Sprite3 Export/Import.

src/serialization/sb3.js

@@ -446,15 +446,25 @@ const serializeTarget = function (target) {
 
 /**
  * Serializes the specified VM runtime.
- * @param  {!Runtime} runtime VM runtime instance to be serialized.
+ * @param {!Runtime} runtime VM runtime instance to be serialized.
+ * @param {string=} targetId Optional target id if serializing only a single target
  * @return {object} Serialized runtime instance.
  */
-const serialize = function (runtime) {
+const serialize = function (runtime, targetId) {
     // Fetch targets
     const obj = Object.create(null);
-    const flattenedOriginalTargets = JSON.parse(JSON.stringify(
+    const flattenedOriginalTargets = JSON.parse(JSON.stringify(targetId ?
+        [runtime.getTargetById(targetId)] :
         runtime.targets.filter(target => target.isOriginal)));
-    obj.targets = flattenedOriginalTargets.map(t => serializeTarget(t, runtime));
+
+    const serializedTargets = flattenedOriginalTargets.map(t => serializeTarget(t, runtime));
+
+    if (targetId) {
+        return serializedTargets[0];
+    }
+
+    obj.targets = serializedTargets;
+
 
     // TODO Serialize monitors
 

src/serialization/serialize-assets.js

@@ -5,10 +5,11 @@
  * to be written and the contents of the file, the serialized asset.
  * @param {Runtime} runtime The runtime with the assets to be serialized
  * @param {string} assetType The type of assets to be serialized: 'sounds' | 'costumes'
+ * @param {string=} optTargetId Optional target id to serialize assets for
  * @returns {Array<object>} An array of file descriptors for each asset
  */
-const serializeAssets = function (runtime, assetType) {
-    const targets = runtime.targets;
+const serializeAssets = function (runtime, assetType, optTargetId) {
+    const targets = optTargetId ? [runtime.getTargetById(optTargetId)] : runtime.targets;
     const assetDescs = [];
     for (let i = 0; i < targets.length; i++) {
         const currTarget = targets[i];
@@ -27,14 +28,16 @@ const serializeAssets = function (runtime, assetType) {
 };
 
 /**
- * Serialize all the sounds in the provided runtime into an array of file
- * descriptors. A file descriptor is an object containing the name of the file
+ * Serialize all the sounds in the provided runtime or, if a target id is provided,
+ * in the specified target into an array of file descriptors.
+ * A file descriptor is an object containing the name of the file
  * to be written and the contents of the file, the serialized sound.
  * @param {Runtime} runtime The runtime with the sounds to be serialized
+ * @param {string=} optTargetId Optional targetid for serializing sounds of a single target
  * @returns {Array<object>} An array of file descriptors for each sound
  */
-const serializeSounds = function (runtime) {
-    return serializeAssets(runtime, 'sounds');
+const serializeSounds = function (runtime, optTargetId) {
+    return serializeAssets(runtime, 'sounds', optTargetId);
 };
 
 /**
@@ -42,10 +45,11 @@ const serializeSounds = function (runtime) {
  * descriptors. A file descriptor is an object containing the name of the file
  * to be written and the contents of the file, the serialized costume.
  * @param {Runtime} runtime The runtime with the costumes to be serialized
+ * @param {string} optTargetId Optional targetid for serializing costumes of a single target
  * @returns {Array<object>} An array of file descriptors for each costume
  */
-const serializeCostumes = function (runtime) {
-    return serializeAssets(runtime, 'costumes');
+const serializeCostumes = function (runtime, optTargetId) {
+    return serializeAssets(runtime, 'costumes', optTargetId);
 };
 
 module.exports = {

src/virtual-machine.js

@@ -263,14 +263,7 @@ class VirtualMachine extends EventEmitter {
 
         // Put everything in a zip file
         zip.file('project.json', projectJson);
-        for (let i = 0; i < soundDescs.length; i++) {
-            const currSound = soundDescs[i];
-            zip.file(currSound.fileName, currSound.fileContent);
-        }
-        for (let i = 0; i < costumeDescs.length; i++) {
-            const currCostume = costumeDescs[i];
-            zip.file(currCostume.fileName, currCostume.fileContent);
-        }
+        this._addFileDescsToZip(soundDescs.concat(costumeDescs), zip);
 
         return zip.generateAsync({
             type: 'blob',
@@ -281,6 +274,31 @@ class VirtualMachine extends EventEmitter {
         });
     }
 
+    _addFileDescsToZip (fileDescs, zip) {
+        for (let i = 0; i < fileDescs.length; i++) {
+            const currFileDesc = fileDescs[i];
+            zip.file(currFileDesc.fileName, currFileDesc.fileContent);
+        }
+    }
+
+    exportSprite (targetId) {
+        const soundDescs = serializeSounds(this.runtime, targetId);
+        const costumeDescs = serializeCostumes(this.runtime, targetId);
+        const spriteJson = JSON.stringify(sb3.serialize(this.runtime, targetId));
+
+        const zip = new JSZip();
+        zip.file('sprite.json', spriteJson);
+        this._addFileDescsToZip(soundDescs.concat(costumeDescs), zip);
+
+        return zip.generateAsync({
+            type: 'blob',
+            compression: 'DEFLATE',
+            compressionOptions: {
+                level: 6
+            }
+        });
+    }
+
     /**
      * Export project as a Scratch 3.0 JSON representation.
      * @return {string} Serialized state of the runtime.