From 0246e2a1326ba6eee1558f0c0564afb706d27bd6 Mon Sep 17 00:00:00 2001
From: Monica Kozbial <kozbial@google.com>
Date: Fri, 5 Mar 2021 11:34:29 -0800
Subject: [PATCH] Fix flyout metrics and workspace scroll (#4674)

* Fix flyout metrics and max scroll logic in scroll

* Fix horizontal scroll wheel logic
---
 core/flyout_horizontal.js | 13 +++++--------
 core/flyout_vertical.js   |  5 +----
 core/workspace_svg.js     |  7 ++++---
 3 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/core/flyout_horizontal.js b/core/flyout_horizontal.js
index 6a3252948..11cbe8302 100644
--- a/core/flyout_horizontal.js
+++ b/core/flyout_horizontal.js
@@ -90,13 +90,13 @@ Blockly.HorizontalFlyout.prototype.getMetrics_ = function() {
   var metrics = {
     contentHeight: optionBox.height * this.workspace_.scale,
     contentWidth: optionBox.width * this.workspace_.scale,
-    contentTop: 0,
-    contentLeft: 0,
+    contentTop: optionBox.y,
+    contentLeft: optionBox.x,
 
     scrollHeight: (optionBox.height + 2 * this.MARGIN) * this.workspace_.scale,
     scrollWidth: (optionBox.width + 2 * this.MARGIN) * this.workspace_.scale,
-    scrollTop: 0,
-    scrollLeft: 0,
+    scrollTop: optionBox.y - this.MARGIN,
+    scrollLeft: optionBox.x - this.MARGIN,
 
     viewHeight: viewHeight,
     viewWidth: viewWidth,
@@ -276,10 +276,7 @@ Blockly.HorizontalFlyout.prototype.wheel_ = function(e) {
 
   if (delta) {
     var metrics = this.getMetrics_();
-    var pos = metrics.viewLeft + delta;
-    var limit = metrics.scrollWidth - metrics.viewWidth;
-    pos = Math.min(pos, limit);
-    pos = Math.max(pos, 0);
+    var pos = (metrics.viewLeft - metrics.scrollLeft) + delta;
     this.workspace_.scrollbar.setX(pos);
     // When the flyout moves from a wheel event, hide WidgetDiv and DropDownDiv.
     Blockly.WidgetDiv.hide();
diff --git a/core/flyout_vertical.js b/core/flyout_vertical.js
index 08ad041d3..576c61b78 100644
--- a/core/flyout_vertical.js
+++ b/core/flyout_vertical.js
@@ -102,7 +102,7 @@ Blockly.VerticalFlyout.prototype.getMetrics_ = function() {
 
     viewHeight: viewHeight,
     viewWidth: viewWidth,
-    viewTop: -this.workspace_.scrollY + optionBox.y,
+    viewTop: -this.workspace_.scrollY,
     viewLeft: -this.workspace_.scrollX,
 
     absoluteTop: absoluteTop,
@@ -267,9 +267,6 @@ Blockly.VerticalFlyout.prototype.wheel_ = function(e) {
   if (scrollDelta.y) {
     var metrics = this.getMetrics_();
     var pos = (metrics.viewTop - metrics.scrollTop) + scrollDelta.y;
-    var limit = metrics.scrollHeight - metrics.viewHeight;
-    pos = Math.min(pos, limit);
-    pos = Math.max(pos, 0);
     this.workspace_.scrollbar.setY(pos);
     // When the flyout moves from a wheel event, hide WidgetDiv and DropDownDiv.
     Blockly.WidgetDiv.hide();
diff --git a/core/workspace_svg.js b/core/workspace_svg.js
index 3146c230a..8e311093e 100644
--- a/core/workspace_svg.js
+++ b/core/workspace_svg.js
@@ -2218,9 +2218,10 @@ Blockly.WorkspaceSvg.prototype.scroll = function(x, y) {
   // to workspace coordinates so we have to inverse them.
   x = Math.min(x, -metrics.scrollLeft);
   y = Math.min(y, -metrics.scrollTop);
-  var maxXScroll = metrics.scrollLeft + metrics.scrollWidth - metrics.viewWidth;
-  var maxYScroll =
-      metrics.scrollTop + metrics.scrollHeight - metrics.viewHeight;
+  var maxXDisplacement = Math.max(0, metrics.scrollWidth - metrics.viewWidth);
+  var maxXScroll = metrics.scrollLeft + maxXDisplacement;
+  var maxYDisplacement = Math.max(0, metrics.scrollHeight - metrics.viewHeight);
+  var maxYScroll = metrics.scrollTop + maxYDisplacement;
   x = Math.max(x, -maxXScroll);
   y = Math.max(y, -maxYScroll);
   this.scrollX = x;