas) {
+  if (typeof OffscreenCanvas === 'function' && canvas instanceof OffscreenCanvas) { // checked on Win Chrome 83, MacOS Chrome 83
     file = await canvas.convertToBlob({ type: fileType, quality })
     file.name = fileName
     file.lastModified = fileLastModified
-  } else {
+  // some browser do not support quality parameter, see: https://developer.mozilla.org/en-US/docs/Web/API/HTMLCanvasElement/toBlob
+  // } else if (typeof canvas.toBlob === 'function') {
+  //   file = await new Promise(resolve => canvas.toBlob(resolve, fileType, quality))
+  } else { // checked on Win Edge 44, Win IE 11, Win Firefox 76, MacOS Firefox 77, MacOS Safari 13.1
     const dataUrl = canvas.toDataURL(fileType, quality)
     file = await getFilefromDataUrl(dataUrl, fileName, fileLastModified)
   }
@@ -257,14 +260,29 @@ export function followExifOrientation (canvas, exifOrientation) {
 
   // transform context before drawing image
   switch (exifOrientation) {
-    case 2: ctx.transform(-1, 0, 0, 1, width, 0); break;
-    case 3: ctx.transform(-1, 0, 0, -1, width, height); break;
-    case 4: ctx.transform(1, 0, 0, -1, 0, height); break;
-    case 5: ctx.transform(0, 1, 1, 0, 0, 0); break;
-    case 6: ctx.transform(0, 1, -1, 0, height, 0); break;
-    case 7: ctx.transform(0, -1, -1, 0, height, width); break;
-    case 8: ctx.transform(0, -1, 1, 0, 0, width); break;
-    default: break;
+    case 2:
+      ctx.transform(-1, 0, 0, 1, width, 0)
+      break
+    case 3:
+      ctx.transform(-1, 0, 0, -1, width, height)
+      break
+    case 4:
+      ctx.transform(1, 0, 0, -1, 0, height)
+      break
+    case 5:
+      ctx.transform(0, 1, 1, 0, 0, 0)
+      break
+    case 6:
+      ctx.transform(0, 1, -1, 0, height, 0)
+      break
+    case 7:
+      ctx.transform(0, -1, -1, 0, height, width)
+      break
+    case 8:
+      ctx.transform(0, -1, 1, 0, 0, width)
+      break
+    default:
+      break
   }
 
   ctx.drawImage(canvas, 0, 0, width, height)