From 07bfc8632795bda70cbf0e11cf9249f34c3532a0 Mon Sep 17 00:00:00 2001
From: osdnk <micosa97@gmail.com>
Date: Thu, 24 Oct 2019 18:50:16 +0200
Subject: [PATCH] fix: keyboard manager in stack for fast swipe

---
 packages/stack/src/views/KeyboardManager.tsx | 37 ++++++++++++++++++--
 1 file changed, 34 insertions(+), 3 deletions(-)

diff --git a/packages/stack/src/views/KeyboardManager.tsx b/packages/stack/src/views/KeyboardManager.tsx
index 4e57be4d..0fb122cd 100644
--- a/packages/stack/src/views/KeyboardManager.tsx
+++ b/packages/stack/src/views/KeyboardManager.tsx
@@ -11,14 +11,27 @@ type Props = {
 };
 
 export default class KeyboardManager extends React.Component<Props> {
+  componentWillUnmount = () => {
+    this.clearKeyboardTimeout();
+  };
   // Numeric id of the previously focused text input
   // When a gesture didn't change the tab, we can restore the focused input with this
   private previouslyFocusedTextInput: number | null = null;
+  private startTimestamp: number = 0;
+  private keyboardTimeout: NodeJS.Timeout | undefined;
+
+  clearKeyboardTimeout = () => {
+    if (this.keyboardTimeout !== undefined) {
+      clearTimeout(this.keyboardTimeout);
+      this.keyboardTimeout = undefined;
+    }
+  };
 
   private handlePageChangeStart = () => {
     if (!this.props.enabled) {
       return;
     }
+    this.clearKeyboardTimeout();
 
     const input = TextInput.State.currentlyFocusedField();
 
@@ -27,12 +40,16 @@ export default class KeyboardManager extends React.Component<Props> {
 
     // Store the id of this input so we can refocus it if change was cancelled
     this.previouslyFocusedTextInput = input;
+
+    // Store timestamp for touch start
+    this.startTimestamp = Date.now();
   };
 
   private handlePageChangeConfirm = () => {
     if (!this.props.enabled) {
       return;
     }
+    this.clearKeyboardTimeout();
 
     Keyboard.dismiss();
 
@@ -44,15 +61,29 @@ export default class KeyboardManager extends React.Component<Props> {
     if (!this.props.enabled) {
       return;
     }
+    this.clearKeyboardTimeout();
 
     // The page didn't change, we should restore the focus of text input
     const input = this.previouslyFocusedTextInput;
 
     if (input) {
-      TextInput.State.focusTextInput(input);
-    }
+      // If the interaction was super short we should make sure keyboard won't hide again.
 
-    this.previouslyFocusedTextInput = null;
+      // Too fast input refocus will result only in keyboard flashing on screen and hiding right away.
+      // During first ~100ms keyboard will be dismissed no matter what,
+      // so we have to make sure it won't interrupt input refocus logic.
+      // That's why when the interaction is shorter than 100ms we add delay so it won't hide once again.
+      // Subtracting timestamps makes us sure the delay is executed only when needed.
+      if (Date.now() - this.startTimestamp < 100) {
+        this.keyboardTimeout = setTimeout(() => {
+          TextInput.State.focusTextInput(input);
+          this.previouslyFocusedTextInput = null;
+        }, 100);
+      } else {
+        TextInput.State.focusTextInput(input);
+        this.previouslyFocusedTextInput = null;
+      }
+    }
   };
 
   render() {