From fc5ea05e48495a21a7ef2043a15ea4c3354b9dec Mon Sep 17 00:00:00 2001
From: Andrew Chen <achen.code@gmail.com>
Date: Tue, 3 Jan 2012 20:32:05 -0800
Subject: [PATCH] Issue 3875: Add more debugging lines to figure out what might
 be wrong with the new swipe algorithm. Fix some variable names.

---
 src/com/fsck/k9/activity/K9Activity.java | 42 ++++++++++++++++++++----
 1 file changed, 35 insertions(+), 7 deletions(-)

diff --git a/src/com/fsck/k9/activity/K9Activity.java b/src/com/fsck/k9/activity/K9Activity.java
index 3bb76c480..1f45d5fb1 100644
--- a/src/com/fsck/k9/activity/K9Activity.java
+++ b/src/com/fsck/k9/activity/K9Activity.java
@@ -7,6 +7,7 @@ import android.app.Activity;
 import android.content.Context;
 import android.content.res.Configuration;
 import android.os.Bundle;
+import android.util.Log;
 import android.view.GestureDetector;
 import android.view.GestureDetector.SimpleOnGestureListener;
 import android.view.MotionEvent;
@@ -164,21 +165,48 @@ public class K9Activity extends Activity {
         public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
             // Do fling-detection if gestures are force-enabled or we have system-wide gestures enabled.
             if (gesturesEnabled || K9.gesturesEnabled()) {
-                // Convert the dips to pixels
+                // Calculate the minimum distance required for this to count as a swipe.
+                // Convert the constant dips to pixels.
                 final float mGestureScale = getResources().getDisplayMetrics().density;
-                int min_distance = (int)(SWIPE_MIN_DISTANCE_DIP * mGestureScale + 0.5f);
-                int min_velocity = (int)(SWIPE_THRESHOLD_VELOCITY_DIP * mGestureScale + 0.5f);
-                int max_off_path = (int)(SWIPE_MAX_OFF_PATH_DIP * mGestureScale + 0.5f);
+                final int minDistance = (int)(SWIPE_MIN_DISTANCE_DIP * mGestureScale + 0.5f);
+                final int minVelocity = (int)(SWIPE_THRESHOLD_VELOCITY_DIP * mGestureScale + 0.5f);
+                final int maxOffPath = (int)(SWIPE_MAX_OFF_PATH_DIP * mGestureScale + 0.5f);
+                
+                // Calculate how much was actually swiped.
+                final float deltaX = e2.getX() - e1.getX();
+                final float deltaY = e2.getY() - e1.getY();
 
+                final boolean movedAcross = (Math.abs(deltaX) > Math.abs(deltaY * 4));
+                final boolean steadyHand = (Math.abs(deltaX / deltaY) > 2);
+                if(K9.DEBUG) {
+                    Log.d(K9.LOG_TAG, "Old swipe algorithm: movedAcross=" + movedAcross + " steadyHand=" + steadyHand + " result=" + (movedAcross && steadyHand));
+                    Log.d(K9.LOG_TAG, String.format("New swipe algorithm: deltaX=%.2f deltaY=%.2f velocity=%.2f (min=%d)", deltaX, deltaY, velocityX, minVelocity));
+                }
 
                 try {
-                    if (Math.abs(e1.getY() - e2.getY()) > max_off_path)
+                    if (Math.abs(deltaY) > maxOffPath) {
+                        if(K9.DEBUG)
+                            Log.d(K9.LOG_TAG, "New swipe algorithm: Swipe too far off horizontal path.");
                         return false;
+                    }
+                    if(Math.abs(velocityX) < minVelocity) {
+                        if(K9.DEBUG)
+                            Log.d(K9.LOG_TAG, "New swipe algorithm: Swipe too slow.");
+                        return false;
+                    }
                     // right to left swipe
-                    if (e1.getX() - e2.getX() > min_distance && Math.abs(velocityX) > min_velocity) {
+                    if (deltaX < minDistance) {
                         onSwipeRightToLeft(e1, e2);
-                    } else if (e2.getX() - e1.getX() > min_distance && Math.abs(velocityX) > min_velocity) {
+                        if(K9.DEBUG)
+                            Log.d(K9.LOG_TAG, "New swipe algorithm: Right to Left swipe OK.");
+                    } else if (deltaX > minDistance) {
                         onSwipeLeftToRight(e1, e2);
+                        if(K9.DEBUG)
+                            Log.d(K9.LOG_TAG, "New swipe algorithm: Left to Right swipe OK.");
+                    } else {
+                        if(K9.DEBUG)
+                            Log.d(K9.LOG_TAG, "New swipe algorithm: Swipe did not meet minimum distance requirements.");
+                        return false;
                     }
                 } catch (Exception e) {
                     // nothing