Add SAX parsing code for .svg files

app/src/main/java/com/simplemobiletools/draw/Svg.java

@@ -1,18 +1,32 @@
 package com.simplemobiletools.draw;
 
+import android.graphics.Color;
 import android.graphics.drawable.ColorDrawable;
+import android.sax.Element;
+import android.sax.RootElement;
+import android.sax.StartElementListener;
+import android.util.Xml;
 
 import com.simplemobiletools.draw.actions.Action;
 
+import org.xml.sax.Attributes;
+
 import java.io.BufferedWriter;
 import java.io.File;
+import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.OutputStreamWriter;
+import java.io.Serializable;
 import java.io.Writer;
+import java.util.ArrayList;
 import java.util.Map;
 
 public class Svg {
+
+    //region Saving
+
     public static void saveSvg(File output, MyCanvas canvas) throws Exception {
         int backgroundColor = ((ColorDrawable) canvas.getBackground()).getColor();
 
@@ -57,4 +71,105 @@ public class Svg {
         writer.write(String.valueOf(options.strokeWidth));
         writer.write("\" stroke-linecap=\"round\"/>");
     }
+
+    //endregion
+
+    //region Loading
+
+    public static void parseSvg(File file) throws Exception {
+        InputStream is = null;
+        final SSvg svg = new SSvg();
+        try {
+            is = new FileInputStream(file);
+
+            // Actual parsing (http://stackoverflow.com/a/4828765)
+            final String ns = "http://www.w3.org/2000/svg";
+            RootElement root = new RootElement(ns, "svg");
+            Element rectElement = root.getChild(ns, "rect");
+            final Element pathElement = root.getChild(ns, "path");
+
+            root.setStartElementListener(new StartElementListener() {
+                @Override
+                public void start(Attributes attributes) {
+                    int width = Integer.parseInt(attributes.getValue("width"));
+                    int height = Integer.parseInt(attributes.getValue("height"));
+                    svg.setSize(width, height);
+                }
+            });
+
+            rectElement.setStartElementListener(new StartElementListener() {
+                @Override
+                public void start(Attributes attributes) {
+                    int width = Integer.parseInt(attributes.getValue("width"));
+                    int height = Integer.parseInt(attributes.getValue("height"));
+                    int color = Color.parseColor(attributes.getValue("fill"));
+                    if (svg.background != null)
+                        throw new UnsupportedOperationException("Unsupported SVG, should only have one <rect>.");
+
+                    svg.background = new SRect(width, height, color);
+                }
+            });
+
+            pathElement.setStartElementListener(new StartElementListener() {
+                public void start(Attributes attributes) {
+                    String d = attributes.getValue("d");
+                    int color = Color.parseColor(attributes.getValue("stroke"));
+                    float width = Float.parseFloat(attributes.getValue("stroke-width"));
+                    svg.paths.add(new SPath(d, color, width));
+                }
+            });
+
+            // Once the parsing is set up, parse this InputStream
+            Xml.parse(is, Xml.Encoding.UTF_8, root.getContentHandler());
+        } finally {
+            if (is != null)
+                is.close();
+        }
+    }
+
+    //region Svg serializable classes
+
+    private static class SSvg implements Serializable {
+        int width;
+        int height;
+        SRect background;
+        final ArrayList<SPath> paths;
+
+        SSvg() {
+            paths = new ArrayList<>();
+        }
+
+        void setSize(int w, int h) {
+            width = w;
+            height = h;
+        }
+    }
+
+    private static class SRect implements Serializable {
+        final int width;
+        final int height;
+        final int color;
+
+        SRect(int w, int h, int c) {
+            width = w;
+            height = h;
+            color = c;
+        }
+    }
+
+    private static class SPath implements Serializable {
+        String data;
+        int color;
+        float strokeWidth;
+
+        SPath(String d, int c, float w) {
+            data = d;
+            color = c;
+            strokeWidth = w;
+        }
+    }
+
+    //endregion
+
+    //endregion
 }