printspooler/util/PageRangeUtils.java

/*
 * Copyright (C) 2014 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.printspooler.util;

import android.print.PageRange;
import android.print.PrintDocumentInfo;

import java.util.Arrays;
import java.util.Comparator;

/**
 * This class contains utility functions for working with page ranges.
 */
public final class PageRangeUtils {

    private static final PageRange[] ALL_PAGES_RANGE = new PageRange[] {PageRange.ALL_PAGES};

    private static final Comparator<PageRange> sComparator = new Comparator<PageRange>() {
        @Override
        public int compare(PageRange lhs, PageRange rhs) {
            return lhs.getStart() - rhs.getStart();
        }
    };

    private PageRangeUtils() {
        /* do nothing - hide constructor */
    }

    /**
     * Gets whether page ranges contains a given page.
     *
     * @param pageRanges The page ranges.
     * @param pageIndex The page for which to check.
     * @return Whether the page is within the ranges.
     */
    public static boolean contains(PageRange[] pageRanges, int pageIndex) {
        final int rangeCount = pageRanges.length;
        for (int i = 0; i < rangeCount; i++) {
            PageRange pageRange = pageRanges[i];
            if (pageRange.contains(pageIndex)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Checks whether one page range array contains another one.
     *
     * @param ourRanges The container page ranges.
     * @param otherRanges The contained page ranges.
     * @param pageCount The total number of pages.
     * @return Whether the container page ranges contains the contained ones.
     */
    public static boolean contains(PageRange[] ourRanges, PageRange[] otherRanges, int pageCount) {
        if (ourRanges == null || otherRanges == null) {
            return false;
        }

        if (Arrays.equals(ourRanges, ALL_PAGES_RANGE)) {
            return true;
        }

        if (Arrays.equals(otherRanges, ALL_PAGES_RANGE)) {
            otherRanges[0] = new PageRange(0, pageCount - 1);
        }

        ourRanges = normalize(ourRanges);
        otherRanges = normalize(otherRanges);

        // Note that the code below relies on the ranges being normalized
        // which is they contain monotonically increasing non-intersecting
        // sub-ranges whose start is less that or equal to the end.
        int otherRangeIdx = 0;
        final int ourRangeCount = ourRanges.length;
        final int otherRangeCount = otherRanges.length;
        for (int ourRangeIdx = 0; ourRangeIdx < ourRangeCount; ourRangeIdx++) {
            PageRange ourRange = ourRanges[ourRangeIdx];
            for (; otherRangeIdx < otherRangeCount; otherRangeIdx++) {
                PageRange otherRange = otherRanges[otherRangeIdx];
                if (otherRange.getStart() > ourRange.getEnd()) {
                    break;
                }
                if (otherRange.getStart() < ourRange.getStart()
                        || otherRange.getEnd() > ourRange.getEnd()) {
                    return false;
                }
            }
        }
        return (otherRangeIdx >= otherRangeCount);
    }

    /**
     * Normalizes a page range, which is the resulting page ranges are
     * non-overlapping with the start lesser than or equal to the end
     * and ordered in an ascending order.
     *
     * @param pageRanges The page ranges to normalize.
     * @return The normalized page ranges.
     */
    public static PageRange[] normalize(PageRange[] pageRanges) {
        if (pageRanges == null) {
            return null;
        }

        final int oldRangeCount = pageRanges.length;
        if (oldRangeCount <= 1) {
            return pageRanges;
        }

        Arrays.sort(pageRanges, sComparator);

        int newRangeCount = 1;
        for (int i = 0; i < oldRangeCount - 1; i++) {
            PageRange currentRange = pageRanges[i];
            PageRange nextRange = pageRanges[i + 1];
            if (currentRange.getEnd() + 1 >= nextRange.getStart()) {
                pageRanges[i] = null;
                pageRanges[i + 1] = new PageRange(currentRange.getStart(),
                        Math.max(currentRange.getEnd(), nextRange.getEnd()));
            } else {
                newRangeCount++;
            }
        }

        if (newRangeCount == oldRangeCount) {
            return pageRanges;
        }

        int normalRangeIndex = 0;
        PageRange[] normalRanges = new PageRange[newRangeCount];
        for (int i = 0; i < oldRangeCount; i++) {
            PageRange normalRange = pageRanges[i];
            if (normalRange != null) {
                normalRanges[normalRangeIndex] = normalRange;
                normalRangeIndex++;
            }
        }

