Initial replay parsing support.

- Basic implementation of viewing replays in the Game state.
- Added OsuReader class for reading certain osu! file types. (author: Markus Jarderot)
- Added Replay, ReplayFrame, and LifeFrame classes to capture replay data. (author: smoogipooo)
- Added 'keyPressed' parameter to HitObject.update().
- Added cursor-drawing methods in UI that take the mouse coordinates and pressed state as parameters.
- Added GameMod methods to retrieve/load the active mods state as a bitmask.
- Added Apache commons-compress dependency for handling LZMA decompression.

Signed-off-by: Jeffrey Han <itdelatrisu@gmail.com>

pom.xml

@@ -197,5 +197,10 @@
 			<artifactId>maven-artifact</artifactId>
 			<version>3.0.3</version>
 		</dependency>
+		<dependency>
+			<groupId>org.apache.commons</groupId>
+			<artifactId>commons-compress</artifactId>
+			<version>1.8</version>
+		</dependency>
 	</dependencies>
 </project>

src/itdelatrisu/opsu/GameData.java

@@ -1212,12 +1212,7 @@ public class GameData {
 		scoreData.score = score;
 		scoreData.combo = comboMax;
 		scoreData.perfect = (comboMax == fullObjectCount);
-		int mods = 0;
-		for (GameMod mod : GameMod.values()) {
-			if (mod.isActive())
-				mods |= mod.getBit();
-		}
-		scoreData.mods = mods;
+		scoreData.mods = GameMod.getModState();
 		return scoreData;
 	}
 

src/itdelatrisu/opsu/GameMod.java

@@ -213,6 +213,27 @@ public enum GameMod {
 		return scoreMultiplier;
 	}
 
+	/**
+	 * Returns the current game mod state (bitwise OR of active mods).
+	 */
+	public static int getModState() {
+		int state = 0;
+		for (GameMod mod : GameMod.values()) {
+			if (mod.isActive())
+				state |= mod.getBit();
+		}
+		return state;
+	}
+
+	/**
+	 * Sets the active states of all game mods to the given state.
+	 * @param state the state (bitwise OR of active mods)
+	 */
+	public static void loadModState(int state) {
+		for (GameMod mod : GameMod.values())
+			mod.active = ((state & mod.getBit()) > 0);
+	}
+
 	/**
 	 * Constructor.
 	 * @param category the category for the mod

src/itdelatrisu/opsu/OsuHitObject.java

@@ -129,6 +129,16 @@ public class OsuHitObject {
 	 */
 	public static float getYMultiplier() { return yMultiplier; }
 
+	/**
+	 * Returns the X offset for coordinates.
+	 */
+	public static int getXOffset() { return xOffset; }
+
+	/**
+	 * Returns the Y offset for coordinates.
+	 */
+	public static int getYOffset() { return yOffset; }
+
 	/**
 	 * Constructor.
 	 * @param line the line to be parsed

