Create libgfx, starting with FloatRect

Creates libgfx, the future home of everything currently in libui and
libgui, which will be rigorously checked with -Weverything (with a few
common-sense exceptions) and clang-tidy and formatted using the included
.clang-format file.

Starts by moving FloatRect out of services/surfaceflinger since it will
be used by other libgfx primitives later.

Test: m
Change-Id: I5045ac089020e6ee380e81e8735117c500264b37
diff --git a/include/gfx/.clang-format b/include/gfx/.clang-format
new file mode 100644
index 0000000..86763a0
--- /dev/null
+++ b/include/gfx/.clang-format
@@ -0,0 +1,11 @@
+BasedOnStyle: Google
+
+AccessModifierOffset: -2
+AllowShortFunctionsOnASingleLine: Inline
+BinPackParameters: false
+ColumnLimit: 100
+CommentPragmas: NOLINT:.*
+ConstructorInitializerAllOnOneLineOrOnePerLine: true
+ConstructorInitializerIndentWidth: 2
+ContinuationIndentWidth: 8
+IndentWidth: 4
diff --git a/include/gfx/FloatRect.h b/include/gfx/FloatRect.h
new file mode 100644
index 0000000..6be5e22
--- /dev/null
+++ b/include/gfx/FloatRect.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+namespace android {
+namespace gfx {
+
+class FloatRect {
+  public:
+    FloatRect() = default;
+    constexpr FloatRect(float _left, float _top, float _right, float _bottom)
+      : left(_left), top(_top), right(_right), bottom(_bottom) {}
+
+    float getWidth() const { return right - left; }
+    float getHeight() const { return bottom - top; }
+
+    float left = 0.0f;
+    float top = 0.0f;
+    float right = 0.0f;
+    float bottom = 0.0f;
+};
+
+inline bool operator==(const FloatRect& a, const FloatRect& b) {
+    return a.left == b.left && a.top == b.top && a.right == b.right && a.bottom == b.bottom;
+}
+
+}  // namespace gfx
+}  // namespace android
diff --git a/include/ui/Rect.h b/include/ui/Rect.h
index a8513a9..d4eea02 100644
--- a/include/ui/Rect.h
+++ b/include/ui/Rect.h
@@ -17,6 +17,7 @@
 #ifndef ANDROID_UI_RECT
 #define ANDROID_UI_RECT
 
+#include <gfx/FloatRect.h>
 #include <utils/Flattenable.h>
 #include <utils/Log.h>
 #include <utils/TypeHelpers.h>
@@ -177,11 +178,15 @@
     // this calculates (Region(*this) - exclude).bounds() efficiently
     Rect reduce(const Rect& exclude) const;
 
-
     // for backward compatibility
     inline int32_t width() const { return getWidth(); }
     inline int32_t height() const { return getHeight(); }
     inline void set(const Rect& rhs) { operator = (rhs); }
+
+    gfx::FloatRect toFloatRect() const {
+        return {static_cast<float>(left), static_cast<float>(top),
+                static_cast<float>(right), static_cast<float>(bottom)};
+    }
 };
 
 ANDROID_BASIC_TYPES_TRAITS(Rect)