src/com/android/launcher3/DeleteDropTarget.java

/*
 * Copyright (C) 2011 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.launcher3;

import android.animation.TimeInterpolator;
import android.animation.ValueAnimator;
import android.animation.ValueAnimator.AnimatorUpdateListener;
import android.content.Context;
import android.graphics.PointF;
import android.graphics.Rect;
import android.os.AsyncTask;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.animation.AnimationUtils;
import android.view.animation.DecelerateInterpolator;

import com.android.launcher3.util.Thunk;
import com.android.launcher3.widget.WidgetsContainerView;

public class DeleteDropTarget extends ButtonDropTarget {

    private static int FLING_DELETE_ANIMATION_DURATION = 350;
    private static float FLING_TO_DELETE_FRICTION = 0.035f;
    private static int MODE_FLING_DELETE_TO_TRASH = 0;
    private static int MODE_FLING_DELETE_ALONG_VECTOR = 1;

    private final int mFlingDeleteMode = MODE_FLING_DELETE_ALONG_VECTOR;

    public DeleteDropTarget(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public DeleteDropTarget(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        // Get the hover color
        mHoverColor = getResources().getColor(R.color.delete_target_hover_tint);

        setDrawable(R.drawable.remove_target_selector);
    }

    public static boolean supportsDrop(Object info) {
        return (info instanceof ShortcutInfo)
                || (info instanceof LauncherAppWidgetInfo)
                || (info instanceof FolderInfo);
    }

    @Override
    protected boolean supportsDrop(DragSource source, Object info) {
        return source.supportsDeleteDropTarget() && supportsDrop(info);
    }

    @Override
    @Thunk void completeDrop(DragObject d) {
        ItemInfo item = (ItemInfo) d.dragInfo;
        if ((d.dragSource instanceof Workspace) || (d.dragSource instanceof Folder)) {
            removeWorkspaceOrFolderItem(mLauncher, item, null);
        }
    }

    /**
     * Removes the item from the workspace. If the view is not null, it also removes the view.
     * @return true if the item was removed.
     */
    public static boolean removeWorkspaceOrFolderItem(Launcher launcher, ItemInfo item, View view) {
        if (item instanceof ShortcutInfo) {
            LauncherModel.deleteItemFromDatabase(launcher, item);
        } else if (item instanceof FolderInfo) {
            FolderInfo folder = (FolderInfo) item;
            launcher.removeFolder(folder);
            LauncherModel.deleteFolderContentsFromDatabase(launcher, folder);
        } else if (item instanceof LauncherAppWidgetInfo) {
            final LauncherAppWidgetInfo widget = (LauncherAppWidgetInfo) item;

            // Remove the widget from the workspace
            launcher.removeAppWidget(widget);
            LauncherModel.deleteItemFromDatabase(launcher, widget);

            final LauncherAppWidgetHost appWidgetHost = launcher.getAppWidgetHost();

            if (appWidgetHost != null && !widget.isCustomWidget()
                    && widget.isWidgetIdValid()) {
                // Deleting an app widget ID is a void call but writes to disk before returning
                // to the caller...
                new AsyncTask<Void, Void, Void>() {
                    public Void doInBackground(Void ... args) {
                        appWidgetHost.deleteAppWidgetId(widget.appWidgetId);
                        return null;
                    }
                }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
            }
        } else {
            return false;
        }

        if (view != null) {
            launcher.getWorkspace().removeWorkspaceItem(view);
            launcher.getWorkspace().stripEmptyScreens();
        }
        return true;
    }

    /**
     * Creates an animation from the current drag view to the delete trash icon.
     */
    private AnimatorUpdateListener createFlingToTrashAnimatorListener(final DragLayer dragLayer,
            DragObject d, PointF vel, ViewConfiguration config) {

        int width = mDrawable.getIntrinsicWidth();
        int height = mDrawable.getIntrinsicHeight();
        final Rect to = getIconRect(d.dragView.getMeasuredWidth(), d.dragView.getMeasuredHeight(),
                width, height);
        final Rect from = new Rect();
        dragLayer.getViewRectRelativeToSelf(d.dragView, from);

