src/wx/audio_mapping_view.cc

   1 /*
   2     Copyright (C) 2013-2020 Carl Hetherington <cth@carlh.net>
   3
   4     This file is part of DCP-o-matic.
   5
   6     DCP-o-matic is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     DCP-o-matic is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
  18
  19 */
  20
  21 /** @file  src/wx/audio_mapping_view.cc
  22  *  @brief AudioMappingView class and helpers.
  23  */
  24
  25 #include "audio_mapping_view.h"
  26 #include "wx_util.h"
  27 #include "audio_gain_dialog.h"
  28 #include "lib/audio_mapping.h"
  29 #include "lib/util.h"
  30 #include <dcp/locale_convert.h>
  31 #include <dcp/types.h>
  32 #include <wx/wx.h>
  33 #include <wx/renderer.h>
  34 #include <wx/grid.h>
  35 #include <wx/graphics.h>
  36 #include <boost/foreach.hpp>
  37 #include <iostream>
  38
  39 using std::cout;
  40 using std::list;
  41 using std::string;
  42 using std::min;
  43 using std::max;
  44 using std::vector;
  45 using std::pair;
  46 using std::make_pair;
  47 using boost::shared_ptr;
  48 using boost::optional;
  49 using dcp::locale_convert;
  50
  51 #define INDICATOR_SIZE 20
  52 #define GRID_SPACING 32
  53 #define LEFT_WIDTH (GRID_SPACING * 3)
  54 #define TOP_HEIGHT (GRID_SPACING * 2)
  55
  56 enum {
  57         ID_off = 1,
  58         ID_minus6dB = 2,
  59         ID_0dB = 3,
  60         ID_plus3dB = 4,
  61         ID_edit = 5
  62 };
  63
  64 AudioMappingView::AudioMappingView (wxWindow* parent, wxString left_label, wxString from, wxString top_label, wxString to)
  65         : wxPanel (parent, wxID_ANY)
  66         , _menu_input (0)
  67         , _menu_output (1)
  68         , _left_label (left_label)
  69         , _from (from)
  70         , _top_label (top_label)
  71         , _to (to)
  72 {
  73         _menu = new wxMenu;
  74         _menu->Append (ID_off, _("Off"));
  75         _menu->Append (ID_minus6dB, _("-6dB"));
  76         _menu->Append (ID_0dB, _("0dB (unchanged)"));
  77         _menu->Append (ID_plus3dB, _("+3dB"));
  78         _menu->Append (ID_edit, _("Edit..."));
  79
  80         _body = new wxPanel (this, wxID_ANY);
  81         _vertical_scroll = new wxScrollBar (this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxSB_VERTICAL);
  82         _horizontal_scroll = new wxScrollBar (this, wxID_ANY);
  83
  84 #ifndef __WXOSX__
  85         SetDoubleBuffered (true);
  86 #endif
  87
  88         Bind (wxEVT_SIZE, boost::bind(&AudioMappingView::size, this, _1));
  89         Bind (wxEVT_MENU, boost::bind(&AudioMappingView::set_gain_from_menu, this, 0), ID_off);
  90         Bind (wxEVT_MENU, boost::bind(&AudioMappingView::set_gain_from_menu, this, db_to_linear(-6)), ID_minus6dB);
  91         Bind (wxEVT_MENU, boost::bind(&AudioMappingView::set_gain_from_menu, this, 1), ID_0dB);
  92         Bind (wxEVT_MENU, boost::bind(&AudioMappingView::set_gain_from_menu, this, db_to_linear(3)), ID_plus3dB);
  93         Bind (wxEVT_MENU, boost::bind(&AudioMappingView::edit, this), ID_edit);
  94         Bind (wxEVT_MOUSEWHEEL, boost::bind(&AudioMappingView::mouse_wheel, this, _1));
  95         _body->Bind (wxEVT_PAINT, boost::bind(&AudioMappingView::paint, this));
  96         _body->Bind (wxEVT_LEFT_DOWN, boost::bind(&AudioMappingView::left_down, this, _1));
  97         _body->Bind (wxEVT_RIGHT_DOWN, boost::bind(&AudioMappingView::right_down, this, _1));
  98         _body->Bind (wxEVT_MOTION, boost::bind(&AudioMappingView::motion, this, _1));
  99         _vertical_scroll->Bind (wxEVT_SCROLL_TOP, boost::bind(&AudioMappingView::scroll, this));
 100         _vertical_scroll->Bind (wxEVT_SCROLL_BOTTOM, boost::bind(&AudioMappingView::scroll, this));
 101         _vertical_scroll->Bind (wxEVT_SCROLL_LINEUP, boost::bind(&AudioMappingView::scroll, this));
 102         _vertical_scroll->Bind (wxEVT_SCROLL_LINEDOWN, boost::bind(&AudioMappingView::scroll, this));
 103         _vertical_scroll->Bind (wxEVT_SCROLL_PAGEUP, boost::bind(&AudioMappingView::scroll, this));
 104         _vertical_scroll->Bind (wxEVT_SCROLL_PAGEDOWN, boost::bind(&AudioMappingView::scroll, this));
