Start with highest quality compression and find a suitable size (#33)

src/lib/images.ts

@@ -1,11 +1,13 @@
 import RNFetchBlob from 'rn-fetch-blob'
 import ImageResizer from '@bam.tech/react-native-image-resizer'
+import {Image as PickedImage} from 'react-native-image-crop-picker'
 
 export interface DownloadAndResizeOpts {
   uri: string
   width: number
   height: number
   mode: 'contain' | 'cover' | 'stretch'
+  maxSize: number
   timeout: number
 }
 
@@ -41,21 +43,55 @@ export async function downloadAndResize(opts: DownloadAndResizeOpts) {
       localUri = `file://${localUri}`
     }
 
-    const resizeRes = await ImageResizer.createResizedImage(
-      localUri,
-      opts.width,
-      opts.height,
-      'JPEG',
-      0.7,
-      undefined,
-      undefined,
-      undefined,
-      {mode: opts.mode},
-    )
-    return resizeRes
+    return await resize(localUri, opts)
   } finally {
     if (downloadRes) {
       downloadRes.flush()
     }
   }
 }
+
+export interface ResizeOpts {
+  width: number
+  height: number
+  mode: 'contain' | 'cover' | 'stretch'
+  maxSize: number
+}
+
+export async function resize(localUri: string, opts: ResizeOpts) {
+  for (let i = 0; i < 9; i++) {
+    const quality = 1.0 - i / 10
+    const resizeRes = await ImageResizer.createResizedImage(
+      localUri,
+      opts.width,
+      opts.height,
+      'JPEG',
+      quality,
+      undefined,
+      undefined,
+      undefined,
+      {mode: opts.mode},
+    )
+    console.log(quality, resizeRes)
+    if (resizeRes.size < opts.maxSize) {
+      return resizeRes
+    }
+  }
+  throw new Error(
+    `This image is too big! We couldn't compress it down to ${opts.maxSize} bytes`,
+  )
+}
+
+export async function compressIfNeeded(img: PickedImage, maxSize: number) {
+  const origUri = `file://${img.path}`
+  if (img.size < maxSize) {
+    return origUri
+  }
+  const resizeRez = await resize(origUri, {
+    width: img.width,
+    height: img.height,
+    mode: 'stretch',
+    maxSize,
+  })
+  return resizeRez.uri
+}