DayPickerViewPager.java

/*
 * Copyright (C) 2015 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 android.widget;

import android.annotation.Nullable;
import android.content.Context;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;

import com.android.internal.widget.PagerAdapter;
import com.android.internal.widget.ViewPager;

import java.util.ArrayList;
import java.util.function.Predicate;

/**
 * This displays a list of months in a calendar format with selectable days.
 */
class DayPickerViewPager extends ViewPager {
    private final ArrayList<View> mMatchParentChildren = new ArrayList<>(1);

    public DayPickerViewPager(Context context) {
        this(context, null);
    }

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

    public DayPickerViewPager(Context context, AttributeSet attrs, int defStyleAttr) {
        this(context, attrs, defStyleAttr, 0);
    }

    public DayPickerViewPager(Context context, AttributeSet attrs, int defStyleAttr,
            int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        populate();

        // Everything below is mostly copied from FrameLayout.
        int count = getChildCount();

        final boolean measureMatchParentChildren =
                MeasureSpec.getMode(widthMeasureSpec) != MeasureSpec.EXACTLY ||
                        MeasureSpec.getMode(heightMeasureSpec) != MeasureSpec.EXACTLY;

        int maxHeight = 0;
        int maxWidth = 0;
        int childState = 0;

        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (child.getVisibility() != GONE) {
                measureChild(child, widthMeasureSpec, heightMeasureSpec);
                final LayoutParams lp = (LayoutParams) child.getLayoutParams();
                maxWidth = Math.max(maxWidth, child.getMeasuredWidth());
                maxHeight = Math.max(maxHeight, child.getMeasuredHeight());
                childState = combineMeasuredStates(childState, child.getMeasuredState());
                if (measureMatchParentChildren) {
                    if (lp.width == LayoutParams.MATCH_PARENT ||
                            lp.height == LayoutParams.MATCH_PARENT) {
                        mMatchParentChildren.add(child);
                    }
                }
            }
        }

        // Account for padding too
        maxWidth += getPaddingLeft() + getPaddingRight();
        maxHeight += getPaddingTop() + getPaddingBottom();

        // Check against our minimum height and width
        maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight());
        maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth());

        // Check against our foreground's minimum height and width
        final Drawable drawable = getForeground();
        if (drawable != null) {
            maxHeight = Math.max(maxHeight, drawable.getMinimumHeight());
            maxWidth = Math.max(maxWidth, drawable.getMinimumWidth());
        }

        setMeasuredDimension(resolveSizeAndState(maxWidth, widthMeasureSpec, childState),
                resolveSizeAndState(maxHeight, heightMeasureSpec,
                        childState << MEASURED_HEIGHT_STATE_SHIFT));

        count = mMatchParentChildren.size();
        if (count > 1) {
            for (int i = 0; i < count; i++) {
                final View child = mMatchParentChildren.get(i);

                final LayoutParams lp = (LayoutParams) child.getLayoutParams();
                final int childWidthMeasureSpec;
                final int childHeightMeasureSpec;

                if (lp.width == LayoutParams.MATCH_PARENT) {
                    childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(
                            getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),
                            MeasureSpec.EXACTLY);
                } else {
                    childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec,
                            getPaddingLeft() + getPaddingRight(),
                            lp.width);
                }

                if (lp.height == LayoutParams.MATCH_PARENT) {
                    childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
                            getMeasuredHeight() - getPaddingTop() - getPaddingBottom(),
                            MeasureSpec.EXACTLY);
                } else {
                    childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec,
                            getPaddingTop() + getPaddingBottom(),
                            lp.height);
                }

                child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
            }
        }

        mMatchParentChildren.clear();
    }

    @Override
    protected View findViewByPredicateTraversal(Predicate<View> predicate, View childToSkip) {
        if (predicate.test(this)) {
            return this;
        }

        // Always try the selected view first.
        final DayPickerPagerAdapter adapter = (DayPickerPagerAdapter) getAdapter();
        final SimpleMonthView current = adapter.getView(getCurrent());
        if (current != childToSkip && current != null) {
            final View v = current.findViewByPredicate(predicate);
            if (v != null) {
                return v;
            }
        }

        final int len = getChildCount();
        for (int i = 0; i < len; i++) {
            final View child = getChildAt(i);

            if (child != childToSkip && child != current) {
                final View v = child.findViewByPredicate(predicate);

                if (v != null) {
                    return v;
                }
            }
        }

        return null;
    }

}