(svn r21497) -Codechange: prepare the viewport selection mechanism for selecting diagonally

src/terraform_gui.cpp

@@ -616,6 +616,15 @@ static void ResetLandscapeConfirmationCallback(Window *w, bool confirmed)
 	}
 }
 
+/**
+ * Checks whether we are currently dragging diagonally.
+ * @returns True iff we are selecting a diagonal rectangle for an action that supports it, otherwise false.
+ */
+bool IsDraggingDiagonal()
+{
+	return false;
+}
+
 struct ScenarioEditorLandscapeGenerationWindow : Window {
 	ScenarioEditorLandscapeGenerationWindow(const WindowDesc *desc, WindowNumber window_number) : Window()
 	{

src/terraform_gui.h

@@ -14,6 +14,8 @@
 
 #include "window_type.h"
 
+bool IsDraggingDiagonal();
+
 Window *ShowTerraformToolbar(Window *link = NULL);
 Window *ShowEditorTerraformToolbar();
 

src/tilehighlight_type.h

@@ -49,10 +49,12 @@ struct TileHighlightData {
 	Point size;          ///< Size, in tile "units", of the white/red selection area.
 	Point offs;          ///< Offset, in tile "units", for the blue coverage area from the selected area's northern tile.
 	Point outersize;     ///< Size, in tile "units", of the blue coverage area excluding the side of the selected area.
+	bool diagonal;       ///< Whether the dragged area is a 45 degrees rotated rectangle.
 
 	Point new_pos;       ///< New value for \a pos; used to determine whether to redraw the selection.
 	Point new_size;      ///< New value for \a size; used to determine whether to redraw the selection.
 	Point new_outersize; ///< New value for \a outersize; used to determine whether to redraw the selection.
+	bool new_diagonal;   ///< New value for \a diagonal; used to determine whether to redraw the selection.
 	byte dirty;          ///< Whether the build station window needs to redraw due to the changed selection.
 
 	Point selstart;      ///< The location where the dragging started.

src/viewport.cpp

@@ -45,6 +45,7 @@
 #include "window_func.h"
 #include "tilehighlight_func.h"
 #include "window_gui.h"
+#include "terraform_gui.h"
 
 #include "table/strings.h"
 
@@ -753,6 +754,38 @@ void EndSpriteCombine()
 	_vd.combine_sprites = SPRITE_COMBINE_NONE;
 }
 
+/**
+ * Check if the parameter "check" is inside the interval between
+ * begin and end, including both begin and end.
+ * @note Whether \c begin or \c end is the biggest does not matter.
+ *       This method will account for that.
+ * @param begin The begin of the interval.
+ * @param end   The end of the interval.
+ * @param check The value to check.
+ */
+static bool IsInRangeInclusive(int begin, int end, int check)
+{
+	if (begin > end) Swap(begin, end);
+	return begin <= check && check <= end;
+}
+
+/**
+ * Checks whether a point is inside the selected a diagonal rectangle given by _thd.size and _thd.pos
+ * @param x The x coordinate of the point to be checked.
+ * @param y The y coordinate of the point to be checked.
+ * @return True if the point is inside the rectangle, else false.
+ */
+bool IsInsideRotatedRectangle(int x, int y)
+{
+	int dist_a = (_thd.size.x + _thd.size.y);      // Rotated coordinate system for selected rectangle.
+	int dist_b = (_thd.size.x - _thd.size.y);      // We don't have to divide by 2. It's all relative!
+	int a = ((x - _thd.pos.x) + (y - _thd.pos.y)); // Rotated coordinate system for the point under scrutiny.
+	int b = ((x - _thd.pos.x) - (y - _thd.pos.y));
+
+	/* Check if a and b are between 0 and dist_a or dist_b respectively. */
+	return IsInRangeInclusive(dist_a, 0, a) && IsInRangeInclusive(dist_b, 0, b);
+}
+
 /**
  * Add a child sprite to a parent sprite.
  *
@@ -940,6 +973,29 @@ static void DrawTileSelection(const TileInfo *ti)
 	/* no selection active? */
 	if (_thd.drawstyle == 0) return;
 
