1 files changed, 115 insertions, 0 deletions
diff --git a/src/com/android/dreams/phototable/DragGestureDetector.java b/src/com/android/dreams/phototable/DragGestureDetector.java
new file mode 100644
index 0000000..739163d
--- /dev/null
+++ b/src/com/android/dreams/phototable/DragGestureDetector.java
@@ -0,0 +1,115 @@
+/*
+ * Copyright (C) 2013 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 com.android.dreams.phototable;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.util.Log;
+import android.view.MotionEvent;
+
+/**
+ * Detect and dispatch edge events.
+ */
+public class DragGestureDetector {
+    private static final String TAG = "DragGestureDetector";
+
+    private final PhotoTable mTable;
+    private final float mTouchGain;
+
+    private int mPointer;
+    private float[] mLast;
+    private float[] mCurrent;
+    private boolean mDrag;
+
+    public DragGestureDetector(Context context, PhotoTable table) {
+        Resources res = context.getResources();
+        mTouchGain = res.getInteger(R.integer.generalized_touch_gain) / 1000000f;
+        mTable = table;
+        mLast = new float[2];
+        mCurrent = new float[2];
+    }
+
+    private void computeAveragePosition(MotionEvent event, float[] position) {
+        computeAveragePosition(event, position, -1);
+    }
+
+    private void computeAveragePosition(MotionEvent event, float[] position, int ignore) {
+        final int pointerCount = event.getPointerCount();
+        position[0] = 0f;
+        position[1] = 0f;
+        float count = 0f;
+        for (int p = 0; p < pointerCount; p++) {
+            if (p != ignore) {
+                position[0] += event.getX(p);
+                position[1] += event.getY(p);
+                count += 1f;
+            }
+        }
+        position[0] /= count;
+        position[1] /= count;
+    }
+
+    public boolean onTouchEvent(MotionEvent event) {
+        int index = event.getActionIndex();
+        switch (event.getActionMasked()) {
+            case MotionEvent.ACTION_DOWN:
+                mPointer = event.getPointerId(index);
+                computeAveragePosition(event, mLast);
+                mDrag = false;
+                break;
+
+            case MotionEvent.ACTION_POINTER_DOWN:
+                mDrag = mTable.hasFocus();
+                computeAveragePosition(event, mLast);
+                break;
+
+            case MotionEvent.ACTION_POINTER_UP:
+                computeAveragePosition(event, mLast, index);
+                break;
+
+            case MotionEvent.ACTION_MOVE:
+                computeAveragePosition(event, mCurrent);
+                if (mDrag) {
+                    move(event, false);
+                }
+                break;
+
+            case MotionEvent.ACTION_CANCEL:
+            case MotionEvent.ACTION_UP:
+                if (mDrag) {
+                    move(event, true);
+                }
+                mDrag = false;
+                break;
+        }
+
+        if (mDrag) {
+            mTable.refreshFocus();
+        }
+
+        return mDrag;
+    }
+
+    private void move(MotionEvent event, boolean drop) {
+        mTable.move(mTable.getFocused(),
+                mTouchGain * (mCurrent[0] - mLast[0]),
+                mTouchGain * (mCurrent[1] - mLast[1]),
+                drop);
+        mLast[0] = mCurrent[0];
+        mLast[1] = mCurrent[1];
+    }
+}
+