pdf.js/web/pdf_print_service.js

/* Copyright 2016 Mozilla Foundation
 *
 * 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.
 */

import { CSS_UNITS, NullL10n } from "./ui_utils";
import { PDFPrintServiceFactory, PDFViewerApplication } from "./app";
import { AppOptions } from "./app_options";

let activeService = null;
let overlayManager = null;

// Renders the page to the canvas of the given print service, and returns
// the suggested dimensions of the output page.
function renderPage(activeServiceOnEntry, pdfDocument, pageNumber, size) {
  let scratchCanvas = activeService.scratchCanvas;

  // The size of the canvas in pixels for printing.
  const PRINT_RESOLUTION = AppOptions.get("printResolution") || 150;
  const PRINT_UNITS = PRINT_RESOLUTION / 72.0;
  scratchCanvas.width = Math.floor(size.width * PRINT_UNITS);
  scratchCanvas.height = Math.floor(size.height * PRINT_UNITS);

  // The physical size of the img as specified by the PDF document.
  let width = Math.floor(size.width * CSS_UNITS) + "px";
  let height = Math.floor(size.height * CSS_UNITS) + "px";

  let ctx = scratchCanvas.getContext("2d");
  ctx.save();
  ctx.fillStyle = "rgb(255, 255, 255)";
  ctx.fillRect(0, 0, scratchCanvas.width, scratchCanvas.height);
  ctx.restore();

  return pdfDocument
    .getPage(pageNumber)
    .then(function(pdfPage) {
      let renderContext = {
        canvasContext: ctx,
        transform: [PRINT_UNITS, 0, 0, PRINT_UNITS, 0, 0],
        viewport: pdfPage.getViewport({ scale: 1, rotation: size.rotation }),
        intent: "print",
      };
      return pdfPage.render(renderContext).promise;
    })
    .then(function() {
      return {
        width,
        height,
      };
    });
}

function PDFPrintService(pdfDocument, pagesOverview, printContainer, l10n) {
  this.pdfDocument = pdfDocument;
  this.pagesOverview = pagesOverview;
  this.printContainer = printContainer;
  this.l10n = l10n || NullL10n;
  this.disableCreateObjectURL =
    pdfDocument.loadingParams["disableCreateObjectURL"];
  this.currentPage = -1;
  // The temporary canvas where renderPage paints one page at a time.
  this.scratchCanvas = document.createElement("canvas");
}

PDFPrintService.prototype = {
  layout() {
    this.throwIfInactive();

    const body = document.querySelector("body");
    body.setAttribute("data-pdfjsprinting", true);

    let hasEqualPageSizes = this.pagesOverview.every(function(size) {
      return (
        size.width === this.pagesOverview[0].width &&
        size.height === this.pagesOverview[0].height
      );
    }, this);
    if (!hasEqualPageSizes) {
      console.warn(
        "Not all pages have the same size. The printed " +
          "result may be incorrect!"
      );
    }

    // Insert a @page + size rule to make sure that the page size is correctly
    // set. Note that we assume that all pages have the same size, because
    // variable-size pages are not supported yet (e.g. in Chrome & Firefox).
    // TODO(robwu): Use named pages when size calculation bugs get resolved
    // (e.g. https://crbug.com/355116) AND when support for named pages is
    // added (http://www.w3.org/TR/css3-page/#using-named-pages).
    // In browsers where @page + size is not supported (such as Firefox,
    // https://bugzil.la/851441), the next stylesheet will be ignored and the
    // user has to select the correct paper size in the UI if wanted.
    this.pageStyleSheet = document.createElement("style");
    let pageSize = this.pagesOverview[0];
    this.pageStyleSheet.textContent =
      // "size:<width> <height>" is what we need. But also add "A4" because
      // Firefox incorrectly reports support for the other value.
      "@supports ((size:A4) and (size:1pt 1pt)) {" +
      "@page { size: " +
      pageSize.width +
      "pt " +
      pageSize.height +
      "pt;}" +
      "}";
    body.appendChild(this.pageStyleSheet);
  },

  destroy() {
    if (activeService !== this) {
      // |activeService| cannot be replaced without calling destroy() first,
      // so if it differs then an external consumer has a stale reference to
      // us.
      return;
    }
    this.printContainer.textContent = "";

    const body = document.querySelector("body");
    body.removeAttribute("data-pdfjsprinting");

    if (this.pageStyleSheet) {
      this.pageStyleSheet.remove();
      this.pageStyleSheet = null;
    }
    this.scratchCanvas.width = this.scratchCanvas.height = 0;
    this.scratchCanvas = null;
    activeService = null;
    ensureOverlay().then(function() {
      if (overlayManager.active !== "printServiceOverlay") {
        return; // overlay was already closed
      }
      overlayManager.close("printServiceOverlay");
    });
  },

  renderPages() {
    let pageCount = this.pagesOverview.length;
    let renderNextPage = (resolve, reject) => {
      this.throwIfInactive();
      if (++this.currentPage >= pageCount) {
        renderProgress(pageCount, pageCount, this.l10n);
        resolve();
        return;
      }
      let index = this.currentPage;
      renderProgress(index, pageCount, this.l10n);
      renderPage(this, this.pdfDocument, index + 1, this.pagesOverview[index])
        .then(this.useRenderedPage.bind(this))
        .then(function() {
          renderNextPage(resolve, reject);
        }, reject);
    };
    return new Promise(renderNextPage);
  },

