src/object_gui.cpp

   1 /* $Id: object_gui.cpp 26241 2014-01-12 18:00:39Z frosch $ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   6  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   7  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   8  */
   9
  10 /** @file object_gui.cpp The GUI for objects. */
  11
  12 #include "stdafx.h"
  13 #include "command_func.h"
  14 #include "newgrf.h"
  15 #include "newgrf_object.h"
  16 #include "newgrf_text.h"
  17 #include "strings_func.h"
  18 #include "viewport_func.h"
  19 #include "tilehighlight_func.h"
  20 #include "window_gui.h"
  21 #include "window_func.h"
  22 #include "zoom_func.h"
  23
  24 #include "widgets/object_widget.h"
  25
  26 #include "table/strings.h"
  27
  28 #include "safeguards.h"
  29
  30 static ObjectClassID _selected_object_class; ///< the currently visible object class
  31 static int _selected_object_index;           ///< the index of the selected object in the current class or -1
  32 static uint8 _selected_object_view;          ///< the view of the selected object
  33
  34 /** The window used for building objects. */
  35 class BuildObjectWindow : public Window {
  36         static const int OBJECT_MARGIN = 4; ///< The margin (in pixels) around an object.
  37         int line_height;                    ///< The height of a single line.
  38         int info_height;                    ///< The height of the info box.
  39         Scrollbar *vscroll;                 ///< The scrollbar.
  40
  41         /** Scroll #WID_BO_CLASS_LIST so that the selected object class is visible. */
  42         void EnsureSelectedObjectClassIsVisible()
  43         {
  44                 uint pos = 0;
  45                 for (int i = 0; i < _selected_object_class; i++) {
  46                         if (ObjectClass::Get((ObjectClassID) i)->GetUISpecCount() == 0) continue;
  47                         pos++;
  48                 }
  49                 this->vscroll->ScrollTowards(pos);
  50         }
  51
  52         /**
  53          * Tests whether the previously selected object can be selected.
  54          * @return \c true if the selected object is available, \c false otherwise.
  55          */
  56         bool CanRestoreSelectedObject()
  57         {
  58                 if (_selected_object_index == -1) return false;
  59
  60                 ObjectClass *sel_objclass = ObjectClass::Get(_selected_object_class);
  61                 if ((int)sel_objclass->GetSpecCount() <= _selected_object_index) return false;
  62
  63                 return sel_objclass->GetSpec(_selected_object_index)->IsAvailable();
  64         }
  65
  66         /**
  67          * Calculate the number of columns of the #WID_BO_SELECT_MATRIX widget.
  68          * @return Number of columns in the matrix.
  69          */
  70         uint GetMatrixColumnCount()
  71         {
  72                 const NWidgetBase *matrix = this->GetWidget<NWidgetBase>(WID_BO_SELECT_MATRIX);
  73                 return 1 + (matrix->current_x - matrix->smallest_x) / matrix->resize_x;
  74         }
  75
  76 public:
  77         BuildObjectWindow(WindowDesc *desc, WindowNumber number) : Window(desc), info_height(1)
  78         {
  79                 this->CreateNestedTree();
  80                 this->vscroll = this->GetScrollbar(WID_BO_SCROLLBAR);
  81                 this->FinishInitNested(number);
  82
  83                 ResetObjectToPlace();
  84
  85                 this->vscroll->SetPosition(0);
  86                 this->vscroll->SetCount(ObjectClass::GetUIClassCount());
  87
  88                 NWidgetMatrix *matrix = this->GetWidget<NWidgetMatrix>(WID_BO_SELECT_MATRIX);
  89                 matrix->SetScrollbar(this->GetScrollbar(WID_BO_SELECT_SCROLL));
  90
  91                 this->SelectOtherClass(_selected_object_class);
  92                 if (this->CanRestoreSelectedObject()) {
  93                         this->SelectOtherObject(_selected_object_index);
  94                 } else {
  95                         this->SelectFirstAvailableObject(true);
