feat(ios-image-source): standardize quality scale in image-source (#5517)

* feat(ios-image-source): standardize quality scale in image-source for both platforms

Normalize quality in saveToFile and toBase64String to follow 0-100 scale - standardize implementation on both platforms

closes #5474

tests/app/image-source/image-source-tests.ts

@@ -54,6 +54,15 @@ export function testSaveToFile() {
     TKUnit.assert(fs.File.exists(path), "Image not saved to file");
 }
 
+export function testSaveToFile_WithQuality() {
+    const img = imageSource.fromFile(imagePath);
+    const folder = fs.knownFolders.documents();
+    const path = fs.path.join(folder.path, "test.png");
+    const saved = img.saveToFile(path, "png", 70);
+    TKUnit.assert(saved, "Image not saved to file");
+    TKUnit.assert(fs.File.exists(path), "Image not saved to file");
+}
+
 export function testFromFile() {
     // >> imagesource-load-local
     const folder = fs.knownFolders.documents();
@@ -187,6 +196,16 @@ export function testBase64Encode_PNG() {
         "Base 64 encoded PNG");
 }
 
+export function testBase64Encode_PNG_WithQuality() {
+    const img = imageSource.fromFile(smallImagePath);
+    let base64String = img.toBase64String("png", 80);
+    base64String = base64String.substr(0, expectedPngStart.length);
+    TKUnit.assertEqual(
+        base64String,
+        expectedPngStart,
+        "Base 64 encoded PNG");
+}
+
 export function testBase64Encode_JPEG() {
     const img = imageSource.fromFile(smallImagePath);
 
@@ -199,6 +218,18 @@ export function testBase64Encode_JPEG() {
         "Base 64 encoded JPEG");
 }
 
+export function testBase64Encode_JPEG_With_Quality() {
+    const img = imageSource.fromFile(smallImagePath);
+
+    let base64String = img.toBase64String("jpeg", 80);
+    base64String = base64String.substr(0, expectedJpegStart.length);
+
+    TKUnit.assertEqual(
+        base64String,
+        expectedJpegStart,
+        "Base 64 encoded JPEG");
+}
+
 export function testLoadFromBase64Encode_JPEG() {
     // >> imagesource-from-base-string
     let img: imageSource.ImageSource;

tns-core-modules/image-source/image-source.d.ts

@@ -98,14 +98,14 @@ export class ImageSource {
     * Saves this instance to the specified file, using the provided image format and quality.
     * @param path The path of the file on the file system to save to.
     * @param format The format (encoding) of the image.
-    * @param quality Optional parameter, specifying the quality of the encoding. Defaults to the maximum available quality.
+    * @param quality Optional parameter, specifying the quality of the encoding. Defaults to the maximum available quality. Quality varies on a scale of 0 to 100.
     */
     saveToFile(path: string, format: "png" | "jpeg" | "jpg", quality?: number): boolean;
 
     /**
      * Converts the image to base64 encoded string, using the provided image format and quality.
      * @param format The format (encoding) of the image.
-     * @param quality Optional parameter, specifying the quality of the encoding. Defaults to the maximum available quality.
+     * @param quality Optional parameter, specifying the quality of the encoding. Defaults to the maximum available quality. Quality varies on a scale of 0 to 100.
      */
     toBase64String(format: "png" | "jpeg" | "jpg", quality?: number): string;
 }

tns-core-modules/image-source/image-source.ios.ts

@@ -130,6 +130,10 @@ export class ImageSource implements ImageSourceDefinition {
             return false;
         }
 
+        if (quality) {
+            quality = quality - 0 / (100 - 0);  // Normalize quality on a scale of 0 to 1
+        }
+
         const data = getImageData(this.ios, format, quality);
         if (data) {
             return NSFileManager.defaultManager.createFileAtPathContentsAttributes(path, data, null);
@@ -144,6 +148,10 @@ export class ImageSource implements ImageSourceDefinition {
             return res;
         }
 
+        if (quality) {
+            quality = quality - 0 / (100 - 0);  // Normalize quality on a scale of 0 to 1
+        }
+
         const data = getImageData(this.ios, format, quality);
         if (data) {
             res = data.base64Encoding();