From 4f67a18a3fb5b3d045c7c48ab1976d8d1656bb31 Mon Sep 17 00:00:00 2001
From: reuk <reuk@users.noreply.github.com>
Date: Tue, 30 May 2023 16:48:40 +0100
Subject: [PATCH] EdgeTable: Avoid integer truncation when rendering paths with
 large coordinates

Previously, if the PathFlatteningIterator returned a line segment with
very large x or y positions, the result of
    roundToInt (iter.y1 * 256.0f)
could be incorrect, if the result was too large to fit in an int.

Using int64_t to store intermediate results, converting to int when
updating the edge table itself produces accurate results for a wider
range of inputs.
---
 .../juce_graphics/geometry/juce_EdgeTable.cpp | 24 ++++++++-----------
 1 file changed, 10 insertions(+), 14 deletions(-)

diff --git a/modules/juce_graphics/geometry/juce_EdgeTable.cpp b/modules/juce_graphics/geometry/juce_EdgeTable.cpp
index 7b66053804..7b9813e1a7 100644
--- a/modules/juce_graphics/geometry/juce_EdgeTable.cpp
+++ b/modules/juce_graphics/geometry/juce_EdgeTable.cpp
@@ -46,17 +46,17 @@ EdgeTable::EdgeTable (Rectangle<int> area, const Path& path, const AffineTransfo
         t += lineStrideElements;
     }
 
-    auto leftLimit   = scale * bounds.getX();
-    auto topLimit    = scale * bounds.getY();
-    auto rightLimit  = scale * bounds.getRight();
-    auto heightLimit = scale * bounds.getHeight();
+    auto leftLimit   = scale * static_cast<int64_t> (bounds.getX());
+    auto topLimit    = scale * static_cast<int64_t> (bounds.getY());
+    auto rightLimit  = scale * static_cast<int64_t> (bounds.getRight());
+    auto heightLimit = scale * static_cast<int64_t> (bounds.getHeight());
 
     PathFlatteningIterator iter (path, transform);
 
     while (iter.next())
     {
-        auto y1 = roundToInt (iter.y1 * 256.0f);
-        auto y2 = roundToInt (iter.y2 * 256.0f);
+        auto y1 = static_cast<int64_t> (iter.y1 * 256.0f);
+        auto y2 = static_cast<int64_t> (iter.y2 * 256.0f);
 
         if (y1 != y2)
         {
@@ -82,19 +82,15 @@ EdgeTable::EdgeTable (Rectangle<int> area, const Path& path, const AffineTransfo
             {
                 const double startX = 256.0f * iter.x1;
                 const double multiplier = (iter.x2 - iter.x1) / (iter.y2 - iter.y1);
-                auto stepSize = jlimit (1, 256, 256 / (1 + (int) std::abs (multiplier)));
+                auto stepSize = static_cast<int64_t> (jlimit (1, 256, 256 / (1 + (int) std::abs (multiplier))));
 
                 do
                 {
                     auto step = jmin (stepSize, y2 - y1, 256 - (y1 & 255));
-                    auto x = roundToInt (startX + multiplier * ((y1 + (step >> 1)) - startY));
+                    auto x = static_cast<int64_t> (startX + multiplier * static_cast<double> ((y1 + (step >> 1)) - startY));
+                    auto clampedX = static_cast<int> (jlimit (leftLimit, rightLimit - 1, x));
 
-                    if (x < leftLimit)
-                        x = leftLimit;
-                    else if (x >= rightLimit)
-                        x = rightLimit - 1;
-
-                    addEdgePoint (x, y1 / scale, direction * step);
+                    addEdgePoint (clampedX, static_cast<int> (y1 / scale), static_cast<int> (direction * step));
                     y1 += step;
                 }
                 while (y1 < y2);