From 11517e221b6111ace4354294b2c79db9c8b5f728 Mon Sep 17 00:00:00 2001
From: Karishma Chadha <kchadha@scratch.mit.edu>
Date: Fri, 4 May 2018 10:45:58 -0400
Subject: [PATCH] Implement when backdrop switches to menu.

---
 src/lib/blocks.js | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/src/lib/blocks.js b/src/lib/blocks.js
index fb54eae3b..1c3e8176c 100644
--- a/src/lib/blocks.js
+++ b/src/lib/blocks.js
@@ -28,6 +28,25 @@ export default function (vm) {
         };
     };
 
+    const jsonForHatBlockMenu = function (hatName, name, menuOptionsFn, colors, start) {
+        return {
+            message0: hatName,
+            args0: [
+                {
+                    type: 'field_dropdown',
+                    name: name,
+                    options: function () {
+                        return start.concat(menuOptionsFn());
+                    }
+                }
+            ],
+            colour: colors.primary,
+            colourSecondary: colors.secondary,
+            colourTertiary: colors.tertiary,
+            extensions: ['shape_hat']
+        };
+    };
+
     const soundsMenu = function () {
         if (vm.editingTarget && vm.editingTarget.sprite.sounds.length > 0) {
             return vm.editingTarget.sprite.sounds.map(sound => [sound.name, sound.name]);
@@ -50,6 +69,14 @@ export default function (vm) {
         return [['', '']];
     };
 
+    const backdropNamesMenu = function () {
+        const stage = vm.runtime.getTargetForStage();
+        if (stage && stage.getCostumes().length > 0) {
+            return stage.getCostumes().map(costume => [costume.name, costume.name]);
+        }
+        return [['', '']];
+    };
+
     const spriteMenu = function () {
         const sprites = [];
         for (const targetId in vm.runtime.targets) {
@@ -87,6 +114,8 @@ export default function (vm) {
 
     const controlColors = ScratchBlocks.Colours.control;
 
+    const eventColors = ScratchBlocks.Colours.event;
+
     ScratchBlocks.Blocks.sound_sounds_menu.init = function () {
         const json = jsonForMenuBlock('SOUND_MENU', soundsMenu, soundColors, []);
         this.jsonInit(json);
@@ -102,6 +131,13 @@ export default function (vm) {
         this.jsonInit(json);
     };
 
+    ScratchBlocks.Blocks.event_whenbackdropswitchesto.init = function () {
+        const json = jsonForHatBlockMenu(
+            ScratchBlocks.Msg.EVENT_WHENBACKDROPSWITCHESTO,
+            'BACKDROP', backdropNamesMenu, eventColors, []);
+        this.jsonInit(json);
+    };
+
     ScratchBlocks.Blocks.motion_pointtowards_menu.init = function () {
         const json = jsonForMenuBlock('TOWARDS', spriteMenu, motionColors, [
             ['mouse-pointer', '_mouse_']