Convert the code in src/core/image.js to use ES6 classes

This removes additional `// eslint-disable-next-line no-shadow` usage, which our old pseudo-classes necessitated.

*Please note:* I'm purposely not doing any `var` to `let`/`const` conversion here, since it's generally better to (if possible) do that automatically on e.g. a directory basis instead.

src/core/image.js

@@ -20,12 +20,11 @@ import { DecodeStream } from "./stream.js";
 import { JpegStream } from "./jpeg_stream.js";
 import { JpxImage } from "./jpx.js";
 
-var PDFImage = (function PDFImageClosure() {
+/**
-  /**
  * Decode and clamp a value. The formula is different from the spec because we
  * don't decode to float range [0,1], we decode it in the [0,max] range.
  */
-  function decodeAndClamp(value, addend, coefficient, max) {
+function decodeAndClamp(value, addend, coefficient, max) {
   value = addend + value * coefficient;
   // Clamp the value to the range
   if (value < 0) {
@@ -34,9 +33,9 @@ var PDFImage = (function PDFImageClosure() {
     value = max;
   }
   return value;
-  }
+}
 
-  /**
+/**
  * Resizes an image mask with 1 component.
  * @param {TypedArray} src - The source buffer.
  * @param {number} bpc - Number of bits per component.
@@ -46,7 +45,7 @@ var PDFImage = (function PDFImageClosure() {
  * @param {number} h2 - New height.
  * @returns {TypedArray} The resized image mask buffer.
  */
-  function resizeImageMask(src, bpc, w1, h1, w2, h2) {
+function resizeImageMask(src, bpc, w1, h1, w2, h2) {
   var length = w2 * h2;
   let dest;
   if (bpc <= 8) {
@@ -77,10 +76,10 @@ var PDFImage = (function PDFImageClosure() {
     }
   }
   return dest;
-  }
+}
 
-  // eslint-disable-next-line no-shadow
+class PDFImage {
-  function PDFImage({
+  constructor({
     xref,
     res,
     image,
@@ -247,11 +246,12 @@ var PDFImage = (function PDFImageClosure() {
       }
     }
   }
+
   /**
    * Handles processing of image data and returns the Promise that is resolved
    * with a PDFImage when the image is ready to be used.
    */
-  PDFImage.buildImage = async function ({
+  static async buildImage({
     xref,
     res,
     image,
@@ -286,9 +286,9 @@ var PDFImage = (function PDFImageClosure() {
       pdfFunctionFactory,
       localColorSpaceCache,
     });
-  };
+  }
 
-  PDFImage.createMask = function ({
+  static createMask({
     imgArray,
     width,
     height,
@@ -340,16 +340,15 @@ var PDFImage = (function PDFImageClosure() {
     }
 
     return { data, width, height };
-  };
+  }
 
-  PDFImage.prototype = {
   get drawWidth() {
     return Math.max(
       this.width,
       (this.smask && this.smask.width) || 0,
       (this.mask && this.mask.width) || 0
     );
-    },
+  }
 
   get drawHeight() {
     return Math.max(
@@ -357,7 +356,7 @@ var PDFImage = (function PDFImageClosure() {
       (this.smask && this.smask.height) || 0,
       (this.mask && this.mask.height) || 0
     );
-    },
+  }
 
   decodeBuffer(buffer) {
     var bpc = this.bpc;
@@ -387,7 +386,7 @@ var PDFImage = (function PDFImageClosure() {
         index++;
       }
     }
-    },
+  }
 
   getComponents(buffer) {
     var bpc = this.bpc;
@@ -477,7 +476,7 @@ var PDFImage = (function PDFImageClosure() {
       }
     }
     return output;
-    },
+  }
 
   fillOpacity(rgbaBuf, width, height, actualHeight, image) {
     if (
@@ -499,14 +498,7 @@ var PDFImage = (function PDFImageClosure() {
       alphaBuf = new Uint8ClampedArray(sw * sh);
       smask.fillGrayBuffer(alphaBuf);
       if (sw !== width || sh !== height) {
-          alphaBuf = resizeImageMask(
+        alphaBuf = resizeImageMask(alphaBuf, smask.bpc, sw, sh, width, height);
-            alphaBuf,
-            smask.bpc,
-            sw,
-            sh,
-            width,
-            height
-          );
       }
     } else if (mask) {
       if (mask instanceof PDFImage) {
@@ -522,14 +514,7 @@ var PDFImage = (function PDFImageClosure() {
         }
 
         if (sw !== width || sh !== height) {
-            alphaBuf = resizeImageMask(
+          alphaBuf = resizeImageMask(alphaBuf, mask.bpc, sw, sh, width, height);
-              alphaBuf,
-              mask.bpc,
-              sw,
-              sh,
-              width,
-              height
-            );
         }
       } else if (Array.isArray(mask)) {
         // Color key mask: if any of the components are outside the range
@@ -564,7 +549,7 @@ var PDFImage = (function PDFImageClosure() {
         rgbaBuf[j] = 255;
       }
     }
-    },
+  }
 
   undoPreblend(buffer, width, height) {
     if (
@@ -600,7 +585,7 @@ var PDFImage = (function PDFImageClosure() {
       buffer[i + 1] = (buffer[i + 1] - matteG) * k + matteG;
       buffer[i + 2] = (buffer[i + 2] - matteB) * k + matteB;
     }
-    },
+  }
 
   createImageData(forceRGBA = false) {
     var drawWidth = this.drawWidth;
@@ -747,7 +732,7 @@ var PDFImage = (function PDFImageClosure() {
     }
 
     return imgData;
-    },
+  }
 
   fillGrayBuffer(buffer) {
     if (
@@ -803,7 +788,7 @@ var PDFImage = (function PDFImageClosure() {
     for (i = 0; i < length; ++i) {
       buffer[i] = scale * comps[i];
     }
-    },
+  }
 
   getImageBytes(length, drawWidth, drawHeight, forceRGB = false) {
     this.image.reset();
@@ -811,9 +796,7 @@ var PDFImage = (function PDFImageClosure() {
     this.image.drawHeight = drawHeight || this.height;
     this.image.forceRGB = !!forceRGB;
     return this.image.getBytes(length, /* forceClamped = */ true);
-    },
+  }
-  };
+}
-  return PDFImage;
-})();
 
 export { PDFImage };