Scrolling a Cairo drawing-area or Gtk layout

[Roger Matthews <roger matthews hotmail com>]

 /*Hello, if there is anybody willing to help with this problem I would be very appreciative and thanks in 
advance. Here is some code and my problem is this: */
/*I create two windows, one with spinbuttons for parameter entry, and the other shows a cairo line which 
results from a simple straight line equation, and*/
/* that extends beyond the bounds of the window. The first window is scrollable and I would like to be able 
to scroll to the end of the line in the second window*/
/*but don't seem to be able to work out how. I've tried putting the darea into the scrolled-window as per 
window1, it compiles and runs but has no scrollbars.*/
/*I've also tried gtk_container_add (darea, swin, layout, and many combination thereof) to window2.*/

/*Having read that a gtk layout supports scrolling natively I assumed it would do this easily. If I declare 
the layout as GtkWidget then gtk_container_add accepts*/
/*the layout but produces no scrollbars and if I declare it as GtkLayout then gtk_container_add won't accept 
it, if I use gtk_layout_put there's problems too.*/
/*If an example of a gtk layout (on one, or more windows) with scrolling (on one, or more windows) could be 
provided I would be happy and could stop tearing*/
/*my hair out, thanks in advance, Roger Matthews.*/
#include <stdio.h>

#include <math.h>

#include <gtk/gtk.h>

#include <cairo.h>

 

/*Global Variables*/

 int i;

 double yvalue1[1001];

 int yvalue1_param1 = 1;

 float yvalue1_param2 =
3.0;

 float const_asp_ratio =
1.0;

/***************************GTK CALLBACK FUNCTIONS**************/

static void get_new_number_integer_yvalue1_param1(GtkWidget
*widget, gpointer data)

{

 yvalue1_param1 =
gtk_spin_button_get_value_as_int(GTK_SPIN_BUTTON(widget));

 write_yvalue1params();

 printf("yvalue1_param1 = %d\n",
yvalue1_param1);

}

/****************************************************************/

static void get_new_number_float_yvalue1_param2(GtkWidget
*widget, gpointer data)

{

 yvalue1_param2 =
gtk_spin_button_get_value(GTK_SPIN_BUTTON(widget));

 write_yvalue1params();

 printf("yvalue1_param2 = %f\n",
yvalue1_param2);

}

/****************************************************************/

static void get_new_number_float_const_asp_ratio(GtkWidget
*widget, gpointer data)

{

 const_asp_ratio =
gtk_spin_button_get_value(GTK_SPIN_BUTTON(widget));

 write_yvalue1params();

 printf("const_asp_ratio = %f\n",
const_asp_ratio);

}

/****************************************************************/

static void do_drawing(cairo_t *, GtkWidget *);

 

static gboolean on_draw_event(GtkWidget *widget, cairo_t *cr, 

    gpointer user_data)

{  

  do_drawing(cr, widget);

  return FALSE;

}

 

static void do_drawing(cairo_t *cr, GtkWidget *widget)

{

 GtkWidget *win =
gtk_widget_get_toplevel(widget);

 int i;

 double yvalue1[1001];

 float const_asp_ratio;

 char yvalue1paramname1,
yvalue1paramname2, yvalue1paramname3;

 FILE*
infile_yvalue1params = fopen("InputParameters/yvalue1params",
"r");

 fscanf(infile_yvalue1params,"%s %d\n%s
%f\n%s %f\n", &yvalue1paramname1, &yvalue1_param1,
&yvalue1paramname2, &yvalue1_param2, &yvalue1paramname3,
&const_asp_ratio);

 fclose(infile_yvalue1params);

 

  /*Create 'yvalue1' */

  for(i = 0; i <= 1000;
i++)

  {

  yvalue1[i] = (float)i;

  }

/*************************/

  int winwidth, winheight;

 
gtk_window_get_size(GTK_WINDOW(win), &winwidth, &winheight);

 

  cairo_set_source_rgb(cr,
0.6, 0.0, 0.0);

  cairo_set_line_width(cr,
1.0);

