From 2af8bb14d7e3d7f9466d2160dd36158128e8714b Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Thu, 7 Apr 2022 14:05:30 +0200
Subject: [PATCH] LibGfx: Add AffineTransform::map_to_quad(Rect)

Unlike map(Rect) which returns a Rect, mapping a Rect to a Quad allows
us to represent the actual result of mapping all four corners of the
Rect through the matrix.
---
 Userland/Libraries/LibGfx/AffineTransform.cpp | 13 ++++++++++++-
 Userland/Libraries/LibGfx/AffineTransform.h   |  4 +++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/Userland/Libraries/LibGfx/AffineTransform.cpp b/Userland/Libraries/LibGfx/AffineTransform.cpp
index 1c60eb508d..7347df38a5 100644
--- a/Userland/Libraries/LibGfx/AffineTransform.cpp
+++ b/Userland/Libraries/LibGfx/AffineTransform.cpp
@@ -1,11 +1,12 @@
 /*
- * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include <AK/Optional.h>
 #include <LibGfx/AffineTransform.h>
+#include <LibGfx/Quad.h>
 #include <LibGfx/Rect.h>
 
 namespace Gfx {
@@ -211,4 +212,14 @@ IntRect AffineTransform::map(IntRect const& rect) const
     return enclosing_int_rect(map(FloatRect(rect)));
 }
 
+Quad<float> AffineTransform::map_to_quad(Rect<float> const& rect) const
+{
+    return {
+        map(rect.top_left()),
+        map(rect.top_right()),
+        map(rect.bottom_right()),
+        map(rect.bottom_left()),
+    };
+}
+
 }
diff --git a/Userland/Libraries/LibGfx/AffineTransform.h b/Userland/Libraries/LibGfx/AffineTransform.h
index 87a8f30b7a..5069c6ae57 100644
--- a/Userland/Libraries/LibGfx/AffineTransform.h
+++ b/Userland/Libraries/LibGfx/AffineTransform.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -37,6 +37,8 @@ public:
     template<typename T>
     Rect<T> map(Rect<T> const&) const;
 
+    Quad<float> map_to_quad(Rect<float> const&) const;
+
     [[nodiscard]] ALWAYS_INLINE float a() const { return m_values[0]; }
     [[nodiscard]] ALWAYS_INLINE float b() const { return m_values[1]; }
     [[nodiscard]] ALWAYS_INLINE float c() const { return m_values[2]; }