validate ignoreMask as pixel data

Author: mourner

README.md

@@ -52,7 +52,7 @@ Implements ideas from the following papers:
 - `diffMask` — Draw the diff over a transparent background (a mask), rather than over the original image. Will not draw anti-aliased pixels (if detected).
 - `checkerboard` — Blend semi-transparent pixels against a checkerboard pattern when comparing (`true`) rather than plain white (`false`), avoiding false matches between colors that only look alike over one background. `true` by default.
 - `windowSize` — If set to a finite number `N`, return the maximum number of differing pixels in any `N`×`N` sliding window instead of the total count (see below). `Infinity` by default.
-- `ignoreMask` — A `Uint8Array` with one value per pixel (`width * height` long); pixels with a non-zero value are excluded from the comparison and drawn as unchanged in the diff output. Not set by default.
+- `ignoreMask` — A `Uint8Array`, `Uint8ClampedArray` or `Buffer` with one value per pixel (`width * height` long); pixels with a non-zero value are excluded from the comparison and drawn as unchanged in the diff output. Not set by default.
 
 Compares two images, writes the output diff and returns the number of mismatched pixels.
 

index.js

@@ -33,7 +33,8 @@ export default function pixelmatch(img1, img2, output, width, height, options =
         ignoreMask
     } = options;
 
-    if (!isPixelData(img1) || !isPixelData(img2) || (output && !isPixelData(output)))
+    if (!isPixelData(img1) || !isPixelData(img2) || (output && !isPixelData(output)) ||
+        (ignoreMask && !isPixelData(ignoreMask)))
         throw new Error('Image data: Uint8Array, Uint8ClampedArray or Buffer expected.');
 
     if (img1.length !== img2.length || (output && output.length !== img1.length))

test/test.js

@@ -163,6 +163,13 @@ test('throws error if provided wrong image data format', () => {
     assert.throws(() => match(bad, arr, null, 20, 20), err);
     assert.throws(() => match(arr, bad, null, 20, 20), err);
     assert.throws(() => match(arr, arr, bad, 20, 20), err);
+    assert.throws(() => match(arr, arr, null, 20, 20, {ignoreMask: new Array(20 * 20).fill(0)}), err);
+    assert.throws(() => match(arr, arr, null, 20, 20, {ignoreMask: new Float32Array(20 * 20)}), err);
+});
+
+test('throws error if ignore mask size does not match width and height', () => {
+    const arr = new Uint8Array(4 * 20 * 20);
+    assert.throws(() => match(arr, arr, null, 20, 20, {ignoreMask: new Uint8Array(20 * 20 * 4)}), 'Ignore mask size does not match');
 });
 
 function diffTest(imgPath1, imgPath2, diffPath, options, expectedMismatch) {