Fix ControlPaint.DrawBorder rendering (#3952)

Fixes #3945 The DrawBorder overload that takes individual side parameters needed to adjust line ends when drawing in GDI. Manually validated output at different widths and transparencies between 3.1 and 5.0. Will follow up with automated regression tests in a separate PR.
dotnet · Sep 19, 2020 · d8fd73b · d8fd73b
1 parent 4649753
commit d8fd73b
Showing 1 changed file with 19 additions and 8 deletions.
diff --git a/src/System.Windows.Forms/src/System/Windows/Forms/ControlPaint.cs b/src/System.Windows.Forms/src/System/Windows/Forms/ControlPaint.cs
@@ -745,7 +745,8 @@ public static void DrawBorder(Graphics graphics, Rectangle bounds, Color color,
                             using var hpen = new Gdi32.CreatePenScope(topColor);
                             for (int i = 0; i < topWidth; i++)
                             {
-                                hdc.DrawLine(hpen, topLineLefts[i], bounds.Y + i, topLineRights[i], bounds.Y + i);
+                                // Need to add one to the destination point for GDI to render the same as GDI+
+                                hdc.DrawLine(hpen, topLineLefts[i], bounds.Y + i, topLineRights[i] + 1, bounds.Y + i);
                             }
                         }
                         else
@@ -778,7 +779,9 @@ topStyle switch
                             using var hpen = new Gdi32.CreatePenScope(topStyle == ButtonBorderStyle.Inset
                                 ? hlsColor.Darker(1.0f - i * inc)
                                 : hlsColor.Lighter(1.0f - i * inc));
-                            hdc.DrawLine(hpen, topLineLefts[i], bounds.Y + i, topLineRights[i], bounds.Y + i);
+
+                            // Need to add one to the destination point for GDI to render the same as GDI+
+                            hdc.DrawLine(hpen, topLineLefts[i], bounds.Y + i, topLineRights[i] + 1, bounds.Y + i);
                         }
                         break;
                     }
@@ -799,7 +802,8 @@ topStyle switch
                             using var hpen = new Gdi32.CreatePenScope(leftColor);
                             for (int i = 0; i < leftWidth; i++)
                             {
-                                hdc.DrawLine(hpen, bounds.X + i, leftLineTops[i], bounds.X + i, leftLineBottoms[i]);
+                                // Need to add one to the destination point for GDI to render the same as GDI+
+                                hdc.DrawLine(hpen, bounds.X + i, leftLineTops[i], bounds.X + i, leftLineBottoms[i] + 1);
                             }
                         }
                         else
@@ -831,7 +835,9 @@ leftStyle switch
                             using var hpen = new Gdi32.CreatePenScope(leftStyle == ButtonBorderStyle.Inset
                                 ? hlsColor.Darker(1.0f - i * inc)
                                 : hlsColor.Lighter(1.0f - i * inc));
-                            hdc.DrawLine(hpen, bounds.X + i, leftLineTops[i], bounds.X + i, leftLineBottoms[i]);
+
+                            // Need to add one to the destination point for GDI to render the same as GDI+
+                            hdc.DrawLine(hpen, bounds.X + i, leftLineTops[i], bounds.X + i, leftLineBottoms[i] + 1);
                         }
                         break;
                     }
@@ -852,11 +858,12 @@ leftStyle switch
                             using var hpen = new Gdi32.CreatePenScope(bottomColor);
                             for (int i = 0; i < bottomWidth; i++)
                             {
+                                // Need to add one to the destination point for GDI to render the same as GDI+
                                 hdc.DrawLine(
                                     hpen,
                                     bottomLineLefts[i],
                                     bounds.Y + bounds.Height - 1 - i,
-                                    bottomLineRights[i],
+                                    bottomLineRights[i] + 1,
                                     bounds.Y + bounds.Height - 1 - i);
                             }
                         }
@@ -894,11 +901,13 @@ bottomStyle switch
                             using var hpen = new Gdi32.CreatePenScope(bottomStyle != ButtonBorderStyle.Inset
                                 ? hlsColor.Darker(1.0f - i * inc)
                                 : hlsColor.Lighter(1.0f - i * inc));
+
+                            // Need to add one to the destination point for GDI to render the same as GDI+
                             hdc.DrawLine(
                                 hpen,
                                 bottomLineLefts[i],
                                 bounds.Y + bounds.Height - 1 - i,
-                                bottomLineRights[i],
+                                bottomLineRights[i] + 1,
                                 bounds.Y + bounds.Height - 1 - i);
                         }
                         break;
@@ -920,12 +929,13 @@ bottomStyle switch
                             using var hpen = new Gdi32.CreatePenScope(rightColor);
                             for (int i = 0; i < rightWidth; i++)
                             {
+                                // Need to add one to the destination point for GDI to render the same as GDI+
                                 hdc.DrawLine(
                                     hpen,
                                     bounds.X + bounds.Width - 1 - i,
                                     rightLineTops[i],
                                     bounds.X + bounds.Width - 1 - i,
-                                    rightLineBottoms[i]);
+                                    rightLineBottoms[i] + 1);
                             }
                         }
                         else
@@ -963,11 +973,12 @@ rightStyle switch
                                 ? hlsColor.Darker(1.0f - i * inc)
                                 : hlsColor.Lighter(1.0f - i * inc));
 
+                            // Need to add one to the destination point for GDI to render the same as GDI+
                             hdc.DrawLine(hpen,
                                 bounds.X + bounds.Width - 1 - i,
                                 rightLineTops[i],
                                 bounds.X + bounds.Width - 1 - i,
-                                rightLineBottoms[i]);
+                                rightLineBottoms[i] + 1);
                         }
                         break;
                     }