Change: Improve graph period markings (#8732)

1 files changed, 21 insertions, 17 deletions

diff --git a/src/graph_gui.cpp b/src/graph_gui.cpp
index 04c3a7581..79c548e9c 100644
--- a/src/graph_gui.cpp
+++ b/src/graph_gui.cpp
@@ -165,10 +165,15 @@ struct ValuesInterval {
 struct BaseGraphWindow : Window {
 protected:
 	static const int GRAPH_MAX_DATASETS     =  64;
+	static const int GRAPH_BASE_COLOUR      =  GREY_SCALE(2);
+	static const int GRAPH_GRID_COLOUR      =  GREY_SCALE(3);
 	static const int GRAPH_AXIS_LINE_COLOUR =  GREY_SCALE(1);
 	static const int GRAPH_ZERO_LINE_COLOUR =  GREY_SCALE(8);
+	static const int GRAPH_YEAR_LINE_COLOUR =  GREY_SCALE(5);
 	static const int GRAPH_NUM_MONTHS       =  24; ///< Number of months displayed in the graph.
 
+	static const TextColour GRAPH_AXIS_LABEL_COLOUR = TC_BLACK; ///< colour of the graph axis label.
+
 	static const int MIN_GRAPH_NUM_LINES_Y  =   9; ///< Minimal number of horizontal lines to draw.
 	static const int MIN_GRID_PIXEL_SIZE    =  20; ///< Minimum distance between graph lines.
 
@@ -176,7 +181,6 @@ protected:
 	byte num_dataset;
 	byte num_on_x_axis;
 	byte num_vert_lines;
-	static const TextColour graph_axis_label_colour = TC_BLACK; ///< colour of the graph axis label.
 
 	/* The starting month and year that values are plotted against. If month is
 	 * 0xFF, use x_values_start and x_values_increment below instead. */
@@ -293,12 +297,10 @@ protected:
 		static_assert(GRAPH_MAX_DATASETS >= (int)NUM_CARGO && GRAPH_MAX_DATASETS >= (int)MAX_COMPANIES);
 		assert(this->num_vert_lines > 0);
 
-		byte grid_colour = GREY_SCALE(3);
-
 		/* Rect r will be adjusted to contain just the graph, with labels being
 		 * placed outside the area. */
 		r.top    += 5 + GetCharacterHeight(FS_SMALL) / 2;
-		r.bottom -= (this->month == 0xFF ? 1 : 3) * GetCharacterHeight(FS_SMALL) + 4;
+		r.bottom -= (this->month == 0xFF ? 1 : 2) * GetCharacterHeight(FS_SMALL) + 4;
 		r.left   += 9;
 		r.right  -= 5;
 
@@ -327,7 +329,7 @@ protected:
 		x_axis_offset = (int)((r.bottom - r.top) * (double)interval.highest / (double)interval_size);
 
 		/* Draw the background of the graph itself. */
-		GfxFillRect(r.left, r.top, r.right, r.bottom, GREY_SCALE(2));
+		GfxFillRect(r.left, r.top, r.right, r.bottom, GRAPH_BASE_COLOUR);
 
 		/* Draw the vertical grid lines. */
 
@@ -335,7 +337,7 @@ protected:
 		x = r.left + x_sep;
 
 		for (int i = 0; i < this->num_vert_lines; i++) {
-			GfxFillRect(x, r.top, x, r.bottom, grid_colour);
+			GfxFillRect(x, r.top, x, r.bottom, GRAPH_GRID_COLOUR);
 			x += x_sep;
 		}
 
@@ -344,7 +346,7 @@ protected:
 
 		for (int i = 0; i < (num_hori_lines + 1); i++) {
 			GfxFillRect(r.left - 3, y, r.left - 1, y, GRAPH_AXIS_LINE_COLOUR);
-			GfxFillRect(r.left, y, r.right, y, grid_colour);
+			GfxFillRect(r.left, y, r.right, y, GRAPH_GRID_COLOUR);
 			y -= y_sep;
 		}
 
