pdf_engine.h

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef PDF_PDF_ENGINE_H_
#define PDF_PDF_ENGINE_H_

#include <stdint.h>

#include <memory>
#include <string>
#include <vector>

#include "base/callback.h"
#include "base/containers/span.h"
#include "base/time/time.h"
#include "base/values.h"
#include "build/build_config.h"
#include "pdf/document_layout.h"
#include "pdf/ppapi_migration/callback.h"
#include "printing/mojom/print.mojom-forward.h"
#include "third_party/abseil-cpp/absl/types/optional.h"
#include "third_party/skia/include/core/SkColor.h"
#include "ui/base/cursor/mojom/cursor_type.mojom-forward.h"
#include "ui/base/window_open_disposition.h"
#include "ui/gfx/geometry/point_f.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/rect_f.h"

#if defined(OS_WIN)
#include <windows.h>
#endif

#if defined(OS_WIN)
typedef void (*PDFEnsureTypefaceCharactersAccessible)(const LOGFONT* font,
                                                      const wchar_t* text,
                                                      size_t text_length);
#endif

class SkBitmap;

namespace base {
class Location;
}  // namespace base

namespace blink {
class WebInputEvent;
struct WebPrintParams;
}  // namespace blink

namespace gfx {
class Point;
class Rect;
class Size;
class SizeF;
class Vector2d;
}  // namespace gfx

namespace chrome_pdf {

class Thumbnail;
class UrlLoader;
struct AccessibilityActionData;
struct AccessibilityFocusInfo;
struct AccessibilityLinkInfo;
struct AccessibilityHighlightInfo;
struct AccessibilityImageInfo;
struct AccessibilityTextFieldInfo;
struct AccessibilityTextRunInfo;
struct DocumentAttachmentInfo;
struct DocumentMetadata;

using SendThumbnailCallback = base::OnceCallback<void(Thumbnail)>;

enum class FontMappingMode {
  // Do not perform font mapping.
  kNoMapping,
  // Perform font mapping in renderer processes using Blink/content APIs.
  kBlink,
  // Perform font mapping in plugin processes using PPAPI.
  // TODO(crbug.com/702993): Remove when PPAPI is gone.
  kPepper,
};

// Do one time initialization of the SDK.
// If `enable_v8` is false, then the PDFEngine will not be able to run
// JavaScript.
void InitializeSDK(bool enable_v8, FontMappingMode font_mapping_mode);
// Tells the SDK that we're shutting down.
void ShutdownSDK();

// This class encapsulates a PDF rendering engine.
class PDFEngine {
 public:
  enum DocumentPermission {
    PERMISSION_COPY,
    PERMISSION_COPY_ACCESSIBLE,
    PERMISSION_PRINT_LOW_QUALITY,
    PERMISSION_PRINT_HIGH_QUALITY,
  };

  // Maximum number of parameters a nameddest view can contain.
  static constexpr size_t kMaxViewParams = 4;

  // Named destination in a document.
  struct NamedDestination {
    // 0-based page number.
    unsigned long page;

    // View fit type (see table 8.2 "Destination syntax" on page 582 of PDF
    // Reference 1.7). Empty string if not present.
    std::string view;

    // Number of parameters for the view.
    unsigned long num_params;

    // Parameters for the view. Their meaning depends on the `view` and their
    // number is defined by `num_params` but is at most `kMaxViewParams`. Note:
    // If a parameter stands for the x/y coordinates, it should be transformed
    // into the corresponding in-screen coordinates before it's sent to the
    // viewport.
    float params[kMaxViewParams];

    // A string of parameters for view fit type XYZ in the format of "x,y,zoom",
    // where x and y parameters are the in-screen coordinates and zoom is the
    // zoom level. If a parameter is "null", then current value of that
    // parameter in the viewport should be retained. Note: This string is empty
    // if the view's fit type is not XYZ.
    std::string xyz_params;
  };

  // The interface that's provided to the rendering engine.
  class Client {
   public:
    virtual ~Client() = default;

    // Proposes a document layout to the client. For the proposed layout to
    // become effective, the client must call PDFEngine::ApplyDocumentLayout()
    // with the new layout options (although this call can be asynchronous).
    virtual void ProposeDocumentLayout(const DocumentLayout& layout) = 0;

    // Informs the client that the given rect needs to be repainted.
    virtual void Invalidate(const gfx::Rect& rect) {}

    // Informs the client to scroll the plugin area by the given offset.
    virtual void DidScroll(const gfx::Vector2d& offset) {}

