feat(ImageSource): resize method (#8678)

nativescript-core/image-source/image-source-common.ts

@@ -0,0 +1,27 @@
+export function getScaledDimensions(
+    width: number,
+    height: number,
+    maxSize: number
+) {
+    if (height >= width) {
+        if (height <= maxSize) {
+            // if image already smaller than the required height
+            return { width, height };
+        }
+
+        return {
+            width: Math.round((maxSize * width) / height),
+            height: maxSize
+        };
+    }
+
+    if (width <= maxSize) {
+        // if image already smaller than the required width
+        return { width, height };
+    }
+
+    return {
+        width: maxSize,
+        height: Math.round((maxSize * height) / width)
+    };
+}