scrollview.h

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// File:        scrollview.h
// Description: ScrollView
// Author:      Joern Wanke
//
// (C) Copyright 2007, Google Inc.
// 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.
//
//
// ScrollView is designed as an UI which can be run remotely. This is the
// client code for it, the server part is written in java. The client consists
// mainly of 2 parts:
// The "core" ScrollView which sets up the remote connection,
// takes care of event handling etc.
// The other part of ScrollView consists of predefined API calls through LUA,
// which can basically be used to get a zoomable canvas in which it is possible
// to draw lines, text etc.
// Technically, thanks to LUA, its even possible to bypass the here defined LUA
// API calls at all and generate a java user interface from scratch (or
// basically generate any kind of java program, possibly even dangerous ones).
 
#ifndef TESSERACT_VIEWER_SCROLLVIEW_H_
#define TESSERACT_VIEWER_SCROLLVIEW_H_
 
#include "image.h"
 
#include <tesseract/export.h>
 
#include <cstdio>
#include <memory>
#include <mutex>
 
namespace tesseract {
 
#if !defined(__GNUC__) && !defined(__attribute__)
# define __attribute__(attr) // compiler without support for __attribute__
#endif
 
class ScrollView;
class SVNetwork;
class SVSemaphore;
struct SVPolyLineBuffer;
 
enum SVEventType {
  SVET_DESTROY,   // Window has been destroyed by user.
  SVET_EXIT,      // User has destroyed the last window by clicking on the 'X'.
  SVET_CLICK,     // Left button pressed.
  SVET_SELECTION, // Left button selection.
  SVET_INPUT,     // There is some input (single key or a whole string).
  SVET_MOUSE,     // The mouse has moved with a button pressed.
  SVET_MOTION,    // The mouse has moved with no button pressed.
  SVET_HOVER,     // The mouse has stayed still for a second.
  SVET_POPUP,     // A command selected through a popup menu.
  SVET_MENU,      // A command selected through the menubar.
  SVET_ANY,       // Any of the above.
 
  SVET_COUNT // Array sizing.
};
 
struct SVEvent {
  ~SVEvent() {
    delete[] parameter;
  }
  std::unique_ptr<SVEvent> copy() const;
  SVEventType type = SVET_DESTROY; // What kind of event.
  ScrollView *window = nullptr;    // Window event relates to.
  char *parameter = nullptr;       // Any string that might have been passed as argument.
  int x = 0;                       // Coords of click or selection.
  int y = 0;
  int x_size = 0; // Size of selection.
  int y_size = 0;
  int command_id = 0; // The ID of the possibly associated event (e.g. MENU)
  int counter = 0;    // Used to detect which kind of event to process next.
 
  SVEvent() = default;
  SVEvent(const SVEvent &);
  SVEvent &operator=(const SVEvent &);
};
 
// The SVEventHandler class is used for Event handling: If you register your
// class as SVEventHandler to a ScrollView Window, the SVEventHandler will be
// called whenever an appropriate event occurs.
class TESS_API SVEventHandler {
public:
  virtual ~SVEventHandler();
 
  // Gets called by the SV Window. Does nothing on default, overwrite this
  // to implement the desired behaviour
  virtual void Notify(const SVEvent *sve) {
    (void)sve;
  }
};
 
// The ScrollView class provides the external API to the scrollviewer process.
// The scrollviewer process manages windows and displays images, graphics and
// text while allowing the user to zoom and scroll the windows arbitrarily.
// Each ScrollView class instance represents one window, and stuff is drawn in
// the window through method calls on the class. The constructor is used to
// create the class instance (and the window).
class TESS_API ScrollView {
public:
  // Color enum for pens and brushes.
  enum Color {
    NONE,
    BLACK,
    WHITE,
    RED,
    YELLOW,
    GREEN,
    CYAN,
    BLUE,
    MAGENTA,
    AQUAMARINE,
    DARK_SLATE_BLUE,
    LIGHT_BLUE,
    MEDIUM_BLUE,
    MIDNIGHT_BLUE,
    NAVY_BLUE,
    SKY_BLUE,
    SLATE_BLUE,
    STEEL_BLUE,
    CORAL,
    BROWN,
    SANDY_BROWN,
    GOLD,
    GOLDENROD,
    DARK_GREEN,
    DARK_OLIVE_GREEN,
    FOREST_GREEN,
    LIME_GREEN,
    PALE_GREEN,
    YELLOW_GREEN,
    LIGHT_GREY,
    DARK_SLATE_GREY,
    DIM_GREY,
    GREY,
    KHAKI,
    MAROON,
    ORANGE,
    ORCHID,
    PINK,
    PLUM,
    INDIAN_RED,
    ORANGE_RED,
    VIOLET_RED,
    SALMON,
    TAN,
    TURQUOISE,
    DARK_TURQUOISE,
    VIOLET,
    WHEAT,
    GREEN_YELLOW // Make sure this one is last.
  };
 