  96                 }
  97                 assert(ObjectClass::Get(_selected_object_class)->GetUISpecCount() > 0); // object GUI should be disables elsewise
  98                 this->EnsureSelectedObjectClassIsVisible();
  99                 this->GetWidget<NWidgetMatrix>(WID_BO_OBJECT_MATRIX)->SetCount(4);
 100         }
 101
 102         virtual void SetStringParameters(int widget) const
 103         {
 104                 switch (widget) {
 105                         case WID_BO_OBJECT_NAME: {
 106                                 const ObjectSpec *spec = ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index);
 107                                 SetDParam(0, spec != nullptr ? spec->name : STR_EMPTY);
 108                                 break;
 109                         }
 110
 111                         case WID_BO_OBJECT_SIZE: {
 112                                 const ObjectSpec *spec = ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index);
 113                                 int size = spec == nullptr ? 0 : spec->size;
 114                                 SetDParam(0, GB(size, HasBit(_selected_object_view, 0) ? 4 : 0, 4));
 115                                 SetDParam(1, GB(size, HasBit(_selected_object_view, 0) ? 0 : 4, 4));
 116                                 break;
 117                         }
 118
 119                         default: break;
 120                 }
 121         }
 122
 123         virtual void UpdateWidgetSize(int widget, Dimension *size, const Dimension &padding, Dimension *fill, Dimension *resize)
 124         {
 125                 switch (widget) {
 126                         case WID_BO_CLASS_LIST: {
 127                                 for (uint i = 0; i < ObjectClass::GetClassCount(); i++) {
 128                                         ObjectClass *objclass = ObjectClass::Get((ObjectClassID)i);
 129                                         if (objclass->GetUISpecCount() == 0) continue;
 130                                         size->width = max(size->width, GetStringBoundingBox(objclass->name).width);
 131                                 }
 132                                 size->width += padding.width;
 133                                 this->line_height = FONT_HEIGHT_NORMAL + WD_MATRIX_TOP + WD_MATRIX_BOTTOM;
 134                                 resize->height = this->line_height;
 135                                 size->height = 5 * this->line_height;
 136
 137                                 size->width = min(size->width, ScaleGUITrad(400));
 138                                 break;
 139                         }
 140
 141                         case WID_BO_OBJECT_NAME:
 142                         case WID_BO_OBJECT_SIZE:
 143                                 /* We do not want the window to resize when selecting objects; better clip texts */
 144                                 size->width = 0;
 145                                 break;
 146
 147                         case WID_BO_OBJECT_MATRIX: {
 148                                 /* Get the right amount of buttons based on the current spec. */
 149                                 const ObjectSpec *spec = ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index);
 150                                 if (spec != nullptr) {
 151                                         if (spec->views >= 2) size->width  += resize->width;
 152                                         if (spec->views >= 4) size->height += resize->height;
 153                                 }
 154                                 resize->width = 0;
 155                                 resize->height = 0;
 156                                 break;
 157                         }
 158
 159                         case WID_BO_OBJECT_SPRITE: {
 160                                 bool two_wide = false;  // Whether there will be two widgets next to each other in the matrix or not.
 161                                 int height[2] = {0, 0}; // The height for the different views; in this case views 1/2 and 4.
