quickstep/src/com/android/launcher3/taskbar/TaskbarDragLayer.java

/*
 * Copyright (C) 2021 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.taskbar;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

import com.android.launcher3.R;
import com.android.launcher3.testing.TestLogging;
import com.android.launcher3.testing.TestProtocol;
import com.android.launcher3.util.TouchController;
import com.android.launcher3.views.BaseDragLayer;
import com.android.systemui.shared.system.ViewTreeObserverWrapper;
import com.android.systemui.shared.system.ViewTreeObserverWrapper.InsetsInfo;
import com.android.systemui.shared.system.ViewTreeObserverWrapper.OnComputeInsetsListener;

/**
 * Top-level ViewGroup that hosts the TaskbarView as well as Views created by it such as Folder.
 */
public class TaskbarDragLayer extends BaseDragLayer<TaskbarActivityContext> {

    private final Paint mTaskbarBackgroundPaint;
    private final Path mInvertedLeftCornerPath, mInvertedRightCornerPath;
    private final OnComputeInsetsListener mTaskbarInsetsComputer = this::onComputeTaskbarInsets;

    // Initialized in init.
    private TaskbarDragLayerController.TaskbarDragLayerCallbacks mControllerCallbacks;
    private float mLeftCornerRadius, mRightCornerRadius;

    private float mTaskbarBackgroundOffset;

    public TaskbarDragLayer(@NonNull Context context) {
        this(context, null);
    }

    public TaskbarDragLayer(@NonNull Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public TaskbarDragLayer(@NonNull Context context, @Nullable AttributeSet attrs,
            int defStyleAttr) {
        this(context, attrs, defStyleAttr, 0);
    }

    public TaskbarDragLayer(@NonNull Context context, @Nullable AttributeSet attrs,
            int defStyleAttr, int defStyleRes) {
        super(context, attrs, 1 /* alphaChannelCount */);
        mTaskbarBackgroundPaint = new Paint();
        mTaskbarBackgroundPaint.setColor(getResources().getColor(R.color.taskbar_background));
        mTaskbarBackgroundPaint.setAlpha(0);
        mTaskbarBackgroundPaint.setFlags(Paint.ANTI_ALIAS_FLAG);
        mTaskbarBackgroundPaint.setStyle(Paint.Style.FILL);

        // Will be set in init(), but this ensures they are always non-null.
        mInvertedLeftCornerPath = new Path();
        mInvertedRightCornerPath = new Path();
    }

    public void init(TaskbarDragLayerController.TaskbarDragLayerCallbacks callbacks) {
        mControllerCallbacks = callbacks;

        // Create the paths for the inverted rounded corners above the taskbar. Start with a filled
        // square, and then subtracting out a circle from the appropriate corner.
        mLeftCornerRadius = mActivity.getLeftCornerRadius();
        mRightCornerRadius = mActivity.getRightCornerRadius();
        Path square = new Path();
        square.addRect(0, 0, mLeftCornerRadius, mLeftCornerRadius, Path.Direction.CW);
        Path circle = new Path();
        circle.addCircle(mLeftCornerRadius, 0, mLeftCornerRadius, Path.Direction.CW);
        mInvertedLeftCornerPath.op(square, circle, Path.Op.DIFFERENCE);
        square.reset();
        square.addRect(0, 0, mRightCornerRadius, mRightCornerRadius, Path.Direction.CW);
        circle.reset();
        circle.addCircle(0, 0, mRightCornerRadius, Path.Direction.CW);
        mInvertedRightCornerPath.op(square, circle, Path.Op.DIFFERENCE);

        recreateControllers();
    }

    @Override
    public void recreateControllers() {
        mControllers = new TouchController[] {mActivity.getDragController()};
    }

    private void onComputeTaskbarInsets(InsetsInfo insetsInfo) {
        if (mControllerCallbacks != null) {
            mControllerCallbacks.updateInsetsTouchability(insetsInfo);
            mControllerCallbacks.updateContentInsets(insetsInfo.contentInsets);
        }
    }

    protected void onDestroy() {
        ViewTreeObserverWrapper.removeOnComputeInsetsListener(mTaskbarInsetsComputer);
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        ViewTreeObserverWrapper.addOnComputeInsetsListener(getViewTreeObserver(),
                mTaskbarInsetsComputer);
    }

    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();

        onDestroy();
    }

    @Override
    protected boolean canFindActiveController() {
        // Unlike super class, we want to be able to find controllers when touches occur in the
        // gesture area. For example, this allows Folder to close itself when touching the Taskbar.
        return true;
    }

    @Override
    public void onViewRemoved(View child) {
        super.onViewRemoved(child);
        if (mControllerCallbacks != null) {
            mControllerCallbacks.onDragLayerViewRemoved();
        }
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        float backgroundHeight = mControllerCallbacks.getTaskbarBackgroundHeight()
                * (1f - mTaskbarBackgroundOffset);
        canvas.save();
        canvas.translate(0, canvas.getHeight() - backgroundHeight);

        // Draw the background behind taskbar content.
        canvas.drawRect(0, 0, canvas.getWidth(), backgroundHeight, mTaskbarBackgroundPaint);

        // Draw the inverted rounded corners above the taskbar.
        canvas.translate(0, -mLeftCornerRadius);
        canvas.drawPath(mInvertedLeftCornerPath, mTaskbarBackgroundPaint);
        canvas.translate(0, mLeftCornerRadius);
        canvas.translate(canvas.getWidth() - mRightCornerRadius, -mRightCornerRadius);
        canvas.drawPath(mInvertedRightCornerPath, mTaskbarBackgroundPaint);

        canvas.restore();
        super.dispatchDraw(canvas);
    }

    /**
     * Sets the alpha of the background color behind all the Taskbar contents.
     * @param alpha 0 is fully transparent, 1 is fully opaque.
     */
    protected void setTaskbarBackgroundAlpha(float alpha) {
        mTaskbarBackgroundPaint.setAlpha((int) (alpha * 255));
        invalidate();
    }

    /**
     * Sets the translation of the background color behind all the Taskbar contents.
     * @param offset 0 is fully onscreen, 1 is fully offscreen.
     */
    protected void setTaskbarBackgroundOffset(float offset) {
        mTaskbarBackgroundOffset = offset;
        invalidate();
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        TestLogging.recordMotionEvent(TestProtocol.SEQUENCE_MAIN, "Touch event", ev);
        return super.dispatchTouchEvent(ev);
    }
}