 105         _vertical_scroll->Bind (wxEVT_SCROLL_THUMBTRACK, boost::bind(&AudioMappingView::scroll, this));
 106         _vertical_scroll->Bind (wxEVT_SCROLL_THUMBRELEASE, boost::bind(&AudioMappingView::scroll, this));
 107         _horizontal_scroll->Bind (wxEVT_SCROLL_TOP, boost::bind(&AudioMappingView::scroll, this));
 108         _horizontal_scroll->Bind (wxEVT_SCROLL_BOTTOM, boost::bind(&AudioMappingView::scroll, this));
 109         _horizontal_scroll->Bind (wxEVT_SCROLL_LINEUP, boost::bind(&AudioMappingView::scroll, this));
 110         _horizontal_scroll->Bind (wxEVT_SCROLL_LINEDOWN, boost::bind(&AudioMappingView::scroll, this));
 111         _horizontal_scroll->Bind (wxEVT_SCROLL_PAGEUP, boost::bind(&AudioMappingView::scroll, this));
 112         _horizontal_scroll->Bind (wxEVT_SCROLL_PAGEDOWN, boost::bind(&AudioMappingView::scroll, this));
 113         _horizontal_scroll->Bind (wxEVT_SCROLL_THUMBTRACK, boost::bind(&AudioMappingView::scroll, this));
 114         _horizontal_scroll->Bind (wxEVT_SCROLL_THUMBRELEASE, boost::bind(&AudioMappingView::scroll, this));
 115 }
 116
 117 void
 118 AudioMappingView::size (wxSizeEvent& ev)
 119 {
 120         setup ();
 121         ev.Skip ();
 122 }
 123
 124 void
 125 AudioMappingView::setup ()
 126 {
 127         wxSize const s = GetSize();
 128         int const w = _vertical_scroll->GetSize().GetWidth();
 129         int const h = _horizontal_scroll->GetSize().GetHeight();
 130
 131         _vertical_scroll->SetPosition (wxPoint(s.GetWidth() - w, 0));
 132         _vertical_scroll->SetSize (wxSize(w, max(0, s.GetHeight() - h)));
 133
 134         _body->SetSize (wxSize(max(0, s.GetWidth() - w), max(0, s.GetHeight() - h)));
 135
 136         _horizontal_scroll->SetPosition (wxPoint(0, s.GetHeight() - h));
 137         _horizontal_scroll->SetSize (wxSize(max(0, s.GetWidth() - w), h));
 138
 139         _vertical_scroll->SetScrollbar (
 140                 _vertical_scroll->GetThumbPosition(),
 141                 s.GetHeight() - h - 8,
 142                 GRID_SPACING * (2 + _input_channels.size()),
 143                 GRID_SPACING,
 144                 true
 145                 );
 146
 147         _horizontal_scroll->SetScrollbar (
 148                 _horizontal_scroll->GetThumbPosition(),
 149                 s.GetWidth() - w - 8,
 150                 GRID_SPACING * (3 + _output_channels.size()),
 151                 GRID_SPACING,
 152                 true);
 153 }
 154
 155 void
 156 AudioMappingView::scroll ()
 157 {
 158         Refresh ();
 159 }
 160
 161 void
 162 AudioMappingView::paint_static (wxDC& dc)
 163 {
 164         dc.SetFont (wxSWISS_FONT->Bold());
 165         wxCoord label_width;
 166         wxCoord label_height;
 167
 168         dc.GetTextExtent (_top_label, &label_width, &label_height);
 169         dc.DrawText (_top_label, LEFT_WIDTH + (_output_channels.size() * GRID_SPACING - label_width) / 2, (GRID_SPACING - label_height) / 2);
 170
 171         dc.GetTextExtent (_left_label, &label_width, &label_height);
 172         dc.DrawRotatedText (
 173                 _left_label,
 174                 (GRID_SPACING - label_height) / 2,
 175                 TOP_HEIGHT + (_input_channels.size() * GRID_SPACING + label_width) / 2,
 176                 90
 177                 );
 178
 179         dc.SetFont (*wxSWISS_FONT);
 180 }
 181
 182 void
 183 AudioMappingView::paint_column_labels (wxDC& dc)
 184 {
 185         wxCoord label_width;
 186         wxCoord label_height;
 187         int N = 0;
 188         BOOST_FOREACH (string i, _output_channels) {
 189                 dc.GetTextExtent (std_to_wx(i), &label_width, &label_height);
 190                 dc.DrawText (std_to_wx(i), LEFT_WIDTH + GRID_SPACING * N + (GRID_SPACING - label_width) / 2, GRID_SPACING + (GRID_SPACING - label_height) / 2);
 191                 ++N;
 192         }
 193
 194         dc.DrawLine(wxPoint(LEFT_WIDTH, GRID_SPACING), wxPoint(LEFT_WIDTH + _output_channels.size() * GRID_SPACING, GRID_SPACING));
 195         dc.DrawLine(wxPoint(LEFT_WIDTH, GRID_SPACING * 2), wxPoint(LEFT_WIDTH + _output_channels.size() * GRID_SPACING, GRID_SPACING * 2));
 196 }
 197
 198 void