src/itdelatrisu/opsu/OsuReader.java

@@ -0,0 +1,175 @@
+/*
+ * opsu! - an open-source osu! client
+ * Copyright (C) 2014, 2015 Jeffrey Han
+ *
+ * opsu! is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * opsu! is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with opsu!.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package itdelatrisu.opsu;
+
+import java.io.DataInputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.util.Date;
+
+/**
+ * Reader for osu! file types.
+ *
+ * @author Markus Jarderot (http://stackoverflow.com/questions/28788616)
+ */
+public class OsuReader {
+	/** Input stream reader. */
+	private DataInputStream reader;
+
+	/**
+	 * Constructor.
+	 * @param file the file to read from
+	 * @throws IOException
+	 */
+	public OsuReader(File file) throws IOException {
+		this(new FileInputStream(file));
+	}
+
+	/**
+	 * Constructor.
+	 * @param source the input stream to read from
+	 */
+	public OsuReader(InputStream source) {
+		this.reader = new DataInputStream(source);
+	}
+
+	/**
+	 * Returns the input stream in use.
+	 */
+	public InputStream getInputStream() { return reader; }
+
+	/**
+	 * Closes the input stream.
+	 */
+	public void close() throws IOException { reader.close(); }
+
+	/**
+	 * Reads a 1-byte value.
+	 */
+	public byte readByte() throws IOException {
+		return this.reader.readByte();
+	}
+
+	/**
+	 * Reads a 2-byte little endian value.
+	 */
+	public short readShort() throws IOException {
+		byte[] bytes = new byte[2];
+		this.reader.readFully(bytes);
+		ByteBuffer bb = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN);
+		return bb.getShort();
+	}
+
+	/**
+	 * Reads a 4-byte little endian value.
+	 */
+	public int readInt() throws IOException {
+		byte[] bytes = new byte[4];
+		this.reader.readFully(bytes);
+		ByteBuffer bb = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN);
+		return bb.getInt();
+	}
+
+	/**
+	 * Reads an 8-byte little endian value.
+	 */
+	public long readLong() throws IOException {
+		byte[] bytes = new byte[8];
+		this.reader.readFully(bytes);
+		ByteBuffer bb = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN);
+		return bb.getLong();
+	}
+
+	/**
+	 * Reads a 4-byte little endian float.
+	 */
+	public float readSingle() throws IOException {
+		byte[] bytes = new byte[4];
+		this.reader.readFully(bytes);
+		ByteBuffer bb = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN);
+		return bb.getFloat();
+	}
+
+	/**
+	 * Reads an 8-byte little endian double.
+	 */
+	public double readDouble() throws IOException {
+		byte[] bytes = new byte[8];
+		this.reader.readFully(bytes);
+		ByteBuffer bb = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN);
+		return bb.getDouble();
+	}
+
+	/**
+	 * Reads a 1-byte value as a boolean.
+	 */
+	public boolean readBoolean() throws IOException {
+		return this.reader.readBoolean();
+	}
+
+	/**
+	 * Reads an unsigned variable length integer (ULEB128).
+	 */
+	public int readULEB128() throws IOException {
+		int value = 0;
+		for (int shift = 0; shift < 32; shift += 7) {
+			byte b = this.reader.readByte();
+			value |= (b & 0x7F) << shift;
+			if (b >= 0)
+				return value;  // MSB is zero. End of value.
+		}
+		throw new IOException("ULEB128 too large");
+	}
+
+	/**
+	 * Reads a variable-length string of 1-byte characters.
+	 */
+	public String readString() throws IOException {
+		// 00 = empty string
+		// 0B <length> <char>* = normal string
+		// <length> is encoded as an LEB, and is the byte length of the rest.
+		// <char>* is encoded as UTF8, and is the string content.
+		byte kind = this.reader.readByte();
+		if (kind == 0)
+			return "";
+		if (kind != 0x0B)
+			throw new IOException(String.format("String format error: Expected 0x0B or 0x00, found 0x%02X", kind & 0xFF));
+		int length = readULEB128();
+		if (length == 0)
+			return "";
+		byte[] utf8bytes = new byte[length];
+		this.reader.readFully(utf8bytes);
+		return new String(utf8bytes, "UTF-8");
+	}
+
+	/**
+	 * Reads an 8-byte date in Windows ticks.
+	 */
+	public Date readDate() throws IOException {
+		long ticks = readLong();
+		final long TICKS_AT_EPOCH = 621355968000000000L;
+		final long TICKS_PER_MILLISECOND = 10000;
+
+		return new Date((ticks - TICKS_AT_EPOCH) / TICKS_PER_MILLISECOND);
+	}
+}

src/itdelatrisu/opsu/ScoreData.java

@@ -19,6 +19,7 @@
 package itdelatrisu.opsu;
 
 import itdelatrisu.opsu.GameData.Grade;
+import itdelatrisu.opsu.replay.Replay;
 import itdelatrisu.opsu.states.SongMenu;
 
 import java.sql.ResultSet;
@@ -59,6 +60,9 @@ public class ScoreData implements Comparable<ScoreData> {
 	/** Game mod bitmask. */
 	public int mods;
 
+	/** The replay. */
+	public Replay replay;
+
 	/** Time since the score was achieved. */
 	private String timeSince;
 
@@ -153,6 +157,7 @@ public class ScoreData implements Comparable<ScoreData> {
 		this.combo = rs.getInt(15);
 		this.perfect = rs.getBoolean(16);
 		this.mods = rs.getInt(17);
+//		this.replay = ;  // TODO
 	}
 
 	/**

src/itdelatrisu/opsu/UI.java

@@ -120,6 +120,20 @@ public class UI {
 		drawCursor();
 	}
 
+	/**
+	 * Draws the global UI components: cursor, FPS, volume bar, bar notifications.
+	 * @param g the graphics context
+	 * @param mouseX the mouse x coordinate
+	 * @param mouseY the mouse y coordinate
+	 * @param mousePressed whether or not the mouse button is pressed
+	 */
+	public static void draw(Graphics g, int mouseX, int mouseY, boolean mousePressed) {
+		drawBarNotification(g);
+		drawVolume(g);
+		drawFPS();
+		drawCursor(mouseX, mouseY, mousePressed);
+	}
+
 	/**
 	 * Resets the necessary UI components upon entering a state.
 	 */
@@ -161,6 +175,21 @@ public class UI {
 	 * Draws the cursor.
 	 */
 	public static void drawCursor() {
+		int state = game.getCurrentStateID();
+		boolean mousePressed =
+			(((state == Opsu.STATE_GAME || state == Opsu.STATE_GAMEPAUSEMENU) && Utils.isGameKeyPressed()) ||
+			((input.isMouseButtonDown(Input.MOUSE_LEFT_BUTTON) || input.isMouseButtonDown(Input.MOUSE_RIGHT_BUTTON)) &&
+			!(state == Opsu.STATE_GAME && Options.isMouseDisabled())));
+		drawCursor(input.getMouseX(), input.getMouseY(), mousePressed);
+	}
+
+	/**
+	 * Draws the cursor.
+	 * @param mouseX the mouse x coordinate
+	 * @param mouseY the mouse y coordinate
+	 * @param mousePressed whether or not the mouse button is pressed
+	 */
+	public static void drawCursor(int mouseX, int mouseY, boolean mousePressed) {
 		// determine correct cursor image
 		// TODO: most beatmaps don't skin CURSOR_MIDDLE, so how to determine style?
 		Image cursor = null, cursorMiddle = null, cursorTrail = null;
@@ -176,7 +205,6 @@ public class UI {
 		if (newStyle)
 			cursorMiddle = GameImage.CURSOR_MIDDLE.getImage();
 
