Add animated rectangle on drag latency page

android/WALT/app/src/main/java/org/chromium/latency/walt/TouchCatcherView.java

@@ -1,20 +1,62 @@
 package org.chromium.latency.walt;
 
 import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
 import android.util.AttributeSet;
 import android.view.View;
 
-/**
- * Created by kamrik on 7/5/16.
- */
+
+
 public class TouchCatcherView extends View {
+
+    private Paint linePaint = new Paint();
+    private ClockManager clockManager;
+
     public TouchCatcherView(Context context, AttributeSet attrs) {
         super(context, attrs);
-
+        clockManager = ClockManager.getInstance(context);
         initialisePaint();
     }
 
     private void initialisePaint() {
         float density = getResources().getDisplayMetrics().density;
+        float lineWidth = 10f * density;
+        linePaint.setColor(Color.RED);
+        linePaint.setStrokeWidth(lineWidth);
+    }
+
+    public static double markerPosition(long t_us) {
+        int period = 1000000;  // microseconds
+        // Normalized time within period, goes from 0 to 1
+        double t = (t_us % period) / (double) period;
+        // Triangular wave with amplitude 1
+        double x_tri = -1 + 4 * Math.abs(t - 0.5);
+
+        // Apply some smoothing to get rid of the sharp edges of triangular wave.
+        // beta is a dimensionless smoothing parameter used below, experimentally derived.
+        // Higher value gives less smoothing.
+        double beta = 4;
+        // Multiply by the smoothing function 1/{1 + exp(b(|x|-1))/(b-1)}
+        // This is a Fermi function, modified to have a zero derivative at x = 1.
+        double x_smooth = x_tri / (1 + Math.exp(beta*(Math.abs(x_tri)-1))/(beta - 1));
+        return x_smooth;
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+
+        int h = getHeight();
+        double normPos = markerPosition(clockManager.micros());
+        double amplitude = 0.4; // Of View height
+        int pos = (int) (h * (0.5 + amplitude * normPos));
+        // Log.i("AnimatedView", "Pos is " + pos);
+        int w = getWidth();
+        canvas.drawLine(w/3, pos, w*2/3, pos, linePaint);
+
+        // Run every frame
+        invalidate();
     }
 }