tesseract-ocr/viewer/svpaint.cpp

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// Copyright 2007 Google Inc. All Rights Reserved.
//
// Author: Joern Wanke
//
// Simple drawing program to illustrate ScrollView capabilities.
//
// Functionality:
// - The menubar is used to select from different sample styles of input.
// - With the RMB it is possible to change the RGB values in different
//   popup menus.
// - A LMB click either draws point-to-point, point or text.
// - A LMB dragging either draws a line, a rectangle or ellipse.

#include "scrollview.h"
#include "svmnode.h"
#include <stdlib.h>
#include <iostream>

#ifndef GRAPHICS_DISABLED
// The current color values we use, initially white (== ScrollView::WHITE).
int rgb[3] = { 255, 255, 255 };

class SVPaint : public SVEventHandler {
 public:
   SVPaint(const char* server_name);
// This is the main event handling function that we need to overwrite, defined
// in SVEventHandler.
   void Notify(const SVEvent* sv_event);
 private:
// The Handler take care of the SVET_POPUP, SVET_MENU, SVET_CLICK and
// SVET_SELECTION events.
   void PopupHandler(const SVEvent* sv_event);
   void MenuBarHandler(const SVEvent* sv_event);
   void ClickHandler(const SVEvent* sv_event);
   void SelectionHandler(const SVEvent* sv_event);

// Convenience functions to build little menus.
   SVMenuNode* BuildPopupMenu();
   SVMenuNode* BuildMenuBar();

// Our window.
   ScrollView* window_;

// The mode we are in when an SVET_CLICK or an SVET_SELECTION event occurs.
   int click_mode_;
   int drag_mode_;

// In the point-to-point drawing mode, we need to set a start-point the first
// time we call it (e.g. call SetCursor).
   bool has_start_point_;
};

// Build a sample popup menu.
SVMenuNode* SVPaint::BuildPopupMenu() {
  SVMenuNode* root = new SVMenuNode();  // Empty root node
  // Initial color is white, so we  all values to 255.
  root->AddChild("R",                   // Shown caption.
                  1,                    // assoc. command_id.
                 "255",                 // initial value.
                 "Red Color Value?");  // Shown description.
  root->AddChild("G", 2, "255", "Green Color Value?");
  root->AddChild("B", 3, "255", "Blue Color Value?");
  return root;
}

// Build a sample menu bar.
SVMenuNode* SVPaint::BuildMenuBar() {
  SVMenuNode* root = new SVMenuNode();  // Empty root node

  // Create some submenus and add them to the root.
  SVMenuNode* click = root->AddChild("Clicking");
  SVMenuNode* drag = root->AddChild("Dragging");
  
  // Put some nodes into the submenus.
  click->AddChild("Point to Point Drawing",  // Caption.
                  1);                       // command_id.
  click->AddChild("Point Drawing", 2);
  click->AddChild("Text Drawing", 3);
  drag->AddChild("Line Drawing", 4);
  drag->AddChild("Rectangle Drawing", 5);
  drag->AddChild("Ellipse Drawing", 6);
  return root;
}

// Takes care of the SVET_POPUP events.
// In our case, SVET_POPUP is used to set RGB values.
void SVPaint::PopupHandler(const SVEvent* sv_event) {
  // Since we only have the RGB values as popup items,
  // we take a shortcut to not bloat up code:
  rgb[sv_event->command_id - 1] = atoi(sv_event->parameter);
  window_->Pen(rgb[0], rgb[1], rgb[2]);
}

// Takes care of the SVET_MENU events.
// In our case, we change either the click_mode_ (commands 1-3)
// or the drag_mode_ (commands 4-6).
void SVPaint::MenuBarHandler(const SVEvent* sv_event) {
  if ((sv_event->command_id > 0) && (sv_event->command_id < 4)) { 
  click_mode_ = sv_event->command_id;   
  has_start_point_ = false;
  } else { drag_mode_ = sv_event->command_id; }
}

