From 1202ab8348e63cbaf3146346d1988484869c36a4 Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Sun, 25 Feb 2024 11:35:51 -0500
Subject: [PATCH 01/14] core: config: Add pen protocol version to config

---
 src/core/generic/config.hpp      |  9 +++++++++
 src/core/linux/config-loader.hpp | 14 ++++++++++++++
 src/core/linux/errors.hpp        |  3 +++
 3 files changed, 26 insertions(+)

diff --git a/src/core/generic/config.hpp b/src/core/generic/config.hpp
index fb90d6f..075a784 100644
--- a/src/core/generic/config.hpp
+++ b/src/core/generic/config.hpp
@@ -17,6 +17,14 @@ namespace iptsd::core {
 
 class Config {
 public:
+	// Enum to denote which Pen Protocol is being used.
+	enum class MPPVersion {
+		// Used for Microsoft Pen Protocol v1 compliant pens.
+		V1,
+		// Used for Microsoft Pen Protocol v2 compliant pens.
+		V2,
+	};
+
 	// [Config]
 	bool invert_x = false;
 	bool invert_y = false;
@@ -49,6 +57,7 @@ class Config {
 	// [Stylus]
 	bool stylus_disable = false;
 	f64 stylus_tip_distance = 0;
+	MPPVersion mpp_version = MPPVersion::V1;
 
 	// [DFT]
 	usize dft_position_min_amp = 50;
diff --git a/src/core/linux/config-loader.hpp b/src/core/linux/config-loader.hpp
index 61b57a3..f9b45c2 100644
--- a/src/core/linux/config-loader.hpp
+++ b/src/core/linux/config-loader.hpp
@@ -161,6 +161,7 @@ class ConfigLoader {
 
 		this->get(ini, "Stylus", "Disable", m_config.stylus_disable);
 		this->get(ini, "Stylus", "TipDistance", m_config.stylus_tip_distance);
+		this->get(ini, "Stylus", "MPPVersion", m_config.mpp_version);
 
 		this->get(ini, "DFT", "PositionMinAmp", m_config.dft_position_min_amp);
 		this->get(ini, "DFT", "PositionMinMag", m_config.dft_position_min_mag);
@@ -199,6 +200,19 @@ class ConfigLoader {
 			value = gsl::narrow_cast<T>(ini.GetReal(section, name, value));
 		else if constexpr (std::is_same_v<T, std::string>)
 			value = ini.GetString(section, name, value);
+		else if constexpr (std::is_same_v<T, Config::MPPVersion>) {
+			// Parse the pen protocol verison by first reading into a string.
+			const auto mpp_version = ini.GetString(section, name, "");
+			if (!mpp_version.empty()) {
+				if (mpp_version == "v1") {
+					value = Config::MPPVersion::V1;
+				} else if (mpp_version == "v2") {
+					value = Config::MPPVersion::V2;
+				} else {
+					throw common::Error<Error::ParsingInvalidValue> {"Stylus mpp_version was not 'v1' or 'v2', got: " + mpp_version};
+				}
+			}
+		}
 		else
 			throw common::Error<Error::ParsingTypeNotImplemented> {typeid(T).name()};
 	}
diff --git a/src/core/linux/errors.hpp b/src/core/linux/errors.hpp
index 80a4478..b152b7d 100644
--- a/src/core/linux/errors.hpp
+++ b/src/core/linux/errors.hpp
@@ -9,6 +9,7 @@ namespace iptsd::core::linux {
 
 enum class Error {
 	ParsingFailed,
+	ParsingInvalidValue,
 	ParsingTypeNotImplemented,
 	RunnerInitError,
 
@@ -25,6 +26,8 @@ inline std::string format_as(Error err)
 	switch (err) {
 	case Error::ParsingFailed:
 		return "core: linux: Failed to parse INI file {}!";
+	case Error::ParsingInvalidValue:
+		return "core: linux: Parsing encountered invalid value {}!";
 	case Error::ParsingTypeNotImplemented:
 		return "core: linux: Parsing not implemented for type {}!";
 	case Error::RunnerInitError:

From b844a0783e523b3f07615190d97d06a0211f939a Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Sun, 25 Feb 2024 12:52:34 -0500
Subject: [PATCH 02/14] ipts: Handle MPP v2 button detection.

---
 src/core/generic/dft.hpp  | 51 +++++++++++++++++++++++++++++++++++++++
 src/ipts/parser.hpp       |  3 ++-
 src/ipts/protocol/dft.hpp |  1 +
 3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/src/core/generic/dft.hpp b/src/core/generic/dft.hpp
index ee297b0..558a329 100644
--- a/src/core/generic/dft.hpp
+++ b/src/core/generic/dft.hpp
@@ -28,6 +28,12 @@ class DftStylus {
 	i32 m_imag = 0;
 	std::optional<u32> m_group = std::nullopt;
 
+	// This is a bit of a hack, for the MPP v2 button detection we only
+	// care about the first 0x0a dft window, but there's two in the frame,
+	// here we keep track of the group when 0x0a was encountered, this
+	// allows comparing against this group and only using the first 0x0a
+	// frame.
+	std::optional<u32> m_dft_0x0a_group = std::nullopt;
 public:
 	DftStylus(Config config, const std::optional<const ipts::Metadata> &metadata)
 		: m_config {std::move(config)},
@@ -50,6 +56,9 @@ class DftStylus {
 		case ipts::protocol::dft::Type::Pressure:
 			this->handle_pressure(dft);
 			break;
+		case ipts::protocol::dft::Type::Dft0x0a:
+			this->handle_dft_0x0a(dft);
+			break;
 		default:
 			// Ignored
 			break;
@@ -160,6 +169,11 @@ class DftStylus {
 	 */
 	void handle_button(const ipts::DftWindow &dft)
 	{
+		// Only use this for pen v1.
+		if (m_config.mpp_version != Config::MPPVersion::V1) {
+			return;
+		}
+
 		if (dft.x.empty())
 			return;
 