 

  cairo_move_to(cr,
winwidth/8, (float)yvalue1_param1*(winheight/8)+yvalue1_param2);

  for (i=0; i <= 1000;
i++)

  {

  cairo_line_to(cr,
i+(winwidth/8), (float)yvalue1_param1*(winheight/8)+(yvalue1[i]*const_asp_ratio)+yvalue1_param2);

  }

  cairo_stroke(cr);

 

}/* End of do_drawing() */

/****************************************************************/

int main(int argc, char *argv[])

{

GtkWidget *window, *swin, *grid, *box;

GtkAdjustment *horizontal, *vertical;

GtkWidget *quitbutton;

/*********/

GtkWidget *label_yvalue1_param1;

GtkWidget *spin_int_yvalue1_param1;

GtkAdjustment *integer_yvalue1_param1;

/*********/

GtkWidget *label_yvalue1_param2;

GtkWidget *spin_float_yvalue1_param2;

GtkAdjustment *float_yvalue1_param2;

/*********/

GtkWidget *label_const_asp_ratio;

GtkWidget *spin_float_const_asp_ratio;

GtkAdjustment *float_const_asp_ratio;

/*********/

GtkWidget *window2;

GtkWidget *darea;

GtkWidget *layout2;

GtkWidget *swin2;

GtkWidget *box2;

GtkWidget *scrollbar1;

/****************************************************************/

gtk_init (&argc, &argv);

 

window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

gtk_window_set_title (GTK_WINDOW (window), "Scrolled
Window");

gtk_container_set_border_width (GTK_CONTAINER (window), 10);

gtk_widget_set_size_request (window, 200, 100);

g_signal_connect (G_OBJECT(window), "destroy",
G_CALLBACK (gtk_main_quit), NULL);

 

grid = gtk_grid_new ();

/**********************************************/

label_yvalue1_param1 = gtk_label_new("param1");

gtk_grid_attach (GTK_GRID (grid), label_yvalue1_param1, 0, 0, 1,
1);

/******/

integer_yvalue1_param1 = GTK_ADJUSTMENT (gtk_adjustment_new
(yvalue1_param1, 0.0, 10.0, 1.0, 1.0, 1.0));

spin_int_yvalue1_param1 = gtk_spin_button_new
(integer_yvalue1_param1, 2.0, 0);

g_signal_connect (spin_int_yvalue1_param1,
"value-changed", G_CALLBACK

(get_new_number_integer_yvalue1_param1), NULL);

gtk_grid_attach (GTK_GRID (grid), spin_int_yvalue1_param1, 0, 1,
1, 1);

/**********************************************/

label_yvalue1_param2 = gtk_label_new ("param2");

gtk_grid_attach (GTK_GRID (grid), label_yvalue1_param2, 1, 0, 1,
1);

/******/

float_yvalue1_param2 = GTK_ADJUSTMENT (gtk_adjustment_new
(yvalue1_param2, 0.0, 10.0, 1.0, 1.0, 1.0));

spin_float_yvalue1_param2 = gtk_spin_button_new
(float_yvalue1_param2, 1.0, 0);

g_signal_connect (spin_float_yvalue1_param2,
"value-changed", G_CALLBACK(get_new_number_float_yvalue1_param2),
NULL);

gtk_grid_attach (GTK_GRID (grid), spin_float_yvalue1_param2, 1,
1, 1, 1);

/**********************************************/

label_const_asp_ratio = gtk_label_new ("Gradient");

gtk_grid_attach (GTK_GRID (grid), label_const_asp_ratio, 2, 0,
1, 1);

/******/

float_const_asp_ratio = GTK_ADJUSTMENT (gtk_adjustment_new
(const_asp_ratio, 0.1, 10.0, 0.1, 0.1, 0.1));

spin_float_const_asp_ratio = gtk_spin_button_new
(float_const_asp_ratio, 1.0, 1);

g_signal_connect (spin_float_const_asp_ratio,
"value-changed", G_CALLBACK(get_new_number_float_const_asp_ratio),
NULL);

gtk_grid_attach (GTK_GRID (grid), spin_float_const_asp_ratio, 2,
1, 1, 1);