        // Calculate how far along the velocity vector we should put the intermediate point on
        // the bezier curve
        float velocity = Math.abs(vel.length());
        float vp = Math.min(1f, velocity / (config.getScaledMaximumFlingVelocity() / 2f));
        int offsetY = (int) (-from.top * vp);
        int offsetX = (int) (offsetY / (vel.y / vel.x));
        final float y2 = from.top + offsetY;                        // intermediate t/l
        final float x2 = from.left + offsetX;
        final float x1 = from.left;                                 // drag view t/l
        final float y1 = from.top;
        final float x3 = to.left;                                   // delete target t/l
        final float y3 = to.top;

        final TimeInterpolator scaleAlphaInterpolator = new TimeInterpolator() {
            @Override
            public float getInterpolation(float t) {
                return t * t * t * t * t * t * t * t;
            }
        };
        return new AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                final DragView dragView = (DragView) dragLayer.getAnimatedView();
                float t = ((Float) animation.getAnimatedValue()).floatValue();
                float tp = scaleAlphaInterpolator.getInterpolation(t);
                float initialScale = dragView.getInitialScale();
                float finalAlpha = 0.5f;
                float scale = dragView.getScaleX();
                float x1o = ((1f - scale) * dragView.getMeasuredWidth()) / 2f;
                float y1o = ((1f - scale) * dragView.getMeasuredHeight()) / 2f;
                float x = (1f - t) * (1f - t) * (x1 - x1o) + 2 * (1f - t) * t * (x2 - x1o) +
                        (t * t) * x3;
                float y = (1f - t) * (1f - t) * (y1 - y1o) + 2 * (1f - t) * t * (y2 - x1o) +
                        (t * t) * y3;

                dragView.setTranslationX(x);
                dragView.setTranslationY(y);
                dragView.setScaleX(initialScale * (1f - tp));
                dragView.setScaleY(initialScale * (1f - tp));
                dragView.setAlpha(finalAlpha + (1f - finalAlpha) * (1f - tp));
            }
        };
    }

    /**
     * Creates an animation from the current drag view along its current velocity vector.
     * For this animation, the alpha runs for a fixed duration and we update the position
     * progressively.
     */
    private static class FlingAlongVectorAnimatorUpdateListener implements AnimatorUpdateListener {
        private DragLayer mDragLayer;
        private PointF mVelocity;
        private Rect mFrom;
        private long mPrevTime;
        private boolean mHasOffsetForScale;
        private float mFriction;

        private final TimeInterpolator mAlphaInterpolator = new DecelerateInterpolator(0.75f);

        public FlingAlongVectorAnimatorUpdateListener(DragLayer dragLayer, PointF vel, Rect from,
                long startTime, float friction) {
            mDragLayer = dragLayer;
            mVelocity = vel;
            mFrom = from;
            mPrevTime = startTime;
            mFriction = 1f - (dragLayer.getResources().getDisplayMetrics().density * friction);
        }

        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            final DragView dragView = (DragView) mDragLayer.getAnimatedView();
            float t = ((Float) animation.getAnimatedValue()).floatValue();
            long curTime = AnimationUtils.currentAnimationTimeMillis();

            if (!mHasOffsetForScale) {
                mHasOffsetForScale = true;
                float scale = dragView.getScaleX();
                float xOffset = ((scale - 1f) * dragView.getMeasuredWidth()) / 2f;
                float yOffset = ((scale - 1f) * dragView.getMeasuredHeight()) / 2f;

                mFrom.left += xOffset;
                mFrom.top += yOffset;
            }

            mFrom.left += (mVelocity.x * (curTime - mPrevTime) / 1000f);
            mFrom.top += (mVelocity.y * (curTime - mPrevTime) / 1000f);