@@ -211,6 +225,43 @@ class DftStylus {
 		}
 	}
 
+
+	/*!
+	 * Determines the current button state from the 0x0a frame.
+	 */
+	void handle_dft_0x0a(const ipts::DftWindow &dft)
+	{
+		if (m_config.mpp_version != Config::MPPVersion::V2) {
+			return;
+		}
+
+		// Second time we see the 0x0a frame in this group, skip it.
+		if (!dft.group.has_value() || m_dft_0x0a_group == dft.group)
+			return;
+
+		m_dft_0x0a_group = dft.group;
+
+		// Now, we can process the frame to determine button state.
+		// First, collapse x and y, they convey the same information.
+		const auto mag_4 = dft.x[4].magnitude + dft.y[4].magnitude;
+		const auto mag_5 = dft.x[5].magnitude + dft.y[5].magnitude;
+		const auto threshold = 2 * m_config.dft_button_min_mag;
+
+		if (mag_4 < threshold && mag_5 < threshold) {
+			// Not enough signal, lets disable the button
+			m_stylus.button = false;
+			m_stylus.rubber = false;
+			return;
+		}
+
+		// One of them is above the threshold, if 5 is higher than 4, button
+		// is held.
+		m_stylus.button = mag_4 < mag_5;
+
+		// This needs a todo still :)
+		m_stylus.rubber = false;
+	}
+
 	/*!
 	 * Interpolates the current stylus position from a list of antenna measurements.
 	 *
diff --git a/src/ipts/parser.hpp b/src/ipts/parser.hpp
index dff29f8..0bea855 100644
--- a/src/ipts/parser.hpp
+++ b/src/ipts/parser.hpp
@@ -16,6 +16,8 @@
 #include <common/reader.hpp>
 #include <common/types.hpp>
 
+#include <spdlog/spdlog.h>
+
 #include <gsl/gsl>
 
 #include <functional>
@@ -71,7 +73,6 @@ class Parser {
 	{
 		Reader reader(data);
 		reader.skip(header);
-
 		this->parse_hid_frame(reader);
 	}
 
diff --git a/src/ipts/protocol/dft.hpp b/src/ipts/protocol/dft.hpp
index f6267bc..ee23016 100644
--- a/src/ipts/protocol/dft.hpp
+++ b/src/ipts/protocol/dft.hpp
@@ -17,6 +17,7 @@ enum class Type : u8 {
 	Position = 6,
 	Button = 9,
 	Pressure = 11,
+	Dft0x0a = 0x0a,
 };
 
 struct [[gnu::packed]] Metadata {

From c80f1f5ae451be402cfcf539650623380b5e8738 Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Sun, 25 Feb 2024 12:52:49 -0500
Subject: [PATCH 03/14] etc: presets: Add Surface Pro 9 preset

---
 etc/presets/surface-pro-9.conf | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 etc/presets/surface-pro-9.conf

diff --git a/etc/presets/surface-pro-9.conf b/etc/presets/surface-pro-9.conf
new file mode 100644
index 0000000..3bd5451
--- /dev/null
+++ b/etc/presets/surface-pro-9.conf
@@ -0,0 +1,6 @@
+[Stylus]
+MPPVersion = v2
+
+[DFT]
+ButtonMinMag = 1000
+PositionMinMag = 500

From c8cfcecdec9e721aaed7323eccf227c50d353b91 Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Sun, 25 Feb 2024 13:13:45 -0500
Subject: [PATCH 04/14] ipts: Fix eraser for MPP v2, change button threshold.

---
 etc/presets/surface-pro-9.conf |  3 ++-
 src/core/generic/dft.hpp       | 18 +++++++-----------
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/etc/presets/surface-pro-9.conf b/etc/presets/surface-pro-9.conf
index 3bd5451..9e4680f 100644
--- a/etc/presets/surface-pro-9.conf
+++ b/etc/presets/surface-pro-9.conf
@@ -2,5 +2,6 @@
 MPPVersion = v2
 
 [DFT]
-ButtonMinMag = 1000
+# This is really high, but SP2 creates a strong signal.
+ButtonMinMag = 50000
 PositionMinMag = 500
diff --git a/src/core/generic/dft.hpp b/src/core/generic/dft.hpp
index 558a329..9b2e862 100644
--- a/src/core/generic/dft.hpp
+++ b/src/core/generic/dft.hpp
@@ -169,11 +169,6 @@ class DftStylus {
 	 */
 	void handle_button(const ipts::DftWindow &dft)
 	{
-		// Only use this for pen v1.
-		if (m_config.mpp_version != Config::MPPVersion::V1) {
-			return;
-		}
-
 		if (dft.x.empty())
 			return;
 
@@ -199,7 +194,10 @@ class DftStylus {
 			rubber = val > 0;
 		}
 
-		m_stylus.button = button;
+		// Only set the button value if we're using a v1 pen.
+		if (m_config.mpp_version == Config::MPPVersion::V1) {
+			m_stylus.button = button;
+		}
 		m_stylus.rubber = rubber;
 	}
 
@@ -227,7 +225,9 @@ class DftStylus {
 
 
 	/*!
-	 * Determines the current button state from the 0x0a frame.
+	 * Determines the current button state from the 0x0a frame, it can
+	 * only be used for MPP v2 pens. The eraser is still obtained from the
+     * phase using the button frame.
 	 */
 	void handle_dft_0x0a(const ipts::DftWindow &dft)
 	{
@@ -250,16 +250,12 @@ class DftStylus {
 		if (mag_4 < threshold && mag_5 < threshold) {
 			// Not enough signal, lets disable the button
 			m_stylus.button = false;
-			m_stylus.rubber = false;
 			return;
 		}
 
 		// One of them is above the threshold, if 5 is higher than 4, button
 		// is held.
 		m_stylus.button = mag_4 < mag_5;
-
-		// This needs a todo still :)
-		m_stylus.rubber = false;
 	}
 
 	/*!

From b4b466a460f1d9187afa21f0ceb7db274db65199 Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Sun, 25 Feb 2024 17:41:10 -0500
Subject: [PATCH 05/14] core: linux: Improve configuration logging

Print paths to loaded configuration files, warn if no configuration file
is loaded at all.
---
 src/core/generic/dft.hpp         |  4 ++--
 src/core/linux/config-loader.hpp | 20 ++++++++++++++++----
 src/ipts/parser.hpp              |  2 --
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/src/core/generic/dft.hpp b/src/core/generic/dft.hpp
index 9b2e862..eb01368 100644
--- a/src/core/generic/dft.hpp
+++ b/src/core/generic/dft.hpp
@@ -34,6 +34,7 @@ class DftStylus {
 	// allows comparing against this group and only using the first 0x0a
 	// frame.
 	std::optional<u32> m_dft_0x0a_group = std::nullopt;
+
 public:
 	DftStylus(Config config, const std::optional<const ipts::Metadata> &metadata)
 		: m_config {std::move(config)},
@@ -223,11 +224,10 @@ class DftStylus {
 		}
 	}
 