 162
 163                                 /* Get the height and view information. */
 164                                 for (int i = 0; i < NUM_OBJECTS; i++) {
 165                                         const ObjectSpec *spec = ObjectSpec::Get(i);
 166                                         if (!spec->IsEverAvailable()) continue;
 167                                         two_wide |= spec->views >= 2;
 168                                         height[spec->views / 4] = max<int>(ObjectSpec::Get(i)->height, height[spec->views / 4]);
 169                                 }
 170
 171                                 /* Determine the pixel heights. */
 172                                 for (size_t i = 0; i < lengthof(height); i++) {
 173                                         height[i] *= ScaleGUITrad(TILE_HEIGHT);
 174                                         height[i] += ScaleGUITrad(TILE_PIXELS) + 2 * OBJECT_MARGIN;
 175                                 }
 176
 177                                 /* Now determine the size of the minimum widgets. When there are two columns, then
 178                                  * we want these columns to be slightly less wide. When there are two rows, then
 179                                  * determine the size of the widgets based on the maximum size for a single row
 180                                  * of widgets, or just the twice the widget height of the two row ones. */
 181                                 size->height = max(height[0], height[1] * 2 + 2);
 182                                 if (two_wide) {
 183                                         size->width  = (3 * ScaleGUITrad(TILE_PIXELS) + 2 * OBJECT_MARGIN) * 2 + 2;
 184                                 } else {
 185                                         size->width  = 4 * ScaleGUITrad(TILE_PIXELS) + 2 * OBJECT_MARGIN;
 186                                 }
 187
 188                                 /* Get the right size for the single widget based on the current spec. */
 189                                 const ObjectSpec *spec = ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index);
 190                                 if (spec != nullptr) {
 191                                         if (spec->views >= 2) size->width  = size->width  / 2 - 1;
 192                                         if (spec->views >= 4) size->height = size->height / 2 - 1;
 193                                 }
 194                                 break;
 195                         }
 196
 197                         case WID_BO_INFO:
 198                                 size->height = this->info_height;
 199                                 break;
 200
 201                         case WID_BO_SELECT_MATRIX:
 202                                 fill->height = 1;
 203                                 resize->height = 1;
 204                                 break;
 205
 206                         case WID_BO_SELECT_IMAGE:
 207                                 size->width  = ScaleGUITrad(64) + 2;
 208                                 size->height = ScaleGUITrad(58) + 2;
 209                                 break;
 210
 211                         default: break;
 212                 }
 213         }
 214
 215         virtual void DrawWidget(const Rect &r, int widget) const
 216         {
 217                 switch (GB(widget, 0, 16)) {
 218                         case WID_BO_CLASS_LIST: {
 219                                 int y = r.top;
 220                                 uint pos = 0;
 221                                 for (uint i = 0; i < ObjectClass::GetClassCount(); i++) {
 222                                         ObjectClass *objclass = ObjectClass::Get((ObjectClassID)i);
 223                                         if (objclass->GetUISpecCount() == 0) continue;
 224                                         if (!this->vscroll->IsVisible(pos++)) continue;
 225                                         DrawString(r.left + WD_MATRIX_LEFT, r.right - WD_MATRIX_RIGHT, y + WD_MATRIX_TOP, objclass->name,
 226                                                         ((int)i == _selected_object_class) ? TC_WHITE : TC_BLACK);
 227                                         y += this->line_height;
 228                                 }
 229                                 break;
 230                         }
 231
 232                         case WID_BO_OBJECT_SPRITE: {
 233                                 const ObjectSpec *spec = ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index);
 234                                 if (spec == nullptr) break;
 235
 236                                 /* Height of the selection matrix.
