From d0abdd4332cc33a6a7385b7ec2c37dd81fbdab2c Mon Sep 17 00:00:00 2001
From: Joe <joe@joefiorini.com>
Date: Thu, 30 Jan 2020 09:10:32 -0500
Subject: [PATCH 1/3] Allow scroll top to be data bound

---
 examples/ScrollView.re          | 20 +++++++++++++++++++-
 src/UI_Components/ScrollView.re | 10 ++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/examples/ScrollView.re b/examples/ScrollView.re
index fed70929c..f9a4b9c79 100644
--- a/examples/ScrollView.re
+++ b/examples/ScrollView.re
@@ -26,9 +26,27 @@ let innerBox =
 
 module Sample = {
   let%component make = () => {
+    let%hook (scrollTop, setScrollTop) = Hooks.state(0);
     let%hook (bounce, setBounce) = Hooks.state(true);
 
+    let handleScrollTop = s => setScrollTop(_ => Float.to_int(s));
+    Console.out("scrollTop: ");
+    Console.log(scrollTop);
+
     <View style=containerStyle>
+      <Text
+        text="Scroll top"
+        style=Style.[
+          marginBottom(10),
+          fontFamily("Roboto-Regular.ttf"),
+          fontSize(20),
+        ]
+      />
+      <Slider
+        onValueChanged=handleScrollTop
+        value={Float.of_int(scrollTop)}
+        maximumValue=450.0
+      />
       <Text
         text="Bounce"
         style=Style.[
@@ -42,7 +60,7 @@ module Sample = {
         checked=bounce
         style=Style.[marginBottom(10)]
       />
-      <ScrollView style=outerBox bounce>
+      <ScrollView style=outerBox bounce scrollTop>
         <Image
           src="outrun-logo.png"
           /* Exercise the case in #579 */
diff --git a/src/UI_Components/ScrollView.re b/src/UI_Components/ScrollView.re
index 01e3ccef2..c533e76db 100644
--- a/src/UI_Components/ScrollView.re
+++ b/src/UI_Components/ScrollView.re
@@ -56,6 +56,16 @@ let%component make =
     Hooks.state(None);
   let%hook (actualScrollLeft, setScrollLeft) = Hooks.state(scrollLeft);
   let%hook (bouncingState, setBouncingState) = Hooks.state(Idle);
+  let%hook () =
+    Hooks.effect(
+      Always,
+      () => {
+        if (scrollTop != actualScrollTop) {
+          dispatch(ScrollUpdated(scrollTop));
+        };
+        None;
+      },
+    );
 
   let%hook (actualScrollTop, _bounceAnimationState, resetBouncingAnimation) =
     switch (bouncingState) {

From 750f777495bc841fe3f3ccaf4c45fe0ae69a4f39 Mon Sep 17 00:00:00 2001
From: Joe <joe@joefiorini.com>
Date: Thu, 30 Jan 2020 09:54:55 -0500
Subject: [PATCH 2/3] Make ScrollView fully controllable

---
 examples/ScrollView.re          |  5 +++--
 src/UI_Components/ScrollView.re | 23 ++++++++++++++++++-----
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/examples/ScrollView.re b/examples/ScrollView.re
index f9a4b9c79..807d2a7ae 100644
--- a/examples/ScrollView.re
+++ b/examples/ScrollView.re
@@ -39,7 +39,7 @@ module Sample = {
         style=Style.[
           marginBottom(10),
           fontFamily("Roboto-Regular.ttf"),
-          fontSize(20),
+          fontSize(20.),
         ]
       />
       <Slider
@@ -60,7 +60,8 @@ module Sample = {
         checked=bounce
         style=Style.[marginBottom(10)]
       />
-      <ScrollView style=outerBox bounce scrollTop>
+      <ScrollView
+        style=outerBox bounce scrollTop onScroll={v => setScrollTop(_ => v)}>
         <Image
           src="outrun-logo.png"
           /* Exercise the case in #579 */
diff --git a/src/UI_Components/ScrollView.re b/src/UI_Components/ScrollView.re
index c533e76db..153aa7f1a 100644
--- a/src/UI_Components/ScrollView.re
+++ b/src/UI_Components/ScrollView.re
@@ -47,6 +47,7 @@ let%component make =
                 ~scrollLeft=0,
                 ~scrollTop=0,
                 ~bounce=defaultBounce,
+                ~onScroll=?,
                 ~children=React.empty,
                 (),
               ) => {
@@ -61,7 +62,10 @@ let%component make =
       Always,
       () => {
         if (scrollTop != actualScrollTop) {
-          dispatch(ScrollUpdated(scrollTop));
+          switch (onScroll) {
+          | Some(f) => dispatch(ScrollUpdated(scrollTop))
+          | None => ()
+          };
         };
         None;
       },
@@ -124,11 +128,18 @@ let%component make =
 
       let isVerticalScrollbarVisible = maxHeight > 0;
       let isHorizontalScrollbarVisible = maxWidth > 0;
+      let updateScrollPos = v => {
+        dispatch(ScrollUpdated(v));
+        switch (onScroll) {
+        | Some(f) => f(v)
+        | None => ()
+        };
+      };
 
       let verticalScrollBar =
         isVerticalScrollbarVisible
           ? <Slider
-              onValueChanged={v => dispatch(ScrollUpdated(int_of_float(v)))}
+              onValueChanged={v => updateScrollPos(int_of_float(v))}
               minimumValue=0.
               maximumValue={float_of_int(maxHeight)}
               sliderLength={outerMeasurements.height}
@@ -180,11 +191,13 @@ let%component make =
         | Bouncing(_) => ()
         | Idle when !bounce && (isAtTop || isAtBottom) =>
           let clampedScrollTop = isAtTop ? 0 : maxHeight;
-          dispatch(ScrollUpdated(clampedScrollTop));
+          updateScrollPos(clampedScrollTop);
         | Idle when bounce && (isAtTop || isAtBottom) =>
           setBouncingState(_ => Bouncing(- delta * 2));
-          dispatch(ScrollUpdated(isAtTop ? 0 : maxHeight));
-        | Idle => dispatch(ScrollUpdated(newScrollTop))
+          updateScrollPos(isAtTop ? 0 : maxHeight);
+        | Idle =>
+          dispatch(ScrollUpdated(newScrollTop));
+          updateScrollPos(newScrollTop);
         };
       };
       (horizontalScrollbar, verticalScrollBar, scroll);

From ea43ba33ec143a5a15b1e981be5a6e6820ef7411 Mon Sep 17 00:00:00 2001
From: Joe <joe@joefiorini.com>
Date: Thu, 30 Jan 2020 10:21:31 -0500
Subject: [PATCH 3/3] Fix CI

---
 src/UI_Components/ScrollView.re | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/UI_Components/ScrollView.re b/src/UI_Components/ScrollView.re
index 153aa7f1a..476ec16f6 100644
--- a/src/UI_Components/ScrollView.re
+++ b/src/UI_Components/ScrollView.re
@@ -63,7 +63,7 @@ let%component make =
       () => {
         if (scrollTop != actualScrollTop) {
           switch (onScroll) {
-          | Some(f) => dispatch(ScrollUpdated(scrollTop))
+          | Some(_) => dispatch(ScrollUpdated(scrollTop))
           | None => ()
           };
         };