// Takes care of the SVET_CLICK events.
// Depending on the click_mode_ we are in, either do Point-to-Point drawing,
// point drawing, or draw text.
void SVPaint::ClickHandler(const SVEvent* sv_event) {
  switch (click_mode_) {
  case 1: //Point to Point
    if (has_start_point_) { window_->DrawTo(sv_event->x, sv_event->y);
    } else {
        has_start_point_ = true; 
        window_->SetCursor(sv_event->x, sv_event->y);
    }
    break;
  case 2: //Point Drawing..simulated by drawing a 1 pixel line.
    window_->Line(sv_event->x, sv_event->y, sv_event->x, sv_event->y);
    break;
  case 3: //Text
    // We show a modal input dialog on our window, then draw the input and
    // finally delete the input pointer.
    char* p = window_->ShowInputDialog("Text:");
    window_->Text(sv_event->x, sv_event->y, p);
    delete p;
    break;
  }
}

// Takes care of the SVET_SELECTION events.
// Depending on the drag_mode_ we are in, either draw a line, a rectangle or
// an ellipse.
void SVPaint::SelectionHandler(const SVEvent* sv_event) {
  switch (drag_mode_) {
  //FIXME inversed x_size, y_size
    case 4: //Line
      window_->Line(sv_event->x, sv_event->y, 
                    sv_event->x - sv_event->x_size,
                    sv_event->y - sv_event->y_size);
      break;
    case 5: //Rectangle
      window_->Rectangle(sv_event->x, sv_event->y,
                         sv_event->x - sv_event->x_size,
                         sv_event->y - sv_event->y_size);
      break;
    case 6: //Ellipse
      window_->Ellipse(sv_event->x - sv_event->x_size,
                       sv_event->y - sv_event->y_size,
                       sv_event->x_size, sv_event->y_size);
      break;
    }
}

// The event handling function from ScrollView which we have to overwrite.
// We handle CLICK, SELECTION, MENU and POPUP and throw away all other events.
void SVPaint::Notify(const SVEvent* sv_event) {
  if (sv_event->type == SVET_CLICK) { ClickHandler(sv_event); }  
  else if (sv_event->type == SVET_SELECTION) { SelectionHandler(sv_event); }
  else if (sv_event->type == SVET_MENU) { MenuBarHandler(sv_event); }
  else if (sv_event->type == SVET_POPUP) { PopupHandler(sv_event); }
  else {} //throw other events away
}

// Builds a new window, initializes the variables and event handler and builds
// the menu.
SVPaint::SVPaint(const char *server_name) {
  window_ = new ScrollView("ScrollView Paint Example",  // window caption
                            0, 0,                       // x,y window position
                            500, 500,                   // window size
                                    500, 500,                   // canvas size
                            false,      // whether the Y axis is inversed.
                                        // this is included due to legacy 
                                        // reasons for tesseract and enables
                                        // us to have (0,0) as the LOWER left
                                        // of the coordinate system.
                            server_name);               // the server address.

  // Set the start modes to point-to-point and line drawing.
  click_mode_ = 1;
  drag_mode_ = 4;
  has_start_point_ = false;

  // Bild our menus and add them to the window. The flag illustrates whether
  // this is a menu bar.
  SVMenuNode* popup_menu = BuildPopupMenu();
  popup_menu->BuildMenu(window_,false);
        
  SVMenuNode* bar_menu = BuildMenuBar();
  bar_menu->BuildMenu(window_,true);

  // Set the initial color values to White (could also be done by
  // passing (rgb[0], rgb[1], rgb[2]).
  window_->Pen(ScrollView::WHITE);
  window_->Brush(ScrollView::WHITE);

  // Adds the event handler to the window. This actually ensures that Notify
  // gets called when events occur.
  window_->AddEventHandler(this);

  // Set the window visible (calling this is important to actually render
  // everything. Without this call, the window would also be drawn, but the
  // menu bars would be missing.
  window_->SetVisible(true);

  // Rest this thread until its window is destroyed.
  // Note that a special eventhandling thread was created when constructing
  // the window. Due to this, the application will not deadlock here.
  window_->AwaitEvent(SVET_DESTROY);
  // We now have 3 Threads running:
  // (1) The MessageReceiver thread which fetches messages and distributes them
  // (2) The EventHandler thread which handles all events for window_
  // (3) The main thread which waits on window_ for a DESTROY event (blocked)
}

// If a parameter is given, we try to connect to the given server.
// This enables us to test the remote capabilites of ScrollView.
int main(int argc, char** argv) {
        const char* server_name;
        if (argc > 1) { server_name = argv[1]; } else { server_name = "localhost"; }
        SVPaint svp(server_name);
}
#endif  // GRAPHICS_DISABLED