 237                                  * Depending on the number of views, the matrix has a 1x1, 1x2, 2x1 or 2x2 layout. To make the previews
 238                                  * look nice in all layouts, we use the 4x4 layout (smallest previews) as starting point. For the bigger
 239                                  * previews in the layouts with less views we add space homogeneously on all sides, so the 4x4 preview-rectangle
 240                                  * is centered in the 2x1, 1x2 resp. 1x1 buttons. */
 241                                 uint matrix_height = this->GetWidget<NWidgetMatrix>(WID_BO_OBJECT_MATRIX)->current_y;
 242
 243                                 DrawPixelInfo tmp_dpi;
 244                                 /* Set up a clipping area for the preview. */
 245                                 if (FillDrawPixelInfo(&tmp_dpi, r.left, r.top, r.right - r.left + 1, r.bottom - r.top + 1)) {
 246                                         DrawPixelInfo *old_dpi = _cur_dpi;
 247                                         _cur_dpi = &tmp_dpi;
 248                                         if (spec->grf_prop.grffile == nullptr) {
 249                                                 extern const DrawTileSprites _objects[];
 250                                                 const DrawTileSprites *dts = &_objects[spec->grf_prop.local_id];
 251                                                 DrawOrigTileSeqInGUI((r.right - r.left) / 2 - 1, (r.bottom - r.top + matrix_height / 2) / 2 - OBJECT_MARGIN - ScaleGUITrad(TILE_PIXELS), dts, PAL_NONE);
 252                                         } else {
 253                                                 DrawNewObjectTileInGUI((r.right - r.left) / 2 - 1, (r.bottom - r.top + matrix_height / 2) / 2 - OBJECT_MARGIN - ScaleGUITrad(TILE_PIXELS), spec, GB(widget, 16, 16));
 254                                         }
 255                                         _cur_dpi = old_dpi;
 256                                 }
 257                                 break;
 258                         }
 259
 260                         case WID_BO_SELECT_IMAGE: {
 261                                 ObjectClass *objclass = ObjectClass::Get(_selected_object_class);
 262                                 int obj_index = objclass->GetIndexFromUI(GB(widget, 16, 16));
 263                                 if (obj_index < 0) break;
 264                                 const ObjectSpec *spec = objclass->GetSpec(obj_index);
 265                                 if (spec == nullptr) break;
 266
 267                                 if (!spec->IsAvailable()) {
 268                                         GfxFillRect(r.left + 1, r.top + 1, r.right - 1, r.bottom - 1, PC_BLACK, FILLRECT_CHECKER);
 269                                 }
 270                                 DrawPixelInfo tmp_dpi;
 271                                 /* Set up a clipping area for the preview. */
 272                                 if (FillDrawPixelInfo(&tmp_dpi, r.left + 1, r.top, (r.right - 1) - (r.left + 1) + 1, r.bottom - r.top + 1)) {
 273                                         DrawPixelInfo *old_dpi = _cur_dpi;
 274                                         _cur_dpi = &tmp_dpi;
 275                                         if (spec->grf_prop.grffile == nullptr) {
 276                                                 extern const DrawTileSprites _objects[];
 277                                                 const DrawTileSprites *dts = &_objects[spec->grf_prop.local_id];
 278                                                 DrawOrigTileSeqInGUI((r.right - r.left) / 2 - 1, r.bottom - r.top - OBJECT_MARGIN - ScaleGUITrad(TILE_PIXELS), dts, PAL_NONE);
 279                                         } else {
 280                                                 DrawNewObjectTileInGUI((r.right - r.left) / 2 - 1, r.bottom - r.top - OBJECT_MARGIN - ScaleGUITrad(TILE_PIXELS), spec,
 281                                                                 min(_selected_object_view, spec->views - 1));
 282                                         }
 283                                         _cur_dpi = old_dpi;
 284                                 }
 285                                 break;
 286                         }
 287
 288                         case WID_BO_INFO: {
 289                                 const ObjectSpec *spec = ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index);
 290                                 if (spec == nullptr) break;
 291
 292                                 /* Get the extra message for the GUI */
 293                                 if (HasBit(spec->callback_mask, CBM_OBJ_FUND_MORE_TEXT)) {
 294                                         uint16 callback_res = GetObjectCallback(CBID_OBJECT_FUND_MORE_TEXT, 0, 0, spec, nullptr, INVALID_TILE, _selected_object_view);
