fix: fix bug with rowsPerStrip (#79)

Author: EscapedGibbon

img/female.tiff

@@ -207,6 +207,22 @@ const files: TiffFile[] = [
     components: 1,
     alpha: false,
   },
+  {
+    name: 'jellybeans.tiff',
+    width: 256,
+    height: 256,
+    bitsPerSample: 8,
+    components: 3,
+    alpha: false,
+  },
+  {
+    name: 'female.tiff',
+    width: 256,
+    height: 256,
+    bitsPerSample: 8,
+    components: 3,
+    alpha: false,
+  },
   // Checks only the first frame of the image.
   {
     name: 'dog.tiff',
@@ -385,7 +401,7 @@ test('should decode image compressed with deflate algorithm', () => {
   });
 });
 
-test('should decode basic 2x2 1-bit image ', () => {
+test('should decode basic 2x2 1-bit image', () => {
   const decoded = decode(readImage('bw1bit.tif'));
 
   expect(decoded).toHaveLength(1);
@@ -500,3 +516,19 @@ test('should decode multiframe image', () => {
   expect(decoded[1].samplesPerPixel).toBe(2);
   expect(decoded[1].data.slice(352, 384)).toStrictEqual(secondFrameTwelvethRow);
 });
+
+test('should decode image with undefined rowsPerStrip', () => {
+  const decodedFemale = decode(readImage('female.tiff'));
+
+  expect(decodedFemale[0].rowsPerStrip).toStrictEqual(2 ** 32 - 1);
+  expect(decodedFemale[0].data.slice(0, 10)).toStrictEqual(
+    new Uint8Array([94, 0, 115, 27, 61, 103, 26, 60, 104, 27]),
+  );
+
+  const decodedJellybeans = decode(readImage('jellybeans.tiff'));
+
+  expect(decodedJellybeans[0].rowsPerStrip).toStrictEqual(2 ** 32 - 1);
+  expect(decodedJellybeans[0].data.slice(0, 10)).toStrictEqual(
+    new Uint8Array([139, 132, 90, 141, 136, 92, 142, 131, 89, 143]),
+  );
+});

img/jellybeans.tiff

@@ -293,6 +293,7 @@ export default class TIFFDecoder extends IOBuffer {
       ifd.bitsPerSample !== 1
         ? width * ifd.samplesPerPixel * height
         : Math.ceil((width * ifd.samplesPerPixel) / 8) * height;
+
     // Compressed Strip Layout
     const stripOffsets = ifd.stripOffsets;
     const stripByteCounts = ifd.stripByteCounts || guessStripByteCounts(ifd);
@@ -302,6 +303,7 @@ export default class TIFFDecoder extends IOBuffer {
       ifd.bitsPerSample !== 1
         ? width * ifd.samplesPerPixel * ifd.rowsPerStrip
         : Math.ceil((width * ifd.samplesPerPixel) / 8) * ifd.rowsPerStrip;
+
     const readSamples = this.createSampleReader(
       ifd.sampleFormat,
       ifd.bitsPerSample,

src/__tests__/decode.test.ts

@@ -91,7 +91,7 @@ export default class TiffIfd extends Ifd {
     return this.get('SamplesPerPixel') || 1;
   }
   public get rowsPerStrip(): number {
-    return this.get('RowsPerStrip');
+    return this.get('RowsPerStrip') || 2 ** 32 - 1;
   }
   public get stripByteCounts(): number[] {
     return alwaysArray(this.get('StripByteCounts'));