[PATCH 0/2] MR6685: win32u: Fixes for arc drawing.

[PATCH 1/2] win32u: Allocate the whole max_points for the top_points array.

[Elizabeth Figura]

From: Elizabeth Figura

The eventual array will only need 1/2 of the points, but we need the whole
max_points to generate the ellipse top half.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=57306
---
 dlls/win32u/dibdrv/graphics.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/win32u/dibdrv/graphics.c b/dlls/win32u/dibdrv/graphics.c
index 414737fa8ca..197e91a7f5d 100644
--- a/dlls/win32u/dibdrv/graphics.c
+++ b/dlls/win32u/dibdrv/graphics.c
@@ -1529,7 +1529,7 @@ BOOL dibdrv_RoundRect( PHYSDEV dev, INT left, INT top, INT right, INT bottom,
      * is exactly as many as in one ellipse arc. */
     max_points = get_arc_max_points( dc, &rect );
     points = malloc( max_points * sizeof(*points) );
-    top_points = malloc( max_points / 2 * sizeof(*points) );
+    top_points = malloc( max_points * sizeof(*points) );
     if (!points || !top_points)
     {
         free( points );

[PATCH 2/2] win32u: Always select the point that's closer to the ellipse.

[Elizabeth Figura]

From: Elizabeth Figura

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=57296
---
 dlls/win32u/dibdrv/graphics.c | 45 ++++++++++++++++++++++-------------
 1 file changed, 29 insertions(+), 16 deletions(-)

diff --git a/dlls/win32u/dibdrv/graphics.c b/dlls/win32u/dibdrv/graphics.c
index 197e91a7f5d..cc62d6a681b 100644
--- a/dlls/win32u/dibdrv/graphics.c
+++ b/dlls/win32u/dibdrv/graphics.c
@@ -217,7 +217,7 @@ static unsigned int generate_ellipse_top_half( const DC *dc, double width, doubl
         double dy = -(a * pt.x + b * pt.y);
         int x_inc = (dx > 0 ? 1 : -1);
         int y_inc = (dy > 0 ? 1 : -1);
-        double sigma;
+        double sigma1, sigma2;

points[pos++] = pt;

@@ -226,29 +226,42 @@ static unsigned int generate_ellipse_top_half( const DC *dc, double width, doubl
             /* Increment y, maybe increment x. */
             pt.y += y_inc;

-            sigma = (a * pt.x * pt.x) + (2 * b * pt.x * pt.y) + (c * pt.y * pt.y) - d;
-            /* σ < 0 if the next point would be inside the ellipse.
-             * If we are moving towards a vertical or horizontal tangent point,
-             * and (x, y+1) is outside the ellipse, then it's certainly
-             * closer to the ellipse than (x-1, y+1). [Same for the 180°
-             * rotation.] Hence we want to increment x if σ < 0.
-             * If we are moving away from a tangent point, the opposite applies,
-             * and we want to increment x if σ > 0.
-             * We are moving towards a tangent point if (dx > 0 XOR dy > 0),
-             * so want to increment x if (dx > 0 XOR dy > 0 XOR σ > 0). */
-            if (sigma != 0.0 && (dx > 0) ^ (dy > 0) ^ (sigma > 0))
+            /* If this point has 45° slope, and it's directly adjacent to one
+             * we just wrote, using the algorithm as-is will select this point
+             * and then the one horizontally adjacent to it (our reflection
+             * across the 45° line.) This creates an L-shaped corner, which we
+             * don't want. Force incrementing X to skip that corner. */
+            if (fabs(b * pt.x + c * pt.y) == fabs(a * pt.x + b * pt.y))
+            {
                 pt.x += x_inc;
+                continue;
+            }
+
+            sigma1 = (a * pt.x * pt.x) + (2 * b * pt.x * pt.y) + (c * pt.y * pt.y) - d;
+            pt.x += x_inc;
+            sigma2 = (a * pt.x * pt.x) + (2 * b * pt.x * pt.y) + (c * pt.y * pt.y) - d;
+
+            /* Pick whichever point is closer to the ellipse. */
+            if (fabs(sigma2) > fabs(sigma1))
+                pt.x -= x_inc;
         }
         else
         {
             /* Increment x, maybe increment y. */
             pt.x += x_inc;

-            sigma = (a * pt.x * pt.x) + (2 * b * pt.x * pt.y) + (c * pt.y * pt.y) - d;
-            /* As above, but we are moving towards a tangent point if the
-             * opposite condition is true, i.e. (dx < 0 XOR dy > 0). */
-            if (sigma != 0.0 && (dx < 0) ^ (dy > 0) ^ (sigma > 0))
+            if (fabs(b * pt.x + c * pt.y) == fabs(a * pt.x + b * pt.y))
+            {
                 pt.y += y_inc;
+                continue;
+            }
+
+            sigma1 = (a * pt.x * pt.x) + (2 * b * pt.x * pt.y) + (c * pt.y * pt.y) - d;
+            pt.y += y_inc;
+            sigma2 = (a * pt.x * pt.x) + (2 * b * pt.x * pt.y) + (c * pt.y * pt.y) - d;
+
+            if (fabs(sigma2) > fabs(sigma1))
+                pt.y -= y_inc;
         }
     }
     return pos;

[PATCH 2/2] win32u: Always select the point that's closer to the ellipse.

[Marvin]

Hi,

It looks like your patch introduced the new failures shown below.
Please investigate and fix them before resubmitting your patch.
If they are not new, fixing them anyway would help a lot. Otherwise
please ask for the known failures list to be updated.

The full results can be found at:
https://testbot.winehq.org/JobDetails.pl?Key=149049

Your paranoid android.

=== debian11 (build log) ===

error: patch failed: dlls/win32u/dibdrv/graphics.c:217
Task: Patch failed to apply

=== debian11b (build log) ===

error: patch failed: dlls/win32u/dibdrv/graphics.c:217
Task: Patch failed to apply

[PATCH 0/2] MR6685: win32u: Fixes for arc drawing. - approved

[Huw Davies (＠huw)]

This merge request was approved by Huw Davies.