PDFTaggedTest.cpp

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/*
 * Copyright 2018 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
#include "include/core/SkTypes.h"
 
#ifdef SK_SUPPORT_PDF
#include "include/core/SkBitmap.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkDocument.h"
#include "include/core/SkFont.h"
#include "include/core/SkImage.h" // IWYU pragma: keep
#include "include/core/SkPaint.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkSize.h"
#include "include/core/SkStream.h"
#include "include/core/SkString.h"
#include "include/core/SkTypeface.h"
#include "include/docs/SkPDFDocument.h"
#include "src/pdf/SkPDFUtils.h"
#include "tests/Test.h"
#include "tools/fonts/FontToolUtils.h"
 
#include <memory>
#include <utility>
#include <vector>
 
using PDFTag = SkPDF::StructureElementNode;
 
// Test building a tagged PDF.
// Add this to args.gn to output the PDF to a file:
//   extra_cflags = [ "-DSK_PDF_TEST_TAGS_OUTPUT_PATH=\"/tmp/foo.pdf\"" ]
DEF_TEST(SkPDF_tagged_doc, r) {
    REQUIRE_PDF_DOCUMENT(SkPDF_tagged_doc, r);
#ifdef SK_PDF_TEST_TAGS_OUTPUT_PATH
    SkFILEWStream outputStream(SK_PDF_TEST_TAGS_OUTPUT_PATH);
#else
    SkDynamicMemoryWStream outputStream;
#endif
 
    SkSize pageSize = SkSize::Make(612, 792);  // U.S. Letter
 
    SkPDF::Metadata metadata;
    metadata.fTitle = "Example Tagged PDF";
    metadata.fCreator = "Skia";
    metadata.fOutline = SkPDF::Metadata::Outline::StructureElementHeaders;
    SkPDF::DateTime now;
    SkPDFUtils::GetDateTime(&now);
    metadata.fCreation = now;
    metadata.fModified = now;
 
    // The document tag.
    auto root = std::make_unique<PDFTag>();
    root->fNodeId = 1;
    root->fTypeString = "Document";
 
    // Heading.
    auto h1 = std::make_unique<PDFTag>();
    h1->fNodeId = 2;
    h1->fTypeString = "H1";
    h1->fAlt = "A Header";
    root->fChildVector.push_back(std::move(h1));
 
    // Initial paragraph.
    auto p = std::make_unique<PDFTag>();
    p->fNodeId = 3;
    p->fTypeString = "P";
    root->fChildVector.push_back(std::move(p));
 
    // Hidden div. This is never referenced by marked content
    // so it should not appear in the resulting PDF.
    auto div = std::make_unique<PDFTag>();
    div->fNodeId = 4;
    div->fTypeString = "Div";
    root->fChildVector.push_back(std::move(div));
 
    // A bulleted list of two items.
    auto l = std::make_unique<PDFTag>();
    l->fNodeId = 5;
    l->fTypeString = "L";
 
    auto lm1 = std::make_unique<PDFTag>();
    lm1->fNodeId = 6;
    lm1->fTypeString = "Lbl";
    l->fChildVector.push_back(std::move(lm1));
 
    auto li1 = std::make_unique<PDFTag>();
    li1->fNodeId = 7;
    li1->fTypeString = "LI";
    l->fChildVector.push_back(std::move(li1));
 
    auto lm2 = std::make_unique<PDFTag>();
    lm2->fNodeId = 8;
    lm2->fTypeString = "Lbl";
    l->fChildVector.push_back(std::move(lm2));
    auto li2 = std::make_unique<PDFTag>();
    li2->fNodeId = 9;
    li2->fTypeString = "LI";
    l->fChildVector.push_back(std::move(li2));
 
    root->fChildVector.push_back(std::move(l));
 
    // Paragraph spanning two pages.
    auto p2 = std::make_unique<PDFTag>();
    p2->fNodeId = 10;
    p2->fTypeString = "P";
    root->fChildVector.push_back(std::move(p2));
 
    // Image with alt text.
    auto img = std::make_unique<PDFTag>();
    img->fNodeId = 11;
    img->fTypeString = "Figure";
    img->fAlt = "Red box";
    root->fChildVector.push_back(std::move(img));
 
    metadata.fStructureElementTreeRoot = root.get();
    sk_sp<SkDocument> document = SkPDF::MakeDocument(
        &outputStream, metadata);
 
    SkPaint paint;
    paint.setColor(SK_ColorBLACK);
 
    // First page.
    SkCanvas* canvas =
            document->beginPage(pageSize.width(),
                                pageSize.height());
    SkPDF::SetNodeId(canvas, 2);
    SkFont font(ToolUtils::DefaultTypeface(), 36);
    const char* message = "This is the title";
    canvas->translate(72, 72);
    canvas->drawString(message, 0, 0, font, paint);
 
    SkPDF::SetNodeId(canvas, 3);
    font.setSize(14);
    message = "This is a simple paragraph.";
    canvas->translate(0, 72);
    canvas->drawString(message, 0, 0, font, paint);
 
    SkPDF::SetNodeId(canvas, 6);
    font.setSize(14);
    message = "*";
    canvas->translate(0, 72);
    canvas->drawString(message, 0, 0, font, paint);
 
    SkPDF::SetNodeId(canvas, 7);
    message = "List item 1";
    canvas->translate(36, 0);
    canvas->drawString(message, 0, 0, font, paint);
 
    SkPDF::SetNodeId(canvas, 8);
    message = "*";
    canvas->translate(-36, 36);
    canvas->drawString(message, 0, 0, font, paint);
 
    SkPDF::SetNodeId(canvas, 9);
    message = "List item 2";
    canvas->translate(36, 0);
    canvas->drawString(message, 0, 0, font, paint);
 
    SkPDF::SetNodeId(canvas, 10);
    message = "This is a paragraph that starts on one page";
    canvas->translate(-36, 6 * 72);
    canvas->drawString(message, 0, 0, font, paint);
 
    document->endPage();
 
    // Second page.
    canvas = document->beginPage(pageSize.width(),
                                 pageSize.height());
    SkPDF::SetNodeId(canvas, 10);
    message = "and finishes on the second page.";
    canvas->translate(72, 72);
    canvas->drawString(message, 0, 0, font, paint);
 
    // Test a tagged image with alt text.
    SkPDF::SetNodeId(canvas, 11);
    SkBitmap testBitmap;
    testBitmap.allocN32Pixels(72, 72);
    testBitmap.eraseColor(SK_ColorRED);
    canvas->translate(72, 72);
    canvas->drawImage(testBitmap.asImage(), 0, 0);
 
    // This has a node ID but never shows up in the tag tree so it
    // won't be tagged.
    SkPDF::SetNodeId(canvas, 999);
    message = "Page 2";
    canvas->translate(468, -36);
    canvas->drawString(message, 0, 0, font, paint);
 
    document->endPage();
 
    document->close();
 
    outputStream.flush();
}
#endif