 199 AudioMappingView::paint_column_lines (wxDC& dc)
 200 {
 201         for (size_t i = 0; i < _output_channels.size(); ++i) {
 202                 dc.DrawLine (
 203                         wxPoint(LEFT_WIDTH + GRID_SPACING * i, GRID_SPACING),
 204                         wxPoint(LEFT_WIDTH + GRID_SPACING * i, TOP_HEIGHT + _input_channels.size() * GRID_SPACING)
 205                         );
 206         }
 207
 208         dc.DrawLine (
 209                 wxPoint(LEFT_WIDTH + GRID_SPACING * _output_channels.size(), GRID_SPACING),
 210                 wxPoint(LEFT_WIDTH + GRID_SPACING * _output_channels.size(), TOP_HEIGHT + _input_channels.size() * GRID_SPACING)
 211                 );
 212 }
 213
 214 void
 215 AudioMappingView::paint_row_labels (wxDC& dc)
 216 {
 217         wxCoord label_width;
 218         wxCoord label_height;
 219
 220         /* Row channel labels */
 221
 222         int N = 0;
 223         BOOST_FOREACH (string i, _input_channels) {
 224                 dc.GetTextExtent (std_to_wx(i), &label_width, &label_height);
 225                 dc.DrawText (std_to_wx(i), GRID_SPACING * 2 + (GRID_SPACING - label_width) / 2, TOP_HEIGHT + GRID_SPACING * N + (GRID_SPACING - label_height) / 2);
 226                 ++N;
 227         }
 228
 229         /* Vertical lines on the left */
 230
 231         for (int i = 1; i < 3; ++i) {
 232                 dc.DrawLine (
 233                         wxPoint(GRID_SPACING * i, TOP_HEIGHT),
 234                         wxPoint(GRID_SPACING * i, TOP_HEIGHT + _input_channels.size() * GRID_SPACING)
 235                         );
 236         }
 237
 238         /* Group labels and lines */
 239
 240         int y = TOP_HEIGHT;
 241         BOOST_FOREACH (Group i, _input_groups) {
 242                 int const height = (i.to - i.from + 1) * GRID_SPACING;
 243                 dc.GetTextExtent (std_to_wx(i.name), &label_width, &label_height);
 244                 if (label_width > height) {
 245                         label_width = height - 8;
 246                 }
 247
 248                 {
 249                         int yp = y;
 250                         if ((yp - 2 * GRID_SPACING) < dc.GetLogicalOrigin().y) {
 251                                 yp += dc.GetLogicalOrigin().y;
 252                         }
 253
 254                         dc.DrawRotatedText (
 255                                 std_to_wx(i.name),
 256                                 GRID_SPACING + (GRID_SPACING - label_height) / 2,
 257                                 y + (height + label_width) / 2,
 258                                 90
 259                                 );
 260                 }
 261
 262                 dc.DrawLine (wxPoint(GRID_SPACING, y), wxPoint(GRID_SPACING * 2, y));
 263                 y += height;
 264         }
 265
 266         dc.DrawLine (wxPoint(GRID_SPACING, y), wxPoint(GRID_SPACING * 2, y));
 267         }
 268
 269 void
 270 AudioMappingView::paint_row_lines (wxDC& dc)
 271 {
 272         for (size_t i = 0; i < _input_channels.size(); ++i) {
 273                 dc.DrawLine (
 274                         wxPoint(GRID_SPACING * 2, TOP_HEIGHT + GRID_SPACING * i),
 275                         wxPoint(LEFT_WIDTH + _output_channels.size() * GRID_SPACING, TOP_HEIGHT + GRID_SPACING * i)
 276                         );
 277         }
 278         dc.DrawLine (
 279                 wxPoint(GRID_SPACING * 2, TOP_HEIGHT + GRID_SPACING * _input_channels.size()),
 280                 wxPoint(LEFT_WIDTH + _output_channels.size() * GRID_SPACING, TOP_HEIGHT + GRID_SPACING * _input_channels.size())
 281                 );
 282 }
 283
 284 void
 285 AudioMappingView::paint_indicators (wxDC& dc)
 286 {
 287         /* _{input,output}_channels and _map may not always be in sync, be careful here */
 288         size_t const output = min(_output_channels.size(), size_t(_map.output_channels()));
 289         size_t const input = min(_input_channels.size(), size_t(_map.input_channels()));
 290
 291         for (size_t x = 0; x < output; ++x) {
 292                 for (size_t y = 0; y < input; ++y) {
