commit f859148f62f5c808470705e618dcbf8f9de14e4e
author Chris Ye <lzye@google.com> Fri Apr 17 11:49:17 2020 -0700
committer Chris Ye <lzye@google.com> Wed May 06 09:50:10 2020 -0700
tree c29a26d20b0ecd09bbf51ac9c4501fbe63ce105c
parent 860c01dcc1a6f2cbe88b64cf8b82c6b7f815a986

Represent VelocityTracker Strategy as enum class.

Use enum class to represent VelocityTracker Strategy, instead of
const char*.

Bug: 116843422
Test: atest VelocityTrackerTest

Change-Id: I3049dbefcd5641d67ad919ed3e375d48643dc9b9

include/input/VelocityTracker.h

diff --git a/include/input/VelocityTracker.h b/include/input/VelocityTracker.h
index 727865a..ee010a3 100644
--- a/include/input/VelocityTracker.h
+++ b/include/input/VelocityTracker.h
@@ -18,8 +18,8 @@
 #define _LIBINPUT_VELOCITY_TRACKER_H
 
 #include <input/Input.h>
-#include <utils/Timers.h>
 #include <utils/BitSet.h>
+#include <utils/Timers.h>
 
 namespace android {
 
@@ -30,6 +30,22 @@
  */
 class VelocityTracker {
 public:
+    enum class Strategy : int32_t {
+        DEFAULT = -1,
+        MIN = 0,
+        IMPULSE = 0,
+        LSQ1 = 1,
+        LSQ2 = 2,
+        LSQ3 = 3,
+        WLSQ2_DELTA = 4,
+        WLSQ2_CENTRAL = 5,
+        WLSQ2_RECENT = 6,
+        INT1 = 7,
+        INT2 = 8,
+        LEGACY = 9,
+        MAX = LEGACY,
+    };
+
     struct Position {
         float x, y;
     };
@@ -62,8 +78,8 @@
     };
 
     // Creates a velocity tracker using the specified strategy.
-    // If strategy is NULL, uses the default strategy for the platform.
-    VelocityTracker(const char* strategy = nullptr);
+    // If strategy is not provided, uses the default strategy for the platform.
+    VelocityTracker(const Strategy strategy = Strategy::DEFAULT);
 
     ~VelocityTracker();
 
@@ -102,16 +118,21 @@
     inline BitSet32 getCurrentPointerIdBits() const { return mCurrentPointerIdBits; }
 
 private:
-    static const char* DEFAULT_STRATEGY;
+    // The default velocity tracker strategy.
+    // Although other strategies are available for testing and comparison purposes,
+    // this is the strategy that applications will actually use.  Be very careful
+    // when adjusting the default strategy because it can dramatically affect
+    // (often in a bad way) the user experience.
+    static const Strategy DEFAULT_STRATEGY = Strategy::LSQ2;
 
     nsecs_t mLastEventTime;
     BitSet32 mCurrentPointerIdBits;
     int32_t mActivePointerId;
-    VelocityTrackerStrategy* mStrategy;
+    std::unique_ptr<VelocityTrackerStrategy> mStrategy;
 
-    bool configureStrategy(const char* strategy);
+    bool configureStrategy(const Strategy strategy);
 
-    static VelocityTrackerStrategy* createStrategy(const char* strategy);
+    static std::unique_ptr<VelocityTrackerStrategy> createStrategy(const Strategy strategy);
 };