-		int mouseX = input.getMouseX(), mouseY = input.getMouseY();
 		int removeCount = 0;
 		int FPSmod = (Options.getTargetFPS() / 60);
 
@@ -226,10 +254,7 @@ public class UI {
 
 		// increase the cursor size if pressed
 		final float scale = 1.25f;
-		int state = game.getCurrentStateID();
-		if (((state == Opsu.STATE_GAME || state == Opsu.STATE_GAMEPAUSEMENU) && Utils.isGameKeyPressed()) ||
-		    ((input.isMouseButtonDown(Input.MOUSE_LEFT_BUTTON) || input.isMouseButtonDown(Input.MOUSE_RIGHT_BUTTON)) &&
-		    !(state == Opsu.STATE_GAME && Options.isMouseDisabled()))) {
+		if (mousePressed) {
 			cursor = cursor.getScaledCopy(scale);
 			if (newStyle)
 				cursorMiddle = cursorMiddle.getScaledCopy(scale);

src/itdelatrisu/opsu/Utils.java

@@ -41,6 +41,7 @@ import java.util.Arrays;
 import java.util.Date;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Scanner;
 
 import javax.imageio.ImageIO;
 
@@ -546,4 +547,15 @@ public class Utils {
 			throw e;
 		}
 	}
+
+	/**
+	 * Converts an input stream to a string.
+	 * @param is the input stream
+	 * @author Pavel Repin, earcam (http://stackoverflow.com/a/5445161)
+	 */
+	public static String convertStreamToString(InputStream is) {
+		try (Scanner s = new Scanner(is)) {
+			return s.useDelimiter("\\A").hasNext() ? s.next() : "";
+		}
+	}
 }

src/itdelatrisu/opsu/objects/Circle.java

@@ -150,7 +150,7 @@ public class Circle implements HitObject {
 	}
 
 	@Override
-	public boolean update(boolean overlap, int delta, int mouseX, int mouseY) {
+	public boolean update(boolean overlap, int delta, int mouseX, int mouseY, boolean keyPressed) {
 		int time = hitObject.getTime();
 		float x = hitObject.getX(), y = hitObject.getY();
 

src/itdelatrisu/opsu/objects/HitObject.java

@@ -37,9 +37,10 @@ public interface HitObject {
 	 * @param delta the delta interval since the last call
 	 * @param mouseX the x coordinate of the mouse
 	 * @param mouseY the y coordinate of the mouse
+	 * @param keyPressed whether or not a game key is currently pressed
 	 * @return true if object ended
 	 */
-	public boolean update(boolean overlap, int delta, int mouseX, int mouseY);
+	public boolean update(boolean overlap, int delta, int mouseX, int mouseY, boolean keyPressed);
 
 	/**
 	 * Processes a mouse click.

src/itdelatrisu/opsu/objects/Slider.java

@@ -294,7 +294,7 @@ public class Slider implements HitObject {
 	}
 
 	@Override
-	public boolean update(boolean overlap, int delta, int mouseX, int mouseY) {
+	public boolean update(boolean overlap, int delta, int mouseX, int mouseY, boolean keyPressed) {
 		int repeatCount = hitObject.getRepeatCount();
 
 		// slider time and tick calculations
@@ -355,7 +355,7 @@ public class Slider implements HitObject {
 			tickIntervals++;
 
