Functions to add Sprite2/costumes/backdrops

src/import/sb2import.js

@@ -19,12 +19,14 @@ var List = require('../engine/list');
  * and process the top-level object (the stage object).
  * @param {!string} json SB2-format JSON to load.
  * @param {!Runtime} runtime Runtime object to load all structures into.
+ * @param {Boolean=} opt_forceSprite If set, treat as sprite (Sprite2).
+ * @return {?Target} Top-level target created (stage or sprite).
  */
-function sb2import (json, runtime) {
-    parseScratchObject(
+function sb2import (json, runtime, opt_forceSprite) {
+    return parseScratchObject(
         JSON.parse(json),
         runtime,
-        true
+        !opt_forceSprite
     );
 }
 
@@ -33,6 +35,7 @@ function sb2import (json, runtime) {
  * @param {!Object} object From-JSON "Scratch object:" sprite, stage, watcher.
  * @param {!Runtime} runtime Runtime object to load all structures into.
  * @param {boolean} topLevel Whether this is the top-level object (stage).
+ * @return {?Target} Target created (stage or sprite).
  */
 function parseScratchObject (object, runtime, topLevel) {
     if (!object.hasOwnProperty('objName')) {
@@ -128,6 +131,7 @@ function parseScratchObject (object, runtime, topLevel) {
             parseScratchObject(object.children[m], runtime, false);
         }
     }
+    return target;
 }
 
 /**

src/index.js

@@ -175,14 +175,50 @@ VirtualMachine.prototype.loadProject = function (json) {
     this.clear();
     // @todo: Handle other formats, e.g., Scratch 1.4, Scratch 3.0.
     sb2import(json, this.runtime);
-    // Select the first target for editing, e.g., the stage.
-    this.editingTarget = this.runtime.targets[0];
+    // Select the first target for editing, e.g., the first sprite.
+    this.editingTarget = this.runtime.targets[1];
+    // Update the VM user's knowledge of targets and blocks on the workspace.
+    this.emitTargetsUpdate();
+    this.emitWorkspaceUpdate();
+    this.runtime.setEditingTarget(this.editingTarget);
+};
+
+/**
+ * Add a single sprite from the "Sprite2" (i.e., SB2 sprite) format.
+ * @param {?string} json JSON string representing the sprite.
+ */
+VirtualMachine.prototype.addSprite2 = function (json) {
+    // Select new sprite.
+    this.editingTarget = sb2import(json, this.runtime, true);
     // Update the VM user's knowledge of targets and blocks on the workspace.
     this.emitTargetsUpdate();
     this.emitWorkspaceUpdate();
     this.runtime.setEditingTarget(this.editingTarget);
 };
 
+/**
+ * Add a costume to the current editing target.
+ * @param {!Object} costumeObject Object representing the costume.
+ */
+VirtualMachine.prototype.addCostume = function (costumeObject) {
+    this.editingTarget.sprite.costumes.push(costumeObject);
+    // Switch to the costume.
+    this.editingTarget.setCostume(
+        this.editingTarget.sprite.costumes.length - 1
+    );
+};
+
+/**
+ * Add a backdrop to the stage.
+ * @param {!Object} backdropObject Object representing the backdrop.
+ */
+VirtualMachine.prototype.addBackdrop = function (backdropObject) {
+    var stage = this.runtime.getTargetForStage();
+    stage.sprite.costumes.push(backdropObject);
+    // Switch to the backdrop.
+    stage.setCostume(stage.sprite.costumes.length - 1);
+};
+
 /**
  * Temporary way to make an empty project, in case the desired project
  * cannot be loaded from the online server.