-
 	/*!
 	 * Determines the current button state from the 0x0a frame, it can
 	 * only be used for MPP v2 pens. The eraser is still obtained from the
-     * phase using the button frame.
+	 * phase using the button frame.
 	 */
 	void handle_dft_0x0a(const ipts::DftWindow &dft)
 	{
diff --git a/src/core/linux/config-loader.hpp b/src/core/linux/config-loader.hpp
index f9b45c2..5dd76c9 100644
--- a/src/core/linux/config-loader.hpp
+++ b/src/core/linux/config-loader.hpp
@@ -27,6 +27,8 @@ class ConfigLoader {
 	Config m_config {};
 	DeviceInfo m_info;
 
+	bool m_loaded_config {false};
+
 public:
 	ConfigLoader(const DeviceInfo &info, const std::optional<const ipts::Metadata> &metadata)
 		: m_info {info}
@@ -48,14 +50,21 @@ class ConfigLoader {
 		 * known working main system configuration.
 		 */
 		if (const char *config_file_path = std::getenv("IPTSD_CONFIG_FILE")) {
+			spdlog::info("Loading config {}, specified with IPTSD_CONFIG_FILE.",
+			             config_file_path);
 			this->load_file(config_file_path);
 			return;
 		}
 
-		if (std::filesystem::exists(common::buildopts::ConfigFile))
+		if (std::filesystem::exists(common::buildopts::ConfigFile)) {
+			spdlog::info("Loading config {}.", common::buildopts::ConfigFile);
 			this->load_file(common::buildopts::ConfigFile);
+		}
 
 		this->load_dir(common::buildopts::ConfigDir, false);
+
+		if (!m_loaded_config)
+			spdlog::warn("No config file loaded at all, this is not good.");
 	}
 
 	/*!
@@ -95,6 +104,7 @@ class ConfigLoader {
 					continue;
 			}
 
+			spdlog::info("Loading config {}.", p.path().c_str());
 			this->load_file(p.path());
 		}
 	}
@@ -176,6 +186,7 @@ class ConfigLoader {
 		this->get(ini, "Contacts", "SizeThreshold", m_config.contacts_size_thresh_max);
 
 		// clang-format on
+		m_loaded_config = true;
 	}
 
 	/*!
@@ -209,11 +220,12 @@ class ConfigLoader {
 				} else if (mpp_version == "v2") {
 					value = Config::MPPVersion::V2;
 				} else {
-					throw common::Error<Error::ParsingInvalidValue> {"Stylus mpp_version was not 'v1' or 'v2', got: " + mpp_version};
+					throw common::Error<Error::ParsingInvalidValue> {
+						"Stylus mpp_version was not 'v1' or 'v2', got: " +
+						mpp_version};
 				}
 			}
-		}
-		else
+		} else
 			throw common::Error<Error::ParsingTypeNotImplemented> {typeid(T).name()};
 	}
 };
diff --git a/src/ipts/parser.hpp b/src/ipts/parser.hpp
index 0bea855..b56bbce 100644
--- a/src/ipts/parser.hpp
+++ b/src/ipts/parser.hpp
@@ -16,8 +16,6 @@
 #include <common/reader.hpp>
 #include <common/types.hpp>
 
-#include <spdlog/spdlog.h>
-
 #include <gsl/gsl>
 
 #include <functional>

From 3fad8016e9467cf3ed233573d719cb1c2fbdf369 Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Sun, 25 Feb 2024 19:04:06 -0500
Subject: [PATCH 06/14] ipts: Add more reliable contact detection for MPP v2

If there's contact, the pen signal clearly switches columns in the Position2 window.
---
 etc/presets/surface-pro-9.conf   |  6 ++++-
 src/core/generic/config.hpp      |  1 +
 src/core/generic/dft.hpp         | 43 +++++++++++++++++++++++++++++++-
 src/core/linux/config-loader.hpp |  1 +
 src/ipts/protocol/dft.hpp        |  1 +
 5 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/etc/presets/surface-pro-9.conf b/etc/presets/surface-pro-9.conf
index 9e4680f..f9ba5e6 100644
--- a/etc/presets/surface-pro-9.conf
+++ b/etc/presets/surface-pro-9.conf
@@ -1,7 +1,11 @@
+[Device]
+Vendor = 0x045E
+Product = 0x0C52
+
 [Stylus]
 MPPVersion = v2
 
 [DFT]
-# This is really high, but SP2 creates a strong signal.
 ButtonMinMag = 50000
+ContactMinMag = 50000
 PositionMinMag = 500
diff --git a/src/core/generic/config.hpp b/src/core/generic/config.hpp
index 075a784..cba47a5 100644
--- a/src/core/generic/config.hpp
+++ b/src/core/generic/config.hpp
@@ -66,6 +66,7 @@ class Config {
 	usize dft_button_min_mag = 1000;
 	usize dft_freq_min_mag = 10000;
 	usize dft_tilt_min_mag = 10000;
+	usize dft_contact_min_mag = 10000;
 	f64 dft_tilt_distance = 0.6;
 
 public:
diff --git a/src/core/generic/dft.hpp b/src/core/generic/dft.hpp
index eb01368..dda8a71 100644
--- a/src/core/generic/dft.hpp
+++ b/src/core/generic/dft.hpp
@@ -35,6 +35,10 @@ class DftStylus {
 	// frame.
 	std::optional<u32> m_dft_0x0a_group = std::nullopt;
 
+	// Boolean to track whether the pen is in contact, used by the method
+	// that processes the pressure frame.
+	bool m_mppv2_in_contact {false};
+
 public:
 	DftStylus(Config config, const std::optional<const ipts::Metadata> &metadata)
 		: m_config {std::move(config)},
@@ -57,6 +61,9 @@ class DftStylus {
 		case ipts::protocol::dft::Type::Pressure:
 			this->handle_pressure(dft);
 			break;
+		case ipts::protocol::dft::Type::Position2:
+			this->handle_position2(dft);
+			break;
 		case ipts::protocol::dft::Type::Dft0x0a:
 			this->handle_dft_0x0a(dft);
 			break;
@@ -219,7 +226,7 @@ class DftStylus {
 			m_stylus.contact = true;
 			m_stylus.pressure = std::clamp(p, 0.0, 1.0);
 		} else {
-			m_stylus.contact = false;
+			m_stylus.contact = false || m_mppv2_in_contact; // NOLINT
 			m_stylus.pressure = 0;
 		}
 	}
@@ -235,6 +242,11 @@ class DftStylus {
 			return;
 		}
 
