Kinectic Scrolling

for SongNodes, Scores, Download Results, Download Info

src/itdelatrisu/opsu/ui/KinecticScrolling.java

@@ -0,0 +1,155 @@
+package itdelatrisu.opsu.ui;
+
+/**
+ * Drag to scroll based on:
+ * http://ariya.ofilabs.com/2013/11/javascript-kinetic-scrolling-part-2.html
+ * 
+ * @author fluddokt (https://github.com/fluddokt)
+ */
+public class KinecticScrolling {
+
+	/** The moving averaging constant */
+	final static private float AVG_CONST = 0.2f;
+	final static private float ONE_MINUS_AVG_CONST = 1 - AVG_CONST;
+
+	/** The constant used to determine how fast the target position will be reach. */
+	final static private int TIME_CONST = 200;
+	
+	/** The constant used to determine how much of the velocity will be used to launch to the target. */
+	final static private float AMPLITUDE_CONST = 0.25f;
+	
+	/** The current position. */
+	float position;
+
+	/** The offset to scroll to the target position. */
+	float amplitude;
+	
+	/** The current target to scroll to. */
+	float target;
+	
+	/** The total amount of time since the mouse button was released. */
+	float totalDelta;
+
+	/** The maximum and minimum value the position can reach. */
+	float max = Float.MAX_VALUE;
+	float min = -Float.MAX_VALUE;
+
+	/** Whether the mouse is currently pressed or not */
+	boolean pressed = false;
+
+	/** The change in position since the last update */
+	float deltaPosition;
+	
+	/** The moving average of the velocity. */
+	float avgVelocity;
+	
+	/**
+	 * Returns the current Position.
+	 * @return the position.
+	 */
+	public float getPosition() {
+		return position;
+	}
+	
+	/**
+	 * Updates the scrolling.
+	 * @param delta the elapsed time since the last update
+	 */
+	public void update(float delta) {
+		if (!pressed) {
+			totalDelta += delta;
+			position = target + (float) (-amplitude * Math.exp(-totalDelta / TIME_CONST));
+		} else {
+			avgVelocity = (ONE_MINUS_AVG_CONST * avgVelocity + AVG_CONST * (deltaPosition * 1000f / delta));
+			
+			position += deltaPosition;
+			target = position ;
+			deltaPosition = 0;
+		}
+		if (position > max) {
+			amplitude = 0;
+			target = position = max;
+		}
+		if (position < min) {
+			amplitude = 0;
+			target = position = min;
+		}
+	}
+
+	/**
+	 * Scrolls to the position.
+	 * @param newPosition the position to scroll to.
+	 */
+	public void scrollToPosition(float newPosition) {
+		amplitude = newPosition - position;
+		target = newPosition;
+		totalDelta = 0;
+	}
+
+	/**
+	 * Scrolls to an offset from target.
+	 * @param offset the offset from the target to scroll to.
+	 */
+	public void scrollOffset(float offset) {
+		scrollToPosition(target + offset);
+	}
+
+	/**
+	 * Sets the position.
+	 * @param newPosition the position to be set
+	 */
+	public void setPosition(float newPosition) {
+		pressed();
+		release();
+		target = newPosition;
+		position = target;
+	}
+
+	/**
+	 * Set the position relative to an offset.
+	 * @param offset the offset from the position.
+	 */
+	public void addOffset(float offset) {
+		setPosition(position + offset);
+	}
+
+	/**
+	 * Call this when the mouse button has been pressed.
+	 */
+	public void pressed() {
+		if (pressed)
+			return;
+		pressed = true;
+		avgVelocity = 0;
+	}
+
+	/**
+	 * Call this when the mouse button has been released.
+	 */
+	public void release() {
+		if (!pressed)
+			return;
+		pressed = false;
+		amplitude = AMPLITUDE_CONST * avgVelocity;
+		target = Math.round(target + amplitude);
+		totalDelta = 0;
+	}
+
+	/**
+	 * Call this when the mouse has been dragged.
+	 * @param distance the amount that the mouse has been dragged
+	 */
+	public void dragged(float distance) {
+		deltaPosition += distance;
+	}
+
+	/**
+	 * Set the minimum and maximum bound.
+	 * @param min the minimum bound
+	 * @param max the maximum bound
+	 */
+	public void setMinMax(float min, float max) {
+		this.min = min;
+		this.max = max;
+	}
+}

src/itdelatrisu/opsu/ui/UI.java

@@ -318,28 +318,25 @@ public class UI {
 	/**
 	 * Draws a scroll bar.
 	 * @param g the graphics context
-	 * @param unitIndex the unit index
-	 * @param totalUnits the total number of units
-	 * @param maxShown the maximum number of units shown at one time
-	 * @param unitBaseX the base x coordinate of the units
-	 * @param unitBaseY the base y coordinate of the units
+	 * @param position the position in the virtual area
+	 * @param totalLength the total length of the virtual area
+	 * @param lengthShown the length of the virtual area shown
+	 * @param unitBaseX the base x coordinate
+	 * @param unitBaseY the base y coordinate
 	 * @param unitWidth the width of a unit
-	 * @param unitHeight the height of a unit
-	 * @param unitOffsetY the y offset between units
+	 * @param scrollAreaHeight the height of the scroll area
 	 * @param bgColor the scroll bar area background color (null if none)
 	 * @param scrollbarColor the scroll bar color
 	 * @param right whether or not to place the scroll bar on the right side of the unit
 	 */
 	public static void drawScrollbar(
-			Graphics g, int unitIndex, int totalUnits, int maxShown,
-			float unitBaseX, float unitBaseY, float unitWidth, float unitHeight, float unitOffsetY,
+			Graphics g, float position, float totalLength, float lengthShown,
+			float unitBaseX, float unitBaseY, float unitWidth, float scrollAreaHeight,
 			Color bgColor, Color scrollbarColor, boolean right
 	) {
 		float scrollbarWidth = container.getWidth() * 0.00347f;
-		float heightRatio = (float) (2.6701f * Math.exp(-0.81 * Math.log(totalUnits)));
-		float scrollbarHeight = container.getHeight() * heightRatio;
-		float scrollAreaHeight = unitHeight + unitOffsetY * (maxShown - 1);
-		float offsetY = (scrollAreaHeight - scrollbarHeight) * ((float) unitIndex / (totalUnits - maxShown));
+		float scrollbarHeight = scrollAreaHeight * lengthShown / totalLength;
+		float offsetY = (scrollAreaHeight - scrollbarHeight) * (position / (totalLength - lengthShown));
 		float scrollbarX = unitBaseX + unitWidth - ((right) ? scrollbarWidth : 0);
 		if (bgColor != null) {
 			g.setColor(bgColor);