+	if (_thd.diagonal) { // We're drawing a 45 degrees rotated (diagonal) rectangle
+		if (IsInsideRotatedRectangle((int)ti->x, (int)ti->y)) {
+			if (_thd.drawstyle & HT_RECT) { // Highlighting a square (clear land)
+				/* Don't mark tiles outside the map. */
+				if (!IsValidTile(ti->tile)) return;
+
+				SpriteID image = SPR_SELECT_TILE + SlopeToSpriteOffset(ti->tileh);
+				DrawSelectionSprite(image, _thd.make_square_red ? PALETTE_SEL_TILE_RED : PAL_NONE, ti, 7, FOUNDATION_PART_NORMAL);
+			} else { // Highlighting a dot (level land)
+				/* Figure out the Z coordinate for the single dot. */
+				byte z = ti->z;
+				if (ti->tileh & SLOPE_N) {
+					z += TILE_HEIGHT;
+					if (!(ti->tileh & SLOPE_S) && (ti->tileh & SLOPE_STEEP)) {
+						z += TILE_HEIGHT;
+					}
+				}
+				AddTileSpriteToDraw(_cur_dpi->zoom != 2 ? SPR_DOT : SPR_DOT_SMALL, PAL_NONE, ti->x, ti->y, z);
+			}
+		}
+		return;
+	}
+
 	/* Inside the inner area? */
 	if (IsInsideBS(ti->x, _thd.pos.x, _thd.size.x) &&
 			IsInsideBS(ti->y, _thd.pos.y, _thd.size.y)) {
@@ -1621,12 +1677,13 @@ void MarkTileDirtyByTile(TileIndex tile)
  */
 static void SetSelectionTilesDirty()
 {
-	int x_start = _thd.pos.x;
-	int y_start = _thd.pos.y;
-
 	int x_size = _thd.size.x;
 	int y_size = _thd.size.y;
 
+	if (!_thd.diagonal) { // Selecting in a straigth rectangle (or a single square)
+		int x_start = _thd.pos.x;
+		int y_start = _thd.pos.y;
+
 		if (_thd.outersize.x != 0) {
 			x_size  += _thd.outersize.x;
 			x_start += _thd.offs.x;
@@ -1703,6 +1760,24 @@ static void SetSelectionTilesDirty()
 				bot_x -= TILE_SIZE;
 			}
 		} while (bot_x >= top_x);
+	} else { // Selecting in a 45 degrees rotated (diagonal) rectangle.
+		/* a_size, b_size describe a rectangle with rotated coordinates */
+		int a_size = x_size + y_size, b_size = x_size - y_size;
+
+		int interval_a = a_size < 0 ? -TILE_SIZE : TILE_SIZE;
+		int interval_b = b_size < 0 ? -TILE_SIZE : TILE_SIZE;
+
+		for (int a = -interval_a; a != a_size + interval_a; a += interval_a) {
+			for (int b = -interval_b; b != b_size + interval_b; b += interval_b) {
+				uint x = (_thd.pos.x + (a + b) / 2) / TILE_SIZE;
+				uint y = (_thd.pos.y + (a - b) / 2) / TILE_SIZE;
+
+				if (x < MapMaxX() && y < MapMaxY()) {
+					MarkTileDirtyByTile(TileXY(x, y));
+				}
+			}
+		}
+	}
 }
 
 
@@ -1963,6 +2038,7 @@ void UpdateTileSelection()
 	int y1;
 
 	_thd.new_drawstyle = HT_NONE;
+	_thd.new_diagonal = false;
 
 	if (_thd.place_mode == HT_SPECIAL) {
 		x1 = _thd.selend.x;
@@ -1973,12 +2049,20 @@ void UpdateTileSelection()
 			x1 &= ~TILE_UNIT_MASK;
 			y1 &= ~TILE_UNIT_MASK;
 
+			if (IsDraggingDiagonal()) {
+				_thd.new_diagonal = true;
+			} else {
 				if (x1 >= x2) Swap(x1, x2);
 				if (y1 >= y2) Swap(y1, y2);
+			}
 			_thd.new_pos.x = x1;
 			_thd.new_pos.y = y1;
-			_thd.new_size.x = x2 - x1 + TILE_SIZE;
-			_thd.new_size.y = y2 - y1 + TILE_SIZE;
+			_thd.new_size.x = x2 - x1;
+			_thd.new_size.y = y2 - y1;
+			if (!_thd.new_diagonal) {
+				_thd.new_size.x += TILE_SIZE;
+				_thd.new_size.y += TILE_SIZE;
+			}
 			_thd.new_drawstyle = _thd.next_drawstyle;
 		}
 	} else if ((_thd.place_mode & HT_DRAG_MASK) != HT_NONE) {
@@ -2033,7 +2117,8 @@ void UpdateTileSelection()
 			_thd.pos.x != _thd.new_pos.x || _thd.pos.y != _thd.new_pos.y ||
 			_thd.size.x != _thd.new_size.x || _thd.size.y != _thd.new_size.y ||
 			_thd.outersize.x != _thd.new_outersize.x ||
-			_thd.outersize.y != _thd.new_outersize.y) {
+			_thd.outersize.y != _thd.new_outersize.y ||
+			_thd.diagonal    != _thd.new_diagonal) {
 		/* clear the old selection? */
 		if (_thd.drawstyle) SetSelectionTilesDirty();
 
@@ -2041,6 +2126,7 @@ void UpdateTileSelection()
 		_thd.pos = _thd.new_pos;
 		_thd.size = _thd.new_size;
 		_thd.outersize = _thd.new_outersize;
+		_thd.diagonal = _thd.new_diagonal;
 		_thd.dirty = 0xff;
 
 		/* draw the new selection? */