+		if (dft.x.size() <= 5) { // not sure if this can happen?
+			m_stylus.button = false;
+			return;
+		}
+
 		// Second time we see the 0x0a frame in this group, skip it.
 		if (!dft.group.has_value() || m_dft_0x0a_group == dft.group)
 			return;
@@ -258,6 +270,35 @@ class DftStylus {
 		m_stylus.button = mag_4 < mag_5;
 	}
 
+	/*!
+	 * Determines whether the pen is making contact with the screen, it can
+	 * only be used for MPP v2 pens.
+	 */
+	void handle_position2(const ipts::DftWindow &dft)
+	{
+		if (m_config.mpp_version != Config::MPPVersion::V2) {
+			return;
+		}
+
+		// Set to false in case we return early.
+		m_mppv2_in_contact = false;
+
+		if (dft.x.size() <= 3) { // not sure if this can happen?
+			return;
+		}
+
+		const auto mag_2 = dft.x[2].magnitude + dft.y[2].magnitude;
+		const auto mag_3 = dft.x[3].magnitude + dft.y[3].magnitude;
+
+		const auto threshold = 2 * m_config.dft_contact_min_mag;
+		if (mag_2 < threshold && mag_3 < threshold) {
+			return;
+		}
+
+		// The pen switches the row from two to three when there's contact.
+		m_mppv2_in_contact = mag_2 < mag_3;
+	}
+
 	/*!
 	 * Interpolates the current stylus position from a list of antenna measurements.
 	 *
diff --git a/src/core/linux/config-loader.hpp b/src/core/linux/config-loader.hpp
index 5dd76c9..ff51e4d 100644
--- a/src/core/linux/config-loader.hpp
+++ b/src/core/linux/config-loader.hpp
@@ -176,6 +176,7 @@ class ConfigLoader {
 		this->get(ini, "DFT", "PositionMinAmp", m_config.dft_position_min_amp);
 		this->get(ini, "DFT", "PositionMinMag", m_config.dft_position_min_mag);
 		this->get(ini, "DFT", "PositionExp", m_config.dft_position_exp);
+		this->get(ini, "DFT", "ContactMinMag", m_config.dft_contact_min_mag);
 		this->get(ini, "DFT", "ButtonMinMag", m_config.dft_button_min_mag);
 		this->get(ini, "DFT", "FreqMinMag", m_config.dft_freq_min_mag);
 		this->get(ini, "DFT", "TiltMinMag", m_config.dft_tilt_min_mag);
diff --git a/src/ipts/protocol/dft.hpp b/src/ipts/protocol/dft.hpp
index ee23016..9539f88 100644
--- a/src/ipts/protocol/dft.hpp
+++ b/src/ipts/protocol/dft.hpp
@@ -15,6 +15,7 @@ constexpr u8 PRESSURE_ROWS = 6;
 
 enum class Type : u8 {
 	Position = 6,
+	Position2 = 7,
 	Button = 9,
 	Pressure = 11,
 	Dft0x0a = 0x0a,

From 1f8d6bf10cbbe4f6442f2dee910217cbc44de98d Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Mon, 26 Feb 2024 08:35:05 -0500
Subject: [PATCH 07/14] core: Prefix MPP version with stylus

---
 src/core/generic/config.hpp      | 2 +-
 src/core/generic/dft.hpp         | 6 +++---
 src/core/linux/config-loader.hpp | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/core/generic/config.hpp b/src/core/generic/config.hpp
index cba47a5..509cc90 100644
--- a/src/core/generic/config.hpp
+++ b/src/core/generic/config.hpp
@@ -57,7 +57,7 @@ class Config {
 	// [Stylus]
 	bool stylus_disable = false;
 	f64 stylus_tip_distance = 0;
-	MPPVersion mpp_version = MPPVersion::V1;
+	MPPVersion stylus_mpp_version = MPPVersion::V1;
 
 	// [DFT]
 	usize dft_position_min_amp = 50;
diff --git a/src/core/generic/dft.hpp b/src/core/generic/dft.hpp
index dda8a71..2f7d12f 100644
--- a/src/core/generic/dft.hpp
+++ b/src/core/generic/dft.hpp
@@ -203,7 +203,7 @@ class DftStylus {
 		}
 
 		// Only set the button value if we're using a v1 pen.
-		if (m_config.mpp_version == Config::MPPVersion::V1) {
+		if (m_config.stylus_mpp_version == Config::MPPVersion::V1) {
 			m_stylus.button = button;
 		}
 		m_stylus.rubber = rubber;
@@ -238,7 +238,7 @@ class DftStylus {
 	 */
 	void handle_dft_0x0a(const ipts::DftWindow &dft)
 	{
-		if (m_config.mpp_version != Config::MPPVersion::V2) {
+		if (m_config.stylus_mpp_version != Config::MPPVersion::V2) {
 			return;
 		}
 
@@ -276,7 +276,7 @@ class DftStylus {
 	 */
 	void handle_position2(const ipts::DftWindow &dft)
 	{
-		if (m_config.mpp_version != Config::MPPVersion::V2) {
+		if (m_config.stylus_mpp_version != Config::MPPVersion::V2) {
 			return;
 		}
 
diff --git a/src/core/linux/config-loader.hpp b/src/core/linux/config-loader.hpp
index ff51e4d..0a421ce 100644
--- a/src/core/linux/config-loader.hpp
+++ b/src/core/linux/config-loader.hpp
@@ -171,7 +171,7 @@ class ConfigLoader {
 
 		this->get(ini, "Stylus", "Disable", m_config.stylus_disable);
 		this->get(ini, "Stylus", "TipDistance", m_config.stylus_tip_distance);
-		this->get(ini, "Stylus", "MPPVersion", m_config.mpp_version);
+		this->get(ini, "Stylus", "MPPVersion", m_config.stylus_mpp_version);
 
 		this->get(ini, "DFT", "PositionMinAmp", m_config.dft_position_min_amp);
 		this->get(ini, "DFT", "PositionMinMag", m_config.dft_position_min_mag);

From 772fbaf8003288bab37fe3a2875d2e796d0d2506 Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Mon, 26 Feb 2024 16:16:46 -0500
Subject: [PATCH 08/14] core: Eliminate specifying pen version

Instead, rely on magnitude for determining if the v2 signal is present.
---
 etc/presets/surface-pro-9.conf   |  8 ++----
 src/core/generic/config.hpp      | 11 ++------
 src/core/generic/dft.hpp         | 48 +++++++++++++++++---------------
 src/core/linux/config-loader.hpp | 19 ++-----------
 4 files changed, 34 insertions(+), 52 deletions(-)

diff --git a/etc/presets/surface-pro-9.conf b/etc/presets/surface-pro-9.conf
index f9ba5e6..6429481 100644
--- a/etc/presets/surface-pro-9.conf
+++ b/etc/presets/surface-pro-9.conf
@@ -2,10 +2,8 @@
 Vendor = 0x045E
 Product = 0x0C52
 