  ~ScrollView();
 
#ifndef GRAPHICS_DISABLED
 
  // Create a window. The pixel size of the window may be 0,0, in which case
  // a default size is selected based on the size of your canvas.
  // The canvas may not be 0,0 in size!
  ScrollView(const char *name, int x_pos, int y_pos, int x_size, int y_size, int x_canvas_size,
             int y_canvas_size);
  // With a flag whether the x axis is reversed.
  ScrollView(const char *name, int x_pos, int y_pos, int x_size, int y_size, int x_canvas_size,
             int y_canvas_size, bool y_axis_reversed);
  // Connect to a server other than localhost.
  ScrollView(const char *name, int x_pos, int y_pos, int x_size, int y_size, int x_canvas_size,
             int y_canvas_size, bool y_axis_reversed, const char *server_name);
  /*******************************************************************************
   * Event handling
   * To register as listener, the class has to derive from the SVEventHandler
   * class, which consists of a notifyMe(SVEvent*) function that should be
   * overwritten to process the event the way you want.
   *******************************************************************************/
 
  // Add an Event Listener to this ScrollView Window.
  void AddEventHandler(SVEventHandler *listener);
 
  // Block until an event of the given type is received.
  std::unique_ptr<SVEvent> AwaitEvent(SVEventType type);
 
  /*******************************************************************************
   * Getters and Setters
   *******************************************************************************/
 
  // Returns the title of the window.
  const char *GetName() {
    return window_name_;
  }
 
  // Returns the unique ID of the window.
  int GetId() {
    return window_id_;
  }
 
  /*******************************************************************************
   * API functions for LUA calls
   * the implementations for these can be found in svapi.cc
   * (keep in mind that the window is actually created through the ScrollView
   * constructor, so this is not listed here)
   *******************************************************************************/
 
  // Draw an image on (x,y).
  void Draw(Image image, int x_pos, int y_pos);
 
  // Flush buffers and update display.
  static void Update();
 
  // Exit the program.
  static void Exit();
 
  // Update the contents of a specific window.
  void UpdateWindow();
 
  // Erase all content from the window, but do not destroy it.
  void Clear();
 
  // Set pen color with an enum.
  void Pen(Color color);
 
  // Set pen color to RGB (0-255).
  void Pen(int red, int green, int blue);
 
  // Set pen color to RGBA (0-255).
  void Pen(int red, int green, int blue, int alpha);
 
  // Set brush color with an enum.
  void Brush(Color color);
 
  // Set brush color to RGB (0-255).
  void Brush(int red, int green, int blue);
 
  // Set brush color to RGBA (0-255).
  void Brush(int red, int green, int blue, int alpha);
 
  // Set attributes for future text, like font name (e.g.
  // "Times New Roman"), font size etc..
  // Note: The underlined flag is currently not supported
  void TextAttributes(const char *font, int pixel_size, bool bold, bool italic, bool underlined);
 
  // Draw line from (x1,y1) to (x2,y2) with the current pencolor.
  void Line(int x1, int y1, int x2, int y2);
 
  // Set the stroke width of the pen.
  void Stroke(float width);
 
  // Draw a rectangle given upper left corner and lower right corner.
  // The current pencolor is used as outline, the brushcolor to fill the shape.
  void Rectangle(int x1, int y1, int x2, int y2);
 
  // Draw an ellipse centered on (x,y).
  // The current pencolor is used as outline, the brushcolor to fill the shape.
  void Ellipse(int x, int y, int width, int height);
 
  // Draw text with the current pencolor
  void Text(int x, int y, const char *mystring);
 
  // Draw an image from a local filename. This should be faster than
  // createImage. WARNING: This only works on a local machine. This also only
  // works image types supported by java (like bmp,jpeg,gif,png) since the image
  // is opened by the server.
  void Draw(const char *image, int x_pos, int y_pos);
 
  // Set the current position to draw from (x,y). In conjunction with...
  void SetCursor(int x, int y);
 
  // ...this function, which draws a line from the current to (x,y) and then
  // sets the new position to the new (x,y), this can be used to easily draw
  // polygons using vertices
  void DrawTo(int x, int y);
 
  // Set the SVWindow visible/invisible.
  void SetVisible(bool visible);
 
  // Set the SVWindow always on top or not always on top.
  void AlwaysOnTop(bool b);
 
  // Shows a modal dialog with "msg" as question and returns 'y' or 'n'.
  int ShowYesNoDialog(const char *msg);
 
  // Shows a modal dialog with "msg" as question and returns a char* string.
  // Constraint: As return, only words (e.g. no whitespaces etc.) are allowed.
  char *ShowInputDialog(const char *msg);
 
  // Adds a messagebox to the SVWindow. This way, it can show the messages...
  void AddMessageBox();
 
