Add a simple, JSON-based serialization mechanism.

app/src/main/java/com/codigoparallevar/minicards/PartCanvasView.java

@@ -16,6 +16,18 @@ import com.codigoparallevar.minicards.parts.Placeholder;
 import com.codigoparallevar.minicards.parts.buttons.RoundButton;
 import com.codigoparallevar.minicards.parts.types.Position;
 
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.FileReader;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
 import java.util.ArrayList;
 
 class PartCanvasView extends View {
@@ -35,14 +47,63 @@ class PartCanvasView extends View {
     @Nullable
     private MotionMode.Type motionMode;
 
+    @NonNull
+    private String name = "default";
     private final static float touchTimeForLongTouchInMillis = 500;
 
     public PartCanvasView(Context context) {
         super(context);
         this.setBackgroundColor(Color.rgb(4, 69, 99));
+
+        if (!loadState()){
             parts.add(new Placeholder(50, 50, 750, 500));
             parts.add(new RoundButton(500, 1200, 80, 100));
         }
+    }
+
+    private boolean loadState(){
+        File filesDir = getContext().getFilesDir();
+        File file = new File(filesDir + "/" + name);
+        FileReader fileIn = null;
+        try {
+            fileIn = new FileReader(file);
+            char[] data = new char[(int) file.length()];
+            fileIn.read(data);
+            JSONArray jsonParts = new JSONArray(new String(data ));
+            for (int i = 0; i < jsonParts.length(); i++){
+                deserializeObject(jsonParts.getJSONObject(i));
+            }
+        } catch (IOException e) {
+            parts.clear();
+            Log.w("PartCanvasView", e.getMessage());
+            return false;
+        } catch (JSONException e) {
+            parts.clear();
+            Log.w("PartCanvasView", e.getMessage());
+            return false;
+        }
+
+        try {
+            fileIn.close();
+        } catch (IOException e) {
+            Log.w("PartCanvasView", e.getMessage());
+            return false;
+        }
+        return true;
+    }
+
+    private void deserializeObject(JSONObject jsonObject) throws JSONException {
+        String type = jsonObject.getString("_type");
+        if(type.equals(RoundButton.class.getName())) {
+            parts.add(RoundButton.deserialize(jsonObject.getJSONObject("_data")));
+        }
+        else if (type.equals(Placeholder.class.getName())) {
+            parts.add(Placeholder.deserialize(jsonObject.getJSONObject("_data")));
+        }
+        else {
+            throw new JSONException("Expected known class, found " + type);
+        }
+    }
 
     @Override
     public void onDraw(Canvas canvas){
@@ -110,6 +171,11 @@ class PartCanvasView extends View {
                 motionMode = null;
                 selectedPart = null;
             }
+            try {
+                saveState();
+            } catch (IOException e) {
+                Log.w("PartCanvasView", e.getMessage());
+            }
             break;
 
             case MotionEvent.ACTION_MOVE:
@@ -137,6 +203,33 @@ class PartCanvasView extends View {
         return true;
     }
 
+    private void saveState() throws IOException {
+        File filesDir = getContext().getFilesDir();
+        FileOutputStream fileOut = new FileOutputStream(filesDir + "/" + name);
+
+        byte[] serialized = serializeState();
+        fileOut.write(serialized);
+
+        fileOut.close();
+    }
+
+    private byte[] serializeState() throws IOException {
+        JSONArray partArray = new JSONArray();
+        for (Part part : parts) {
+            JSONObject serializedPart = new JSONObject();
+            try {
+                serializedPart.put("_type", part.getClass().getName());
+                serializedPart.put("_data", part.serialize());
+            } catch (JSONException e) {
+                throw new IOException(e.getMessage(), e.getCause());
+            }
+
+            partArray.put(serializedPart);
+        }
+
+        return partArray.toString().getBytes("UTF-8");
+    }
+
     @Nullable
     private MotionMode.Type getMotionMode(boolean canWait) {
         if (selectedPart == null){

app/src/main/java/com/codigoparallevar/minicards/parts/Part.java

@@ -2,6 +2,9 @@ package com.codigoparallevar.minicards.parts;
 
 import android.graphics.Canvas;
 
+import org.json.JSONException;
+import org.json.JSONObject;
+
 public interface Part {
     int getLeft();
     int getRight();
@@ -13,4 +16,6 @@ public interface Part {
     void move(int x, int y);
 
     void touched();
+
+    JSONObject serialize() throws JSONException;
 }

app/src/main/java/com/codigoparallevar/minicards/parts/Placeholder.java

@@ -5,6 +5,9 @@ import android.graphics.Color;
 import android.graphics.Paint;
 import android.util.Log;
 
+import org.json.JSONException;
+import org.json.JSONObject;
+
 public class Placeholder implements Part {
     private int _left;
     private int _top;
@@ -73,4 +76,25 @@ public class Placeholder implements Part {
     public void touched() {
         Log.d("Placeholder", "Placeholder touched");
     }
+
+    @Override
+    public JSONObject serialize() throws JSONException {
+        JSONObject serialized = new JSONObject();
+
+        serialized.put("left", _left);
+        serialized.put("top", _top);
+        serialized.put("right", _right);
+        serialized.put("bottom", _bottom);
+
+        return serialized;
+    }
+
+    public static Part deserialize(JSONObject data) throws JSONException {
+        int left = data.getInt("left");
+        int top = data.getInt("top");
+        int right = data.getInt("right");
+        int bottom = data.getInt("bottom");
+
+        return new Placeholder(left, top, right, bottom);
+    }
 }

app/src/main/java/com/codigoparallevar/minicards/parts/buttons/RoundButton.java

@@ -7,6 +7,9 @@ import android.util.Log;
 
 import com.codigoparallevar.minicards.parts.Part;
 
+import org.json.JSONException;
+import org.json.JSONObject;
+
 public class RoundButton implements Part {
 
 
@@ -66,4 +69,27 @@ public class RoundButton implements Part {
     public void touched() {
         Log.d("RoundButton", "Round button touched");
     }
+
+    @Override
+    public JSONObject serialize() throws JSONException {
+        JSONObject serialized = new JSONObject();
+
+        serialized.put("x_center", _xCenter);
+        serialized.put("y_center", _yCenter);
+        serialized.put("inner_radius", _innerRadius);
+        serialized.put("outer_radius", _outerRadius);
+        serialized.put("outer_radius_thickness", _outerRadiusThickness);
+
+        return serialized;
+    }
+
+    public static Part deserialize(JSONObject data) throws JSONException {
+        int xCenter = data.getInt("x_center");
+        int yCenter = data.getInt("y_center");
+
+        int innerRadius = data.getInt("inner_radius");
+        int outerRadius = data.getInt("outer_radius");
+
+        return new RoundButton(xCenter, yCenter, innerRadius, outerRadius);
+    }
 }