From 96e8fc794ed8c52f4bcfaa5643dcef185337bed9 Mon Sep 17 00:00:00 2001
From: Monica Kozbial <kozbial@google.com>
Date: Fri, 18 Sep 2020 16:08:39 -0700
Subject: [PATCH] Don't render children of collapsed blocks (#4264)

* Partially revert collapsed block changes and add additional handling for setting children of collapsed blocks to not rendered

* Improve performance by checking if child is rendered in updateDisabled
---
 core/block_svg.js           | 16 +++++++++++++---
 core/input.js               |  3 +++
 core/rendered_connection.js |  8 ++++++++
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/core/block_svg.js b/core/block_svg.js
index 929f7d0bb..19ee4bf9b 100644
--- a/core/block_svg.js
+++ b/core/block_svg.js
@@ -87,7 +87,6 @@ Blockly.BlockSvg = function(workspace, prototypeName, opt_id) {
    */
   this.renderIsInProgress_ = false;
 
-
   /** @type {!Blockly.WorkspaceSvg} */
   this.workspace = workspace;
 
@@ -643,14 +642,21 @@ Blockly.BlockSvg.prototype.updateCollapsed_ = function() {
   var collapsedInputName = Blockly.Block.COLLAPSED_INPUT_NAME;
   var collapsedFieldName = Blockly.Block.COLLAPSED_FIELD_NAME;
 
+  var renderList = [];
+  // Show/hide the inputs.
   for (var i = 0, input; (input = this.inputList[i]); i++) {
     if (input.name != collapsedInputName) {
-      input.setVisible(!collapsed);
+      renderList.push.apply(renderList, input.setVisible(!collapsed));
     }
   }
 
   if (!collapsed) {
     this.removeInput(collapsedInputName);
+    if (this.rendered) {
+      for (var i = 0, block; (block = renderList[i]); i++) {
+        block.render();
+      }
+    }
     return;
   }
 
@@ -975,7 +981,9 @@ Blockly.BlockSvg.prototype.updateDisabled = function() {
   var children = this.getChildren(false);
   this.applyColour();
   for (var i = 0, child; (child = children[i]); i++) {
-    child.updateDisabled();
+    if (child.rendered) {
+      child.updateDisabled();
+    }
   }
 };
 
@@ -1626,10 +1634,12 @@ Blockly.BlockSvg.prototype.render = function(opt_bubble) {
     if (this.isCollapsed()) {
       this.updateCollapsed_();
     }
+
     this.workspace.getRenderer().render(this);
     this.updateConnectionLocations_();
 
     if (opt_bubble !== false) {
+      // Render all blocks above this one (propogate a reflow).
       var parentBlock = this.getParent();
       if (parentBlock) {
         parentBlock.render(true);
diff --git a/core/input.js b/core/input.js
index 40a454e31..b8b95e846 100644
--- a/core/input.js
+++ b/core/input.js
@@ -200,6 +200,9 @@ Blockly.Input.prototype.setVisible = function(visible) {
     }
     var child = this.connection.targetBlock();
     if (child) {
+      if (!visible) {
+        child.rendered = false;
+      }
       child.getSvgRoot().style.display = visible ? 'block' : 'none';
     }
   }
diff --git a/core/rendered_connection.js b/core/rendered_connection.js
index 5188d5504..b16cc1a00 100644
--- a/core/rendered_connection.js
+++ b/core/rendered_connection.js
@@ -459,6 +459,11 @@ Blockly.RenderedConnection.prototype.onFailedConnect = function(
  */
 Blockly.RenderedConnection.prototype.disconnectInternal_ = function(parentBlock,
     childBlock) {
+  // The input the child block was connected to (if any).
+  var parentInput = parentBlock.getInputWithBlock(childBlock);
+  if (parentInput && !parentInput.isVisible()) {
+    childBlock.rendered = true;
+  }
   Blockly.RenderedConnection.superClass_.disconnectInternal_.call(this,
       parentBlock, childBlock);
   // Rerender the parent so that it may reflow.
@@ -544,6 +549,9 @@ Blockly.RenderedConnection.prototype.connect_ = function(childConnection) {
   var parentInput = parentBlock.getInputWithBlock(childBlock);
   if (parentInput) {
     var visible = parentInput.isVisible();
+    if (!visible) {
+      childBlock.rendered = false;
+    }
     childBlock.getSvgRoot().style.display = visible ? 'block' : 'none';
   }
 };