@@ -370,13 +372,13 @@ protected:
 		for (int i = 0; i < (num_hori_lines + 1); i++) {
 			SetDParam(0, this->format_str_y_axis);
 			SetDParam(1, y_label);
-			DrawString(r.left - label_width - 4, r.left - 4, y, STR_GRAPH_Y_LABEL, graph_axis_label_colour, SA_RIGHT);
+			DrawString(r.left - label_width - 4, r.left - 4, y, STR_GRAPH_Y_LABEL, GRAPH_AXIS_LABEL_COLOUR, SA_RIGHT);
 
 			y_label -= y_label_separation;
 			y += y_sep;
 		}
 
-		/* draw strings on the x axis */
+		/* Draw x-axis labels and markings for graphs based on financial quarters and years.  */
 		if (this->month != 0xFF) {
 			x = r.left;
 			y = r.bottom + 2;
@@ -384,26 +386,28 @@ protected:
 			Year year  = this->year;
 			for (int i = 0; i < this->num_on_x_axis; i++) {
 				SetDParam(0, month + STR_MONTH_ABBREV_JAN);
-				SetDParam(1, month + STR_MONTH_ABBREV_JAN + 2);
-				SetDParam(2, year);
-				DrawStringMultiLine(x, x + x_sep, y, this->height, month == 0 ? STR_GRAPH_X_LABEL_MONTH_YEAR : STR_GRAPH_X_LABEL_MONTH, graph_axis_label_colour);
+				SetDParam(1, year);
+				DrawStringMultiLine(x, x + x_sep, y, this->height, month == 0 ? STR_GRAPH_X_LABEL_MONTH_YEAR : STR_GRAPH_X_LABEL_MONTH, GRAPH_AXIS_LABEL_COLOUR, SA_LEFT);
 
 				month += 3;
 				if (month >= 12) {
 					month = 0;
 					year++;
+
+					/* Draw a lighter grid line between years. Top and bottom adjustments ensure we don't draw over top and bottom horizontal grid lines. */
+					GfxFillRect(x + x_sep, r.top + 1, x + x_sep, r.bottom - 1, GRAPH_YEAR_LINE_COLOUR);
 				}
 				x += x_sep;
 			}
 		} else {
-			/* Draw the label under the data point rather than on the grid line. */
+			/* Draw x-axis labels for graphs not based on quarterly performance (cargo payment rates). */
 			x = r.left;
 			y = r.bottom + 2;
 			uint16 label = this->x_values_start;
 
 			for (int i = 0; i < this->num_on_x_axis; i++) {
 				SetDParam(0, label);
-				DrawString(x + 1, x + x_sep - 1, y, STR_GRAPH_Y_LABEL_NUMBER, graph_axis_label_colour, SA_HOR_CENTER);
+				DrawString(x + 1, x + x_sep - 1, y, STR_GRAPH_Y_LABEL_NUMBER, GRAPH_AXIS_LABEL_COLOUR, SA_HOR_CENTER);
 
 				label += this->x_values_increment;
 				x += x_sep;
@@ -493,13 +497,13 @@ public:
 
 		uint x_label_width = 0;
 
+		/* Draw x-axis labels and markings for graphs based on financial quarters and years.  */
 		if (this->month != 0xFF) {
 			byte month = this->month;
 			Year year  = this->year;
 			for (int i = 0; i < this->num_on_x_axis; i++) {
 				SetDParam(0, month + STR_MONTH_ABBREV_JAN);
-				SetDParam(1, month + STR_MONTH_ABBREV_JAN + 2);
-				SetDParam(2, year);
+				SetDParam(1, year);
 				x_label_width = std::max(x_label_width, GetStringBoundingBox(month == 0 ? STR_GRAPH_X_LABEL_MONTH_YEAR : STR_GRAPH_X_LABEL_MONTH).width);
 
 				month += 3;
@@ -509,7 +513,7 @@ public:
 				}
 			}
 		} else {
-			/* Draw the label under the data point rather than on the grid line. */
+			/* Draw x-axis labels for graphs not based on quarterly performance (cargo payment rates). */
 			SetDParamMaxValue(0, this->x_values_start + this->num_on_x_axis * this->x_values_increment, 0, FS_SMALL);
 			x_label_width = GetStringBoundingBox(STR_GRAPH_Y_LABEL_NUMBER).width;
 		}