app/scroll_tool.c

   1 /* Dia -- an diagram creation/manipulation program
   2  * Copyright (C) 1998 Alexander Larsson
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  */
  18 #include <config.h>
  19
  20 #include "scroll_tool.h"
  21 #include "handle_ops.h"
  22 #include "object_ops.h"
  23 #include "connectionpoint_ops.h"
  24 #include "message.h"
  25 #include "cursor.h"
  26
  27 static void scroll_button_press(ScrollTool *tool, GdkEventButton *event,
  28                                  DDisplay *ddisp);
  29 static void scroll_button_release(ScrollTool *tool, GdkEventButton *event,
  30                                   DDisplay *ddisp);
  31 static void scroll_motion(ScrollTool *tool, GdkEventMotion *event,
  32                           DDisplay *ddisp);
  33 static void scroll_double_click(ScrollTool *tool, GdkEventButton *event,
  34                                 DDisplay *ddisp);
  35
  36 Tool *
  37 create_scroll_tool(void)
  38 {
  39   ScrollTool *tool;
  40
  41   tool = g_new(ScrollTool, 1);
  42   tool->tool.type = SCROLL_TOOL;
  43   tool->tool.button_press_func = (ButtonPressFunc) &scroll_button_press;
  44   tool->tool.button_release_func = (ButtonReleaseFunc) &scroll_button_release;
  45   tool->tool.motion_func = (MotionFunc) &scroll_motion;
  46   tool->tool.double_click_func = (DoubleClickFunc) &scroll_double_click;
  47
  48   tool->scrolling = FALSE;
  49   tool->use_hand = TRUE;
  50
  51   ddisplay_set_all_cursor(get_cursor(CURSOR_GRAB));
  52
  53   return (Tool *)tool;
  54 }
  55
  56
  57 void
  58 free_scroll_tool(Tool *tool)
  59 {
  60   g_free(tool);
  61   ddisplay_set_all_cursor(default_cursor);
  62
  63 }
  64
  65 static void
  66 scroll_double_click(ScrollTool *tool, GdkEventButton *event,
  67                     DDisplay *ddisp)
  68 {
  69   /* Do nothing */
  70 }
  71
  72 static void
  73 scroll_button_press(ScrollTool *tool, GdkEventButton *event,
  74                      DDisplay *ddisp)
  75 {
  76   Point clickedpoint;
  77
  78   tool->use_hand = (event->state & GDK_SHIFT_MASK) == 0;
  79   if (tool->use_hand)
  80     ddisplay_set_all_cursor(get_cursor(CURSOR_GRABBING));
  81   else
  82     ddisplay_set_all_cursor(get_cursor(CURSOR_SCROLL));
  83
  84   ddisplay_untransform_coords(ddisp,
  85                               (int)event->x, (int)event->y,
  86                               &clickedpoint.x, &clickedpoint.y);
  87
  88   tool->scrolling = TRUE;
  89   tool->last_pos = clickedpoint;
  90 }
  91
  92
  93
  94
  95 static void
  96 scroll_motion(ScrollTool *tool, GdkEventMotion *event,
  97               DDisplay *ddisp)
  98 {
  99   Point to;
 100   Point delta;
 101
 102   /* set the cursor appropriately, and change use_hand if needed */
 103   if (!tool->scrolling) {
 104     /* try to minimise the number of cursor type changes */
 105     if ((event->state & GDK_SHIFT_MASK) == 0) {
 106       if (!tool->use_hand) {
 107         tool->use_hand = TRUE;
 108         ddisplay_set_all_cursor(get_cursor(CURSOR_GRAB));
 109       }
 110     } else
 111       if (tool->use_hand) {
 112         tool->use_hand = FALSE;
 113         ddisplay_set_all_cursor(get_cursor(CURSOR_SCROLL));
 114       }
 115     return;
 116   }
 117
 118   ddisplay_untransform_coords(ddisp, event->x, event->y, &to.x, &to.y);
 119
 120   if (tool->use_hand) {
 121     delta = tool->last_pos;
 122     point_sub(&delta, &to);
 123
 124     tool->last_pos = to;
 125     point_add(&tool->last_pos, &delta);
 126
 127     /* we use this so you can scroll past the edge of the image */
 128     point_add(&delta, &ddisp->origo);
 129     ddisplay_set_origo(ddisp, delta.x, delta.y);
 130     ddisplay_update_scrollbars(ddisp);
 131     ddisplay_add_update_all(ddisp);
 132   } else {
 133     delta = to;
 134     point_sub(&delta, &tool->last_pos);
 135     point_scale(&delta, 0.5);
 136
 137     ddisplay_scroll(ddisp, &delta);
 138     tool->last_pos = to;
 139   }
 140   ddisplay_flush(ddisp);
 141 }
 142
 143
 144 static void
 145 scroll_button_release(ScrollTool *tool, GdkEventButton *event,
 146                       DDisplay *ddisp)
 147 {
 148   tool->use_hand = (event->state & GDK_SHIFT_MASK) == 0;
 149   if (tool->use_hand) {
 150     ddisplay_set_all_cursor(get_cursor(CURSOR_GRAB));
 151   } else
 152     ddisplay_set_all_cursor(get_cursor(CURSOR_SCROLL));
 153
 154   tool->scrolling = FALSE;
 155 }
 156