 			// check if cursor pressed and within end circle
-			if (Utils.isGameKeyPressed() || GameMod.RELAX.isActive()) {
+			if (keyPressed || GameMod.RELAX.isActive()) {
 				float[] c = curve.pointAt(getT(trackPosition, false));
 				double distance = Math.hypot(c[0] - mouseX, c[1] - mouseY);
 				int followCircleRadius = GameImage.SLIDER_FOLLOWCIRCLE.getImage().getWidth() / 2;
@@ -404,7 +404,7 @@ public class Slider implements HitObject {
 		float[] c = curve.pointAt(getT(trackPosition, false));
 		double distance = Math.hypot(c[0] - mouseX, c[1] - mouseY);
 		int followCircleRadius = GameImage.SLIDER_FOLLOWCIRCLE.getImage().getWidth() / 2;
-		if (((Utils.isGameKeyPressed() || GameMod.RELAX.isActive()) && distance < followCircleRadius) || isAutoMod) {
+		if (((keyPressed || GameMod.RELAX.isActive()) && distance < followCircleRadius) || isAutoMod) {
 			// mouse pressed and within follow circle
 			followCircleActive = true;
 			data.changeHealth(delta * GameData.HP_DRAIN_MULTIPLIER);

src/itdelatrisu/opsu/objects/Spinner.java

@@ -194,7 +194,7 @@ public class Spinner implements HitObject {
 	public boolean mousePressed(int x, int y) { return false; }  // not used
 
 	@Override
-	public boolean update(boolean overlap, int delta, int mouseX, int mouseY) {
+	public boolean update(boolean overlap, int delta, int mouseX, int mouseY, boolean keyPressed) {
 		int trackPosition = MusicController.getPosition();
 
 		// end of spinner
@@ -204,7 +204,7 @@ public class Spinner implements HitObject {
 		}
 
 		// game button is released
-		if (isSpinning && !(Utils.isGameKeyPressed() || GameMod.RELAX.isActive()))
+		if (isSpinning && !(keyPressed || GameMod.RELAX.isActive()))
 			isSpinning = false;
 
 		// spin automatically
@@ -224,7 +224,7 @@ public class Spinner implements HitObject {
 			angle = (float) Math.atan2(mouseY - (height / 2), mouseX - (width / 2));
 
 			// set initial angle to current mouse position to skip first click
-			if (!isSpinning && (Utils.isGameKeyPressed() || GameMod.RELAX.isActive())) {
+			if (!isSpinning && (keyPressed || GameMod.RELAX.isActive())) {
 				lastAngle = angle;
 				isSpinning = true;
 				return false;

src/itdelatrisu/opsu/replay/LifeFrame.java

@@ -0,0 +1,57 @@
+/*
+ * opsu! - an open-source osu! client
+ * Copyright (C) 2014, 2015 Jeffrey Han
+ *
+ * opsu! is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * opsu! is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with opsu!.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * Captures a single life frame.
+ *
+ * @author smoogipooo (https://github.com/smoogipooo/osu-Replay-API/)
+ */
+package itdelatrisu.opsu.replay;
+
+public class LifeFrame {
+	/** Time. */
+	private int time;
+
+	/** Percentage. */
+	private float percentage;
+
+	/**
+	 * Constructor.
+	 * @param time the time
+	 * @param percentage the percentage
+	 */
+	public LifeFrame(int time, float percentage) {
+		this.time = time;
+		this.percentage = percentage;
+	}
+
+	/**
+	 * Returns the frame time.
+	 */
+	public int getTime() { return time; }
+
+	/**
+	 * Returns the frame percentage.
+	 */
+	public float getPercentage() { return percentage; }
+
+	@Override
+	public String toString() {
+		return String.format("(%d, %.2f)", time, percentage);
+	}
+}