/**********************************************/

quitbutton = gtk_button_new_with_label ("Quit");

g_signal_connect (quitbutton, "clicked", G_CALLBACK
(gtk_main_quit), NULL);

gtk_grid_attach (GTK_GRID (grid), quitbutton, 0, 6, 1, 1);

/**********************************************/

swin = gtk_scrolled_window_new (NULL, NULL);

horizontal = gtk_scrolled_window_get_hadjustment
(GTK_SCROLLED_WINDOW (swin));

vertical = gtk_scrolled_window_get_vadjustment
(GTK_SCROLLED_WINDOW (swin));

gtk_container_set_border_width (GTK_CONTAINER (swin), 5);

gtk_container_add (GTK_CONTAINER (swin), grid);

 

/*Pack the widgets into a GtkBox and then into the window.*/

box = gtk_box_new (TRUE, 5);

gtk_box_pack_start (GTK_BOX (box), swin, TRUE, TRUE, 5);

gtk_container_add (GTK_CONTAINER (window), box);

gtk_widget_show_all (window);

 

/*Write inputparams files with default values */

write_yvalue1params();

/*****************************************************************/

  /*window2 =
gtk_window_new(GTK_WINDOW_TOPLEVEL);

  darea =
gtk_drawing_area_new();

 
gtk_container_add(GTK_CONTAINER(window2), darea);

 
g_signal_connect(G_OBJECT(darea), "draw",
G_CALLBACK(on_draw_event), NULL);

 
g_signal_connect(G_OBJECT(darea), "destroy",
G_CALLBACK(gtk_widget_destroy), NULL);

 
gtk_window_set_default_size(GTK_WINDOW(window2), 600, 400);

 
gtk_window_set_title(GTK_WINDOW(window2), "Graph");

 
gtk_widget_show_all(window2);*/

 

  window2 =
gtk_window_new(GTK_WINDOW_TOPLEVEL);

  layout2 =
gtk_layout_new(NULL, NULL);

 
g_signal_connect(G_OBJECT(layout2), "draw",
G_CALLBACK(on_draw_event), NULL);

 
g_signal_connect(G_OBJECT(layout2), "destroy",
G_CALLBACK(gtk_widget_destroy), NULL);

 
gtk_window_set_default_size(GTK_WINDOW(window2), 600, 400);

 
gtk_window_set_title(GTK_WINDOW(window2), "Graph");

  gtk_container_add
(GTK_CONTAINER (window2), layout2);

 
gtk_widget_show_all(window2);

 

  /*swin2 =
gtk_scrolled_window_new (NULL, NULL);

  horizontal =
gtk_scrolled_window_get_hadjustment (GTK_SCROLLED_WINDOW (swin2));

  vertical =
gtk_scrolled_window_get_vadjustment (GTK_SCROLLED_WINDOW (swin2));

  gtk_container_set_border_width
(GTK_CONTAINER (swin2), 5);

  gtk_container_add
(GTK_CONTAINER (swin2), /*grid*//*darea*//*layout2);

/*Pack the widgets into a GtkBox and then into the window.*/

  /*box2 = gtk_box_new
(TRUE, 5);

  gtk_box_pack_start
(GTK_BOX (box2), swin2, TRUE, TRUE, 5);

  gtk_container_add
(GTK_CONTAINER (window2), box2);

 
gtk_widget_show_all(window2);*/

/**************************************************************/

gtk_main();

/**************************************************************/

return 0;

} /* End of main() */

/**************************************************************/

 

int write_yvalue1params()

{

 FILE*
outfile_yvalue1params = fopen("InputParameters/yvalue1params",
"w");

 fprintf(outfile_yvalue1params,"yvalue1_param1,
%d\nyvalue1_param2, %f\nconst_asp_ratio, %f\n", yvalue1_param1,
yvalue1_param2, const_asp_ratio);

 fclose(outfile_yvalue1params);

return;

}  /* End of
write_yvalue1params() */