  useRenderedPage(printItem) {
    this.throwIfInactive();
    let img = document.createElement("img");
    img.style.width = printItem.width;
    img.style.height = printItem.height;

    let scratchCanvas = this.scratchCanvas;
    if ("toBlob" in scratchCanvas && !this.disableCreateObjectURL) {
      scratchCanvas.toBlob(function(blob) {
        img.src = URL.createObjectURL(blob);
      });
    } else {
      img.src = scratchCanvas.toDataURL();
    }

    let wrapper = document.createElement("div");
    wrapper.appendChild(img);
    this.printContainer.appendChild(wrapper);

    return new Promise(function(resolve, reject) {
      img.onload = resolve;
      img.onerror = reject;
    });
  },

  performPrint() {
    this.throwIfInactive();
    return new Promise(resolve => {
      // Push window.print in the macrotask queue to avoid being affected by
      // the deprecation of running print() code in a microtask, see
      // https://github.com/mozilla/pdf.js/issues/7547.
      setTimeout(() => {
        if (!this.active) {
          resolve();
          return;
        }
        print.call(window);
        // Delay promise resolution in case print() was not synchronous.
        setTimeout(resolve, 20); // Tidy-up.
      }, 0);
    });
  },

  get active() {
    return this === activeService;
  },

  throwIfInactive() {
    if (!this.active) {
      throw new Error("This print request was cancelled or completed.");
    }
  },
};

let print = window.print;
window.print = function print() {
  if (activeService) {
    console.warn("Ignored window.print() because of a pending print job.");
    return;
  }
  ensureOverlay().then(function() {
    if (activeService) {
      overlayManager.open("printServiceOverlay");
    }
  });

  try {
    dispatchEvent("beforeprint");
  } finally {
    if (!activeService) {
      console.error("Expected print service to be initialized.");
      ensureOverlay().then(function() {
        if (overlayManager.active === "printServiceOverlay") {
          overlayManager.close("printServiceOverlay");
        }
      });
      return; // eslint-disable-line no-unsafe-finally
    }
    let activeServiceOnEntry = activeService;
    activeService
      .renderPages()
      .then(function() {
        return activeServiceOnEntry.performPrint();
      })
      .catch(function() {
        // Ignore any error messages.
      })
      .then(function() {
        // aborts acts on the "active" print request, so we need to check
        // whether the print request (activeServiceOnEntry) is still active.
        // Without the check, an unrelated print request (created after aborting
        // this print request while the pages were being generated) would be
        // aborted.
        if (activeServiceOnEntry.active) {
          abort();
        }
      });
  }
};

function dispatchEvent(eventType) {
  let event = document.createEvent("CustomEvent");
  event.initCustomEvent(eventType, false, false, "custom");
  window.dispatchEvent(event);
}

function abort() {
  if (activeService) {
    activeService.destroy();
    dispatchEvent("afterprint");
  }
}

function renderProgress(index, total, l10n) {
  let progressContainer = document.getElementById("printServiceOverlay");
  let progress = Math.round((100 * index) / total);
  let progressBar = progressContainer.querySelector("progress");
  let progressPerc = progressContainer.querySelector(".relative-progress");
  progressBar.value = progress;
  l10n.get("print_progress_percent", { progress }, progress + "%").then(msg => {
    progressPerc.textContent = msg;
  });
}

window.addEventListener(
  "keydown",
  function(event) {
    // Intercept Cmd/Ctrl + P in all browsers.
    // Also intercept Cmd/Ctrl + Shift + P in Chrome and Opera
    if (
      event.keyCode === /* P= */ 80 &&
      (event.ctrlKey || event.metaKey) &&
      !event.altKey &&
      (!event.shiftKey || window.chrome || window.opera)
    ) {
      window.print();

      // The (browser) print dialog cannot be prevented from being shown in IE11.
      event.preventDefault();
      if (event.stopImmediatePropagation) {
        event.stopImmediatePropagation();
      } else {
        event.stopPropagation();
      }
    }
  },
  true
);

if ("onbeforeprint" in window) {
  // Do not propagate before/afterprint events when they are not triggered
  // from within this polyfill. (FF /IE / Chrome 63+).
  let stopPropagationIfNeeded = function(event) {
    if (event.detail !== "custom" && event.stopImmediatePropagation) {
      event.stopImmediatePropagation();
    }
  };
  window.addEventListener("beforeprint", stopPropagationIfNeeded);
  window.addEventListener("afterprint", stopPropagationIfNeeded);
}

let overlayPromise;
function ensureOverlay() {
  if (!overlayPromise) {
    overlayManager = PDFViewerApplication.overlayManager;
    if (!overlayManager) {
      throw new Error("The overlay manager has not yet been initialized.");
    }

    overlayPromise = overlayManager.register(
      "printServiceOverlay",
      document.getElementById("printServiceOverlay"),
      abort,
      true
    );
    document.getElementById("printCancel").onclick = abort;
  }
  return overlayPromise;
}

PDFPrintServiceFactory.instance = {
  supportsPrinting: true,

  createPrintService(pdfDocument, pagesOverview, printContainer, l10n) {
    if (activeService) {
      throw new Error("The print service is created and active.");
    }
    activeService = new PDFPrintService(
      pdfDocument,
      pagesOverview,
      printContainer,
      l10n
    );
    return activeService;
  },
};

export { PDFPrintService };