Changed Workspace to inherit from PagedView

- adds support for seeing dimmed side-pages on
home
- adds workspace support for pages that are
smaller than workspace itself
- removing a lot of code duplicated between
PagedView and Workspace
- tested new Workspace on Nexus One, and perf.
was indistinguishable from old Workspace in my
tests

Change-Id: Ie33ab4e8b35ac01b22894cff66650bb0ece8dfcc

1 files changed, 159 insertions, 0 deletions

diff --git a/src/com/android/launcher2/SmoothPagedView.java b/src/com/android/launcher2/SmoothPagedView.java
new file mode 100644
index 000000000..321834902
--- /dev/null
+++ b/src/com/android/launcher2/SmoothPagedView.java
@@ -0,0 +1,159 @@
+/*
+ * Copyright (C) 2008 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.launcher2;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.animation.Interpolator;
+import android.widget.Scroller;
+
+
+public abstract class SmoothPagedView extends PagedView {
+    private static final float SMOOTHING_SPEED = 0.75f;
+    private static final float SMOOTHING_CONSTANT = (float) (0.016 / Math.log(SMOOTHING_SPEED));
+
+
+    private static final float BASELINE_FLING_VELOCITY = 2500.f;
+    private static final float FLING_VELOCITY_INFLUENCE = 0.4f;
+
+    private WorkspaceOvershootInterpolator mScrollInterpolator;
+
+    private static class WorkspaceOvershootInterpolator implements Interpolator {
+        private static final float DEFAULT_TENSION = 1.3f;
+        private float mTension;
+
+        public WorkspaceOvershootInterpolator() {
+            mTension = DEFAULT_TENSION;
+        }
+
+        public void setDistance(int distance) {
+            mTension = distance > 0 ? DEFAULT_TENSION / distance : DEFAULT_TENSION;
+        }
+
+        public void disableSettle() {
+            mTension = 0.f;
+        }
+
+        public float getInterpolation(float t) {
+            // _o(t) = t * t * ((tension + 1) * t + tension)
+            // o(t) = _o(t - 1) + 1
+            t -= 1.0f;
+            return t * t * ((mTension + 1) * t + mTension) + 1.0f;
+        }
+    }
+
+    /**
+     * Used to inflate the Workspace from XML.
+     *
+     * @param context The application's context.
+     * @param attrs The attributes set containing the Workspace's customization values.
+     */
+    public SmoothPagedView(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    /**
+     * Used to inflate the Workspace from XML.
+     *
+     * @param context The application's context.
+     * @param attrs The attributes set containing the Workspace's customization values.
+     * @param defStyle Unused.
+     */
+    public SmoothPagedView(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+
+        mUsePagingTouchSlop = false;
+
+        // This means that we'll take care of updating the scroll parameter ourselves (we do it
+        // in computeScroll)
+        mDeferScrollUpdate = true;
+    }
+
+    /**
+     * Initializes various states for this workspace.
+     */
+    @Override
+    protected void init() {
+        super.init();
+        mScrollInterpolator = new WorkspaceOvershootInterpolator();
+        // overwrite the previous mScroller
+        mScroller = new Scroller(getContext(), mScrollInterpolator);
+    }
+
+    @Override
+    protected void snapToDestination() {
+        snapToPageWithVelocity(mCurrentPage, 0);
+    }
+
+    @Override
+    protected void snapToPageWithVelocity(int whichPage, int velocity) {
+        snapToPageWithVelocity(whichPage, 0, true);
+    }
+
+    void snapToPageWithVelocity(int whichPage, int velocity, boolean settle) {
+            // if (!mScroller.isFinished()) return;
+
+        whichPage = Math.max(0, Math.min(whichPage, getChildCount() - 1));
+
+        final int screenDelta = Math.max(1, Math.abs(whichPage - mCurrentPage));
+        final int newX = whichPage * getWidth();
+        final int delta = newX - mScrollX;
+        int duration = (screenDelta + 1) * 100;
+
+        if (!mScroller.isFinished()) {
+            mScroller.abortAnimation();
+        }
+
+        if (settle) {
+            mScrollInterpolator.setDistance(screenDelta);
+        } else {
+            mScrollInterpolator.disableSettle();
+        }
+
+        velocity = Math.abs(velocity);
+        if (velocity > 0) {
+            duration += (duration / (velocity / BASELINE_FLING_VELOCITY))
+                    * FLING_VELOCITY_INFLUENCE;
+        } else {
+            duration += 100;
+        }
+        snapToPage(whichPage, delta, duration);
+    }
+
+    @Override
+    protected void snapToPage(int whichPage) {
+        snapToPageWithVelocity(whichPage, 0, false);
+    }
+
+    @Override
+    public void computeScroll() {
+        boolean scrollComputed = computeScrollHelper();
+
+        if (!scrollComputed && mTouchState == TOUCH_STATE_SCROLLING) {
+            final float now = System.nanoTime() / NANOTIME_DIV;
+            final float e = (float) Math.exp((now - mSmoothingTime) / SMOOTHING_CONSTANT);
+            final float dx = mTouchX - mScrollX;
+            mScrollX += dx * e;
+            mSmoothingTime = now;
+
+            // Keep generating points as long as we're more than 1px away from the target
+            if (dx > 1.f || dx < -1.f) {
+                invalidate();
+            }
+        }
+    }
+}