From d3e6d3e763544511a870b354f657600d25c42b91 Mon Sep 17 00:00:00 2001
From: Jeff Brown <jeffbrown@google.com>
Date: Tue, 12 Apr 2011 22:39:53 -0700
Subject: [PATCH] Initial checkin of spot presentation for touchpad gestures.
 (DO NOT MERGE)

Added a new PointerIcon API (hidden for now) for loading
pointer icons.

Fixed a starvation problem in the native Looper's sendMessage
implementation which caused new messages to be posted ahead
of old messages sent with sendMessageDelayed.

Redesigned the touch pad gestures to be defined in terms of
more fluid finger / spot movements.  The objective is to reinforce
the natural mapping between fingers and spots which means there
must not be any discontinuities in spot motion relative to
the fingers.

Removed the SpotController stub and folded its responsibilities
into PointerController.

Change-Id: Ib647dbd7a57a7f30dd9c6e2c260df51d7bbdd18e
---
 include/ui/Input.h    | 5 +++++
 libs/ui/Input.cpp     | 9 +++++++++
 libs/utils/Looper.cpp | 3 ++-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/include/ui/Input.h b/include/ui/Input.h
index 1ef36d007..fb6152e9f 100644
--- a/include/ui/Input.h
+++ b/include/ui/Input.h
@@ -608,6 +608,11 @@ private:
     // Oldest sample to consider when calculating the velocity.
     static const nsecs_t MAX_AGE = 200 * 1000000; // 200 ms
 
+    // When the total duration of the window of samples being averaged is less
+    // than the window size, the resulting velocity is scaled to reduce the impact
+    // of overestimation in short traces.
+    static const nsecs_t MIN_WINDOW = 100 * 1000000; // 100 ms
+
     // The minimum duration between samples when estimating velocity.
     static const nsecs_t MIN_DURATION = 10 * 1000000; // 10 ms
 
diff --git a/libs/ui/Input.cpp b/libs/ui/Input.cpp
index 0a53d69be..684c332d1 100644
--- a/libs/ui/Input.cpp
+++ b/libs/ui/Input.cpp
@@ -831,6 +831,7 @@ bool VelocityTracker::getVelocity(uint32_t id, float* outVx, float* outVy) const
         const Position& oldestPosition =
                 oldestMovement.positions[oldestMovement.idBits.getIndexOfBit(id)];
         nsecs_t lastDuration = 0;
+
         while (numTouches-- > 1) {
             if (++index == HISTORY_SIZE) {
                 index = 0;
@@ -857,6 +858,14 @@ bool VelocityTracker::getVelocity(uint32_t id, float* outVx, float* outVy) const
 
         // Make sure we used at least one sample.
         if (samplesUsed != 0) {
+            // Scale the velocity linearly if the window of samples is small.
+            nsecs_t totalDuration = newestMovement.eventTime - oldestMovement.eventTime;
+            if (totalDuration < MIN_WINDOW) {
+                float scale = float(totalDuration) / float(MIN_WINDOW);
+                accumVx *= scale;
+                accumVy *= scale;
+            }
+
             *outVx = accumVx;
             *outVy = accumVy;
             return true;
diff --git a/libs/utils/Looper.cpp b/libs/utils/Looper.cpp
index d5dd12606..b54fb9dd7 100644
--- a/libs/utils/Looper.cpp
+++ b/libs/utils/Looper.cpp
@@ -662,7 +662,8 @@ void Looper::wakeAndLock() {
 #endif
 
 void Looper::sendMessage(const sp<MessageHandler>& handler, const Message& message) {
-    sendMessageAtTime(LLONG_MIN, handler, message);
+    nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
+    sendMessageAtTime(now, handler, message);
 }
 
 void Looper::sendMessageDelayed(nsecs_t uptimeDelay, const sp<MessageHandler>& handler,