pdf/pdf_view_plugin_base.h

// Copyright 2020 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_VIEW_PLUGIN_BASE_H_
#define PDF_PDF_VIEW_PLUGIN_BASE_H_

#include <stdint.h>

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

#include "base/memory/weak_ptr.h"
#include "pdf/paint_manager.h"
#include "pdf/pdf_engine.h"
#include "pdf/pdfium/pdfium_form_filler.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkColor.h"
#include "ui/gfx/geometry/point.h"
#include "ui/gfx/geometry/point_f.h"
#include "ui/gfx/geometry/rect.h"

namespace base {
class Value;
}  // namespace base

namespace chrome_pdf {

class Image;
class PDFiumEngine;
class UrlLoader;
struct AccessibilityActionData;
struct AccessibilityCharInfo;
struct AccessibilityDocInfo;
struct AccessibilityPageInfo;
struct AccessibilityPageObjects;
struct AccessibilityTextRunInfo;
struct AccessibilityViewportInfo;

// Common base to share code between the two plugin implementations,
// `OutOfProcessInstance` (Pepper) and `PdfViewWebPlugin` (Blink).
class PdfViewPluginBase : public PDFEngine::Client,
                          public PaintManager::Client {
 public:
  using PDFEngine::Client::ScheduleTaskOnMainThread;

  PdfViewPluginBase(const PdfViewPluginBase& other) = delete;
  PdfViewPluginBase& operator=(const PdfViewPluginBase& other) = delete;

  // PDFEngine::Client:
  void Invalidate(const gfx::Rect& rect) override;
  SkColor GetBackgroundColor() override;

  // PaintManager::Client
  void OnPaint(const std::vector<gfx::Rect>& paint_rects,
               std::vector<PaintReadyRect>& ready,
               std::vector<gfx::Rect>& pending) override;

  // Enable accessibility for PDF plugin.
  void EnableAccessibility();

  // Handle invoked accessibility actions.
  void HandleAccessibilityAction(const AccessibilityActionData& action_data);

 protected:
  enum class AccessibilityState {
    kOff = 0,  // Off.
    kPending,  // Enabled but waiting for doc to load.
    kLoaded,   // Fully loaded.
  };

  enum class DocumentLoadState {
    kLoading = 0,
    kComplete,
    kFailed,
  };

  struct BackgroundPart {
    gfx::Rect location;
    uint32_t color;
  };

  PdfViewPluginBase();
  ~PdfViewPluginBase() override;

  // Initializes the main `PDFiumEngine`. Any existing engine will be replaced.
  void InitializeEngine(PDFiumFormFiller::ScriptOption script_option);

  // Destroys the main `PDFiumEngine`. Subclasses should call this method in
  // their destructor to ensure the engine is destroyed first.
  void DestroyEngine();

  PDFiumEngine* engine() { return engine_.get(); }

  PaintManager& paint_manager() { return paint_manager_; }

  // Starts loading `url`. If `is_print_preview` is `true`, load for print
  // preview instead of normal PDF viewing.
  void LoadUrl(const std::string& url, bool is_print_preview);

  // Gets a weak pointer with a lifetime matching the derived class.
  virtual base::WeakPtr<PdfViewPluginBase> GetWeakPtr() = 0;

  // Creates a URL loader and allows it to access all urls, i.e. not just the
  // frame's origin.
  virtual std::unique_ptr<UrlLoader> CreateUrlLoaderInternal() = 0;

  // Handles `LoadUrl()` result.
  virtual void DidOpen(std::unique_ptr<UrlLoader> loader, int32_t result) = 0;

  // Handles `LoadUrl()` result for print preview.
  virtual void DidOpenPreview(std::unique_ptr<UrlLoader> loader,
                              int32_t result) = 0;

  // Handles `postMessage()` calls from the embedder.
  void HandleMessage(const base::Value& message);

  // Enqueues a "message" event carrying `message` to the embedder. Messages are
  // guaranteed to be received in the order that they are sent. This method is
  // non-blocking.
  virtual void SendMessage(base::Value message) = 0;

  // Initialize image buffer(s) according to the new context size.
  virtual void InitImageData(const gfx::Size& size) = 0;

  // Schedules invalidation tasks after painting finishes.
  void InvalidateAfterPaintDone();

  // Updates the available area and the background parts, notifies the PDF
  // engine, and updates the accessibility information.
  void OnGeometryChanged(double old_zoom, float old_device_scale);

  // Returns the plugin-specific image data buffer.
  virtual Image GetPluginImageData() const;

  // Updates the geometry of the plugin and its image data if the view's
  // size or scale has changed.
  void UpdateGeometryOnViewChanged(const gfx::Rect& new_view_rect,
                                   float new_device_scale);

  // A helper of OnGeometryChanged() which updates the available area and
  // the background parts, and notifies the PDF engine of geometry changes.
  void RecalculateAreas(double old_zoom, float old_device_scale);

  // Figures out the location of any background rectangles (i.e. those that
  // aren't painted by the PDF engine).
  void CalculateBackgroundParts();

  // Bound the given scroll position to the document.
  gfx::PointF BoundScrollPositionToDocument(const gfx::PointF& scroll_position);

  // Computes document width/height in device pixels, based on current zoom and
  // device scale
  int GetDocumentPixelWidth() const;
  int GetDocumentPixelHeight() const;

  // Starts loading accessibility information.
  void LoadAccessibility();

  // Sets the accessibility information about the PDF document in the renderer.
  virtual void SetAccessibilityDocInfo(
      const AccessibilityDocInfo& doc_info) = 0;

  // Sets the accessibility information about the given |page_index| in the
  // renderer.
  void PrepareAndSetAccessibilityPageInfo(int32_t page_index);

