From b42dd39aae4acbe11a19d624a37492dfbb2b29dc Mon Sep 17 00:00:00 2001
From: Calixte Denizet <calixte.denizet@gmail.com>
Date: Tue, 31 Mar 2026 21:47:24 +0200
Subject: [PATCH] Fix radial gradient when the two circles have an intersection

Fix #257.
---
 src/display/pattern_helper.js | 20 +++++++++-----------
 test/test_manifest.json       | 10 ++++++++++
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/src/display/pattern_helper.js b/src/display/pattern_helper.js
index d56e92423..df4f76869 100644
--- a/src/display/pattern_helper.js
+++ b/src/display/pattern_helper.js
@@ -84,21 +84,19 @@ class RadialAxialShadingPattern extends BaseShadingPattern {
     return this._type === "radial";
   }
 
-  // Returns true when the smaller circle's center (p0 when r0 ≤ r1) lies
-  // outside the larger circle. In that case the canvas radial gradient picks
-  // t > 1 solutions for points inside the outer circle and maps them to the
-  // transparent stop we append for extendEnd=false, making the gradient
-  // invisible. A two-pass draw (reversed first, normal on top) fixes this
-  // (see #20851).
-  _isCircleCenterOutside() {
-    if (!this.isRadial() || this._r0 > this._r1) {
+  // Return true when the a circle of a radial gradient isn't fully included in
+  // the other circle, which means that the gradient is conic and we need to
+  // draw the reversed gradient first to correctly render the pattern (see
+  // #20851 and #257).
+  areConic() {
+    if (!this.isRadial()) {
       return false;
     }
     const dist = Math.hypot(
       this._p0[0] - this._p1[0],
       this._p0[1] - this._p1[1]
     );
-    return dist > this._r1;
+    return dist + this._r1 > this._r0 && dist + this._r0 > this._r1;
   }
 
   _createGradient(ctx, transform = null) {
@@ -242,7 +240,7 @@ class RadialAxialShadingPattern extends BaseShadingPattern {
       }
       applyBoundingBox(tmpCtx, this._bbox);
 
-      if (this._isCircleCenterOutside()) {
+      if (this.areConic()) {
         tmpCtx.fillStyle = this._createReversedGradient(tmpCtx);
         tmpCtx.fill();
       }
@@ -257,7 +255,7 @@ class RadialAxialShadingPattern extends BaseShadingPattern {
       // Shading fills are applied relative to the current matrix which is also
       // how canvas gradients work, so there's no need to do anything special
       // here.
-      if (this._isCircleCenterOutside()) {
+      if (this.areConic()) {
         // Draw the reversed gradient first so the normal gradient can
         // correctly overlay it (see _isCircleCenterOutside for details).
         ctx.save();
diff --git a/test/test_manifest.json b/test/test_manifest.json
index 98d6d0192..70782ca2b 100644
--- a/test/test_manifest.json
+++ b/test/test_manifest.json
@@ -14042,5 +14042,15 @@
     "md5": "7796f0131e7d6428c1bf24a73ff13f95",
     "rounds": 1,
     "type": "eq"
+  },
+  {
+    "id": "pdfspec-radial-gradient",
+    "file": "pdfs/pdf.pdf",
+    "md5": "dbdb23c939d2be09b43126c3c56060c7",
+    "link": true,
+    "firstPage": 1144,
+    "lastPage": 1144,
+    "rounds": 1,
+    "type": "eq"
   }
 ]