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-rw-r--r--src/graph_gui.cpp37
1 files changed, 21 insertions, 16 deletions
diff --git a/src/graph_gui.cpp b/src/graph_gui.cpp
index f01f2b2f5..3fb750aad 100644
--- a/src/graph_gui.cpp
+++ b/src/graph_gui.cpp
@@ -69,8 +69,6 @@ static void DrawGraph(const GraphDrawer *gw)
int right;
int64 highest_value;
int adj_height;
- uint64 y_scaling;
- int64 value;
uint sel;
/* the colors and cost array of GraphDrawer must accomodate
@@ -121,7 +119,11 @@ static void DrawGraph(const GraphDrawer *gw)
assert(gw->num_on_x_axis > 0);
assert(gw->num_dataset > 0);
- highest_value = 0;
+ /* Start of with a value of twice the height of the graph in pixels. It's a
+ * bit arbitrary, but it makes the cargo payment graph look a little nicer,
+ * and prevents division by zero when calculating where the datapoint
+ * should be drawn. */
+ highest_value = adj_height * 2;
/* bit selection for the showing of various players, base max element
* on to-be shown player-information. This way the graph can scale */
@@ -142,19 +144,19 @@ static void DrawGraph(const GraphDrawer *gw)
sel >>= 1;
}
- /* setup scaling */
- y_scaling = INVALID_VALUE;
- value = adj_height * 2;
-
- if (highest_value > value) {
- highest_value = ALIGN(highest_value, 8);
- y_scaling = (((uint64) (value>>1) << 32) / highest_value);
- value = highest_value;
- }
+ /* Round up highest_value so that it will divide cleanly into the number of
+ * axis labels used. */
+ int round_val = highest_value % (GRAPH_NUM_LINES_Y - 1);
+ if (round_val != 0) highest_value += (GRAPH_NUM_LINES_Y - 1 - round_val);
/* draw text strings on the y axis */
- int64 y_label = value;
- if (gw->include_neg) y_label /= 2;
+ int64 y_label = highest_value;
+ int64 y_label_separation = highest_value / (GRAPH_NUM_LINES_Y - 1);
+
+ /* If there are negative values, the graph goes from highest_value to
+ * -highest_value, not highest_value to 0. */
+ if (gw->include_neg) y_label_separation *= 2;
+
x = gw->left + GRAPH_X_POSITION_BEGINNING + 1;
y = gw->top - 3;
@@ -162,7 +164,8 @@ static void DrawGraph(const GraphDrawer *gw)
SetDParam(0, gw->format_str_y_axis);
SetDParam64(1, y_label);
DrawStringRightAligned(x, y, STR_0170, GRAPH_AXIS_LABEL_COLOUR);
- y_label -= (value / (GRAPH_NUM_LINES_Y - 1));
+
+ y_label -= y_label_separation;
y += (gw->height / (GRAPH_NUM_LINES_Y - 1));
}
@@ -215,7 +218,9 @@ static void DrawGraph(const GraphDrawer *gw)
int64 datapoint = gw->cost[i][j];
if (datapoint != INVALID_VALUE) {
- y = adj_height - BIGMULSS64(datapoint, y_scaling >> 1, 31) + gw->top;
+ /* XXX: This can overflow if adj_height * datapoint is too
+ * big to fit in an int64. */
+ y = gw->top + adj_height - (adj_height * datapoint) / highest_value;
GfxFillRect(x-1, y-1, x+1, y+1, color);
if (old_x != INVALID_VALUE)