From c920b9cfceec243ceb6452ee41a37167eb08f7a8 Mon Sep 17 00:00:00 2001
From: Koen Punt <koen@koenpunt.nl>
Date: Fri, 28 Apr 2017 07:55:15 +0200
Subject: [PATCH] add headerBackTitleStyle screen option (#1083)

* add headerBackTitleStyle screen option

since the title is customizable, the back title should too.

* add documentation for `headerBackTitleStyle`

* make absence of headerBackTitle not affect return value

* merge styles so current scene can override

If there's no last scene, return the `headerBackTitleStyle` from the
current scene.
Otherwise return the `headerTitleStyle` from the last scene, and the
`headerBackTitleStyle` from the current scene, with the latter having
precedence.

* take headerBackTitleStyle from current scene

also the title style of the last scene is no longer taken into account
---
 .../react-navigation/docs/api/navigators/StackNavigator.md  | 4 ++++
 packages/react-navigation/src/TypeDefinition.js             | 1 +
 packages/react-navigation/src/views/Header.js               | 1 +
 packages/react-navigation/src/views/HeaderBackButton.js     | 6 ++++--
 4 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/packages/react-navigation/docs/api/navigators/StackNavigator.md b/packages/react-navigation/docs/api/navigators/StackNavigator.md
index e73dde31..8d8e7f76 100644
--- a/packages/react-navigation/docs/api/navigators/StackNavigator.md
+++ b/packages/react-navigation/docs/api/navigators/StackNavigator.md
@@ -128,6 +128,10 @@ Style object for the header
 
 Style object for the title component
 
+#### `headerBackTitleStyle`
+
+Style object for the back title
+
 #### `headerTintColor`
 
 Tint color for the header
diff --git a/packages/react-navigation/src/TypeDefinition.js b/packages/react-navigation/src/TypeDefinition.js
index 680e2b81..69084937 100644
--- a/packages/react-navigation/src/TypeDefinition.js
+++ b/packages/react-navigation/src/TypeDefinition.js
@@ -221,6 +221,7 @@ export type NavigationStackScreenOptions = NavigationScreenOptions & {
   headerLeft?: React.Element<*>,
   headerBackTitle?: string,
   headerTruncatedBackTitle?: string,
+  headerBackTitleStyle?: Style,
   headerPressColorAndroid?: string,
   headerRight?: React.Element<*>,
   headerStyle?: Style,
diff --git a/packages/react-navigation/src/views/Header.js b/packages/react-navigation/src/views/Header.js
index ecbfc975..22c15a37 100644
--- a/packages/react-navigation/src/views/Header.js
+++ b/packages/react-navigation/src/views/Header.js
@@ -136,6 +136,7 @@ class Header extends React.PureComponent<void, HeaderProps, HeaderState> {
         tintColor={options.headerTintColor}
         title={backButtonTitle}
         truncatedTitle={truncatedBackButtonTitle}
+        titleStyle={options.headerBackTitleStyle}
         width={width}
       />
     );
diff --git a/packages/react-navigation/src/views/HeaderBackButton.js b/packages/react-navigation/src/views/HeaderBackButton.js
index 23af608d..050d9eda 100644
--- a/packages/react-navigation/src/views/HeaderBackButton.js
+++ b/packages/react-navigation/src/views/HeaderBackButton.js
@@ -10,7 +10,7 @@ import {
   StyleSheet,
 } from 'react-native';
 
-import type { LayoutEvent } from '../TypeDefinition';
+import type { LayoutEvent, Style } from '../TypeDefinition';
 
 import TouchableItem from './TouchableItem';
 
@@ -18,6 +18,7 @@ type Props = {
   onPress?: () => void,
   pressColorAndroid?: ?string,
   title?: ?string,
+  titleStyle?: ?Style,
   tintColor?: ?string,
   truncatedTitle?: ?string,
   width?: ?number,
@@ -59,6 +60,7 @@ class HeaderBackButton extends React.PureComponent<DefaultProps, Props, State> {
       pressColorAndroid,
       width,
       title,
+      titleStyle,
       tintColor,
       truncatedTitle,
     } = this.props;
@@ -92,7 +94,7 @@ class HeaderBackButton extends React.PureComponent<DefaultProps, Props, State> {
             title &&
             <Text
               onLayout={this._onTextLayout}
-              style={[styles.title, { color: tintColor }]}
+              style={[styles.title, { color: tintColor }, titleStyle]}
               numberOfLines={1}
             >
               {backButtonTitle}