 293                         dc.SetBrush (*wxWHITE_BRUSH);
 294                         dc.DrawRectangle (
 295                                 wxRect(
 296                                         LEFT_WIDTH + x * GRID_SPACING + (GRID_SPACING - INDICATOR_SIZE) / 2,
 297                                         TOP_HEIGHT + y * GRID_SPACING + (GRID_SPACING - INDICATOR_SIZE) / 2,
 298                                         INDICATOR_SIZE, INDICATOR_SIZE
 299                                         )
 300                                 );
 301
 302                         float const value_dB = linear_to_db(_map.get(y, x));
 303                         wxColour const colour = value_dB <= 0 ? wxColour(0, 255, 0) : wxColour(255, 150, 0);
 304                         int const range = 18;
 305                         int height = 0;
 306                         if (value_dB > -range) {
 307                                 height = min(INDICATOR_SIZE, static_cast<int>(INDICATOR_SIZE * (1 + value_dB / range)));
 308                         }
 309
 310                         dc.SetBrush (*wxTheBrushList->FindOrCreateBrush(colour, wxBRUSHSTYLE_SOLID));
 311                         dc.DrawRectangle (
 312                                 wxRect(
 313                                         LEFT_WIDTH + x * GRID_SPACING + (GRID_SPACING - INDICATOR_SIZE) / 2,
 314                                         TOP_HEIGHT + y * GRID_SPACING + (GRID_SPACING - INDICATOR_SIZE) / 2 + INDICATOR_SIZE - height,
 315                                         INDICATOR_SIZE, height
 316                                         )
 317                                 );
 318                 }
 319         }
 320 }
 321
 322 static
 323 void clip (wxDC& dc, int x, int y, int w, int h)
 324 {
 325         dc.SetClippingRegion (x, y, w, h);
 326 }
 327
 328 static
 329 void translate (wxDC& dc, int x, int y)
 330 {
 331         dc.SetLogicalOrigin (x, y);
 332 }
 333
 334 static
 335 void restore (wxDC& dc)
 336 {
 337         dc.SetLogicalOrigin (0, 0);
 338         dc.DestroyClippingRegion ();
 339 }
 340
 341 void
 342 AudioMappingView::paint ()
 343 {
 344         wxPaintDC dc (_body);
 345
 346         int const hs = _horizontal_scroll->GetThumbPosition ();
 347         int const vs = _vertical_scroll->GetThumbPosition ();
 348
 349         paint_static (dc);
 350
 351         clip (
 352                 dc,
 353                 LEFT_WIDTH,
 354                 0,
 355                 GRID_SPACING * _output_channels.size(),
 356                 GRID_SPACING * (2 + _input_channels.size())
 357              );
 358         translate (dc, hs, 0);
 359         paint_column_labels (dc);
 360         restore (dc);
 361
 362         clip (
 363                 dc,
 364                 0,
 365                 TOP_HEIGHT,
 366                 GRID_SPACING * 3,
 367                 min(int(GRID_SPACING * _input_channels.size()), GetSize().GetHeight() - TOP_HEIGHT)
 368              );
 369         translate (dc, 0, vs);
 370         paint_row_labels (dc);
 371         restore (dc);
 372
 373         clip (
 374                 dc,
 375                 GRID_SPACING * 2,
 376                 TOP_HEIGHT,
 377                 GRID_SPACING * (1 + _output_channels.size()),
 378                 min(int(GRID_SPACING * (2 + _input_channels.size())), GetSize().GetHeight() - TOP_HEIGHT)
 379              );
 380         translate (dc, hs, vs);
 381         paint_row_lines (dc);
 382         restore (dc);
 383
 384         clip (
 385                 dc,
 386                 LEFT_WIDTH,
 387                 GRID_SPACING,
 388                 GRID_SPACING * (1 + _output_channels.size()),
 389                 min(int(GRID_SPACING * (1 + _input_channels.size())), GetSize().GetHeight() - GRID_SPACING)
 390              );
 391         translate (dc, hs, vs);
 392         paint_column_lines (dc);
 393         restore (dc);
 394
 395         clip (
 396                 dc,
 397                 LEFT_WIDTH,
 398                 TOP_HEIGHT,
 399                 GRID_SPACING * _output_channels.size(),
 400                 min(int(GRID_SPACING * _input_channels.size()), GetSize().GetHeight() - TOP_HEIGHT)