-[Stylus]
-MPPVersion = v2
-
 [DFT]
-ButtonMinMag = 50000
-ContactMinMag = 50000
+ButtonMinMag = 10000
+Mpp2ContactMinMag = 50000
+Mpp2ButtonMinMag = 50000
 PositionMinMag = 500
diff --git a/src/core/generic/config.hpp b/src/core/generic/config.hpp
index 509cc90..a23a1bb 100644
--- a/src/core/generic/config.hpp
+++ b/src/core/generic/config.hpp
@@ -17,14 +17,6 @@ namespace iptsd::core {
 
 class Config {
 public:
-	// Enum to denote which Pen Protocol is being used.
-	enum class MPPVersion {
-		// Used for Microsoft Pen Protocol v1 compliant pens.
-		V1,
-		// Used for Microsoft Pen Protocol v2 compliant pens.
-		V2,
-	};
-
 	// [Config]
 	bool invert_x = false;
 	bool invert_y = false;
@@ -57,7 +49,6 @@ class Config {
 	// [Stylus]
 	bool stylus_disable = false;
 	f64 stylus_tip_distance = 0;
-	MPPVersion stylus_mpp_version = MPPVersion::V1;
 
 	// [DFT]
 	usize dft_position_min_amp = 50;
@@ -67,6 +58,8 @@ class Config {
 	usize dft_freq_min_mag = 10000;
 	usize dft_tilt_min_mag = 10000;
 	usize dft_contact_min_mag = 10000;
+	usize dft_mpp2_button_min_mag = 50000;
+	usize dft_mpp2_contact_min_mag = 50000;
 	f64 dft_tilt_distance = 0.6;
 
 public:
diff --git a/src/core/generic/dft.hpp b/src/core/generic/dft.hpp
index 2f7d12f..427855b 100644
--- a/src/core/generic/dft.hpp
+++ b/src/core/generic/dft.hpp
@@ -35,9 +35,13 @@ class DftStylus {
 	// frame.
 	std::optional<u32> m_dft_0x0a_group = std::nullopt;
 
-	// Boolean to track whether the pen is in contact, used by the method
-	// that processes the pressure frame.
-	bool m_mppv2_in_contact {false};
+	// Boolean to track whether the pen is in contact according to mpp v2.
+	// This is used to override the contact state in the pressure frame handling.
+	std::optional<bool> m_mppv2_in_contact = std::nullopt;
+
+	// Boolean to track whether the button is held according to mpp v2.
+	// This is used to override the button state in the button frame handling.
+	std::optional<bool> m_mppv2_button = std::nullopt;
 
 public:
 	DftStylus(Config config, const std::optional<const ipts::Metadata> &metadata)
@@ -202,10 +206,12 @@ class DftStylus {
 			rubber = val > 0;
 		}
 
-		// Only set the button value if we're using a v1 pen.
-		if (m_config.stylus_mpp_version == Config::MPPVersion::V1) {
-			m_stylus.button = button;
-		}
+		// Check if the v2 version of the protocol detect the button state, if so
+		// overwrite the state that was calculated here.
+		if (m_mppv2_button.has_value())
+			button = m_mppv2_button.value();
+
+		m_stylus.button = button;
 		m_stylus.rubber = rubber;
 	}
 
@@ -226,7 +232,8 @@ class DftStylus {
 			m_stylus.contact = true;
 			m_stylus.pressure = std::clamp(p, 0.0, 1.0);
 		} else {
-			m_stylus.contact = false || m_mppv2_in_contact; // NOLINT
+			m_stylus.contact =
+				m_mppv2_in_contact.has_value() ? m_mppv2_in_contact.value() : false;
 			m_stylus.pressure = 0;
 		}
 	}
@@ -238,12 +245,10 @@ class DftStylus {
 	 */
 	void handle_dft_0x0a(const ipts::DftWindow &dft)
 	{
-		if (m_config.stylus_mpp_version != Config::MPPVersion::V2) {
-			return;
-		}
+		// Clearing the state in case we can't determine it.
+		m_mppv2_button = std::nullopt;
 
 		if (dft.x.size() <= 5) { // not sure if this can happen?
-			m_stylus.button = false;
 			return;
 		}
 
@@ -260,14 +265,13 @@ class DftStylus {
 		const auto threshold = 2 * m_config.dft_button_min_mag;
 
 		if (mag_4 < threshold && mag_5 < threshold) {
-			// Not enough signal, lets disable the button
-			m_stylus.button = false;
+			// Not enough signal to make a decision.
 			return;
 		}
 
 		// One of them is above the threshold, if 5 is higher than 4, button
 		// is held.
-		m_stylus.button = mag_4 < mag_5;
+		m_mppv2_button = mag_4 < mag_5;
 	}
 
 	/*!
@@ -276,12 +280,8 @@ class DftStylus {
 	 */
 	void handle_position2(const ipts::DftWindow &dft)
 	{
-		if (m_config.stylus_mpp_version != Config::MPPVersion::V2) {
-			return;
-		}
-
-		// Set to false in case we return early.
-		m_mppv2_in_contact = false;
+		// Clearing the state in case we can't determine it.
+		m_mppv2_in_contact = std::nullopt;
 
 		if (dft.x.size() <= 3) { // not sure if this can happen?
 			return;
@@ -290,8 +290,9 @@ class DftStylus {
 		const auto mag_2 = dft.x[2].magnitude + dft.y[2].magnitude;
 		const auto mag_3 = dft.x[3].magnitude + dft.y[3].magnitude;
 
-		const auto threshold = 2 * m_config.dft_contact_min_mag;
+		const auto threshold = 2 * m_config.dft_mpp2_contact_min_mag;
 		if (mag_2 < threshold && mag_3 < threshold) {
+			// Not enough signal to make a decision.
 			return;
 		}
 