 295                                         if (callback_res != CALLBACK_FAILED && callback_res != 0x400) {
 296                                                 if (callback_res > 0x400) {
 297                                                         ErrorUnknownCallbackResult(spec->grf_prop.grffile->grfid, CBID_OBJECT_FUND_MORE_TEXT, callback_res);
 298                                                 } else {
 299                                                         StringID message = GetGRFStringID(spec->grf_prop.grffile->grfid, 0xD000 + callback_res);
 300                                                         if (message != STR_NULL && message != STR_UNDEFINED) {
 301                                                                 StartTextRefStackUsage(spec->grf_prop.grffile, 6);
 302                                                                 /* Use all the available space left from where we stand up to the
 303                                                                  * end of the window. We ALSO enlarge the window if needed, so we
 304                                                                  * can 'go' wild with the bottom of the window. */
 305                                                                 int y = DrawStringMultiLine(r.left, r.right, r.top, UINT16_MAX, message, TC_ORANGE) - r.top;
 306                                                                 StopTextRefStackUsage();
 307                                                                 if (y > this->info_height) {
 308                                                                         BuildObjectWindow *bow = const_cast<BuildObjectWindow *>(this);
 309                                                                         bow->info_height = y + 2;
 310                                                                         bow->ReInit();
 311                                                                 }
 312                                                         }
 313                                                 }
 314                                         }
 315                                 }
 316                         }
 317                 }
 318         }
 319
 320         /**
 321          * Select the specified object class.
 322          * @param object_class_index Object class index to select.
 323          */
 324         void SelectOtherClass(ObjectClassID object_class_index)
 325         {
 326                 _selected_object_class = object_class_index;
 327                 this->GetWidget<NWidgetMatrix>(WID_BO_SELECT_MATRIX)->SetCount(ObjectClass::Get(_selected_object_class)->GetUISpecCount());
 328         }
 329
 330         /**
 331          * Select the specified object in #_selected_object_class class.
 332          * @param object_index Object index to select, \c -1 means select nothing.
 333          */
 334         void SelectOtherObject(int object_index)
 335         {
 336                 _selected_object_index = object_index;
 337                 if (_selected_object_index != -1) {
 338                         const ObjectSpec *spec = ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index);
 339                         _selected_object_view = min(_selected_object_view, spec->views - 1);
 340                         this->ReInit();
 341                 } else {
 342                         _selected_object_view = 0;
 343                 }
 344
 345                 if (_selected_object_index != -1) {
 346                         SetObjectToPlaceWnd(SPR_CURSOR_TRANSMITTER, PAL_NONE, HT_RECT, this);
 347                 }
 348
 349                 this->UpdateButtons(_selected_object_class, _selected_object_index, _selected_object_view);
 350         }
 351
 352         void UpdateSelectSize()
 353         {
 354                 if (_selected_object_index == -1) {
 355                         SetTileSelectSize(1, 1);
 356                 } else {
 357                         const ObjectSpec *spec = ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index);
 358                         int w = GB(spec->size, HasBit(_selected_object_view, 0) ? 4 : 0, 4);
 359                         int h = GB(spec->size, HasBit(_selected_object_view, 0) ? 0 : 4, 4);
 360                         SetTileSelectSize(w, h);
 361                 }
 362         }
 363
 364         /**
 365          * Update buttons to show the selection to the user.
 366          * @param sel_class The class of the selected object.
 367          * @param sel_index Index of the object to select, or \c -1 .
 368          * @param sel_view View of the object to select.
 369          */
 370         void UpdateButtons(ObjectClassID sel_class, int sel_index, uint sel_view)
 371         {
 372                 int view_number, object_number;
 373                 if (sel_index == -1) {
 374                         view_number = -1; // If no object selected, also hide the selected view.