    // Scroll the horizontal/vertical scrollbars to a given position.
    // Values are in screen coordinates, where 0 is the top/left of the document
    // and a positive value is the distance in pixels from that line.
    virtual void ScrollToX(int x_screen_coords) {}
    virtual void ScrollToY(int y_screen_coords) {}

    // Scroll by a given delta relative to the current position.
    virtual void ScrollBy(const gfx::Vector2d& delta) {}

    // Scroll to zero-based `page`.
    virtual void ScrollToPage(int page) {}

    // Navigate to the given url.
    virtual void NavigateTo(const std::string& url,
                            WindowOpenDisposition disposition) {}

    // Navigate to the given destination. Zero-based `page` index. `x`, `y` and
    // `zoom` are optional and can be nullptr.
    virtual void NavigateToDestination(int page,
                                       const float* x,
                                       const float* y,
                                       const float* zoom) {}

    // Updates the cursor.
    virtual void UpdateCursor(ui::mojom::CursorType new_cursor_type) {}

    // Updates the tick marks in the vertical scrollbar.
    virtual void UpdateTickMarks(const std::vector<gfx::Rect>& tickmarks) {}

    // Updates the number of find results for the current search term.  If
    // there are no matches 0 should be passed in.  Only when the plugin has
    // finished searching should it pass in the final count with final_result
    // set to true.
    virtual void NotifyNumberOfFindResultsChanged(int total,
                                                  bool final_result) {}

    // Updates the index of the currently selected search item.
    virtual void NotifySelectedFindResultChanged(int current_find_index) {}

    virtual void NotifyTouchSelectionOccurred() {}

    // Prompts the user for a password to open this document. The callback is
    // called when the password is retrieved.
    virtual void GetDocumentPassword(
        base::OnceCallback<void(const std::string&)> callback) {}

    // Play a "beeping" sound.
    virtual void Beep() {}

    // Puts up an alert with the given message.
    virtual void Alert(const std::string& message) {}

    // Puts up a confirm with the given message, and returns true if the user
    // presses OK, or false if they press cancel.
    virtual bool Confirm(const std::string& message) = 0;

    // Puts up a prompt with the given message and default answer and returns
    // the answer.
    virtual std::string Prompt(const std::string& question,
                               const std::string& default_answer) = 0;

    // Returns the url of the pdf.
    virtual std::string GetURL() = 0;

    // Send an email.
    virtual void Email(const std::string& to,
                       const std::string& cc,
                       const std::string& bcc,
                       const std::string& subject,
                       const std::string& body) {}

    // Put up the print dialog.
    virtual void Print() {}

    // Submit the data using HTTP POST.
    virtual void SubmitForm(const std::string& url,
                            const void* data,
                            int length) {}

    // Creates and returns new URL loader for partial document requests.
    virtual std::unique_ptr<UrlLoader> CreateUrlLoader() = 0;

    // Searches the given string for "term" and returns the results.  Unicode-
    // aware.
    struct SearchStringResult {
      int start_index;
      int length;
    };
    virtual std::vector<SearchStringResult> SearchString(
        const char16_t* string,
        const char16_t* term,
        bool case_sensitive) = 0;

    // Notifies the client that the document has finished loading.
    virtual void DocumentLoadComplete() {}

    // Notifies the client that the document has failed to load.
    virtual void DocumentLoadFailed() {}

    // Asks the client to set the last plugin instance when applicable.
    // TODO(crbug.com/702993): Remove after migrating away from PPAPI.
    virtual void SetLastPluginInstance() {}

    // Notifies that an unsupported feature in the PDF was encountered.
    virtual void DocumentHasUnsupportedFeature(const std::string& feature) {}

    // Notifies the client about document load progress.
    virtual void DocumentLoadProgress(uint32_t available, uint32_t doc_size) {}

    // Notifies the client about focus changes for form text fields.
    virtual void FormTextFieldFocusChange(bool in_focus) {}

    // Returns true if the plugin has been opened within print preview.
    virtual bool IsPrintPreview() = 0;

    // Get the background color of the PDF.
    virtual SkColor GetBackgroundColor() = 0;

    // Sets selection status.
    virtual void SetIsSelecting(bool is_selecting) {}

    virtual void SelectionChanged(const gfx::Rect& left,
                                  const gfx::Rect& right) {}

    // Notifies the client that the PDF has been edited.
    virtual void EnteredEditMode() {}

    // Notifies the client about focus changes for the document.
    virtual void DocumentFocusChanged(bool document_has_focus) {}

    // Sets selected text.
    virtual void SetSelectedText(const std::string& selected_text) = 0;

    // Sets the link under cursor.
    virtual void SetLinkUnderCursor(const std::string& link_under_cursor) = 0;

