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(svn r8366) -Codechange: [Graphs] Make the scaling code less cryptic, and fix two longstanding bugs. 

1) If the graph contained negative values, the y axis labels were half the size they should have been.
2) If the maximum value was larger than the height of the graph in pixels << 32, all datapoints were scaled to 0.
This commit is contained in:
maedhros 2007-01-23 10:21:51 +00:00
parent 294723d03f
commit 75e7b2e6df
1 changed files with 21 additions and 16 deletions
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37
src/graph_gui.cpp
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@ -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)