@@ -423,6 +424,9 @@ class DftStylus {
 		m_stylus.contact = false;
 		m_stylus.button = false;
 		m_stylus.rubber = false;
+
+		m_mppv2_in_contact = std::nullopt;
+		m_mppv2_button = std::nullopt;
 	}
 };
 
diff --git a/src/core/linux/config-loader.hpp b/src/core/linux/config-loader.hpp
index 0a421ce..dbca90f 100644
--- a/src/core/linux/config-loader.hpp
+++ b/src/core/linux/config-loader.hpp
@@ -171,7 +171,6 @@ class ConfigLoader {
 
 		this->get(ini, "Stylus", "Disable", m_config.stylus_disable);
 		this->get(ini, "Stylus", "TipDistance", m_config.stylus_tip_distance);
-		this->get(ini, "Stylus", "MPPVersion", m_config.stylus_mpp_version);
 
 		this->get(ini, "DFT", "PositionMinAmp", m_config.dft_position_min_amp);
 		this->get(ini, "DFT", "PositionMinMag", m_config.dft_position_min_mag);
@@ -181,6 +180,8 @@ class ConfigLoader {
 		this->get(ini, "DFT", "FreqMinMag", m_config.dft_freq_min_mag);
 		this->get(ini, "DFT", "TiltMinMag", m_config.dft_tilt_min_mag);
 		this->get(ini, "DFT", "TiltDistance", m_config.dft_tilt_distance);
+		this->get(ini, "DFT", "Mpp2ContactMinMag", m_config.dft_mpp2_contact_min_mag);
+		this->get(ini, "DFT", "Mpp2ButtonMinMag", m_config.dft_mpp2_button_min_mag);
 
 		// Legacy options that are kept for compatibility
 		this->get(ini, "DFT", "TipDistance", m_config.stylus_tip_distance);
@@ -212,21 +213,7 @@ class ConfigLoader {
 			value = gsl::narrow_cast<T>(ini.GetReal(section, name, value));
 		else if constexpr (std::is_same_v<T, std::string>)
 			value = ini.GetString(section, name, value);
-		else if constexpr (std::is_same_v<T, Config::MPPVersion>) {
-			// Parse the pen protocol verison by first reading into a string.
-			const auto mpp_version = ini.GetString(section, name, "");
-			if (!mpp_version.empty()) {
-				if (mpp_version == "v1") {
-					value = Config::MPPVersion::V1;
-				} else if (mpp_version == "v2") {
-					value = Config::MPPVersion::V2;
-				} else {
-					throw common::Error<Error::ParsingInvalidValue> {
-						"Stylus mpp_version was not 'v1' or 'v2', got: " +
-						mpp_version};
-				}
-			}
-		} else
+		else
 			throw common::Error<Error::ParsingTypeNotImplemented> {typeid(T).name()};
 	}
 };

From 9aee2cd463207fb476c5296c90569653ba3aa7f9 Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Mon, 26 Feb 2024 16:32:15 -0500
Subject: [PATCH 09/14] core, ipts: Incorporate minor PR feedback.

---
 src/core/generic/dft.hpp         | 12 ++++++------
 src/core/linux/config-loader.hpp | 12 ++----------
 src/ipts/parser.hpp              |  1 +
 src/ipts/protocol/dft.hpp        | 10 +++++-----
 4 files changed, 14 insertions(+), 21 deletions(-)

diff --git a/src/core/generic/dft.hpp b/src/core/generic/dft.hpp
index 427855b..489f7ee 100644
--- a/src/core/generic/dft.hpp
+++ b/src/core/generic/dft.hpp
@@ -65,11 +65,11 @@ class DftStylus {
 		case ipts::protocol::dft::Type::Pressure:
 			this->handle_pressure(dft);
 			break;
-		case ipts::protocol::dft::Type::Position2:
-			this->handle_position2(dft);
+		case ipts::protocol::dft::Type::PositionMPP_2:
+			this->handle_position_mpp_2(dft);
 			break;
-		case ipts::protocol::dft::Type::Dft0x0a:
-			this->handle_dft_0x0a(dft);
+		case ipts::protocol::dft::Type::BinaryMPP_2:
+			this->handle_dft_binary_mpp_2(dft);
 			break;
 		default:
 			// Ignored
@@ -243,7 +243,7 @@ class DftStylus {
 	 * only be used for MPP v2 pens. The eraser is still obtained from the
 	 * phase using the button frame.
 	 */
-	void handle_dft_0x0a(const ipts::DftWindow &dft)
+	void handle_dft_binary_mpp_2(const ipts::DftWindow &dft)
 	{
 		// Clearing the state in case we can't determine it.
 		m_mppv2_button = std::nullopt;
@@ -278,7 +278,7 @@ class DftStylus {
 	 * Determines whether the pen is making contact with the screen, it can
 	 * only be used for MPP v2 pens.
 	 */
-	void handle_position2(const ipts::DftWindow &dft)
+	void handle_position_mpp_2(const ipts::DftWindow &dft)
 	{
 		// Clearing the state in case we can't determine it.
 		m_mppv2_in_contact = std::nullopt;
diff --git a/src/core/linux/config-loader.hpp b/src/core/linux/config-loader.hpp
index dbca90f..623a7f1 100644
--- a/src/core/linux/config-loader.hpp
+++ b/src/core/linux/config-loader.hpp
@@ -27,8 +27,6 @@ class ConfigLoader {
 	Config m_config {};
 	DeviceInfo m_info;
 
-	bool m_loaded_config {false};
-
 public:
 	ConfigLoader(const DeviceInfo &info, const std::optional<const ipts::Metadata> &metadata)
 		: m_info {info}
@@ -50,21 +48,15 @@ class ConfigLoader {
 		 * known working main system configuration.
 		 */
 		if (const char *config_file_path = std::getenv("IPTSD_CONFIG_FILE")) {
-			spdlog::info("Loading config {}, specified with IPTSD_CONFIG_FILE.",
-			             config_file_path);
 			this->load_file(config_file_path);
 			return;
 		}
 
 		if (std::filesystem::exists(common::buildopts::ConfigFile)) {
-			spdlog::info("Loading config {}.", common::buildopts::ConfigFile);
 			this->load_file(common::buildopts::ConfigFile);
 		}
 
 		this->load_dir(common::buildopts::ConfigDir, false);
-
-		if (!m_loaded_config)
-			spdlog::warn("No config file loaded at all, this is not good.");
 	}
 
 	/*!
@@ -104,7 +96,6 @@ class ConfigLoader {
 					continue;
 			}
 
-			spdlog::info("Loading config {}.", p.path().c_str());
 			this->load_file(p.path());
 		}
 	}
@@ -137,6 +128,8 @@ class ConfigLoader {
 	 */
 	void load_file(const std::filesystem::path &path)
 	{
+		spdlog::info("Loading config {}.", path.c_str());
+
 		const INIReader ini {path};
 
 		if (ini.ParseError() != 0)
@@ -188,7 +181,6 @@ class ConfigLoader {
 		this->get(ini, "Contacts", "SizeThreshold", m_config.contacts_size_thresh_max);
 