            dragView.setTranslationX(mFrom.left);
            dragView.setTranslationY(mFrom.top);
            dragView.setAlpha(1f - mAlphaInterpolator.getInterpolation(t));

            mVelocity.x *= mFriction;
            mVelocity.y *= mFriction;
            mPrevTime = curTime;
        }
    };
    private AnimatorUpdateListener createFlingAlongVectorAnimatorListener(final DragLayer dragLayer,
            DragObject d, PointF vel, final long startTime, final int duration,
            ViewConfiguration config) {
        final Rect from = new Rect();
        dragLayer.getViewRectRelativeToSelf(d.dragView, from);

        return new FlingAlongVectorAnimatorUpdateListener(dragLayer, vel, from, startTime,
                FLING_TO_DELETE_FRICTION);
    }

    public void onFlingToDelete(final DragObject d, int x, int y, PointF vel) {
        final boolean isWidgets = d.dragSource instanceof WidgetsContainerView;
        final boolean isAllapps = d.dragSource instanceof AppsContainerView;

        // Don't highlight the icon as it's animating
        d.dragView.setColor(0);
        d.dragView.updateInitialScaleToCurrentScale();
        // Don't highlight the target if we are flinging from AllApps
        if (isWidgets || isAllapps) {
            resetHoverColor();
        }

        if (mFlingDeleteMode == MODE_FLING_DELETE_TO_TRASH) {
            // Defer animating out the drop target if we are animating to it
            mSearchDropTargetBar.deferOnDragEnd();
            mSearchDropTargetBar.finishAnimations();
        }

        final ViewConfiguration config = ViewConfiguration.get(mLauncher);
        final DragLayer dragLayer = mLauncher.getDragLayer();
        final int duration = FLING_DELETE_ANIMATION_DURATION;
        final long startTime = AnimationUtils.currentAnimationTimeMillis();

        // NOTE: Because it takes time for the first frame of animation to actually be
        // called and we expect the animation to be a continuation of the fling, we have
        // to account for the time that has elapsed since the fling finished.  And since
        // we don't have a startDelay, we will always get call to update when we call
        // start() (which we want to ignore).
        final TimeInterpolator tInterpolator = new TimeInterpolator() {
            private int mCount = -1;
            private float mOffset = 0f;

            @Override
            public float getInterpolation(float t) {
                if (mCount < 0) {
                    mCount++;
                } else if (mCount == 0) {
                    mOffset = Math.min(0.5f, (float) (AnimationUtils.currentAnimationTimeMillis() -
                            startTime) / duration);
                    mCount++;
                }
                return Math.min(1f, mOffset + t);
            }
        };
        AnimatorUpdateListener updateCb = null;
        if (mFlingDeleteMode == MODE_FLING_DELETE_TO_TRASH) {
            updateCb = createFlingToTrashAnimatorListener(dragLayer, d, vel, config);
        } else if (mFlingDeleteMode == MODE_FLING_DELETE_ALONG_VECTOR) {
            updateCb = createFlingAlongVectorAnimatorListener(dragLayer, d, vel, startTime,
                    duration, config);
        }

        Runnable onAnimationEndRunnable = new Runnable() {
            @Override
            public void run() {
                // If we are dragging from AllApps, then we allow AppsCustomizePagedView to clean up
                // itself, otherwise, complete the drop to initiate the deletion process
                if (!isWidgets || !isAllapps) {
                    mLauncher.exitSpringLoadedDragMode();
                    completeDrop(d);
                }
                mLauncher.getDragController().onDeferredEndFling(d);
            }
        };
        dragLayer.animateView(d.dragView, updateCb, duration, tInterpolator, onAnimationEndRunnable,
                DragLayer.ANIMATION_END_DISAPPEAR, null);
    }

    @Override
    protected String getAccessibilityDropConfirmation() {
        return getResources().getString(R.string.item_removed);
    }
}