Merge pull request #1275 from formigone/master

Add recipe for resizing captured images

docs/QA.md

@@ -1,5 +1,9 @@
 ## Q & A
 
+ + [meta-data android 26](#meta-data-android-26)
+ + [Manifest merger failed](#when-i-try-to-build-my-project-i-get-following-error)
+ + [How can I resize captured images?](#how-can-i-resize-captured-images)
+
 #### meta-data android 26
 ```
   AndroidManifest.xml:25:13-35 Error:
@@ -29,6 +33,8 @@ Add this to your AndroidManifest.xml:
     >
 ```
 
+---
+
 #### When I try to build my project, I get following error:
 ```
 Execution failed for task ':app:processDebugManifest'.
@@ -58,3 +64,67 @@ dependencies {
     // }
 }
 ```
+
+---
+
+#### How can I resize captured images?
+
+Currently, `RNCamera` does not allow for specifying the desired resolution of the captured image, nor does it natively expose any functionality to resize images.
+One way to achieve this (without any additional dependencies )is using [react-native.ImageEditor.cropImage](https://facebook.github.io/react-native/docs/imageeditor.html#cropimage).
+
+The strategy is:
+
+ 1. Capture an image using `RNCamera`, which uses the device's max resolution.
+ 2. Use `react-native.ImageEditor.cropImage()` to crop the image using the image's native size as the crop size (thus maintaiing the original image), and the desired new size as the `displaySize` attribute (thus resizing the image).
+ 
+```javascript
+import React, { Component } from 'react';
+import { Button, ImageEditor } from 'react-native';
+import { RNCamera } from 'react-native-camera';
+
+class CameraComponent extends Component {
+  // ...
+  
+  capturePicture = function () {
+    if (this.camera) {
+      // 1) Capture the image using RNCamera API
+      this.camera.takePictureAsync(options)
+        .then((capturedImg) => {
+          // 2a) Extract a reference to the captured image, 
+          //    along with its natural dimensions
+          const { uri, width, height } = capturedImg;
+            
+          const cropData = {
+            // 2b) By cropping from (0, 0) to (imgWidth, imgHeight),
+            //    we maintain the original image's dimensions
+            offset: { x: 0, y: 0 },
+            size: { width, height },
+              
+            // 2c) Use the displaySize option to specify the new image size
+            displaySize: { width: RESIZED_WIDTH, height: RESIZED_HEIGHT },
+          };
+        
+          ImageEditor.cropImage(uri, cropData, (resizedImage) => {
+              // resizedImage == 'file:///data/.../img.jpg'
+            }, (error) => {
+              console.error('Error resizing image: ', error.getMessage());
+          });
+        })
+        .catch((error) => {
+          console.log('Could not capture image.', error.getMessage());
+        });
+    }
+  
+  render() {
+    return (
+      <RNCamera
+        ref={ref => (this.camera = ref)}
+        // ...
+      />
+      
+      <Button onPress={() => this.capturePicture()}>Capture</Button>
+    );
+  }
+}
+
+```