First commit

app/src/main/java/com/android/launcher2/PagedViewWithDraggableItems.java

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+/*
+ * Copyright (C) 2010 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.MotionEvent;
+import android.view.View;
+
+
+/* Class that does most of the work of enabling dragging items out of a PagedView by performing a
+ * vertical drag. Used by both CustomizePagedView and AllAppsPagedView.
+ * Subclasses must do the following:
+ *   * call setDragSlopeThreshold after making an instance of the PagedViewWithDraggableItems
+ *   * call child.setOnLongClickListener(this) and child.setOnTouchListener(this) on all children
+ *       (good place to do it is in syncPageItems)
+ *   * override beginDragging(View) (but be careful to call super.beginDragging(View)
+ *
+ */
+public abstract class PagedViewWithDraggableItems extends PagedView
+    implements View.OnLongClickListener, View.OnTouchListener {
+    private View mLastTouchedItem;
+    private boolean mIsDragging;
+    private boolean mIsDragEnabled;
+    private float mDragSlopeThreshold;
+    private Launcher mLauncher;
+
+    public PagedViewWithDraggableItems(Context context) {
+        this(context, null);
+    }
+
+    public PagedViewWithDraggableItems(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public PagedViewWithDraggableItems(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+        mLauncher = (Launcher) context;
+    }
+
+    protected boolean beginDragging(View v) {
+        boolean wasDragging = mIsDragging;
+        mIsDragging = true;
+        return !wasDragging;
+    }
+
+    protected void cancelDragging() {
+        mIsDragging = false;
+        mLastTouchedItem = null;
+        mIsDragEnabled = false;
+    }
+
+    private void handleTouchEvent(MotionEvent ev) {
+        final int action = ev.getAction();
+        switch (action & MotionEvent.ACTION_MASK) {
+            case MotionEvent.ACTION_DOWN:
+                cancelDragging();
+                mIsDragEnabled = true;
+                break;
+            case MotionEvent.ACTION_MOVE:
+                if (mTouchState != TOUCH_STATE_SCROLLING && !mIsDragging && mIsDragEnabled) {
+                    determineDraggingStart(ev);
+                }
+                break;
+        }
+    }
+
+    @Override
+    public boolean onInterceptTouchEvent(MotionEvent ev) {
+        handleTouchEvent(ev);
+        return super.onInterceptTouchEvent(ev);
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent ev) {
+        handleTouchEvent(ev);
+        return super.onTouchEvent(ev);
+    }
+
+    @Override
+    public boolean onTouch(View v, MotionEvent event) {
+        mLastTouchedItem = v;
+        mIsDragEnabled = true;
+        return false;
+    }
+
+    @Override
+    public boolean onLongClick(View v) {
+        // Return early if this is not initiated from a touch
+        if (!v.isInTouchMode()) return false;
+        // Return early if we are still animating the pages
+        if (mNextPage != INVALID_PAGE) return false;
+        // When we have exited all apps or are in transition, disregard long clicks
+        if (!mLauncher.isAllAppsVisible() ||
+                mLauncher.getWorkspace().isSwitchingState()) return false;
+        // Return if global dragging is not enabled
+        if (!mLauncher.isDraggingEnabled()) return false;
+
+        return beginDragging(v);
+    }
+
+    /*
+     * Determines if we should change the touch state to start scrolling after the
+     * user moves their touch point too far.
+     */
+    protected void determineScrollingStart(MotionEvent ev) {
+        if (!mIsDragging) super.determineScrollingStart(ev);
+    }
+
+    /*
+     * Determines if we should change the touch state to start dragging after the
+     * user moves their touch point far enough.
+     */
+    protected void determineDraggingStart(MotionEvent ev) {
+        /*
+         * Locally do absolute value. mLastMotionX is set to the y value
+         * of the down event.
+         */
+        final int pointerIndex = ev.findPointerIndex(mActivePointerId);
+        final float x = ev.getX(pointerIndex);
+        final float y = ev.getY(pointerIndex);
+        final int xDiff = (int) Math.abs(x - mLastMotionX);
+        final int yDiff = (int) Math.abs(y - mLastMotionY);
+
+        final int touchSlop = mTouchSlop;
+        boolean yMoved = yDiff > touchSlop;
+        boolean isUpwardMotion = (yDiff / (float) xDiff) > mDragSlopeThreshold;
+
+        if (isUpwardMotion && yMoved && mLastTouchedItem != null) {
+            // Drag if the user moved far enough along the Y axis
+            beginDragging(mLastTouchedItem);
+
+            // Cancel any pending long press
+            if (mAllowLongPress) {
+                mAllowLongPress = false;
+                // Try canceling the long press. It could also have been scheduled
+                // by a distant descendant, so use the mAllowLongPress flag to block
+                // everything
+                final View currentPage = getPageAt(mCurrentPage);
+                if (currentPage != null) {
+                    currentPage.cancelLongPress();
+                }
+            }
+        }
+    }
+
+    public void setDragSlopeThreshold(float dragSlopeThreshold) {
+        mDragSlopeThreshold = dragSlopeThreshold;
+    }
+
+    @Override
+    protected void onDetachedFromWindow() {
+        cancelDragging();
+        super.onDetachedFromWindow();
+    }
+
+    /** Show the scrolling indicators when we move the page */
+    protected void onPageBeginMoving() {
+        showScrollingIndicator(false);
+    }
+    protected void onPageEndMoving() {
+        hideScrollingIndicator(false);
+    }
+}