  // Sets the accessibility information about the page in the renderer.
  virtual void SetAccessibilityPageInfo(
      AccessibilityPageInfo page_info,
      std::vector<AccessibilityTextRunInfo> text_runs,
      std::vector<AccessibilityCharInfo> chars,
      AccessibilityPageObjects page_objects) = 0;

  // Prepares the accessibility information about the current viewport. Calls
  // SetAccessibilityViewportInfo() internally to set this information in the
  // renderer. This is done once when accessibility is first loaded and again
  // when the geometry changes.
  void PrepareAndSetAccessibilityViewportInfo();

  // Sets the accessibility information about the current viewport in the
  // renderer.
  virtual void SetAccessibilityViewportInfo(
      const AccessibilityViewportInfo& viewport_info) = 0;

  const SkBitmap& image_data() const { return image_data_; }
  SkBitmap& mutable_image_data() { return image_data_; }

  const gfx::Rect& available_area() const { return available_area_; }

  void set_document_size(const gfx::Size& size) { document_size_ = size; }

  const gfx::Size& plugin_size() const { return plugin_size_; }

  const gfx::Point& plugin_offset() const { return plugin_offset_; }

  void SetBackgroundColor(SkColor background_color) {
    background_color_ = background_color;
  }

  // Sets the new zoom scale.
  void SetZoom(double scale);

  double zoom() const { return zoom_; }

  float device_scale() const { return device_scale_; }

  bool stop_scrolling() const { return stop_scrolling_; }
  void set_stop_scrolling(bool stop_scrolling) {
    stop_scrolling_ = stop_scrolling;
  }

  DocumentLoadState document_load_state() { return document_load_state_; }
  void set_document_load_state(DocumentLoadState state) {
    document_load_state_ = state;
  }

  AccessibilityState accessibility_state() { return accessibility_state_; }

 private:
  // Message handlers.
  void HandleDisplayAnnotationsMessage(const base::Value& message);
  void HandleGetNamedDestinationMessage(const base::Value& message);
  void HandleGetSelectedTextMessage(const base::Value& message);
  void HandleRotateClockwiseMessage(const base::Value& /*message*/);
  void HandleRotateCounterclockwiseMessage(const base::Value& /*message*/);
  void HandleSelectAllMessage(const base::Value& /*message*/);
  void HandleSetBackgroundColorMessage(const base::Value& message);
  void HandleSetReadOnlyMessage(const base::Value& message);
  void HandleSetTwoUpViewMessage(const base::Value& message);
  void HandleViewportMessage(const base::Value& message);

  // Paints the given invalid area of the plugin to the given graphics device.
  // PaintManager::Client::OnPaint() should be its only caller.
  void DoPaint(const std::vector<gfx::Rect>& paint_rects,
               std::vector<PaintReadyRect>& ready,
               std::vector<gfx::Rect>& pending);

  // The preparation when painting on the image data buffer for the first
  // time.
  void PrepareForFirstPaint(std::vector<PaintReadyRect>& ready);

  // Callback to clear deferred invalidates after painting finishes.
  void ClearDeferredInvalidates(int32_t /*unused_but_required*/);

  std::unique_ptr<PDFiumEngine> engine_;
  PaintManager paint_manager_{this};

  // Image data buffer for painting.
  SkBitmap image_data_;

  std::vector<BackgroundPart> background_parts_;

  // Deferred invalidates while |in_paint_| is true.
  std::vector<gfx::Rect> deferred_invalidates_;

  // Remaining area, in pixels, to render the pdf in after accounting for
  // horizontal centering.
  gfx::Rect available_area_;

  // The size of the entire document in pixels (i.e. if each page is 800 pixels
  // high and there are 10 pages, the height will be 8000).
  gfx::Size document_size_;

  // Size, in pixels, of plugin rectangle.
  gfx::Size plugin_size_;

  // Size, in DIPs, of plugin rectangle.
  gfx::Size plugin_dip_size_;

  // Positional offset, in CSS pixels, of the plugin rectangle.
  gfx::Point plugin_offset_;

  // The background color of the PDF viewer.
  SkColor background_color_ = SK_ColorTRANSPARENT;

  // Current zoom factor.
  double zoom_ = 1.0;

  // Current device scale factor. Multiply by `device_scale_` to convert from
  // viewport to screen coordinates. Divide by `device_scale_` to convert from
  // screen to viewport coordinates.
  float device_scale_ = 1.0f;

  // True if we haven't painted the plugin viewport yet.
  bool first_paint_ = true;

  // Whether OnPaint() is in progress or not.
  bool in_paint_ = false;

  // True if last bitmap was smaller than the screen.
  bool last_bitmap_smaller_ = false;

  // True if we request a new bitmap rendering.
  bool needs_reraster_ = true;

  // The scroll position for the last raster, before any transformations are
  // applied.
  gfx::PointF scroll_position_at_last_raster_;

  // If this is true, then don't scroll the plugin in response to the messages
  // from DidChangeView() or HandleUpdateScrollMessage(). This will be true when
  // the extension page is in the process of zooming the plugin so that
  // flickering doesn't occur while zooming.
  bool stop_scrolling_ = false;

  // Whether the plugin has received a viewport changed message. Nothing should
  // be painted until this is received.
  bool received_viewport_message_ = false;

  // The current state of document load.
  DocumentLoadState document_load_state_ = DocumentLoadState::kLoading;

  // The current state of accessibility.
  AccessibilityState accessibility_state_ = AccessibilityState::kOff;

  // The next accessibility page index, used to track interprocess calls when
  // reconstructing the tree for new document layouts.
  int32_t next_accessibility_page_index_ = 0;
};

}  // namespace chrome_pdf

#endif  // PDF_PDF_VIEW_PLUGIN_BASE_H_