        return normalRanges;
    }

    /**
     * Offsets a the start and end of page ranges with the given value.
     *
     * @param pageRanges The page ranges to offset.
     * @param offset The offset value.
     */
    public static void offset(PageRange[] pageRanges, int offset) {
        if (offset == 0) {
            return;
        }
        final int pageRangeCount = pageRanges.length;
        for (int i = 0; i < pageRangeCount; i++) {
            final int start = pageRanges[i].getStart() + offset;
            final int end = pageRanges[i].getEnd() + offset;
            pageRanges[i] = new PageRange(start, end);
        }
    }

    /**
     * Gets the number of pages in a normalized range array.
     *
     * @param pageRanges Normalized page ranges.
     * @param layoutPageCount Page count after reported after layout pass.
     * @return The page count in the ranges.
     */
    public static int getNormalizedPageCount(PageRange[] pageRanges, int layoutPageCount) {
        int pageCount = 0;
        if (pageRanges != null) {
            final int pageRangeCount = pageRanges.length;
            for (int i = 0; i < pageRangeCount; i++) {
                PageRange pageRange = pageRanges[i];
                if (PageRange.ALL_PAGES.equals(pageRange)) {
                    return layoutPageCount;
                }
                pageCount += pageRange.getSize();
            }
        }
        return pageCount;
    }

    public static PageRange asAbsoluteRange(PageRange pageRange, int pageCount) {
        if (PageRange.ALL_PAGES.equals(pageRange)) {
            return new PageRange(0, pageCount - 1);
        }
        return pageRange;
    }

    public static boolean isAllPages(PageRange[] pageRanges) {
        final int pageRangeCount = pageRanges.length;
        for (int i = 0; i < pageRangeCount; i++) {
            PageRange pageRange = pageRanges[i];
            if (isAllPages(pageRange)) {
                return true;
            }
        }
        return false;
    }

    public static boolean isAllPages(PageRange pageRange) {
        return PageRange.ALL_PAGES.equals(pageRange);
    }

    public static boolean isAllPages(PageRange[] pageRanges, int pageCount) {
        final int pageRangeCount = pageRanges.length;
        for (int i = 0; i < pageRangeCount; i++) {
            PageRange pageRange = pageRanges[i];
            if (isAllPages(pageRange, pageCount)) {
                return true;
            }
        }
        return false;
    }

    public static boolean isAllPages(PageRange pageRanges, int pageCount) {
        return pageRanges.getStart() == 0 && pageRanges.getEnd() == pageCount - 1;
    }

    public static PageRange[] computePrintedPages(PageRange[] requestedPages,
            PageRange[] writtenPages, int pageCount) {
        // Adjust the print job pages based on what was requested and written.
        // The cases are ordered in the most expected to the least expected
        // with a special case first where the app does not know the page count
        // so we ask for all to be written.
        if (Arrays.equals(requestedPages, ALL_PAGES_RANGE)
                && pageCount == PrintDocumentInfo.PAGE_COUNT_UNKNOWN) {
            return ALL_PAGES_RANGE;
        } else if (Arrays.equals(writtenPages, requestedPages)) {
            // We got a document with exactly the pages we wanted. Hence,
            // the printer has to print all pages in the data.
            return ALL_PAGES_RANGE;
        } else if (Arrays.equals(writtenPages, ALL_PAGES_RANGE)) {
            // We requested specific pages but got all of them. Hence,
            // the printer has to print only the requested pages.
            return requestedPages;
        } else if (PageRangeUtils.contains(writtenPages, requestedPages, pageCount)) {
            // We requested specific pages and got more but not all pages.
            // Hence, we have to offset appropriately the printed pages to
            // be based off the start of the written ones instead of zero.
            // The written pages are always non-null and not empty.
            final int offset = -writtenPages[0].getStart();
            PageRangeUtils.offset(requestedPages, offset);
            return requestedPages;
        } else if (Arrays.equals(requestedPages, ALL_PAGES_RANGE)
                && isAllPages(writtenPages, pageCount)) {
            // We requested all pages via the special constant and got all
            // of them as an explicit enumeration. Hence, the printer has
            // to print only the requested pages.
            return ALL_PAGES_RANGE;
        }

        return null;
    }
}