src/itdelatrisu/opsu/replay/Replay.java

@@ -0,0 +1,221 @@
+/*
+ * opsu! - an open-source osu! client
+ * Copyright (C) 2014, 2015 Jeffrey Han
+ *
+ * opsu! is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * opsu! is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with opsu!.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package itdelatrisu.opsu.replay;
+
+import itdelatrisu.opsu.OsuReader;
+import itdelatrisu.opsu.Utils;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+
+import org.apache.commons.compress.compressors.lzma.LZMACompressorInputStream;
+import org.newdawn.slick.util.Log;
+
+/**
+ * Captures osu! replay data.
+ * https://osu.ppy.sh/wiki/Osr_%28file_format%29
+ *
+ * @author smoogipooo (https://github.com/smoogipooo/osu-Replay-API/)
+ */
+public class Replay {
+	/** The associated file. */
+	private File file;
+
+	/** The game mode. */
+	public byte mode;
+
+	/** Game version when the replay was created. */
+	public int version;
+
+	/** Beatmap MD5 hash. */
+	public String beatmapHash;
+
+	/** The player's name. */
+	public String playerName;
+
+	/** Replay MD5 hash. */
+	public String replayHash;
+
+	/** Hit result counts. */
+	public short hit300, hit100, hit50, geki, katu, miss;
+
+	/** The score. */
+	public long score;
+
+	/** The max combo. */
+	public short combo;
+
+	/** Whether or not a full combo was achieved. */
+	public boolean perfect;
+
+	/** Game mod bitmask. */
+	public int mods;
+
+	/** Life frames. */
+	public LifeFrame[] lifeFrames;
+
+	/** The time when the replay was created. */
+	public Date timestamp;
+
+	/** Length of the replay data. */
+	public int replayLength;
+
+	/** Replay frames. */
+	public ReplayFrame[] frames;
+
+	/**
+	 * Constructor.
+	 * @param file the file to load from
+	 */
+	public Replay(File file) {
+		this.file = file;
+		try {
+			OsuReader reader = new OsuReader(file);
+			loadHeader(reader);
+			loadData(reader);
+			reader.close();
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+
+	/**
+	 * Loads the replay header data.
+	 * @param reader the associated reader
+	 * @throws IOException
+	 */
+	private void loadHeader(OsuReader reader) throws IOException {
+		this.mode = reader.readByte();
+		this.version = reader.readInt();
+		this.beatmapHash = reader.readString();
+		this.playerName = reader.readString();
+		this.replayHash = reader.readString();
+		this.hit300 = reader.readShort();
+		this.hit100 = reader.readShort();
+		this.hit50 = reader.readShort();
+		this.geki = reader.readShort();
+		this.katu = reader.readShort();
+		this.miss = reader.readShort();
+		this.score = reader.readInt();
+		this.combo = reader.readShort();
+		this.perfect = reader.readBoolean();
+		this.mods = reader.readInt();
+	}
+
+	/**
+	 * Loads the replay data.
+	 * @param reader the associated reader
+	 * @throws IOException
+	 */
+	private void loadData(OsuReader reader) throws IOException {
+		// life data
+		String[] lifeData = reader.readString().split(",");
+		List<LifeFrame> lifeFrameList = new ArrayList<LifeFrame>(lifeData.length);
+		for (String frame : lifeData) {
+			String[] tokens = frame.split("\\|");
+			if (tokens.length < 2)
+				continue;
+			try {
+				int time = Integer.parseInt(tokens[0]);
+				float percentage = Float.parseFloat(tokens[1]);
+				lifeFrameList.add(new LifeFrame(time, percentage));
+			} catch (NumberFormatException | NullPointerException e) {
+				Log.warn(String.format("Failed to life frame: '%s'", frame), e);
+			}
+		}
+		this.lifeFrames = lifeFrameList.toArray(new LifeFrame[lifeFrameList.size()]);
+
+		// timestamp
+		this.timestamp = reader.readDate();
+
+		// LZMA-encoded replay data
+		this.replayLength = reader.readInt();
+		if (replayLength > 0) {
+			LZMACompressorInputStream lzma = new LZMACompressorInputStream(reader.getInputStream());
+			String[] replayFrames = Utils.convertStreamToString(lzma).split(",");
+			List<ReplayFrame> replayFrameList = new ArrayList<ReplayFrame>(replayFrames.length);
+			int lastTime = 0;
+			for (String frame : replayFrames) {
+				if (frame.isEmpty())
+					continue;
+				String[] tokens = frame.split("\\|");
+				if (tokens.length < 4)
+					continue;
+				try {
+					int timeDiff = Integer.parseInt(tokens[0]);
+					int time = timeDiff + lastTime;
+					float x = Float.parseFloat(tokens[1]);
+					float y = Float.parseFloat(tokens[2]);
+					int keys = Integer.parseInt(tokens[3]);
+					replayFrameList.add(new ReplayFrame(timeDiff, time, x, y, keys));
+					lastTime = time;
+				} catch (NumberFormatException | NullPointerException e) {
+					Log.warn(String.format("Failed to parse frame: '%s'", frame), e);
+				}
+			}
+			this.frames = replayFrameList.toArray(new ReplayFrame[replayFrameList.size()]);
+		}
+	}
+
+	@Override
+	public String toString() {
+		final int LINE_SPLIT = 10;
+		StringBuilder sb = new StringBuilder();
+		sb.append("File: "); sb.append(file.getName()); sb.append('\n');
+		sb.append("Mode: "); sb.append(mode); sb.append('\n');
+		sb.append("Version: "); sb.append(version); sb.append('\n');
+		sb.append("Beatmap hash: "); sb.append(beatmapHash); sb.append('\n');
+		sb.append("Player name: "); sb.append(playerName); sb.append('\n');
+		sb.append("Replay hash: "); sb.append(replayHash); sb.append('\n');
+		sb.append("Hits: ");
+		sb.append(hit300); sb.append(' ');
+		sb.append(hit100); sb.append(' ');
+		sb.append(hit50); sb.append(' ');
+		sb.append(geki); sb.append(' ');
+		sb.append(katu); sb.append(' ');
+		sb.append(miss); sb.append('\n');
+		sb.append("Score: "); sb.append(score); sb.append('\n');
+		sb.append("Max combo: "); sb.append(combo); sb.append('\n');
+		sb.append("Perfect: "); sb.append(perfect); sb.append('\n');
+		sb.append("Mods: "); sb.append(mods); sb.append('\n');
+		sb.append("Life data:\n");
+		for (int i = 0; i < lifeFrames.length; i++) {
+			if (i % LINE_SPLIT == 0)
+				sb.append('\t');
+			sb.append(lifeFrames[i]);
+			sb.append((i % LINE_SPLIT == LINE_SPLIT - 1) ? '\n' : ' ');
+		}
+		sb.append('\n');
+		sb.append("Timestamp: "); sb.append(timestamp); sb.append('\n');
+		sb.append("Replay length: "); sb.append(replayLength); sb.append('\n');
+		if (frames != null) {
+			sb.append("Frames:\n");
+			for (int i = 0; i < frames.length; i++) {
+				if (i % LINE_SPLIT == 0)
+					sb.append('\t');
+				sb.append(frames[i]);
+				sb.append((i % LINE_SPLIT == LINE_SPLIT - 1) ? '\n' : ' ');
+			}
+		}
+		return sb.toString();
+	}
+}