 		// clang-format on
-		m_loaded_config = true;
 	}
 
 	/*!
diff --git a/src/ipts/parser.hpp b/src/ipts/parser.hpp
index b56bbce..dff29f8 100644
--- a/src/ipts/parser.hpp
+++ b/src/ipts/parser.hpp
@@ -71,6 +71,7 @@ class Parser {
 	{
 		Reader reader(data);
 		reader.skip(header);
+
 		this->parse_hid_frame(reader);
 	}
 
diff --git a/src/ipts/protocol/dft.hpp b/src/ipts/protocol/dft.hpp
index 9539f88..c85db86 100644
--- a/src/ipts/protocol/dft.hpp
+++ b/src/ipts/protocol/dft.hpp
@@ -14,11 +14,11 @@ constexpr u8 MAX_ROWS = 16;
 constexpr u8 PRESSURE_ROWS = 6;
 
 enum class Type : u8 {
-	Position = 6,
-	Position2 = 7,
-	Button = 9,
-	Pressure = 11,
-	Dft0x0a = 0x0a,
+	Position = 0x6,
+	PositionMPP_2 = 0x7,
+	Button = 0x9,
+	BinaryMPP_2 = 0xA,
+	Pressure = 0xB,
 };
 
 struct [[gnu::packed]] Metadata {

From b4ef3bdd6243c21f4af33c86abb84ff6d74a5e17 Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Tue, 27 Feb 2024 18:53:30 -0500
Subject: [PATCH 10/14] presets: Remove surface pro 9 config

It is unnecessary now that the mppv2 values are separate.
---
 etc/presets/surface-pro-9.conf | 9 ---------
 1 file changed, 9 deletions(-)
 delete mode 100644 etc/presets/surface-pro-9.conf

diff --git a/etc/presets/surface-pro-9.conf b/etc/presets/surface-pro-9.conf
deleted file mode 100644
index 6429481..0000000
--- a/etc/presets/surface-pro-9.conf
+++ /dev/null
@@ -1,9 +0,0 @@
-[Device]
-Vendor = 0x045E
-Product = 0x0C52
-
-[DFT]
-ButtonMinMag = 10000
-Mpp2ContactMinMag = 50000
-Mpp2ButtonMinMag = 50000
-PositionMinMag = 500

From 1623671b32151f52cefffb0043235bb0ef515813 Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Tue, 27 Feb 2024 18:54:26 -0500
Subject: [PATCH 11/14] core: linux: Add info when no configuration files are
 loaded

---
 src/core/linux/config-loader.hpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/core/linux/config-loader.hpp b/src/core/linux/config-loader.hpp
index 623a7f1..66007be 100644
--- a/src/core/linux/config-loader.hpp
+++ b/src/core/linux/config-loader.hpp
@@ -27,6 +27,8 @@ class ConfigLoader {
 	Config m_config {};
 	DeviceInfo m_info;
 
+	bool m_loaded_config = false;
+
 public:
 	ConfigLoader(const DeviceInfo &info, const std::optional<const ipts::Metadata> &metadata)
 		: m_info {info}
@@ -52,11 +54,13 @@ class ConfigLoader {
 			return;
 		}
 
-		if (std::filesystem::exists(common::buildopts::ConfigFile)) {
+		if (std::filesystem::exists(common::buildopts::ConfigFile))
 			this->load_file(common::buildopts::ConfigFile);
-		}
 
 		this->load_dir(common::buildopts::ConfigDir, false);
+
+		if (!m_loaded_config)
+			spdlog::info("No config file loaded, using default values.");
 	}
 
 	/*!
@@ -181,6 +185,7 @@ class ConfigLoader {
 		this->get(ini, "Contacts", "SizeThreshold", m_config.contacts_size_thresh_max);
 
 		// clang-format on
+		m_loaded_config = true;
 	}
 
 	/*!

From 5f399fee731786d990e3e2982455efa4bf299621 Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Tue, 27 Feb 2024 18:55:21 -0500
Subject: [PATCH 12/14] core: Incorporate PR feedback around mppv2

---
 src/core/generic/dft.hpp  | 25 +++++++++++--------------
 src/core/linux/errors.hpp |  3 ---
 2 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/src/core/generic/dft.hpp b/src/core/generic/dft.hpp
index 489f7ee..10682cd 100644
--- a/src/core/generic/dft.hpp
+++ b/src/core/generic/dft.hpp
@@ -29,11 +29,10 @@ class DftStylus {
 	std::optional<u32> m_group = std::nullopt;
 
 	// This is a bit of a hack, for the MPP v2 button detection we only
-	// care about the first 0x0a dft window, but there's two in the frame,
-	// here we keep track of the group when 0x0a was encountered, this
-	// allows comparing against this group and only using the first 0x0a
-	// frame.
-	std::optional<u32> m_dft_0x0a_group = std::nullopt;
+	// care about the first binary (0x0a) dft window, but there's two in the
+	// frame, here we keep track of the group when 0x0a was encountered,
+	// this allows comparing against this group and only using the first frame.
+	std::optional<u32> m_mppv2_binary_group = std::nullopt;
 
 	// Boolean to track whether the pen is in contact according to mpp v2.
 	// This is used to override the contact state in the pressure frame handling.
@@ -232,8 +231,7 @@ class DftStylus {
 			m_stylus.contact = true;
 			m_stylus.pressure = std::clamp(p, 0.0, 1.0);
 		} else {
-			m_stylus.contact =
-				m_mppv2_in_contact.has_value() ? m_mppv2_in_contact.value() : false;
+			m_stylus.contact = m_mppv2_in_contact.value_or(false);
 			m_stylus.pressure = 0;
 		}
 	}
@@ -245,24 +243,23 @@ class DftStylus {
 	 */
 	void handle_dft_binary_mpp_2(const ipts::DftWindow &dft)
 	{
-		// Clearing the state in case we can't determine it.
-		m_mppv2_button = std::nullopt;
-
 		if (dft.x.size() <= 5) { // not sure if this can happen?
 			return;
 		}
 
-		// Second time we see the 0x0a frame in this group, skip it.
-		if (!dft.group.has_value() || m_dft_0x0a_group == dft.group)
+		// Second time we see this dft window in this group, skip it.
+		if (!dft.group.has_value() || m_mppv2_binary_group == dft.group)
 			return;
+		m_mppv2_binary_group = dft.group;
 
-		m_dft_0x0a_group = dft.group;
+		// Clearing the state in case we can't determine it.
+		m_mppv2_button = std::nullopt;
 
