From 4a48dd2d5dacb9a0ba8fdc357d56eb13e20680c4 Mon Sep 17 00:00:00 2001
From: Kjell Ahlstedt <kjellahlstedt@gmail.com>
Date: Wed, 12 Aug 2020 16:55:40 +0200
Subject: Add Context::get_source_for_surface()

Fixes #5
---
 cairomm/context.cc    | 15 +++++++++++++++
 cairomm/context.h     | 10 +++++++++-
 tests/test-context.cc | 17 +++++++++++++++++
 3 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/cairomm/context.cc b/cairomm/context.cc
index dd2c6dc..a4125ba 100644
--- a/cairomm/context.cc
+++ b/cairomm/context.cc
@@ -701,6 +701,21 @@ RefPtr<const Pattern> Context::get_source() const
   return RefPtr<const Pattern>::cast_const (get_pattern_wrapper (pattern));
 }
 
+RefPtr<SurfacePattern> Context::get_source_for_surface()
+{
+  auto pattern = cairo_get_source(cobj());
+  check_object_status_and_throw_exception(*this);
+  auto pattern_type = cairo_pattern_get_type(pattern);
+  if (pattern_type != CAIRO_PATTERN_TYPE_SURFACE)
+    return {};
+  return RefPtr<SurfacePattern>(new SurfacePattern(pattern, false /* does not have reference */));
+}
+
+RefPtr<const SurfacePattern> Context::get_source_for_surface() const
+{
+  return const_cast<Context*>(this)->get_source_for_surface();
+}
+
 double Context::get_tolerance() const
 {
   const auto result = cairo_get_tolerance(const_cast<cobject*>(cobj()));
diff --git a/cairomm/context.h b/cairomm/context.h
index 93ab2ce..c8c1c43 100644
--- a/cairomm/context.h
+++ b/cairomm/context.h
@@ -1300,10 +1300,18 @@ public:
   Operator get_operator() const;
 
   /// @{
-  /** Gets the current source pattern for the Context
+  /** Gets the current source pattern for the %Context
    */
   RefPtr<Pattern> get_source();
   RefPtr<const Pattern> get_source() const;
+
+  /** Gets the current source surface pattern for the %Context, if any.
+   *
+   * @returns The source pattern, if it is a surface pattern,
+   *          else an empty RefPtr.
+   */
+  RefPtr<SurfacePattern> get_source_for_surface();
+  RefPtr<const SurfacePattern> get_source_for_surface() const;
   /// @}
 
   /** Gets the current tolerance value, as set by set_tolerance()
diff --git a/tests/test-context.cc b/tests/test-context.cc
index d2c359b..4d0a959 100644
--- a/tests/test-context.cc
+++ b/tests/test-context.cc
@@ -84,6 +84,7 @@ BOOST_AUTO_TEST_CASE(test_source)
     Cairo::SolidPattern::create_rgb (1.0, 0.5, 0.25);
   auto gradient_pattern =
     Cairo::LinearGradient::create (0.0, 0.0, 1.0, 1.0);
+  auto surface = Cairo::ImageSurface::create(Cairo::FORMAT_ARGB32, 1, 1);
 
   cr->set_source (solid_pattern);
   {
@@ -101,6 +102,13 @@ BOOST_AUTO_TEST_CASE(test_source)
     auto retrieved_solid2 =
       Cairo::RefPtr<const Cairo::SolidPattern>::cast_dynamic(cr2->get_source ());
     BOOST_REQUIRE (retrieved_solid2);
+
+    // Check that get_source_for_surface() returns an empty RefPtr,
+    // when the source is not a surface.
+    auto surface_pattern = cr->get_source_for_surface();
+    BOOST_CHECK(!surface_pattern);
+    auto surface_pattern2 = cr2->get_source_for_surface();
+    BOOST_CHECK(!surface_pattern2);
   }
 
   cr->set_source (gradient_pattern);
@@ -127,6 +135,7 @@ BOOST_AUTO_TEST_CASE(test_source)
     BOOST_CHECK_EQUAL (0.5, gx);
     BOOST_CHECK_EQUAL (0.25, bx);
   }
+
   cr->set_source_rgba (0.1, 0.3, 0.5, 0.7);
   {
     auto solid =
@@ -139,6 +148,14 @@ BOOST_AUTO_TEST_CASE(test_source)
     BOOST_CHECK_EQUAL (0.5, bx);
     BOOST_CHECK_EQUAL (0.7, ax);
   }
+
+  cr->set_source (surface, 0.0, 0.0);
+  {
+    auto surface_pattern = cr->get_source_for_surface();
+    BOOST_REQUIRE (surface_pattern);
+    surface_pattern->set_filter(Cairo::FILTER_NEAREST);
+    BOOST_CHECK_EQUAL (Cairo::FILTER_NEAREST, surface_pattern->get_filter());
+  }
 }
 
 BOOST_AUTO_TEST_CASE(test_tolerance)
-- 
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