    // If the link cannot be converted to JS payload struct, then it is not
    // possible to pass it to JS. In this case, ignore the link like other PDF
    // viewers.
    // See https://crbug.com/312882 for an example.
    virtual bool IsValidLink(const std::string& url) = 0;

    // Schedules work to be executed on a main thread after a specific delay.
    // The `result` parameter will be passed as the argument to the `callback`.
    // `result` is needed sometimes to emulate calls of some callbacks, but it's
    // not always needed. `delay` should be no longer than `INT32_MAX`
    // milliseconds for the Pepper plugin implementation to prevent integer
    // overflow.
    virtual void ScheduleTaskOnMainThread(const base::Location& from_here,
                                          ResultCallback callback,
                                          int32_t result,
                                          base::TimeDelta delay) = 0;
  };

  virtual ~PDFEngine() = default;

  // Most of these functions are similar to the Pepper functions of the same
  // name, so not repeating the description here unless it's different.
  virtual bool New(const char* url, const char* headers) = 0;
  virtual void PageOffsetUpdated(const gfx::Vector2d& page_offset) = 0;
  virtual void PluginSizeUpdated(const gfx::Size& size) = 0;
  virtual void ScrolledToXPosition(int position) = 0;
  virtual void ScrolledToYPosition(int position) = 0;
  // Paint is called a series of times. Before these n calls are made, PrePaint
  // is called once. After Paint is called n times, PostPaint is called once.
  virtual void PrePaint() = 0;
  virtual void Paint(const gfx::Rect& rect,
                     SkBitmap& image_data,
                     std::vector<gfx::Rect>& ready,
                     std::vector<gfx::Rect>& pending) = 0;
  virtual void PostPaint() = 0;
  virtual bool HandleDocumentLoad(std::unique_ptr<UrlLoader> loader) = 0;
  virtual bool HandleInputEvent(const blink::WebInputEvent& event) = 0;
  virtual void PrintBegin() = 0;
  virtual std::vector<uint8_t> PrintPages(
      const std::vector<int>& page_numbers,
      const blink::WebPrintParams& print_params) = 0;
  virtual void PrintEnd() = 0;
  virtual void StartFind(const std::string& text, bool case_sensitive) = 0;
  virtual bool SelectFindResult(bool forward) = 0;
  virtual void StopFind() = 0;
  virtual void ZoomUpdated(double new_zoom_level) = 0;
  virtual void RotateClockwise() = 0;
  virtual void RotateCounterclockwise() = 0;
  virtual bool IsReadOnly() const = 0;
  virtual void SetReadOnly(bool enable) = 0;
  virtual void SetTwoUpView(bool enable) = 0;
  virtual void DisplayAnnotations(bool display) = 0;

  // Applies the document layout options proposed by a call to
  // PDFEngine::Client::ProposeDocumentLayout(), returning the overall size of
  // the new effective layout.
  virtual gfx::Size ApplyDocumentLayout(
      const DocumentLayout::Options& options) = 0;