 375                         object_number = -1;
 376                 } else {
 377                         view_number = sel_view;
 378                         object_number = ObjectClass::Get(sel_class)->GetUIFromIndex(sel_index);
 379                 }
 380
 381                 this->GetWidget<NWidgetMatrix>(WID_BO_OBJECT_MATRIX)->SetClicked(view_number);
 382                 this->GetWidget<NWidgetMatrix>(WID_BO_SELECT_MATRIX)->SetClicked(object_number);
 383                 this->UpdateSelectSize();
 384                 this->SetDirty();
 385         }
 386
 387         virtual void OnResize()
 388         {
 389                 this->vscroll->SetCapacityFromWidget(this, WID_BO_CLASS_LIST);
 390         }
 391
 392         virtual void OnClick(Point pt, int widget, int click_count)
 393         {
 394                 switch (GB(widget, 0, 16)) {
 395                         case WID_BO_CLASS_LIST: {
 396                                 int num_clicked = this->vscroll->GetPosition() + (pt.y - this->nested_array[widget]->pos_y) / this->line_height;
 397                                 if (num_clicked >= (int)ObjectClass::GetUIClassCount()) break;
 398
 399                                 this->SelectOtherClass(ObjectClass::GetUIClass(num_clicked));
 400                                 this->SelectFirstAvailableObject(false);
 401                                 break;
 402                         }
 403
 404                         case WID_BO_SELECT_IMAGE: {
 405                                 ObjectClass *objclass = ObjectClass::Get(_selected_object_class);
 406                                 int num_clicked = objclass->GetIndexFromUI(GB(widget, 16, 16));
 407                                 if (num_clicked >= 0 && objclass->GetSpec(num_clicked)->IsAvailable()) this->SelectOtherObject(num_clicked);
 408                                 break;
 409                         }
 410
 411                         case WID_BO_OBJECT_SPRITE:
 412                                 if (_selected_object_index != -1) {
 413                                         _selected_object_view = GB(widget, 16, 16);
 414                                         this->SelectOtherObject(_selected_object_index); // Re-select the object for a different view.
 415                                 }
 416                                 break;
 417                 }
 418         }
 419
 420         virtual void OnPlaceObject(Point pt, TileIndex tile)
 421         {
 422                 const ObjectSpec* spec = ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index);
 423
 424                 if (spec == nullptr) {
 425                         DoCommandP(tile, INVALID_OBJECT_TYPE, _selected_object_view, CMD_BUILD_OBJECT | CMD_MSG(STR_ERROR_CAN_T_BUILD_OBJECT), CcTerraform);
 426                         return;
 427                 }
 428
 429                 int size_x = GB(spec->size, HasBit(_selected_object_view, 0) ? 4 : 0, 4);
 430                 int size_y = GB(spec->size, HasBit(_selected_object_view, 0) ? 0 : 4, 4);
 431                 ObjectType type = (ObjectType)GB(spec->Index(), 0, 16);
 432
 433                 bool is_draggable = (size_x == 1 && size_y == 1 && type >= NEW_OBJECT_OFFSET);
 434
 435                 if (is_draggable) {
 436                         VpStartPlaceSizing(tile, VPM_X_AND_Y, DDSP_PLACE_OBJECT);
 437                 } else {
 438                         uint32 p2;
 439
 440                         SB(p2, 0, 2, _selected_object_view);
 441                         SB(p2, 2, 30, tile);
 442
 443                         DoCommandP(tile, spec->Index(), p2, CMD_BUILD_OBJECT | CMD_MSG(STR_ERROR_CAN_T_BUILD_OBJECT), CcTerraform);
 444                 }
 445         }
 446
 447         virtual void OnPlaceDrag(ViewportPlaceMethod select_method, ViewportDragDropSelectionProcess select_proc, Point pt)
 448         {
 449                 VpSelectTilesWithMethod(pt.x, pt.y, select_method);
 450         }
 451
 452         virtual void OnPlaceMouseUp(ViewportPlaceMethod select_method, ViewportDragDropSelectionProcess select_proc, Point pt, TileIndex start_tile, TileIndex end_tile)
 453         {
 454                 uint32 p2;
 455
 456                 SB(p2, 0, 2, _selected_object_view);
 457                 SB(p2, 2, 30, start_tile);
 458
 459                 if (pt.x != -1 && select_proc == DDSP_PLACE_OBJECT) {
 460                         DoCommandP(end_tile, ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index)->Index(),
 461                                 p2, CMD_BUILD_OBJECT | CMD_MSG(STR_ERROR_CAN_T_BUILD_OBJECT), CcTerraform);
 462                 }
 463         }
 464
 465         virtual void OnPlaceObjectAbort()
 466         {
 467                 this->UpdateButtons(_selected_object_class, -1, _selected_object_view);
 468         }
 469
 470         /**
 471          * Select the first available object.
