Present ExposureTime, ShutterSpeedValue correctly when value is more …

…than 1 sec #201
mattiasw · Aug 2, 2022 · 8f760cd · 8f760cd
1 parent 75825b5
commit 8f760cd
Show file tree

Hide file tree

Showing 4 changed files with 14 additions and 3 deletions.
diff --git a/dist/exif-reader.js b/dist/exif-reader.js
diff --git a/dist/exif-reader.js.map b/dist/exif-reader.js.map
diff --git a/src/tag-names-exif-ifd.js b/src/tag-names-exif-ifd.js
@@ -9,6 +9,9 @@ export default {
     0x829a: {
         'name': 'ExposureTime',
         'description': (value) => {
+            if (value[0] >= value[1]) {
+                return `${Math.round(value[0] / value[1])}`;
+            }
             if (value[0] !== 0) {
                 return `1/${Math.round(value[1] / value[0])}`;
             }
@@ -105,7 +108,11 @@ export default {
     0x9201: {
         'name': 'ShutterSpeedValue',
         'description': (value) => {
-            return `1/${Math.round(Math.pow(2, value[0] / value[1]))}`;
+            const denominator = Math.pow(2, value[0] / value[1]);
+            if (denominator <= 1) {
+                return `${Math.round(1 / denominator)}`;
+            }
+            return `1/${Math.round(denominator)}`;
         }
     },
     0x9202: {

diff --git a/test/unit/tag-names-exif-ifd-spec.js b/test/unit/tag-names-exif-ifd-spec.js
@@ -11,6 +11,8 @@ describe('tag-names-exif-ifd', () => {
     it('should report correct name and description for ExposureTime', () => {
         expect(TagNamesExifIfd[0x829a].name).to.equal('ExposureTime');
         expect(TagNamesExifIfd[0x829a].description([4, 1000])).to.equal('1/250');
+        expect(TagNamesExifIfd[0x829a].description([6, 1])).to.equal('6');
+        expect(TagNamesExifIfd[0x829a].description([1, 1])).to.equal('1');
         expect(TagNamesExifIfd[0x829a].description([0, 1000])).to.equal('0/1000');
     });
 
@@ -130,6 +132,8 @@ describe('tag-names-exif-ifd', () => {
     it('should have tag ShutterSpeedValue', () => {
         expect(TagNamesExifIfd[0x9201].name).to.equal('ShutterSpeedValue');
         expect(TagNamesExifIfd[0x9201].description([46435, 9999])).to.equal('1/25');
+        expect(TagNamesExifIfd[0x9201].description([-2584963, 1000000])).to.equal('6');
+        expect(TagNamesExifIfd[0x9201].description([0, 1])).to.equal('1');
         expect(TagNamesExifIfd[0x9201].description([2000, 0])).to.equal('1/Infinity');
     });