From abf0ea68634c1d21870c48297ab6898491e0c56f Mon Sep 17 00:00:00 2001
From: Chih-Chung Chang <chihchung@google.com>
Date: Tue, 31 Jul 2012 13:03:24 +0800
Subject: Manually transform the event coordinates on older platforms.

Change-Id: I070b27112ea028f2a1596dcdfa480537765174b9
---
 src/com/android/gallery3d/ui/GLRootView.java | 95 +++++++++++++++++++++++++++-
 1 file changed, 94 insertions(+), 1 deletion(-)

(limited to 'src/com/android/gallery3d')

diff --git a/src/com/android/gallery3d/ui/GLRootView.java b/src/com/android/gallery3d/ui/GLRootView.java
index 9fd9473dc..7f717b7b7 100644
--- a/src/com/android/gallery3d/ui/GLRootView.java
+++ b/src/com/android/gallery3d/ui/GLRootView.java
@@ -25,7 +25,9 @@ import android.os.Build;
 import android.os.Process;
 import android.os.SystemClock;
 import android.util.AttributeSet;
+import android.util.FloatMath;
 import android.view.MotionEvent;
+import android.view.MotionEvent.PointerCoords;
 import android.view.SurfaceHolder;
 import android.view.View;
 
@@ -430,7 +432,7 @@ public class GLRootView extends GLSurfaceView
         }
 
         if (mCompensation != 0) {
-            event.transform(mCompensationMatrix);
+            event = transformEvent(event, mCompensationMatrix);
         }
 
         mRenderLock.lock();
@@ -447,6 +449,97 @@ public class GLRootView extends GLSurfaceView
         }
     }
 
+    private static MotionEvent transformEvent(MotionEvent e, Matrix m) {
+        // We try to use the new transform method if possible because it uses
+        // less memory.
+        if (ApiHelper.HAS_MOTION_EVENT_TRANSFORM) {
+            return transformEventNew(e, m);
+        } else {
+            return transformEventOld(e, m);
+        }
+    }
+
+    @TargetApi(ApiHelper.VERSION_CODES.HONEYCOMB)
+    private static MotionEvent transformEventNew(MotionEvent e, Matrix m) {
+        e.transform(m);
+        return e;
+    }
+
+    // This is copied from Input.cpp in the android framework.
+    private static MotionEvent transformEventOld(MotionEvent e, Matrix m) {
+        long downTime = e.getDownTime();
+        long eventTime = e.getEventTime();
+        int action = e.getAction();
+        int pointerCount = e.getPointerCount();
+        int[] pointerIds = getPointerIds(e);
+        PointerCoords[] pointerCoords = getPointerCoords(e);
+        int metaState = e.getMetaState();
+        float xPrecision = e.getXPrecision();
+        float yPrecision = e.getYPrecision();
+        int deviceId = e.getDeviceId();
+        int edgeFlags = e.getEdgeFlags();
+        int source = e.getSource();
+        int flags = e.getFlags();
+
+        // Copy the x and y coordinates into an array, map them, and copy back.
+        float[] xy = new float[pointerCoords.length * 2];
+        for (int i = 0; i < pointerCount;i++) {
+            xy[2 * i] = pointerCoords[i].x;
+            xy[2 * i + 1] = pointerCoords[i].y;
+        }
+        m.mapPoints(xy);
+        for (int i = 0; i < pointerCount;i++) {
+            pointerCoords[i].x = xy[2 * i];
+            pointerCoords[i].y = xy[2 * i + 1];
+            pointerCoords[i].orientation = transformAngle(
+                m, pointerCoords[i].orientation);
+        }
+
+        MotionEvent n = MotionEvent.obtain(downTime, eventTime, action,
+                pointerCount, pointerIds, pointerCoords, metaState, xPrecision,
+                yPrecision, deviceId, edgeFlags, source, flags);
+
+        return n;
+    }
+
+    private static int[] getPointerIds(MotionEvent e) {
+        int n = e.getPointerCount();
+        int[] r = new int[n];
+        for (int i = 0; i < n; i++) {
+            r[i] = e.getPointerId(i);
+        }
+        return r;
+    }
+
+    private static PointerCoords[] getPointerCoords(MotionEvent e) {
+        int n = e.getPointerCount();
+        PointerCoords[] r = new PointerCoords[n];
+        for (int i = 0; i < n; i++) {
+            r[i] = new PointerCoords();
+            e.getPointerCoords(i, r[i]);
+        }
+        return r;
+    }
+
+    private static float transformAngle(Matrix m, float angleRadians) {
+        // Construct and transform a vector oriented at the specified clockwise
+        // angle from vertical.  Coordinate system: down is increasing Y, right is
+        // increasing X.
+        float[] v = new float[2];
+        v[0] = FloatMath.sin(angleRadians);
+        v[1] = -FloatMath.cos(angleRadians);
+        m.mapVectors(v);
+
+        // Derive the transformed vector's clockwise angle from vertical.
+        float result = (float) Math.atan2(v[0], -v[1]);
+        if (result < -Math.PI / 2) {
+            result += Math.PI;
+        } else if (result > Math.PI / 2) {
+            result -= Math.PI;
+        }
+        return result;
+    }
+
     private class IdleRunner implements Runnable {
         // true if the idle runner is in the queue
         private boolean mActive = false;
-- 
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