add more docs/examples from named fiddles.

ignore offscreen, srgb, and animated fiddles for now.

Change-Id: I923131b684865698e6cda138b004930e11f504d5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/263713
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
diff --git a/docs/examples/radial_gradient_test.cpp b/docs/examples/radial_gradient_test.cpp
new file mode 100644
index 0000000..28c1a89
--- /dev/null
+++ b/docs/examples/radial_gradient_test.cpp
@@ -0,0 +1,24 @@
+// Copyright 2020 Google LLC.
+// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
+#include "tools/fiddle/examples.h"
+REG_FIDDLE(radial_gradient_test, 256, 256, false, 0) {
+void draw(SkCanvas* canvas) {
+#define SIZE 121
+    SkScalar half = SIZE * 0.5f;
+    const SkColor preColor = 0xFFFF0000;   // clamp color before start
+    const SkColor postColor = 0xFF0000FF;  // clamp color after end
+    const SkColor color0 = 0xFF000000;
+    const SkColor color1 = 0xFF00FF00;
+
+    SkColor cs[] = {preColor, color0, color1, postColor};
+    SkScalar pos[] = {0, 0, 1, 1};
+
+    auto s = SkGradientShader::MakeRadial({half, half}, half - 10, cs, pos, 4,
+                                          SkTileMode::kClamp);
+
+    SkPaint p;
+    const SkRect rect = SkRect::MakeWH(SIZE, SIZE);
+    p.setShader(s);
+    canvas->drawRect(rect, p);
+}
+}  // END FIDDLE