diff options
Diffstat (limited to 'src/graph_gui.cpp')
| -rw-r--r-- | src/graph_gui.cpp | 31 |
1 files changed, 25 insertions, 6 deletions
diff --git a/src/graph_gui.cpp b/src/graph_gui.cpp index 7c2543011..ddabf882d 100644 --- a/src/graph_gui.cpp +++ b/src/graph_gui.cpp @@ -65,7 +65,7 @@ struct GraphDrawer { uint height; ///< The height of the graph in pixels. StringID format_str_y_axis; byte colors[GRAPH_MAX_DATASETS]; - Money cost[GRAPH_MAX_DATASETS][24]; ///< last 2 years + OverflowSafeInt64 cost[GRAPH_MAX_DATASETS][24]; ///< last 2 years }; static void DrawGraph(const GraphDrawer *gw) @@ -133,7 +133,7 @@ static void DrawGraph(const GraphDrawer *gw) for (int i = 0; i < gw->num_dataset; i++) { if (!HasBit(gw->excluded_data, i)) { for (int j = 0; j < gw->num_on_x_axis; j++) { - Money datapoint = gw->cost[i][j]; + OverflowSafeInt64 datapoint = gw->cost[i][j]; if (datapoint != INVALID_DATAPOINT) { /* For now, if the graph has negative values the scaling is @@ -215,12 +215,31 @@ static void DrawGraph(const GraphDrawer *gw) uint prev_y = INVALID_DATAPOINT_POS; for (int j = 0; j < gw->num_on_x_axis; j++) { - Money datapoint = gw->cost[i][j]; + OverflowSafeInt64 datapoint = gw->cost[i][j]; if (datapoint != INVALID_DATAPOINT) { - /* XXX: This can overflow if x_axis_offset * datapoint is - * too big to fit in an int64. */ - y = gw->top + x_axis_offset - (x_axis_offset * datapoint) / highest_value; + /* + * Check whether we need to reduce the 'accuracy' of the + * datapoint value and the highest value to splut overflows. + * And when 'drawing' 'one million' or 'one million and one' + * there is no significant difference, so the least + * significant bits can just be removed. + * + * If there are more bits needed than would fit in a 32 bits + * integer, so at about 31 bits because of the sign bit, the + * least significant bits are removed. + */ + int mult_range = FindLastBit(x_axis_offset) + FindLastBit(abs(datapoint)); + int reduce_range = max(mult_range - 31, 0); + + /* Handle negative values differently (don't shift sign) */ + if (datapoint < 0) { + datapoint = -(abs(datapoint) >> reduce_range); + } else { + datapoint >>= reduce_range; + } + + y = gw->top + x_axis_offset - (x_axis_offset * datapoint) / (highest_value >> reduce_range); /* Draw the point. */ GfxFillRect(x - 1, y - 1, x + 1, y + 1, color); |