fix: sửa export/gps/UI theo FIX_PLAN + chụp ảnh camera thật (takePhoto)

- export: encodeToBase64 thay SkData.toString, dùng expo-media-library/legacy
- GPS ảnh gốc: resolver EXIF -> MediaLibrary -> device (ACCESS_MEDIA_LOCATION), tag nguồn watermark
- contrast vào color matrix (có hiệu lực mono), ẩn highlight/shadow, denoise/clarity ghi chú export-only
- init session tuần tự, tách setState lồng nhau, share file bằng expo-sharing, DONE lưu gallery
- Phase 4A: chụp camera thật qua vision-camera takePhoto rồi export filter

src/utils/exportEngine.ts

@@ -1,19 +1,28 @@
 import { Skia, ImageFormat, BlendMode, TileMode } from '@shopify/react-native-skia';
 import * as FileSystem from 'expo-file-system/legacy';
-import * as MediaLibrary from 'expo-media-library';
+import * as MediaLibrary from 'expo-media-library/legacy';
 import { Asset } from 'expo-asset';
 import { Recipe, GPSInfo, FrameId } from '../types';
 import { getSkiaColorMatrix } from './colorUtils';
 import { drawFrameOnCanvas } from './frameUtils';
 import { formatCoordinate } from './locationUtils';
 
+export interface ExportResult {
+  uri: string;
+  savedToLibrary: boolean;
+}
+
+// Fixed filename: every export overwrites the previous one, so temp files
+// never accumulate in the cache directory.
+const EXPORT_FILE = `${FileSystem.cacheDirectory}camrecipe_pro_last_export.jpg`;
+
 export async function processAndExportPhoto(
   sourceUri: string,
   recipe: Recipe,
   frameId: FrameId,
   useGeotag: boolean,
   gpsInfo: GPSInfo | null
-): Promise<string | null> {
+): Promise<ExportResult | null> {
   try {
     // 1. Read source image file into Skia
     const skiaData = await Skia.Data.fromURI(sourceUri);
@@ -47,6 +56,7 @@ export async function processAndExportPhoto(
     const matrix = getSkiaColorMatrix(
       recipe.baseFilter,
       adjustments.exposure,
+      adjustments.contrast,
       adjustments.saturation,
       adjustments.temperature,
       adjustments.tint,
@@ -55,9 +65,9 @@ export async function processAndExportPhoto(
     const colorFilter = Skia.ColorFilter.MakeMatrix(matrix);
     paint.setColorFilter(colorFilter);
 
-    // 4. Highlight & Shadow / Denoise / Clarity Image Filters
+    // 4. Denoise / Clarity Image Filters (export-only enhancements)
     let imageFilter = null;
-    
+
     // Denoise (Subtle blur to smooth noise)
     if (adjustments.denoise > 0) {
       const sigma = (adjustments.denoise / 10) * 0.6; // max 0.6px
@@ -134,12 +144,12 @@ export async function processAndExportPhoto(
       if (!fontAsset.localUri) {
         await fontAsset.downloadAsync();
       }
-      
+
       const fontData = await FileSystem.readAsStringAsync(fontAsset.localUri!, {
         encoding: FileSystem.EncodingType.Base64,
       });
       const typeface = Skia.Typeface.MakeFreeTypeFaceFromData(Skia.Data.fromBase64(fontData));
-      
+
       if (typeface) {
         const fontSize = Math.round(width * 0.032); // 3.2% of image width
         const font = Skia.Font(typeface, fontSize);
@@ -150,42 +160,53 @@ export async function processAndExportPhoto(
         const lonStr = formatCoordinate(gpsInfo.longitude, 'lon');
         const locationName = gpsInfo.locality || 'STREET VIEW';
         const timestampStr = new Date(gpsInfo.timestamp).toLocaleDateString('vi-VN');
+        const sourceTag =
+          gpsInfo.source === 'exif'
+            ? 'EXIF'
+            : gpsInfo.source === 'mediaLibrary'
+            ? 'MEDIA LIB'
+            : gpsInfo.source === 'device'
+            ? 'DEVICE GPS'
+            : null;
+        const captionSuffix = sourceTag ? ` | ${sourceTag}` : ' | SS 1/125 f/2.8';
 
         const yOffset = height - (frameId === 'polaroid' ? height * 0.15 : fontSize * 1.5);
         const xOffset = frameId === 'polaroid' ? width * 0.08 : fontSize * 1.2;
 
         canvas.drawText(`📍 ${locationName}`, xOffset, yOffset - fontSize * 2.2, textPaint, font);
         canvas.drawText(`${latStr}, ${lonStr}`, xOffset, yOffset - fontSize * 1.1, textPaint, font);
-        canvas.drawText(`${timestampStr} | SS 1/125 f/2.8`, xOffset, yOffset, textPaint, font);
+        canvas.drawText(`${timestampStr}${captionSuffix}`, xOffset, yOffset, textPaint, font);
       }
     }
 
-    // 9. Snapshot & Encode to JPEG
+    // 9. Snapshot & Encode to JPEG (base64 string, no SkData round-trip)
     const resultImage = surface.makeImageSnapshot();
-    const jpegBytes = resultImage.encodeToBytes(ImageFormat.JPEG, 95);
+    const base64 = resultImage.encodeToBase64(ImageFormat.JPEG, 95);
 
-    if (!jpegBytes) {
-      console.error('Failed to encode image to JPEG bytes');
+    if (!base64) {
+      console.error('Failed to encode image to JPEG');
       return null;
     }
 
-    // 10. Write binary bytes to temporary local file
-    const tempFileUri = `${FileSystem.cacheDirectory}camrecipe_pro_export_${Date.now()}.jpg`;
-    const base64Bytes = Skia.Data.fromBytes(jpegBytes).toString(); // Convert to base64
-    
-    await FileSystem.writeAsStringAsync(tempFileUri, base64Bytes, {
+    // 10. Write binary bytes to temporary local file (overwrites previous export)
+    await FileSystem.writeAsStringAsync(EXPORT_FILE, base64, {
       encoding: FileSystem.EncodingType.Base64,
     });
 
     // 11. Request Media Library permission & Save to device gallery
     const mediaPermission = await MediaLibrary.requestPermissionsAsync();
     if (mediaPermission.granted) {
-      await MediaLibrary.saveToLibraryAsync(tempFileUri);
+      try {
+        await MediaLibrary.saveToLibraryAsync(EXPORT_FILE);
+        return { uri: EXPORT_FILE, savedToLibrary: true };
+      } catch (e) {
+        console.warn('Save to gallery failed:', e);
+      }
     } else {
       console.warn('Media Library permission denied. Image saved to temporary cache only.');
     }
 
-    return tempFileUri;
+    return { uri: EXPORT_FILE, savedToLibrary: false };
   } catch (error) {
     console.error('Error during photo processing and export:', error);
     return null;