  virtual std::string GetSelectedText() = 0;
  // Returns true if focus is within an editable form text area.
  virtual bool CanEditText() const = 0;
  // Returns true if focus is within an editable form text area and the text
  // area has text.
  virtual bool HasEditableText() const = 0;
  // Replace selected text within an editable form text area with another
  // string. If there is no selected text, append the replacement text after the
  // current caret position.
  virtual void ReplaceSelection(const std::string& text) = 0;
  // Methods to check if undo/redo is possible, and to perform them.
  virtual bool CanUndo() const = 0;
  virtual bool CanRedo() const = 0;
  virtual void Undo() = 0;
  virtual void Redo() = 0;
  // Handles actions invoked by Accessibility clients.
  virtual void HandleAccessibilityAction(
      const AccessibilityActionData& action_data) = 0;
  virtual std::string GetLinkAtPosition(const gfx::Point& point) = 0;
  // Checks the permissions associated with this document.
  virtual bool HasPermission(DocumentPermission permission) const = 0;
  virtual void SelectAll() = 0;
  // Gets the list of DocumentAttachmentInfo from the document.
  virtual const std::vector<DocumentAttachmentInfo>&
  GetDocumentAttachmentInfoList() const = 0;
  // Gets the content of an attachment by the attachment's `index`. `index`
  // must be in the range of [0, attachment_count-1), where `attachment_count`
  // is the number of attachments embedded in the document.
  // The caller of this method is responsible for checking whether the
  // attachment is readable, attachment size is not 0 byte, and the return
  // value's size matches the corresponding DocumentAttachmentInfo's
  // `size_bytes`.
  virtual std::vector<uint8_t> GetAttachmentData(size_t index) = 0;
  // Gets metadata about the document.
  virtual const DocumentMetadata& GetDocumentMetadata() const = 0;
  // Gets the number of pages in the document.
  virtual int GetNumberOfPages() const = 0;
  // Gets the named destination by name.
  virtual absl::optional<PDFEngine::NamedDestination> GetNamedDestination(
      const std::string& destination) = 0;
  // Gets the index of the most visible page, or -1 if none are visible.
  virtual int GetMostVisiblePage() = 0;
  // Gets the rectangle of the page not including the shadow.
  virtual gfx::Rect GetPageBoundsRect(int index) = 0;
  // Gets the rectangle of the page excluding any additional areas.
  virtual gfx::Rect GetPageContentsRect(int index) = 0;
  // Returns a page's rect in screen coordinates, as well as its surrounding
  // border areas and bottom separator.
  virtual gfx::Rect GetPageScreenRect(int page_index) const = 0;
  // Set color / grayscale rendering modes.
  virtual void SetGrayscale(bool grayscale) = 0;
  // Get the number of characters on a given page.
  virtual int GetCharCount(int page_index) = 0;
  // Get the bounds in page pixels of a character on a given page.
  virtual gfx::RectF GetCharBounds(int page_index, int char_index) = 0;
  // Get a given unicode character on a given page.
  virtual uint32_t GetCharUnicode(int page_index, int char_index) = 0;
  // Given a start char index, find the longest continuous run of text that's
  // in a single direction and with the same text style. Return a filled out
  // AccessibilityTextRunInfo on success or absl::nullopt on failure. e.g. When
  // `start_char_index` is out of bounds.
  virtual absl::optional<AccessibilityTextRunInfo> GetTextRunInfo(
      int page_index,
      int start_char_index) = 0;
  // For all the links on page `page_index`, get their urls, underlying text
  // ranges and bounding boxes.
  virtual std::vector<AccessibilityLinkInfo> GetLinkInfo(
      int page_index,
      const std::vector<AccessibilityTextRunInfo>& text_runs) = 0;
  // For all the images in page `page_index`, get their alt texts and bounding
  // boxes.
  virtual std::vector<AccessibilityImageInfo> GetImageInfo(
      int page_index,
      uint32_t text_run_count) = 0;
  // For all the highlights in page `page_index`, get their underlying text
  // ranges and bounding boxes.
  virtual std::vector<AccessibilityHighlightInfo> GetHighlightInfo(
      int page_index,
      const std::vector<AccessibilityTextRunInfo>& text_runs) = 0;
  // For all the text fields in page `page_index`, get their properties like
  // name, value, bounding boxes etc.
  virtual std::vector<AccessibilityTextFieldInfo> GetTextFieldInfo(
      int page_index,
      uint32_t text_run_count) = 0;

  // Gets the PDF document's print scaling preference. True if the document can
  // be scaled to fit.
  virtual bool GetPrintScaling() = 0;
  // Returns number of copies to be printed.
  virtual int GetCopiesToPrint() = 0;
  // Returns the duplex setting.
  virtual printing::mojom::DuplexMode GetDuplexMode() = 0;
  // Returns the uniform page size of the document in points. Returns
  // `absl::nullopt` if the document has more than one page size.
  virtual absl::optional<gfx::Size> GetUniformPageSizePoints() = 0;

  // Returns a list of Values of Bookmarks. Each Bookmark is a dictionary Value
  // which contains the following key/values:
  // - "title" - a string Value.
  // - "page" - an int Value.
  // - "children" - a list of Values, with each entry containing
  //   a dictionary Value of the same structure.
  virtual base::Value GetBookmarks() = 0;

  // Append blank pages to make a 1-page document to a `num_pages` document.
  // Always retain the first page data.
  virtual void AppendBlankPages(size_t num_pages) = 0;
  // Append the first page of the document loaded with the `engine` to this
  // document at page `index`.
  virtual void AppendPage(PDFEngine* engine, int index) = 0;

  virtual std::vector<uint8_t> GetSaveData() = 0;

  virtual void SetCaretPosition(const gfx::Point& position) = 0;
  virtual void MoveRangeSelectionExtent(const gfx::Point& extent) = 0;
  virtual void SetSelectionBounds(const gfx::Point& base,
                                  const gfx::Point& extent) = 0;
  virtual void GetSelection(uint32_t* selection_start_page_index,
                            uint32_t* selection_start_char_index,
                            uint32_t* selection_end_page_index,
                            uint32_t* selection_end_char_index) = 0;

  // Remove focus from form widgets, consolidating the user input.
  virtual void KillFormFocus() = 0;

