Merge pull request #330 from adkenyon/a11y-fallback-for-reduce-transparency

Fallback background color for A11y reduce transparency

README.md

@@ -95,6 +95,8 @@ import { BlurView, VibrancyView } from "@react-native-community/blur";
     - `ultraThinMaterialLight` - An adaptable blur effect that creates the appearance of an ultra-thin material.
 - `blurAmount` (Default: 10, Number)
   - `0-100` - Adjusts blur intensity
+- `reducedTransparencyFallbackColor` (Color) (iOS only)
+  - `black, white, #rrggbb, etc` - background color to use if accessibility setting ReduceTransparency is enabled
 
 > Note: The maximum `blurAmount` on Android is 32, so higher values will be clamped to 32.
 
@@ -122,6 +124,7 @@ export default class Menu extends Component {
           viewRef={this.state.viewRef}
           blurType="light"
           blurAmount={10}
+          reducedTransparencyFallbackColor="white"
         />
         <Text>I'm the non blurred text because I got rendered on top of the BlurView</Text>
       </View>
@@ -146,9 +149,11 @@ const styles = StyleSheet.create({
 
 In this example, the `Image` component will be blurred, because the `BlurView` in positioned on top. But the `Text` will stay unblurred.
 
+If the [accessibility setting `Reduce Transparency`](https://support.apple.com/guide/iphone/display-settings-iph3e2e1fb0/ios) is enabled the `BlurView` will use `reducedTransparencyFallbackColor` as it's background color rather than blurring. If no `reducedTransparencyFallbackColor` is provided, the`BlurView`will use the default fallback color (white, black, or grey depending on `blurType`)
+
 ### VibrancyView
 
-**Uses the same properties as `BlurView` (`blurType` and `blurAmount`).**
+**Uses the same properties as `BlurView` (`blurType`, `blurAmount`, and `reducedTransparencyFallbackColor`).**
 
 > The vibrancy effect lets the content underneath a blurred view show through more vibrantly
 

example/App.js

@@ -60,6 +60,7 @@ export default class Basic extends Component {
           <BlurView
             blurType={this.state.blurBlurType}
             blurAmount={100}
+            reducedTransparencyFallbackColor={'pink'}
             style={[styles.blurView]}>
             <Text style={[styles.text, { color: tintColor }]}>
               Blur component ({platform})
@@ -84,6 +85,7 @@ export default class Basic extends Component {
           <VibrancyView
             blurType={this.state.vibrancyBlurType}
             blurAmount={10}
+            reducedTransparencyFallbackColor={'pink'}
             style={[styles.container, styles.blurContainer]}>
 
             <Text style={styles.text}>

index.d.ts

@@ -2,7 +2,7 @@ import * as React from "react";
 import { StyleProp, ViewStyle } from "react-native";
 
 export interface BlurViewProperties {
-  blurType:
+  blurType?:
     | "xlight"
     | "light"
     | "dark"
@@ -28,6 +28,7 @@ export interface BlurViewProperties {
     // tvOS only
     | "extraDark"
   blurAmount?: number // 0 - 100
+  reducedTransparencyFallbackColor?: string
   style?: StyleProp<ViewStyle>
   blurRadius?: number
   downsampleFactor?: number

index.js.flow

@@ -33,8 +33,9 @@ export type BlurType =
   | 'extraDark';
 
 export type BlurViewProps = {
-  blurType: BlurType,
-  blurAmount: number, // 0 - 100
+  blurType?: BlurType,
+  blurAmount?: number, // 0 - 100,
+  reducedTransparencyFallbackColor?: String,
   style?: ?ViewStyleProp,
 };
 

ios/BlurView.h

@@ -3,11 +3,15 @@
 
 @interface BlurView : UIView
 
-@property (nonatomic, copy) NSString *blurType;
-@property (nonatomic, copy) NSNumber *blurAmount;
+@property (nonatomic, copy, nullable) NSString *blurType;
+@property (nonatomic, copy, nullable) NSNumber *blurAmount;
+@property (nonatomic, copy, nullable) UIColor *reducedTransparencyFallbackColor;
 
-@property (nonatomic, strong) BlurEffectWithAmount *blurEffect;
-@property (nonatomic, strong) UIVisualEffectView *blurEffectView;
+@property (nonatomic, strong, nullable) BlurEffectWithAmount *blurEffect;
+@property (nonatomic, strong, nullable) UIVisualEffectView *blurEffectView;
+@property (nonatomic, strong, nullable) UIView *reducedTransparencyFallbackView;
 
 - (void)updateBlurEffect;
+- (void)updateFallbackView;
+- (BOOL)useReduceTransparencyFallback;
 @end

ios/BlurView.m

@@ -7,15 +7,33 @@
 
 @implementation BlurView
 
-- (instancetype)initWithFrame:(CGRect)frame {
+- (instancetype)init
+{
+  if (self = [super init]) {
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                          selector:@selector(reduceTransparencyStatusDidChange:)
+                                          name:UIAccessibilityReduceTransparencyStatusDidChangeNotification
+                                          object:nil];
+  }
+
+  return self;
+}
+
+- (instancetype)initWithFrame:(CGRect)frame
+{
   if (self = [super initWithFrame:frame]) {
     self.blurEffectView = [[UIVisualEffectView alloc] init];
     self.blurEffectView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
     self.blurEffectView.frame = frame;
 
