Fix slight errors when widths can't be round-tripped through floats. (Bug 467141) r+sr=roc

2008-12-04 08:09:53 -08:00 · 2008-12-04 08:09:53 -08:00 · e3204bb21a
--- a/layout/tables/FixedTableLayoutStrategy.cpp
+++ b/layout/tables/FixedTableLayoutStrategy.cpp
@ -168,6 +168,18 @@ FixedTableLayoutStrategy::MarkIntrinsicWidthsDirty()
    mLastCalcWidth = nscoord_MIN;
 }

+static inline nscoord
+AllocateUnassigned(nscoord aUnassignedSpace, float aShare)
+{
+    if (aShare == 1.0f) {
+        // This happens when the numbers we're dividing to get aShare
+        // are equal.  We want to return unassignedSpace exactly, even
+        // if it can't be precisely round-tripped through float.
+        return aUnassignedSpace;
+    }
+    return NSToCoordRound(float(aUnassignedSpace) * aShare);
+}
+
 /* virtual */ void
 FixedTableLayoutStrategy::ComputeColumnWidths(const nsHTMLReflowState& aReflowState)
 {
@ -357,8 +369,8 @@ FixedTableLayoutStrategy::ComputeColumnWidths(const nsHTMLReflowState& aReflowSt
                if (colFrame->GetPrefPercent() == 0.0f) {
                    NS_ASSERTION(colFrame->GetFinalWidth() <= specUndist,
                                 "widths don't add up");
-                    nscoord toAdd = NSToCoordRound(float(unassignedSpace) *
-                       (float(colFrame->GetFinalWidth()) / float(specUndist)));
+                    nscoord toAdd = AllocateUnassigned(unassignedSpace,
+                       float(colFrame->GetFinalWidth()) / float(specUndist));
                    specUndist -= colFrame->GetFinalWidth();
                    colFrame->SetFinalWidth(colFrame->GetFinalWidth() + toAdd);
                    unassignedSpace -= toAdd;
@ -386,8 +398,8 @@ FixedTableLayoutStrategy::ComputeColumnWidths(const nsHTMLReflowState& aReflowSt
                                 "widths don't add up");
                    pctUndist = colFrame->GetPrefPercent();
                }
-                nscoord toAdd = NSToCoordRound(float(unassignedSpace) *
-                    (colFrame->GetPrefPercent() / pctUndist));
+                nscoord toAdd = AllocateUnassigned(unassignedSpace,
+                    colFrame->GetPrefPercent() / pctUndist);
                colFrame->SetFinalWidth(colFrame->GetFinalWidth() + toAdd);
                unassignedSpace -= toAdd;
                pctUndist -= colFrame->GetPrefPercent();
@ -406,12 +418,13 @@ FixedTableLayoutStrategy::ComputeColumnWidths(const nsHTMLReflowState& aReflowSt
                    continue;
                }
                NS_ASSERTION(colFrame->GetFinalWidth() == 0, "yikes");
-                nscoord toAdd = NSToCoordRound(float(unassignedSpace) /
-                                               float(colsLeft));
+                nscoord toAdd = AllocateUnassigned(unassignedSpace,
+                                                   1.0f / float(colsLeft));
                colFrame->SetFinalWidth(toAdd);
                unassignedSpace -= toAdd;
                --colsLeft;
            }
+            NS_ASSERTION(unassignedSpace == 0, "failed to redistribute");
        }
    }
    for (PRInt32 col = 0; col < colCount; ++col) {
--- a/layout/tables/crashtests/467141-1.html
+++ b/layout/tables/crashtests/467141-1.html
@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<html>
+<head>
+</head>
+<body>
+<table width="16211982" cellspacing="0" style="table-layout: fixed;"><tbody><tr><td width="26"></td></tr></tbody></table>
+</body>
+</html>
--- a/layout/tables/crashtests/crashtests.list
+++ b/layout/tables/crashtests/crashtests.list
@ -56,3 +56,4 @@ load 416845-3.html
 load 423514-1.xhtml
 load 456041.html
 load 457115.html
+load 467141-1.html