1 files changed, 113 insertions, 0 deletions
diff --git a/core/java/android/gesture/Instance.java b/core/java/android/gesture/Instance.java
new file mode 100755
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+++ b/core/java/android/gesture/Instance.java
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+/*
+ * Copyright (C) 2008-2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.gesture;
+
+
+/**
+ * An instance represents a sample if the label is available or a query if the
+ * label is null.
+ */
+class Instance {
+    private static final int SEQUENCE_SAMPLE_SIZE = 16;
+
+    private static final int PATCH_SAMPLE_SIZE = 16;
+
+    private final static float[] ORIENTATIONS = {
+            0, (float) (Math.PI / 4), (float) (Math.PI / 2), (float) (Math.PI * 3 / 4),
+            (float) Math.PI, -0, (float) (-Math.PI / 4), (float) (-Math.PI / 2),
+            (float) (-Math.PI * 3 / 4), (float) -Math.PI
+    };
+
+    // the feature vector
+    final float[] vector;
+
+    // the label can be null
+    final String label;
+
+    // the id of the instance
+    final long id;
+
+    private Instance(long id, float[] sample, String sampleName) {
+        this.id = id;
+        vector = sample;
+        label = sampleName;
+    }
+
+    private void normalize() {
+        float[] sample = vector;
+        float sum = 0;
+
+        int size = sample.length;
+        for (int i = 0; i < size; i++) {
+            sum += sample[i] * sample[i];
+        }
+
+        float magnitude = (float)Math.sqrt(sum);
+        for (int i = 0; i < size; i++) {
+            sample[i] /= magnitude;
+        }
+    }
+
+    /**
+     * create a learning instance for a single stroke gesture
+     * 
+     * @param gesture
+     * @param label
+     * @return the instance
+     */
+    static Instance createInstance(int sequenceType, int orientationType, Gesture gesture, String label) {
+        float[] pts;
+        Instance instance;
+        if (sequenceType == GestureStore.SEQUENCE_SENSITIVE) {
+            pts = temporalSampler(orientationType, gesture);
+            instance = new Instance(gesture.getID(), pts, label);
+            instance.normalize();
+        } else {
+            pts = spatialSampler(gesture);
+            instance = new Instance(gesture.getID(), pts, label);
+        }
+        return instance;
+    }
+
+    private static float[] spatialSampler(Gesture gesture) {
+        return GestureUtilities.spatialSampling(gesture, PATCH_SAMPLE_SIZE);
+    }
+
+    private static float[] temporalSampler(int orientationType, Gesture gesture) {
+        float[] pts = GestureUtilities.temporalSampling(gesture.getStrokes().get(0),
+                SEQUENCE_SAMPLE_SIZE);
+        float[] center = GestureUtilities.computeCentroid(pts);
+        float orientation = (float)Math.atan2(pts[1] - center[1], pts[0] - center[0]);
+
+        float adjustment = -orientation;
+        if (orientationType == GestureStore.ORIENTATION_SENSITIVE) {
+            int count = ORIENTATIONS.length;
+            for (int i = 0; i < count; i++) {
+                float delta = ORIENTATIONS[i] - orientation;
+                if (Math.abs(delta) < Math.abs(adjustment)) {
+                    adjustment = delta;
+                }
+            }
+        }
+
+        GestureUtilities.translate(pts, -center[0], -center[1]);
+        GestureUtilities.rotate(pts, adjustment);
+
+        return pts;
+    }
+
+}