 472          * @param change_class If true, change the class if no object in the current
 473          *   class is available.
 474          */
 475         void SelectFirstAvailableObject(bool change_class)
 476         {
 477                 /* First try to select an object in the selected class. */
 478                 ObjectClass *sel_objclass = ObjectClass::Get(_selected_object_class);
 479                 for (uint i = 0; i < sel_objclass->GetSpecCount(); i++) {
 480                         const ObjectSpec *spec = sel_objclass->GetSpec(i);
 481                         if (spec->IsAvailable()) {
 482                                 this->SelectOtherObject(i);
 483                                 return;
 484                         }
 485                 }
 486                 if (change_class) {
 487                         /* If that fails, select the first available object
 488                          * from a random class. */
 489                         for (ObjectClassID j = OBJECT_CLASS_BEGIN; j < OBJECT_CLASS_MAX; j++) {
 490                                 ObjectClass *objclass = ObjectClass::Get(j);
 491                                 for (uint i = 0; i < objclass->GetSpecCount(); i++) {
 492                                         const ObjectSpec *spec = objclass->GetSpec(i);
 493                                         if (spec->IsAvailable()) {
 494                                                 this->SelectOtherClass(j);
 495                                                 this->SelectOtherObject(i);
 496                                                 return;
 497                                         }
 498                                 }
 499                         }
 500                 }
 501                 /* If all objects are unavailable, select nothing... */
 502                 if (ObjectClass::Get(_selected_object_class)->GetUISpecCount() == 0) {
 503                         /* ... but make sure that the class is not empty. */
 504                         for (ObjectClassID j = OBJECT_CLASS_BEGIN; j < OBJECT_CLASS_MAX; j++) {
 505                                 if (ObjectClass::Get(j)->GetUISpecCount() > 0) {
 506                                         this->SelectOtherClass(j);
 507                                         break;
 508                                 }
 509                         }
 510                 }
 511                 this->SelectOtherObject(-1);
 512         }
 513 };
 514
 515 static const NWidgetPart _nested_build_object_widgets[] = {
 516         NWidget(NWID_HORIZONTAL),
 517                 NWidget(WWT_CLOSEBOX, COLOUR_DARK_GREEN),
 518                 NWidget(WWT_CAPTION, COLOUR_DARK_GREEN), SetDataTip(STR_OBJECT_BUILD_CAPTION, STR_TOOLTIP_WINDOW_TITLE_DRAG_THIS),
 519                 NWidget(WWT_DEFSIZEBOX, COLOUR_DARK_GREEN),
 520         EndContainer(),
 521         NWidget(WWT_PANEL, COLOUR_DARK_GREEN),
 522                 NWidget(NWID_HORIZONTAL), SetPadding(2, 0, 0, 0),
 523                         NWidget(NWID_VERTICAL),
 524                                 NWidget(NWID_HORIZONTAL), SetPadding(0, 5, 2, 5),
 525                                         NWidget(WWT_MATRIX, COLOUR_GREY, WID_BO_CLASS_LIST), SetFill(1, 0), SetMatrixDataTip(1, 0, STR_OBJECT_BUILD_CLASS_TOOLTIP), SetScrollbar(WID_BO_SCROLLBAR),
