Port GUI rendering improvements from JGRPP

src/company_gui.cpp

@@ -2558,7 +2558,7 @@ struct CompanyWindow : Window
 			case WID_C_VIEW_HQ: {
 				TileIndex tile = Company::Get((CompanyID)this->window_number)->location_of_HQ;
 				if (_ctrl_pressed) {
-					ShowExtraViewPortWindow(tile);
+					ShowExtraViewportWindow(tile);
 				} else {
 					ScrollMainWindowToTile(tile);
 				}

src/core/math_func.hpp

@@ -243,6 +243,7 @@ static inline T Delta(const T a, const T b)
  * @param base The base value of the interval
  * @param size The size of the interval
  * @return True if the value is in the interval, false else.
+ * @see IsInsideMM()
  */
 template <typename T>
 static inline bool IsInsideBS(const T x, const size_t base, const size_t size)
@@ -307,60 +308,85 @@ int DivideApprox(int a, int b);
 
 /**
  * Computes ceil(a / b) for non-negative a and b.
- * @param a Numerator
- * @param b Denominator
- * @return Quotient, rounded up
+ * @param a Numerator.
+ * @param b Denominator.
+ * @return Quotient, rounded up.
  */
-static inline uint CeilDiv(uint a, uint b)
+static inline uint CeilDiv(const uint a, const uint b)
 {
 	return (a + b - 1) / b;
 }
 
 /**
  * Computes ceil(a / b) * b for non-negative a and b.
- * @param a Numerator
- * @param b Denominator
+ * @param a Numerator.
+ * @param b Denominator.
  * @return a rounded up to the nearest multiple of b.
  */
-static inline uint Ceil(uint a, uint b)
+static inline uint Ceil(const uint a, const uint b)
 {
 	return CeilDiv(a, b) * b;
 }
 
 /**
- * Computes round(a / b) for signed a and unsigned b.
- * @param a Numerator
- * @param b Denominator
- * @return Quotient, rounded to nearest
+ * Computes round(a / b) for integer a and positive integer b.
+ * @param a Numerator.
+ * @param b Denominator.
+ * @return Quotient, rounded to nearest.
  */
-static inline int RoundDivSU(int a, uint b)
+static inline int RoundDivSU(const int a, const uint b)
 {
+	const int b_ = static_cast<int>(b);
 	if (a > 0) {
 		/* 0.5 is rounded to 1 */
-		return (a + static_cast<int>(b) / 2) / static_cast<int>(b);
+		return (a + b_ / 2) / b_;
 	} else {
 		/* -0.5 is rounded to 0 */
-		return (a - (static_cast<int>(b) - 1) / 2) / static_cast<int>(b);
+		return (a - (b_ - 1) / 2) / b_;
 	}
 }
 
 /**
- * Computes (a / b) rounded away from zero.
- * @param a Numerator
- * @param b Denominator
- * @return Quotient, rounded away from zero
+ * Computes (a / b) rounded away from zero for integer a and positive integer b.
+ * @param a Numerator.
+ * @param b Denominator.
+ * @return Quotient, rounded away from zero.
  */
-static inline int DivAwayFromZero(int a, uint b)
+static inline int DivAwayFromZero(const int a, const uint b)
 {
-	const int _b = static_cast<int>(b);
+	const int b_ = static_cast<int>(b);
 	if (a > 0) {
-		return (a + _b - 1) / _b;
+		return (a + b_ - 1) / b_;
 	} else {
 		/* Note: Behaviour of negative numerator division is truncation toward zero. */
-		return (a - _b + 1) / _b;
+		return (a - b_ + 1) / b_;
 	}
 }
 
+/**
+ * Computes a / b rounded towards negative infinity for integer a and positive integer b.
+ * @param a Numerator.
+ * @param b Denominator.
+ * @return Quotient, rounded towards negative infinity.
+ */
+static inline int DivTowardsNegativeInf(const int a, const uint b)
+{
+	const int b_ = static_cast<int>(b);
+	return (a / b_) - (a % b_ < 0 ? 1 : 0);
+}
+
+/**
+ * Computes a / b rounded towards positive infinity for integer a and positive integer b.
+ * @param a Numerator.
+ * @param b Denominator.
+ * @return Quotient, rounded towards positive infinity.
+ */
+static inline int DivTowardsPositiveInf(const int a, const uint b)
+{
+	const int b_ = static_cast<int>(b);
+	return (a / b_) + (a % b_ > 0 ? 1 : 0);
+}
+
 uint32 IntSqrt(uint32 num);
 
 #endif /* MATH_FUNC_HPP */

src/depot_gui.cpp

@@ -787,7 +787,7 @@ struct DepotWindow : Window {
 
 			case WID_D_LOCATION:
 				if (_ctrl_pressed) {
-					ShowExtraViewPortWindow(this->window_number);
+					ShowExtraViewportWindow(this->window_number);
 				} else {
 					ScrollMainWindowToTile(this->window_number);
 				}

src/error_gui.cpp

@@ -225,7 +225,7 @@ struct ErrmsgWindow : public Window, ErrorMessageData {
 		int scr_bot = GetMainViewBottom() - 20;
 
 		Point pt = RemapCoords(this->position.x, this->position.y, GetSlopePixelZOutsideMap(this->position.x, this->position.y));
-		const ViewPort *vp = FindWindowById(WC_MAIN_WINDOW, 0)->viewport;
+		const Viewport *vp = FindWindowById(WC_MAIN_WINDOW, 0)->viewport.get();
 		if (this->face == INVALID_COMPANY) {
 			/* move x pos to opposite corner */
 			pt.x = UnScaleByZoom(pt.x - vp->virtual_left, vp->zoom) + vp->left;