src/itdelatrisu/opsu/replay/ReplayFrame.java

@@ -0,0 +1,99 @@
+/*
+ * opsu! - an open-source osu! client
+ * Copyright (C) 2014, 2015 Jeffrey Han
+ *
+ * opsu! is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * opsu! is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with opsu!.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package itdelatrisu.opsu.replay;
+
+import itdelatrisu.opsu.OsuHitObject;
+
+/**
+ * Captures a single replay frame.
+ *
+ * @author smoogipooo (https://github.com/smoogipooo/osu-Replay-API/)
+ */
+public class ReplayFrame {
+	/** Key bits. */
+	public static final int
+		KEY_NONE = 0,
+		KEY_M1 = (1 << 0),
+		KEY_M2 = (1 << 1),
+		KEY_K1 = (1 << 2) | (1 << 0),
+		KEY_K2 = (1 << 3) | (1 << 1);
+
+	/** Time, in milliseconds, since the previous action. */
+	private int timeDiff;
+
+	/** Time, in milliseconds. */
+	private int time;
+
+	/** Cursor coordinates (in OsuPixels). */
+	private float x, y;
+
+	/** Keys pressed (bitmask). */
+    private int keys;
+ 
+	/**
+	 * Constructor.
+	 * @param timeDiff time since the previous action (in ms)
+	 * @param time time (in ms)
+	 * @param x cursor x coordinate [0, 512]
+	 * @param y cursor y coordinate [0, 384]
+	 * @param keys keys pressed (bitmask)
+	 */
+	public ReplayFrame(int timeDiff, int time, float x, float y, int keys) {
+		this.timeDiff = timeDiff;
+		this.time = time;
+		this.x = x;
+		this.y = y;
+		this.keys = keys;
+	}
+
+	/**
+	 * Returns the frame time, in milliseconds.
+	 */
+	public int getTime() { return time; }
+
+	/**
+	 * Returns the time since the previous action, in milliseconds.
+	 */
+	public int getTimeDiff() { return timeDiff; }
+
+	/**
+	 * Returns the scaled cursor x coordinate.
+	 */
+	public int getX() { return (int) (x * OsuHitObject.getXMultiplier() + OsuHitObject.getXOffset()); }
+
+	/**
+	 * Returns the scaled cursor Y coordinate.
+	 */
+	public int getY() { return (int) (y * OsuHitObject.getYMultiplier() + OsuHitObject.getYOffset()); }
+
+	/**
+	 * Returns the keys pressed (KEY_* bitmask).
+	 */
+	public int getKeys() { return keys; }
+
+	/**
+	 * Returns whether or not a key is pressed.
+	 */
+	public boolean isKeyPressed() { return (keys != KEY_NONE); }
+
+	@Override
+	public String toString() {
+		return String.format("(%d, [%.2f, %.2f], %d)", time, x, y, keys);
+	}
+}

src/itdelatrisu/opsu/states/Game.java

@@ -40,6 +40,8 @@ import itdelatrisu.opsu.objects.Circle;
 import itdelatrisu.opsu.objects.HitObject;
 import itdelatrisu.opsu.objects.Slider;
 import itdelatrisu.opsu.objects.Spinner;
+import itdelatrisu.opsu.replay.Replay;
+import itdelatrisu.opsu.replay.ReplayFrame;
 
 import java.io.File;
 import java.util.Stack;
@@ -146,6 +148,24 @@ public class Game extends BasicGameState {
 	/** Number of retries. */
 	private int retries = 0;
 
+	/** The replay, if any. */
+	private Replay replay;
+
+	/** The current replay frame index. */
+	private int replayIndex = 0;
+
+	/** The replay cursor coordinates. */
+	private int replayX, replayY;
+
+	/** Whether a replay key is currently pressed. */
+	private boolean replayKeyPressed;
+
+	/** The replay skip time, or -1 if none. */
+	private int replaySkipTime = -1;
+
+	/** The previous game mod state (before the replay). */
+	private int previousMods = 0;
+
 	// game-related variables
 	private GameContainer container;
 	private StateBasedGame game;
@@ -365,14 +385,24 @@ public class Game extends BasicGameState {
 			cursorCirclePulse.drawCentered(pausedMouseX, pausedMouseY);
 		}
 