+    self.reducedTransparencyFallbackView = [[UIView alloc] init];
+    self.reducedTransparencyFallbackView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
+    self.reducedTransparencyFallbackView.frame = frame;
+
     self.blurAmount = @10;
     self.blurType = @"dark";
     [self updateBlurEffect];
+    [self updateFallbackView];
 
     self.clipsToBounds = true;
 
@@ -25,10 +43,16 @@
   return self;
 }
 
+- (void)dealloc
+{
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+}
+
 - (void)layoutSubviews
 {
   [super layoutSubviews];
   self.blurEffectView.frame = self.bounds;
+  self.reducedTransparencyFallbackView.frame = self.bounds;
 }
 
 - (void)setBlurType:(NSString *)blurType
@@ -47,6 +71,13 @@
   }
 }
 
+- (void)setReducedTransparencyFallbackColor:(nullable UIColor *)reducedTransparencyFallbackColor
+{
+  if (reducedTransparencyFallbackColor && ![self.reducedTransparencyFallbackColor isEqual:reducedTransparencyFallbackColor]) {
+    _reducedTransparencyFallbackColor = reducedTransparencyFallbackColor;
+    [self updateFallbackView];
+  }
+}
 
 - (UIBlurEffectStyle)blurEffectStyle
 {
@@ -89,6 +120,11 @@
   return UIBlurEffectStyleDark;
 }
 
+- (BOOL)useReduceTransparencyFallback
+{
+  return UIAccessibilityIsReduceTransparencyEnabled() == YES && self.reducedTransparencyFallbackColor != NULL;
+}
+
 - (void)updateBlurEffect
 {
   UIBlurEffectStyle style = [self blurEffectStyle];
@@ -96,4 +132,32 @@
   self.blurEffectView.effect = self.blurEffect;
 }
 
+- (void)updateFallbackView
+{
+  if ([self useReduceTransparencyFallback]) {
+    if (![self.subviews containsObject:self.reducedTransparencyFallbackView]) {
+      [self insertSubview:self.reducedTransparencyFallbackView atIndex:0];
+    }
+
+    if ([self.subviews containsObject:self.blurEffectView]) {
+      [self.blurEffectView removeFromSuperview];
+    }
+  } else {
+    if ([self.subviews containsObject:self.reducedTransparencyFallbackView]) {
+      [self.reducedTransparencyFallbackView removeFromSuperview];
+    }
+
+    if (![self.subviews containsObject:self.blurEffectView]) {
+      [self insertSubview:self.blurEffectView atIndex:0];
+    }
+  }
+
+  self.reducedTransparencyFallbackView.backgroundColor = self.reducedTransparencyFallbackColor;
+}
+
+- (void)reduceTransparencyStatusDidChange:(__unused NSNotification *)notification
+{
+  [self updateFallbackView];
+}
+
 @end

ios/BlurViewManager.m

@@ -12,5 +12,6 @@ RCT_EXPORT_MODULE();
 
 RCT_EXPORT_VIEW_PROPERTY(blurType, NSString);
 RCT_EXPORT_VIEW_PROPERTY(blurAmount, NSNumber);
+RCT_EXPORT_VIEW_PROPERTY(reducedTransparencyFallbackColor, UIColor);
 
 @end

ios/VibrancyView.m

@@ -30,8 +30,12 @@
 }
 
 - (void)insertReactSubview:(id<RCTComponent>)subview atIndex:(NSInteger)atIndex {
+  if ([self useReduceTransparencyFallback]) {
+    [self addSubview:(UIView*)subview];
+  } else {
     [self.vibrancyEffectView.contentView addSubview:(UIView*)subview];
   }
+}
 
 - (void)updateBlurEffect
 {
@@ -45,4 +49,24 @@
   self.vibrancyEffectView.effect = self.vibrancyEffect;
 }
 
+- (void)updateFallbackView
+{
+  [super updateFallbackView];
+
+  if ([self useReduceTransparencyFallback]) {
+    for (UIView *subview in self.blurEffectView.contentView.subviews) {
+      [subview removeFromSuperview];
+      [self addSubview:subview];
+    }
+  } else {
+    for (UIView *subview in self.subviews) {
+      if (subview == self.blurEffectView) continue;
+      if (subview == self.reducedTransparencyFallbackView) continue;
+
+      [subview removeFromSuperview];
+      [self.blurEffectView.contentView addSubview:subview];
+    }
+  }
+}
+
 @end

ios/VibrancyViewManager.m

@@ -12,5 +12,6 @@ RCT_EXPORT_MODULE();
 
 RCT_EXPORT_VIEW_PROPERTY(blurType, NSString);
 RCT_EXPORT_VIEW_PROPERTY(blurAmount, NSNumber);
+RCT_EXPORT_VIEW_PROPERTY(reducedTransparencyFallbackColor, UIColor);
 
 @end