 526                                         NWidget(NWID_VSCROLLBAR, COLOUR_GREY, WID_BO_SCROLLBAR),
 527                                 EndContainer(),
 528                                 NWidget(NWID_HORIZONTAL), SetPadding(0, 5, 0, 5),
 529                                         NWidget(NWID_MATRIX, COLOUR_DARK_GREEN, WID_BO_OBJECT_MATRIX), SetPIP(0, 2, 0),
 530                                                 NWidget(WWT_PANEL, COLOUR_GREY, WID_BO_OBJECT_SPRITE), SetDataTip(0x0, STR_OBJECT_BUILD_PREVIEW_TOOLTIP), EndContainer(),
 531                                         EndContainer(),
 532                                 EndContainer(),
 533                                 NWidget(WWT_TEXT, COLOUR_DARK_GREEN, WID_BO_OBJECT_NAME), SetDataTip(STR_ORANGE_STRING, STR_NULL), SetPadding(2, 5, 2, 5),
 534                                 NWidget(WWT_TEXT, COLOUR_DARK_GREEN, WID_BO_OBJECT_SIZE), SetDataTip(STR_OBJECT_BUILD_SIZE, STR_NULL), SetPadding(2, 5, 2, 5),
 535                         EndContainer(),
 536                         NWidget(WWT_PANEL, COLOUR_DARK_GREEN), SetScrollbar(WID_BO_SELECT_SCROLL),
 537                                 NWidget(NWID_HORIZONTAL),
 538                                         NWidget(NWID_MATRIX, COLOUR_DARK_GREEN, WID_BO_SELECT_MATRIX), SetFill(0, 1), SetPIP(0, 2, 0),
 539                                                 NWidget(WWT_PANEL, COLOUR_DARK_GREEN, WID_BO_SELECT_IMAGE), SetMinimalSize(66, 60), SetDataTip(0x0, STR_OBJECT_BUILD_TOOLTIP),
 540                                                                 SetFill(0, 0), SetResize(0, 0), SetScrollbar(WID_BO_SELECT_SCROLL),
 541                                                 EndContainer(),
 542                                         EndContainer(),
 543                                         NWidget(NWID_VSCROLLBAR, COLOUR_DARK_GREEN, WID_BO_SELECT_SCROLL),
 544                                 EndContainer(),
 545                         EndContainer(),
 546                 EndContainer(),
 547                 NWidget(NWID_HORIZONTAL),
 548                         NWidget(WWT_EMPTY, INVALID_COLOUR, WID_BO_INFO), SetPadding(2, 5, 0, 5), SetFill(1, 0), SetResize(1, 0),
 549                         NWidget(NWID_VERTICAL),
 550                                 NWidget(WWT_PANEL, COLOUR_DARK_GREEN), SetFill(0, 1), EndContainer(),
 551                                 NWidget(WWT_RESIZEBOX, COLOUR_DARK_GREEN),
 552                         EndContainer(),
 553                 EndContainer(),
 554         EndContainer(),
 555 };
 556
 557 static WindowDesc _build_object_desc(
 558         WDP_AUTO, "build_object", 0, 0,
 559         WC_BUILD_OBJECT, WC_BUILD_TOOLBAR,
 560         WDF_CONSTRUCTION,
 561         _nested_build_object_widgets, lengthof(_nested_build_object_widgets)
 562 );
 563
 564 /**
 565  * Show our object picker.
 566  * @param w The toolbar window we're associated with.
 567  */
 568 void ShowBuildObjectPicker()
 569 {
 570         /* Don't show the place object button when there are no objects to place. */
 571         if (ObjectClass::GetUIClassCount() > 0) {
 572                 AllocateWindowDescFront<BuildObjectWindow>(&_build_object_desc, 0);
 573         }
 574 }
 575
 576 /** Reset all data of the object GUI. */
 577 void InitializeObjectGui()
 578 {
 579         _selected_object_class = (ObjectClassID)0;
 580 }