  // Notify whether the PDF currently has the focus or not.
  virtual void UpdateFocus(bool has_focus) = 0;

  // Returns the focus info of current focus item.
  virtual AccessibilityFocusInfo GetFocusInfo() = 0;

  virtual uint32_t GetLoadedByteSize() = 0;
  virtual bool ReadLoadedBytes(uint32_t length, void* buffer) = 0;

  // Requests for a thumbnail to be sent using a callback when the page is ready
  // to be rendered. `send_callback` is run with the thumbnail data when ready.
  virtual void RequestThumbnail(int page_index,
                                float device_pixel_ratio,
                                SendThumbnailCallback send_callback) = 0;
};

// Interface for exports that wrap the PDF engine.
class PDFEngineExports {
 public:
  struct RenderingSettings {
    RenderingSettings(const gfx::Size& dpi,
                      const gfx::Rect& bounds,
                      bool fit_to_bounds,
                      bool stretch_to_bounds,
                      bool keep_aspect_ratio,
                      bool center_in_bounds,
                      bool autorotate,
                      bool use_color,
                      bool render_for_printing);
    RenderingSettings(const RenderingSettings& that);

    gfx::Size dpi;
    gfx::Rect bounds;
    bool fit_to_bounds;
    bool stretch_to_bounds;
    bool keep_aspect_ratio;
    bool center_in_bounds;
    bool autorotate;
    bool use_color;
    bool render_for_printing;
  };

  PDFEngineExports() {}
  virtual ~PDFEngineExports() {}

  static PDFEngineExports* Get();

#if defined(OS_CHROMEOS)
  // See the definition of CreateFlattenedPdf in pdf.cc for details.
  virtual std::vector<uint8_t> CreateFlattenedPdf(
      base::span<const uint8_t> input_buffer) = 0;
#endif  // defined(OS_CHROMEOS)

#if defined(OS_WIN)
  // See the definition of RenderPDFPageToDC in pdf.cc for details.
  virtual bool RenderPDFPageToDC(base::span<const uint8_t> pdf_buffer,
                                 int page_number,
                                 const RenderingSettings& settings,
                                 HDC dc) = 0;

  virtual void SetPDFEnsureTypefaceCharactersAccessible(
      PDFEnsureTypefaceCharactersAccessible func) = 0;

  virtual void SetPDFUseGDIPrinting(bool enable) = 0;
  virtual void SetPDFUsePrintMode(int mode) = 0;
#endif  // defined(OS_WIN)

  // See the definition of RenderPDFPageToBitmap in pdf.cc for details.
  virtual bool RenderPDFPageToBitmap(base::span<const uint8_t> pdf_buffer,
                                     int page_number,
                                     const RenderingSettings& settings,
                                     void* bitmap_buffer) = 0;

  // See the definition of ConvertPdfPagesToNupPdf in pdf.cc for details.
  virtual std::vector<uint8_t> ConvertPdfPagesToNupPdf(
      std::vector<base::span<const uint8_t>> input_buffers,
      size_t pages_per_sheet,
      const gfx::Size& page_size,
      const gfx::Rect& printable_area) = 0;

  // See the definition of ConvertPdfDocumentToNupPdf in pdf.cc for details.
  virtual std::vector<uint8_t> ConvertPdfDocumentToNupPdf(
      base::span<const uint8_t> input_buffer,
      size_t pages_per_sheet,
      const gfx::Size& page_size,
      const gfx::Rect& printable_area) = 0;

  virtual bool GetPDFDocInfo(base::span<const uint8_t> pdf_buffer,
                             int* page_count,
                             float* max_page_width) = 0;

  // Whether the PDF is Tagged (see 10.7 "Tagged PDF" in PDF Reference 1.7).
  // Returns true if it's a tagged (accessible) PDF, false if it's a valid
  // PDF but untagged, and nullopt if the PDF can't be parsed.
  virtual absl::optional<bool> IsPDFDocTagged(
      base::span<const uint8_t> pdf_buffer) = 0;

  // Given a tagged PDF (see IsPDFDocTagged, above), return the portion of
  // the structure tree for a given page as a hierarchical tree of base::Values.
  virtual base::Value GetPDFStructTreeForPage(
      base::span<const uint8_t> pdf_buffer,
      int page_index) = 0;

  // See the definition of GetPDFPageSizeByIndex in pdf.cc for details.
  virtual absl::optional<gfx::SizeF> GetPDFPageSizeByIndex(
      base::span<const uint8_t> pdf_buffer,
      int page_number) = 0;
};

}  // namespace chrome_pdf

#endif  // PDF_PDF_ENGINE_H_