-		UI.draw(g);
+		if (replay == null)
+			UI.draw(g);
+		else
+			UI.draw(g, replayX, replayY, replayKeyPressed);
 	}
 
 	@Override
 	public void update(GameContainer container, StateBasedGame game, int delta)
 			throws SlickException {
 		UI.update(delta);
-		int mouseX = input.getMouseX(), mouseY = input.getMouseY();
+		int mouseX, mouseY;
+		if (replay == null) {
+			mouseX = input.getMouseX();
+			mouseY = input.getMouseY();
+		} else {
+			mouseX = replayX;
+			mouseY = replayY;
+		}
 		skipButton.hoverUpdate(delta, mouseX, mouseY);
 
 		if (isLeadIn()) {  // stop updating during song lead-in
@@ -423,14 +453,14 @@ public class Game extends BasicGameState {
 		if (objectIndex >= hitObjects.length || (MusicController.trackEnded() && objectIndex > 0)) {
 			// track ended before last object was processed: force a hit result
 			if (MusicController.trackEnded() && objectIndex < hitObjects.length)
-				hitObjects[objectIndex].update(true, delta, mouseX, mouseY);
+				hitObjects[objectIndex].update(true, delta, mouseX, mouseY, false);
 
 			if (checkpointLoaded)  // if checkpoint used, skip ranking screen
 				game.closeRequested();
 			else {  // go to ranking screen
 				((GameRanking) game.getState(Opsu.STATE_GAMERANKING)).setGameData(data);
 				ScoreData score = data.getScoreData(osu);
-				if (!GameMod.AUTO.isActive() && !GameMod.RELAX.isActive() && !GameMod.AUTOPILOT.isActive())
+				if (!GameMod.AUTO.isActive() && !GameMod.RELAX.isActive() && !GameMod.AUTOPILOT.isActive() && replay == null)
 					ScoreDB.addScore(score);
 				game.enterState(Opsu.STATE_GAMERANKING, new FadeOutTransition(Color.black), new FadeInTransition(Color.black));
 			}
@@ -453,6 +483,32 @@ public class Game extends BasicGameState {
 			}
 		}
 
+		// replays
+		if (replay != null) {
+			// skip intro
+			if (replaySkipTime > 0 && trackPosition > replaySkipTime) {
+				skipIntro();
+				replaySkipTime = -1;
+			}
+
+			// load next frame(s)
+			int replayKey = ReplayFrame.KEY_NONE;
+			while (replayIndex < replay.frames.length && trackPosition >= replay.frames[replayIndex].getTime()) {
+				ReplayFrame frame = replay.frames[replayIndex];
+				replayX = frame.getX();
+				replayY = frame.getY();
+				replayKeyPressed = frame.isKeyPressed();
+				if (replayKeyPressed)
+					replayKey = frame.getKeys();
+				replayIndex++;
+			}
+
+			// send a key press
+			if (replayKey != ReplayFrame.KEY_NONE)
+				gameKeyPressed(((replayKey & ReplayFrame.KEY_M1) > 0) ?
+						Input.MOUSE_LEFT_BUTTON : Input.MOUSE_RIGHT_BUTTON, replayX, replayY);
+		}
+
 		// song beginning
 		if (objectIndex == 0 && trackPosition < osu.objects[0].getTime())
 			return;  // nothing to do here
@@ -478,7 +534,7 @@ public class Game extends BasicGameState {
 		}
 
 		// pause game if focus lost
-		if (!container.hasFocus() && !GameMod.AUTO.isActive()) {
+		if (!container.hasFocus() && !GameMod.AUTO.isActive() && replay == null) {
 			if (pauseTime < 0) {
 				pausedMouseX = mouseX;
 				pausedMouseY = mouseY;
@@ -503,18 +559,21 @@ public class Game extends BasicGameState {
 			}
 
 			// game over, force a restart
-			restart = Restart.LOSE;
-			game.enterState(Opsu.STATE_GAMEPAUSEMENU);
+			if (replay == null) {
+				restart = Restart.LOSE;
+				game.enterState(Opsu.STATE_GAMEPAUSEMENU);
+			}
 		}
 
 		// update objects (loop in unlikely event of any skipped indexes)
+		boolean keyPressed = ((replay != null && replayKeyPressed) || Utils.isGameKeyPressed());
 		while (objectIndex < hitObjects.length && trackPosition > osu.objects[objectIndex].getTime()) {
 			// check if we've already passed the next object's start time
 			boolean overlap = (objectIndex + 1 < hitObjects.length &&
 					trackPosition > osu.objects[objectIndex + 1].getTime() - hitResultOffset[GameData.HIT_300]);
 