  // ...which can be added by this command.
  // This is intended as an "debug" output window.
  void AddMessage(const char *message);
  void AddMessageF(const char *format, ...) __attribute__((format(gnu_printf, 2, 3)));
 
  // Zoom the window to the rectangle given upper left corner and
  // lower right corner.
  void ZoomToRectangle(int x1, int y1, int x2, int y2);
 
  // Custom messages (manipulating java code directly) can be send through this.
  // Send a message to the server and attach the Id of the corresponding window.
  // Note: This should only be called if you are know what you are doing, since
  // you are fiddling with the Java objects on the server directly. Calling
  // this just for fun will likely break your application!
  // It is public so you can actually take use of the LUA functionalities, but
  // be careful!
  void SendMsg(const char* msg, ...) __attribute__((format(gnu_printf, 2, 3)));
 
  // Custom messages (manipulating java code directly) can be send through this.
  // Send a message to the server without adding the
  // window id. Used for global events like Exit().
  // Note: This should only be called if you are know what you are doing, since
  // you are fiddling with the Java objects on the server directly. Calling
  // this just for fun will likely break your application!
  // It is public so you can actually take use of the LUA functionalities, but
  // be careful!
  static void SendRawMessage(const char *msg);
 
  /*******************************************************************************
   * Add new menu entries to parent. If parent is "", the entry gets added to
   *the main menubar (toplevel).
   *******************************************************************************/
  // This adds a new submenu to the menubar.
  void MenuItem(const char *parent, const char *name);
 
  // This adds a new (normal) menu entry with an associated eventID, which
  // should be unique among menubar eventIDs.
  void MenuItem(const char *parent, const char *name, int cmdEvent);
 
  // This adds a new checkbox entry, which might initially be flagged.
  void MenuItem(const char *parent, const char *name, int cmdEvent, bool flagged);
 
  // This adds a new popup submenu to the popup menu. If parent is "", the entry
  // gets added at "toplevel" popupmenu.
  void PopupItem(const char *parent, const char *name);
 
  // This adds a new popup entry with the associated eventID, which should be
  // unique among popup eventIDs.
  // If value and desc are given, on a click the server will ask you to modify
  // the value and return the new value.
  void PopupItem(const char *parent, const char *name, int cmdEvent, const char *value,
                 const char *desc);
 
  // Returns the correct Y coordinate for a window, depending on whether it
  // might have to be flipped (by ySize).
  int TranslateYCoordinate(int y);
 
  char Wait();
 
private:
  // Transfers a binary Image.
  void TransferBinaryImage(Image image);
  // Transfers a gray scale Image.
  void TransferGrayImage(Image image);
  // Transfers a 32-Bit Image.
  void Transfer32bppImage(Image image);
 
  // Sets up ScrollView, depending on the variables from the constructor.
  void Initialize(const char *name, int x_pos, int y_pos, int x_size, int y_size, int x_canvas_size,
                  int y_canvas_size, bool y_axis_reversed, const char *server_name);
 
  // Send the current buffered polygon (if any) and clear it.
  void SendPolygon();
 
  // Start the message receiving thread.
  static void MessageReceiver();
 
  // Place an event into the event_table (synchronized).
  void SetEvent(const SVEvent *svevent);
 
  // Wake up the semaphore.
  void Signal();
 
  // Returns the unique, shared network stream.
  static SVNetwork *GetStream() {
    return stream_;
  }
 
  // Starts a new event handler.
  // Called asynchronously whenever a new window is created.
  void StartEventHandler();
 
  // Escapes the ' character with a \, so it can be processed by LUA.
  char *AddEscapeChars(const char *input);
 
  // The event handler for this window.
  SVEventHandler *event_handler_;
  // The name of the window.
  const char *window_name_;
  // The id of the window.
  int window_id_;
  // The points of the currently under-construction polyline.
  SVPolyLineBuffer *points_;
  // Whether the axis is reversed.
  bool y_axis_is_reversed_;
  // Set to true only after the event handler has terminated.
  bool event_handler_ended_;
  // If the y axis is reversed, flip all y values by ySize.
  int y_size_;
  // # of created windows (used to assign an id to each ScrollView* for svmap).
  static int nr_created_windows_;
  // Serial number of sent images to ensure that the viewer knows they
  // are distinct.
  static int image_index_;
 
  // The stream through which the c++ client is connected to the server.
  static SVNetwork *stream_;
 
  // Table of all the currently queued events.
  std::unique_ptr<SVEvent> event_table_[SVET_COUNT];
 
  // Mutex to access the event_table_ in a synchronized fashion.
  std::mutex mutex_;
 
  // Semaphore to the thread belonging to this window.
  SVSemaphore *semaphore_;
#endif // !GRAPHICS_DISABLED
};
 
} // namespace tesseract
 
#endif // TESSERACT_VIEWER_SCROLLVIEW_H_