Add: Add new viewport place methods for rectangles with one side with a fixed length.

src/tilehighlight_func.h

@@ -26,6 +26,8 @@ void VpStartDragging(ViewportDragDropSelectionProcess process);
 void VpStartPlaceSizing(TileIndex tile, ViewportPlaceMethod method, ViewportDragDropSelectionProcess process);
 void VpSetPresizeRange(TileIndex from, TileIndex to);
 void VpSetPlaceSizingLimit(int limit);
+void VpSetPlaceFixedSize(uint8_t fixed_size);
+void VpResetFixedSize();
 
 void UpdateTileSelection();
 

src/tilehighlight_type.h

@@ -60,6 +60,7 @@ struct TileHighlightData {
 	Point selstart;      ///< The location where the dragging started.
 	Point selend;        ///< The location where the drag currently ends.
 	uint8_t sizelimit;   ///< Whether the selection is limited in length, and what the maximum length is.
+	uint8_t fixed_size;  ///< The fixed length for one of the sides.
 
 	HighLightStyle drawstyle;      ///< Lower bits 0-3 are reserved for detailed highlight information.
 	HighLightStyle next_drawstyle; ///< Queued, but not yet drawn style.

src/viewport.cpp

@@ -2680,6 +2680,8 @@ void UpdateTileSelection()
 			}
 			_thd.new_pos.x = x1 & ~TILE_UNIT_MASK;
 			_thd.new_pos.y = y1 & ~TILE_UNIT_MASK;
+			if (_thd.select_method == VPM_LIMITED_X_FIXED_Y) _thd.new_size.y = (TILE_SIZE * _thd.fixed_size) & ~TILE_UNIT_MASK;
+			if (_thd.select_method == VPM_LIMITED_Y_FIXED_X) _thd.new_size.x = (TILE_SIZE * _thd.fixed_size) & ~TILE_UNIT_MASK;
 		}
 	}
 
@@ -2772,6 +2774,15 @@ void VpSetPlaceSizingLimit(int limit)
 	_thd.sizelimit = limit;
 }
 
+void VpSetPlaceFixedSize(uint8_t fixed)
+{
+	_thd.fixed_size = fixed;
+}
+
+void VpResetFixedSize() {
+	VpSetPlaceFixedSize(1);
+}
+
 /**
  * Highlights all tiles between a set of two tiles. Used in dock and tunnel placement
  * @param from TileIndex of the first tile to highlight
@@ -3243,7 +3254,7 @@ void VpSelectTilesWithMethod(int x, int y, ViewportPlaceMethod method)
 	sx = _thd.selstart.x;
 	sy = _thd.selstart.y;
 
-	int limit = 0;
+	int limit = -1;
 
 	switch (method) {
 		case VPM_X_OR_Y: // drag in X or Y direction
@@ -3256,28 +3267,33 @@ void VpSelectTilesWithMethod(int x, int y, ViewportPlaceMethod method)
 			}
 			goto calc_heightdiff_single_direction;
 
+		case VPM_LIMITED_Y_FIXED_X:
 		case VPM_X_LIMITED: // Drag in X direction (limited size).
 			limit = (_thd.sizelimit - 1) * TILE_SIZE;
 			[[fallthrough]];
 
 		case VPM_FIX_X: // drag in Y direction
-			x = sx;
+			x = sx + (method == VPM_LIMITED_Y_FIXED_X ? (TILE_SIZE * (_thd.fixed_size - 1)) : 0) ;
 			style = HT_DIR_Y;
 			goto calc_heightdiff_single_direction;
 
+		case VPM_LIMITED_X_FIXED_Y:
 		case VPM_Y_LIMITED: // Drag in Y direction (limited size).
 			limit = (_thd.sizelimit - 1) * TILE_SIZE;
 			[[fallthrough]];
 
 		case VPM_FIX_Y: // drag in X direction
-			y = sy;
+			y = sy + (method == VPM_LIMITED_X_FIXED_Y ? (TILE_SIZE * (_thd.fixed_size - 1)) : 0) ;
 			style = HT_DIR_X;
 
 calc_heightdiff_single_direction:;
-			if (limit > 0) {
-				x = sx + Clamp(x - sx, -limit, limit);
-				y = sy + Clamp(y - sy, -limit, limit);
+			if (limit >= 0) {
+				if (method != VPM_LIMITED_X_FIXED_Y) y = sy + Clamp(y - sy, -limit, limit);
+				if (method != VPM_LIMITED_Y_FIXED_X) x = sx + Clamp(x - sx, -limit, limit);
 			}
+
+			if (method == VPM_LIMITED_Y_FIXED_X || method == VPM_LIMITED_X_FIXED_Y) goto measure_area;
+
 			if (_settings_client.gui.measure_tooltip) {
 				TileIndex t0 = TileVirtXY(sx, sy);
 				TileIndex t1 = TileVirtXY(x, y);
@@ -3307,6 +3323,7 @@ calc_heightdiff_single_direction:;
 			[[fallthrough]];
 
 		case VPM_X_AND_Y: // drag an X by Y area
+measure_area:
 			if (_settings_client.gui.measure_tooltip) {
 				static const StringID measure_strings_area[] = {
 					STR_NULL, STR_NULL, STR_MEASURE_AREA, STR_MEASURE_AREA_HEIGHTDIFF

src/viewport_type.h

@@ -99,6 +99,8 @@ enum ViewportPlaceMethod {
 	VPM_FIX_VERTICAL    =    6, ///< drag only in vertical direction
 	VPM_X_LIMITED       =    7, ///< Drag only in X axis with limited size
 	VPM_Y_LIMITED       =    8, ///< Drag only in Y axis with limited size
+	VPM_LIMITED_Y_FIXED_X =  9, ///< Drag only in Y axis with limited size and a fixed value for X axis
+	VPM_LIMITED_X_FIXED_Y = 10, ///< Drag only in X axis with limited size and a fixed value for Y axis
 	VPM_RAILDIRS        = 0x40, ///< all rail directions
 	VPM_SIGNALDIRS      = 0x80, ///< similar to VMP_RAILDIRS, but with different cursor
 };