 			// update hit object and check completion status
-			if (hitObjects[objectIndex].update(overlap, delta, mouseX, mouseY))
+			if (hitObjects[objectIndex].update(overlap, delta, mouseX, mouseY, keyPressed))
 				objectIndex++;  // done, so increment object index
 			else
 				break;
@@ -529,7 +588,7 @@ public class Game extends BasicGameState {
 		int trackPosition = MusicController.getPosition();
 
 		// game keys
-		if (!Keyboard.isRepeatEvent()) {
+		if (!Keyboard.isRepeatEvent() && replay == null) {
 			if (key == Options.getGameKeyLeft())
 				gameKeyPressed(Input.MOUSE_LEFT_BUTTON, input.getMouseX(), input.getMouseY());
 			else if (key == Options.getGameKeyRight())
@@ -538,8 +597,8 @@ public class Game extends BasicGameState {
 
 		switch (key) {
 		case Input.KEY_ESCAPE:
-			// "auto" mod: go back to song menu
-			if (GameMod.AUTO.isActive()) {
+			// "auto" mod or watching replay: go back to song menu
+			if (GameMod.AUTO.isActive() || replay != null) {
 				game.closeRequested();
 				break;
 			}
@@ -636,6 +695,10 @@ public class Game extends BasicGameState {
 		if (Options.isMouseDisabled())
 			return;
 
+		// watching replay
+		if (replay != null)
+			return;
+
 		// mouse wheel: pause the game
 		if (button == Input.MOUSE_MIDDLE_BUTTON && !Options.isMouseWheelDisabled()) {
 			int trackPosition = MusicController.getPosition();
@@ -769,6 +832,31 @@ public class Game extends BasicGameState {
 				}
 			}
 
+			// load replay frames
+			if (replay != null) {
+				// load mods
+				previousMods = GameMod.getModState();
+				GameMod.loadModState(replay.mods);
+
+				// load initial data
+				replayX = container.getWidth() / 2;
+				replayY = container.getHeight() / 2;
+				replayKeyPressed = false;
+				replaySkipTime = -1;
+				for (replayIndex = 0; replayIndex < replay.frames.length; replayIndex++) {
+					ReplayFrame frame = replay.frames[replayIndex];
+					if (frame.getY() < 0) {  // skip time (?)
+						if (frame.getTime() > 0)
+							replaySkipTime = frame.getTime();
+					} else if (frame.getTime() == 0) {
+						replayX = frame.getX();
+						replayY = frame.getY();
+						replayKeyPressed = frame.isKeyPressed();
+					} else
+						break;
+				}
+			}
+
 			leadInTime = osu.audioLeadIn + approachTime;
 			restart = Restart.FALSE;
 		}
@@ -776,11 +864,15 @@ public class Game extends BasicGameState {
 		skipButton.resetHover();
 	}
 
-//	@Override
-//	public void leave(GameContainer container, StateBasedGame game)
-//			throws SlickException {
+	@Override
+	public void leave(GameContainer container, StateBasedGame game)
+			throws SlickException {
 //		container.setMouseGrabbed(false);
-//	}
+
+		// reset previous mod state
+		if (replay != null)
+			GameMod.loadModState(previousMods);
+	}
 
 	/**
 	 * Resets all game data and structures.
@@ -816,12 +908,12 @@ public class Game extends BasicGameState {
 	private boolean skipIntro() {
 		int firstObjectTime = osu.objects[0].getTime();
 		int trackPosition = MusicController.getPosition();
-		if (objectIndex == 0 &&
-			trackPosition < firstObjectTime - SKIP_OFFSET) {
+		if (objectIndex == 0 && trackPosition < firstObjectTime - SKIP_OFFSET) {
 			if (isLeadIn()) {
 				leadInTime = 0;
 				MusicController.resume();
 			}
+			replaySkipTime = -1;
 			MusicController.setPosition(firstObjectTime - SKIP_OFFSET);
 			SoundController.playSound(SoundEffect.MENUHIT);
 			return true;
@@ -950,4 +1042,10 @@ public class Game extends BasicGameState {
 	 * Returns the slider multiplier given by the current timing point.
 	 */
 	public float getTimingPointMultiplier() { return beatLength / beatLengthBase; }
+
+	/**
+	 * Sets a replay to view.
+	 * @param replay the replay
+	 */
+	public void setReplay(Replay replay) { this.replay = replay; }
 }

src/itdelatrisu/opsu/states/SongMenu.java

@@ -41,6 +41,7 @@ import itdelatrisu.opsu.audio.SoundController;
 import itdelatrisu.opsu.audio.SoundEffect;
 import itdelatrisu.opsu.db.OsuDB;
 import itdelatrisu.opsu.db.ScoreDB;
+import itdelatrisu.opsu.replay.Replay;
 import itdelatrisu.opsu.states.ButtonMenu.MenuState;
 
 import java.io.File;