 401              );
 402         translate (dc, hs, vs);
 403         paint_indicators (dc);
 404         restore (dc);
 405 }
 406
 407 optional<pair<int, int> >
 408 AudioMappingView::mouse_event_to_channels (wxMouseEvent& ev) const
 409 {
 410         int const x = ev.GetX() + _horizontal_scroll->GetThumbPosition();
 411         int const y = ev.GetY() + _vertical_scroll->GetThumbPosition();
 412
 413         if (x <= LEFT_WIDTH || y < TOP_HEIGHT) {
 414                 return optional<pair<int, int> >();
 415         }
 416
 417         int const input = (y - TOP_HEIGHT) / GRID_SPACING;
 418         int const output = (x - LEFT_WIDTH) / GRID_SPACING;
 419
 420         if (input >= int(_input_channels.size()) || output >= int(_output_channels.size())) {
 421                 return optional<pair<int, int> >();
 422         }
 423
 424         return make_pair (input, output);
 425 }
 426
 427 optional<string>
 428 AudioMappingView::mouse_event_to_input_group_name (wxMouseEvent& ev) const
 429 {
 430         int const x = ev.GetX() + _horizontal_scroll->GetThumbPosition();
 431         if (x < GRID_SPACING || x > (2 * GRID_SPACING)) {
 432                 return optional<string>();
 433         }
 434
 435         int y = (ev.GetY() + _vertical_scroll->GetThumbPosition() - (GRID_SPACING * 2)) / GRID_SPACING;
 436         BOOST_FOREACH (Group i, _input_groups) {
 437                 if (i.from <= y && y <= i.to) {
 438                         return i.name;
 439                 }
 440         }
 441
 442         return optional<string>();
 443 }
 444
 445 void
 446 AudioMappingView::left_down (wxMouseEvent& ev)
 447 {
 448         optional<pair<int, int> > channels = mouse_event_to_channels (ev);
 449         if (!channels) {
 450                 return;
 451         }
 452
 453         if (_map.get(channels->first, channels->second) > 0) {
 454                 _map.set (channels->first, channels->second, 0);
 455         } else {
 456                 _map.set (channels->first, channels->second, 1);
 457         }
 458
 459         map_values_changed ();
 460 }
 461
 462 void
 463 AudioMappingView::right_down (wxMouseEvent& ev)
 464 {
 465         optional<pair<int, int> > channels = mouse_event_to_channels (ev);
 466         if (!channels) {
 467                 return;
 468         }
 469
 470         _menu_input = channels->first;
 471         _menu_output = channels->second;
 472         PopupMenu (_menu, ev.GetPosition());
 473 }
 474
 475 void
 476 AudioMappingView::mouse_wheel (wxMouseEvent& ev)
 477 {
 478         if (ev.ShiftDown()) {
 479                 _horizontal_scroll->SetThumbPosition (
 480                         _horizontal_scroll->GetThumbPosition() + (ev.GetWheelRotation() > 0 ? -GRID_SPACING : GRID_SPACING)
 481                         );
 482
 483         } else {
 484                 _vertical_scroll->SetThumbPosition (
 485                         _vertical_scroll->GetThumbPosition() + (ev.GetWheelRotation() > 0 ? -GRID_SPACING : GRID_SPACING)
 486                         );
 487         }
 488         Refresh ();
 489 }
 490
 491 /** Called when any gain value has changed */
 492 void
 493 AudioMappingView::map_values_changed ()
 494 {
 495         Changed (_map);
 496         _last_tooltip_channels = optional<pair<int, int> >();
 497         Refresh ();
 498 }
 499
 500 void
 501 AudioMappingView::set_gain_from_menu (double linear)
 502 {
 503         _map.set (_menu_input, _menu_output, linear);
 504         map_values_changed ();
 505 }
 506
 507 void
 508 AudioMappingView::edit ()
 509 {
 510         AudioGainDialog* dialog = new AudioGainDialog (this, _menu_input, _menu_output, _map.get(_menu_input, _menu_output));
 511         if (dialog->ShowModal() == wxID_OK) {
 512                 _map.set (_menu_input, _menu_output, dialog->value ());
 513                 map_values_changed ();
 514         }
 515
 516         dialog->Destroy ();
 517 }
 518
 519 void
 520 AudioMappingView::set (AudioMapping map)
 521 {
 522         _map = map;
 523         Refresh ();
 524 }
 525
 526 void
