LibIPC+IPCCompiler: Add IPC::Decoder, let classes decode themselves

This shaves ~5 seconds off of a full build, not too bad. Also it just
seems nicer to push this logic out to classes. It could be better but
it's a start. :^)

Libraries/LibGfx/Color.cpp

@@ -25,6 +25,7 @@
  */
 
 #include <AK/Assertions.h>
+#include <AK/BufferStream.h>
 #include <AK/Optional.h>
 #include <AK/String.h>
 #include <LibGfx/Color.h>
@@ -344,7 +345,17 @@ Optional<Color> Color::from_string(const StringView& string)
 }
 }
 
-inline const LogStream& operator<<(const LogStream& stream, Color value)
+const LogStream& operator<<(const LogStream& stream, Color value)
 {
     return stream << value.to_string();
 }
+
+bool IPC::decode(BufferStream& stream, Color& color)
+{
+    u32 rgba;
+    stream >> rgba;
+    if (stream.handle_read_failure())
+        return false;
+    color = Color::from_rgba(rgba);
+    return true;
+}

Libraries/LibGfx/Color.h

@@ -278,3 +278,7 @@ const LogStream& operator<<(const LogStream&, Color);
 }
 
 using Gfx::Color;
+
+namespace IPC {
+bool decode(BufferStream&, Gfx::Color&);
+}

Libraries/LibGfx/Point.cpp

@@ -24,6 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <AK/BufferStream.h>
 #include <AK/String.h>
 #include <LibGfx/Point.h>
 
@@ -40,3 +41,19 @@ const LogStream& operator<<(const LogStream& stream, const Point& value)
 }
 
 }
+
+namespace IPC {
+
+bool decode(BufferStream& stream, Gfx::Point& point)
+{
+    int x;
+    int y;
+    stream >> x;
+    stream >> y;
+    if (stream.handle_read_failure())
+        return false;
+    point = { x, y };
+    return true;
+}
+
+}

Libraries/LibGfx/Point.h

@@ -159,3 +159,7 @@ private:
 const LogStream& operator<<(const LogStream&, const Point&);
 
 }
+
+namespace IPC {
+bool decode(BufferStream&, Gfx::Point&);
+}

Libraries/LibGfx/Rect.cpp

@@ -142,3 +142,19 @@ const LogStream& operator<<(const LogStream& stream, const Rect& value)
 }
 
 }
+
+namespace IPC {
+
+bool decode(BufferStream& stream, Gfx::Rect& rect)
+{
+    Gfx::Point point;
+    Gfx::Size size;
+    if (!decode(stream, point))
+        return false;
+    if (!decode(stream, size))
+        return false;
+    rect = { point, size };
+    return true;
+}
+
+}

Libraries/LibGfx/Rect.h

@@ -334,3 +334,7 @@ inline void Point::constrain(const Rect& rect)
 const LogStream& operator<<(const LogStream&, const Rect&);
 
 }
+
+namespace IPC {
+bool decode(BufferStream&, Gfx::Rect&);
+}

Libraries/LibGfx/Size.cpp

@@ -24,6 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <AK/BufferStream.h>
 #include <AK/String.h>
 #include <LibGfx/Size.h>
 
@@ -40,3 +41,19 @@ const LogStream& operator<<(const LogStream& stream, const Size& value)
 }
 
 }
+
+namespace IPC {
+
+bool decode(BufferStream& stream, Gfx::Size& size)
+{
+    int width;
+    int height;
+    stream >> width;
+    stream >> height;
+    if (stream.handle_read_failure())
+        return false;
+    size = { width, height };
+    return true;
+}
+
+}

Libraries/LibGfx/Size.h

@@ -111,3 +111,7 @@ private:
 const LogStream& operator<<(const LogStream&, const Size&);
 
 }
+
+namespace IPC {
+bool decode(BufferStream&, Gfx::Size&);
+}