xref: /packages/apps/Car/libs/car-stream-ui-lib/src/com/android/car/view/PagedScrollBarView.java

/*
 * Copyright (C) 2017 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.car.view;

import android.content.Context;
import android.graphics.PorterDuff;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.Interpolator;
import android.widget.FrameLayout;
import android.widget.ImageView;

import com.android.car.stream.ui.R;

/**
 * A custom view to provide list scroll behaviour -- up/down buttons and scroll indicator.
 *
 * @hide
 */
public class PagedScrollBarView extends FrameLayout
        implements View.OnClickListener, View.OnLongClickListener {
    private static final float BUTTON_DISABLED_ALPHA = 0.2f;

    /**
     * Listener for when the list should paginate.
     */
    public interface PaginationListener {
        int PAGE_UP = 0;
        int PAGE_DOWN = 1;

        /** Called when the linked view should be paged in the given direction */
        void onPaginate(int direction);
    }

    private final ImageView mUpButton;
    private final ImageView mDownButton;
    private final ImageView mScrollThumb;
    /** The "filler" view between the up and down buttons */
    private final View mFiller;
    private final Interpolator mPaginationInterpolator = new AccelerateDecelerateInterpolator();
    private final int mMinThumbLength;
    private final int mMaxThumbLength;
    private PaginationListener mPaginationListener;

    public PagedScrollBarView(
            Context context, AttributeSet attrs) {
        this(context, attrs, 0 /*defStyleAttrs*/, 0 /*defStyleRes*/);
    }

    public PagedScrollBarView(
            Context context, AttributeSet attrs, int defStyleAttrs) {
        this(context, attrs, defStyleAttrs, 0 /*defStyleRes*/);
    }

    public PagedScrollBarView(
            Context context, AttributeSet attrs, int defStyleAttrs, int defStyleRes) {
        super(context, attrs, defStyleAttrs, defStyleRes);

        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        inflater.inflate(
                R.layout.car_paged_scrollbar_buttons, this /*root*/, true /*attachToRoot*/);

        mUpButton = (ImageView) findViewById(R.id.page_up);
        mUpButton.setImageDrawable(context.getDrawable(R.drawable.ic_up_button));
        mUpButton.setOnClickListener(this);
        mUpButton.setOnLongClickListener(this);
        mDownButton = (ImageView) findViewById(R.id.page_down);
        mDownButton.setImageDrawable(context.getDrawable(R.drawable.ic_down_button));
        mDownButton.setOnClickListener(this);
        mDownButton.setOnLongClickListener(this);

        mScrollThumb = (ImageView) findViewById(R.id.scrollbar_thumb);
        mScrollThumb.setAlpha(0.5f);

        mFiller = findViewById(R.id.filler);

        mMinThumbLength = getResources().getDimensionPixelSize(R.dimen.min_thumb_height);
        mMaxThumbLength = getResources().getDimensionPixelSize(R.dimen.max_thumb_height);

        if (!context.getResources().getBoolean(R.bool.car_true_for_touch)) {
            // Don't show the pagination buttons if there isn't touch.
            mUpButton.setVisibility(View.GONE);
            mDownButton.setVisibility(View.GONE);
        }
    }

    @Override
    public void onClick(View v) {
        dispatchPageClick(v);
    }

    @Override
    public boolean onLongClick(View v) {
        dispatchPageClick(v);
        return true;
    }

    public void setPaginationListener(PaginationListener listener) {
        mPaginationListener = listener;
    }

    /** Returns {@code true} if the "up" button is pressed */
    public boolean isUpPressed() {
        return mUpButton.isPressed();
    }

    /** Returns {@code true} if the "down" button is pressed */
    public boolean isDownPressed() {
        return mDownButton.isPressed();
    }

    /** Sets the range, offset and extent of the scroll bar. See {@link android.view.View}. */
    protected void setParameters(int range, int offset, int extent, boolean animate) {
        final int size = mFiller.getHeight() - mFiller.getPaddingTop() - mFiller.getPaddingBottom();

        int thumbLength = extent * size / range;
        thumbLength = Math.max(Math.min(thumbLength, mMaxThumbLength), mMinThumbLength);

        int thumbOffset = size - thumbLength;
        if (isDownEnabled()) {
            // We need to adjust the offset so that it fits into the possible space inside the
            // filler with regarding to the constraints set by mMaxThumbLength and mMinThumbLength.
            thumbOffset = (size - thumbLength) * offset / range;
        }

        // Sets the size of the thumb and request a redraw if needed.
        final ViewGroup.LayoutParams lp = mScrollThumb.getLayoutParams();
        if (lp.height != thumbLength) {
            lp.height = thumbLength;
            mScrollThumb.requestLayout();
        }

        moveY(mScrollThumb, thumbOffset, animate);
    }

    /** Sets auto day/night mode */
    protected void setAutoDayNightMode() {
        int color = getResources().getColor(R.color.car_tint);
        mUpButton.setColorFilter(color, PorterDuff.Mode.SRC_IN);
        mUpButton.setBackgroundResource(R.drawable.car_pagination_background);
        mDownButton.setColorFilter(color, PorterDuff.Mode.SRC_IN);
        mDownButton.setBackgroundResource(R.drawable.car_pagination_background);

        mScrollThumb.setBackgroundColor(color);
    }

    /** Sets auto light mode */
    protected void setLightMode() {
        int color = getResources().getColor(R.color.car_tint_light);
        mUpButton.setColorFilter(color, PorterDuff.Mode.SRC_IN);
        mUpButton.setBackgroundResource(R.drawable.car_pagination_background_light);
        mDownButton.setColorFilter(color, PorterDuff.Mode.SRC_IN);
        mDownButton.setBackgroundResource(R.drawable.car_pagination_background_light);

        mScrollThumb.setBackgroundColor(color);
    }

    /** Sets auto dark mode */
    protected void setDarkMode() {
        int color = getResources().getColor(R.color.car_tint_dark);
        mUpButton.setColorFilter(color, PorterDuff.Mode.SRC_IN);
        mUpButton.setBackgroundResource(R.drawable.car_pagination_background_dark);
        mDownButton.setColorFilter(color, PorterDuff.Mode.SRC_IN);
        mDownButton.setBackgroundResource(R.drawable.car_pagination_background_dark);

        mScrollThumb.setBackgroundColor(color);
    }

    protected void setUpEnabled(boolean enabled) {
        mUpButton.setEnabled(enabled);
        mUpButton.setAlpha(enabled ? 1f : BUTTON_DISABLED_ALPHA);
    }

    protected void setDownEnabled(boolean enabled) {
        mDownButton.setEnabled(enabled);
        mDownButton.setAlpha(enabled ? 1f : BUTTON_DISABLED_ALPHA);
    }

    protected boolean isDownEnabled() {
        return mDownButton.isEnabled();
    }

    private void dispatchPageClick(View v) {
        final PaginationListener listener = mPaginationListener;
        if (listener == null) {
            return;
        }

        final int direction = (v.getId() == R.id.page_up)
                ? PaginationListener.PAGE_UP : PaginationListener.PAGE_DOWN;
        listener.onPaginate(direction);
    }

    /** Moves the given view to the specified 'y' position. */
    private void moveY(final View view, float newPosition, boolean animate) {
        final int duration = animate ? 200 : 0;
        view.animate()
                .y(newPosition)
                .setDuration(duration)
                .setInterpolator(mPaginationInterpolator)
                .start();
    }
}