From 4658244e4484cd6ea346e719966edcbd3e593ec3 Mon Sep 17 00:00:00 2001
From: Ilya Laktyushin <ilya@laktyush.in>
Date: Mon, 18 Feb 2019 16:00:52 +0400
Subject: [PATCH] ListView: added visible fraction value for visibility
 property

---
 Display/ListView.swift         | 5 +++--
 Display/ListViewItemNode.swift | 6 +++---
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/Display/ListView.swift b/Display/ListView.swift
index 7dc6fa4960..06cbd5a42d 100644
--- a/Display/ListView.swift
+++ b/Display/ListView.swift
@@ -2973,8 +2973,9 @@ open class ListView: ASDisplayNode, UIScrollViewAccessibilityDelegate, UIGesture
             var visibility: ListViewItemNodeVisibility = .none
             if visibilityRect.intersects(itemFrame) {
                 let itemContentFrame = itemNode.apparentContentFrame
-                let full = itemContentFrame.minY >= visibilityRect.minY && itemContentFrame.maxY <= visibilityRect.maxY
-                visibility = .visible(full)
+                let intersection = itemContentFrame.intersection(visibilityRect)
+                let fraction = intersection.height / itemContentFrame.height
+                visibility = .visible(fraction)
             }
             var updateVisibility = false
             if !onlyPositive {
diff --git a/Display/ListViewItemNode.swift b/Display/ListViewItemNode.swift
index 0aca5a656a..9793f6f3a1 100644
--- a/Display/ListViewItemNode.swift
+++ b/Display/ListViewItemNode.swift
@@ -52,7 +52,7 @@ public struct ListViewItemNodeLayout {
 
 public enum ListViewItemNodeVisibility: Equatable {
     case none
-    case visible(Bool)
+    case visible(CGFloat)
     
     public static func ==(lhs: ListViewItemNodeVisibility, rhs: ListViewItemNodeVisibility) -> Bool {
         switch lhs {
@@ -62,8 +62,8 @@ public enum ListViewItemNodeVisibility: Equatable {
                 } else {
                     return false
                 }
-            case let .visible(full):
-                if case .visible(full) = rhs {
+            case let .visible(fraction):
+                if case .visible(fraction) = rhs {
                     return true
                 } else {
                     return false