 527 AudioMappingView::set_input_channels (vector<string> const & names)
 528 {
 529         _input_channels = names;
 530         setup ();
 531         Refresh ();
 532 }
 533
 534 void
 535 AudioMappingView::set_output_channels (vector<string> const & names)
 536 {
 537         _output_channels = names;
 538         setup ();
 539         Refresh ();
 540 }
 541
 542 wxString
 543 AudioMappingView::safe_input_channel_name (int n) const
 544 {
 545         if (n >= int(_input_channels.size())) {
 546                 return wxString::Format ("%d", n + 1);
 547         }
 548
 549         optional<wxString> group;
 550         BOOST_FOREACH (Group i, _input_groups) {
 551                 if (i.from <= n && n <= i.to) {
 552                         group = std_to_wx (i.name);
 553                 }
 554         }
 555
 556         if (group && !group->IsEmpty()) {
 557                 return wxString::Format ("%s/%s", group->data(), std_to_wx(_input_channels[n]).data());
 558         }
 559
 560         return std_to_wx(_input_channels[n]);
 561 }
 562
 563 wxString
 564 AudioMappingView::safe_output_channel_name (int n) const
 565 {
 566         if (n >= int(_output_channels.size())) {
 567                 return wxString::Format ("%d", n + 1);
 568         }
 569
 570         return std_to_wx(_output_channels[n]);
 571 }
 572
 573 void
 574 AudioMappingView::motion (wxMouseEvent& ev)
 575 {
 576         optional<pair<int, int> > channels = mouse_event_to_channels (ev);
 577         if (channels) {
 578                 if (channels != _last_tooltip_channels) {
 579                         wxString s;
 580                         float const gain = _map.get(channels->first, channels->second);
 581                         if (gain == 0) {
 582                                 s = wxString::Format (
 583                                         _("No audio will be passed from %s channel '%s' to %s channel '%s'."),
 584                                         _from,
 585                                         safe_input_channel_name(channels->first),
 586                                         _to,
 587                                         safe_output_channel_name(channels->second)
 588                                         );
 589                         } else if (gain == 1) {
 590                                 s = wxString::Format (
 591                                         _("Audio will be passed from %s channel %s to %s channel %s unaltered."),
 592                                         _from,
 593                                         safe_input_channel_name(channels->first),
 594                                         _to,
 595                                         safe_output_channel_name(channels->second)
 596                                         );
 597                         } else {
 598                                 float const dB = linear_to_db(gain);
 599                                 s = wxString::Format (
 600                                         _("Audio will be passed from %s channel %s to %s channel %s with gain %.1fdB."),
 601                                         _from,
 602                                         safe_input_channel_name(channels->first),
 603                                         _to,
 604                                         safe_output_channel_name(channels->second),
 605                                         dB
 606                                         );
 607                         }
 608
 609                         SetToolTip (s + " " + _("Right click to change gain."));
 610                 }
 611         } else {
 612                 optional<string> group = mouse_event_to_input_group_name (ev);
 613                 if (group) {
 614                         SetToolTip (std_to_wx(*group));
 615                 } else {
 616                         SetToolTip ("");
 617                 }
 618         }
 619
 620         _last_tooltip_channels = channels;
 621         ev.Skip ();
 622 }
 623
 624 void
 625 AudioMappingView::set_input_groups (vector<Group> const & groups)
 626 {
 627         _input_groups = groups;
 628 }