 		// Now, we can process the frame to determine button state.
 		// First, collapse x and y, they convey the same information.
 		const auto mag_4 = dft.x[4].magnitude + dft.y[4].magnitude;
 		const auto mag_5 = dft.x[5].magnitude + dft.y[5].magnitude;
-		const auto threshold = 2 * m_config.dft_button_min_mag;
+		const auto threshold = 2 * m_config.dft_mpp2_button_min_mag;
 
 		if (mag_4 < threshold && mag_5 < threshold) {
 			// Not enough signal to make a decision.
diff --git a/src/core/linux/errors.hpp b/src/core/linux/errors.hpp
index b152b7d..80a4478 100644
--- a/src/core/linux/errors.hpp
+++ b/src/core/linux/errors.hpp
@@ -9,7 +9,6 @@ namespace iptsd::core::linux {
 
 enum class Error {
 	ParsingFailed,
-	ParsingInvalidValue,
 	ParsingTypeNotImplemented,
 	RunnerInitError,
 
@@ -26,8 +25,6 @@ inline std::string format_as(Error err)
 	switch (err) {
 	case Error::ParsingFailed:
 		return "core: linux: Failed to parse INI file {}!";
-	case Error::ParsingInvalidValue:
-		return "core: linux: Parsing encountered invalid value {}!";
 	case Error::ParsingTypeNotImplemented:
 		return "core: linux: Parsing not implemented for type {}!";
 	case Error::RunnerInitError:

From 2d49ff7673c1a797348b84f48b75b919d507a842 Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Wed, 28 Feb 2024 18:21:02 -0500
Subject: [PATCH 13/14] core: generic: Allow eraser state on mppv2 button state

The mppv2 button detection can also happen when the eraser is pressed through
a thumb button. So instead of assuming it is a barrel button, use the phase to
decide whether it is the eraser or barrel button.
---
 src/core/generic/dft.hpp | 33 +++++++++++++++------------------
 1 file changed, 15 insertions(+), 18 deletions(-)

diff --git a/src/core/generic/dft.hpp b/src/core/generic/dft.hpp
index 10682cd..33e72c9 100644
--- a/src/core/generic/dft.hpp
+++ b/src/core/generic/dft.hpp
@@ -28,20 +28,20 @@ class DftStylus {
 	i32 m_imag = 0;
 	std::optional<u32> m_group = std::nullopt;
 
-	// This is a bit of a hack, for the MPP v2 button detection we only
-	// care about the first binary (0x0a) dft window, but there's two in the
-	// frame, here we keep track of the group when 0x0a was encountered,
-	// this allows comparing against this group and only using the first frame.
+	// For the MPP v2 button detection we only care about the first binary
+	// (0x0a) dft window, but there's two in the group, we keep track of the
+	// group when 0x0a was encountered, this allows comparing against this
+	// value to use only the first window in the group.
 	std::optional<u32> m_mppv2_binary_group = std::nullopt;
 
+	// Boolean to track whether a button is held according to mpp v2.
+	// This is used instead of the button threshold detection.
+	std::optional<bool> m_mppv2_button_or_eraser = std::nullopt;
+
 	// Boolean to track whether the pen is in contact according to mpp v2.
 	// This is used to override the contact state in the pressure frame handling.
 	std::optional<bool> m_mppv2_in_contact = std::nullopt;
 
-	// Boolean to track whether the button is held according to mpp v2.
-	// This is used to override the button state in the button frame handling.
-	std::optional<bool> m_mppv2_button = std::nullopt;
-
 public:
 	DftStylus(Config config, const std::optional<const ipts::Metadata> &metadata)
 		: m_config {std::move(config)},
@@ -191,8 +191,10 @@ class DftStylus {
 		bool button = false;
 		bool rubber = false;
 
-		if (dft.x[0].magnitude > m_config.dft_button_min_mag &&
-		    dft.y[0].magnitude > m_config.dft_button_min_mag) {
+		// If mppv2 has decided on a button state use that, else use the magnitude decision.
+		if (m_mppv2_button_or_eraser.value_or(
+			    dft.x[0].magnitude > m_config.dft_button_min_mag &&
+			    dft.y[0].magnitude > m_config.dft_button_min_mag)) {
 			const i32 real = dft.x[0].real[ipts::protocol::dft::NUM_COMPONENTS / 2] +
 			                 dft.y[0].real[ipts::protocol::dft::NUM_COMPONENTS / 2];
 			const i32 imag = dft.x[0].imag[ipts::protocol::dft::NUM_COMPONENTS / 2] +
@@ -205,11 +207,6 @@ class DftStylus {
 			rubber = val > 0;
 		}
 
-		// Check if the v2 version of the protocol detect the button state, if so
-		// overwrite the state that was calculated here.
-		if (m_mppv2_button.has_value())
-			button = m_mppv2_button.value();
-
 		m_stylus.button = button;
 		m_stylus.rubber = rubber;
 	}
@@ -253,7 +250,7 @@ class DftStylus {
 		m_mppv2_binary_group = dft.group;
 
 		// Clearing the state in case we can't determine it.
-		m_mppv2_button = std::nullopt;
+		m_mppv2_button_or_eraser = std::nullopt;
 
 		// Now, we can process the frame to determine button state.
 		// First, collapse x and y, they convey the same information.
@@ -268,7 +265,7 @@ class DftStylus {
 
 		// One of them is above the threshold, if 5 is higher than 4, button
 		// is held.
-		m_mppv2_button = mag_4 < mag_5;
+		m_mppv2_button_or_eraser = mag_4 < mag_5;
 	}
 
 	/*!
@@ -423,7 +420,7 @@ class DftStylus {
 		m_stylus.rubber = false;
 
 		m_mppv2_in_contact = std::nullopt;
-		m_mppv2_button = std::nullopt;
+		m_mppv2_button_or_eraser = std::nullopt;
 	}
 };
 

From 4895549b95654930869240708e677bfe4a0203fe Mon Sep 17 00:00:00 2001
From: Ivor Wanders <ivor@iwanders.net>
Date: Thu, 29 Feb 2024 07:27:29 -0500
Subject: [PATCH 14/14] core: Remove unused variable from configuration

---
 src/core/generic/config.hpp      | 1 -
 src/core/linux/config-loader.hpp | 1 -
 2 files changed, 2 deletions(-)

diff --git a/src/core/generic/config.hpp b/src/core/generic/config.hpp
index a23a1bb..dfeb0c2 100644
--- a/src/core/generic/config.hpp
+++ b/src/core/generic/config.hpp
@@ -57,7 +57,6 @@ class Config {
 	usize dft_button_min_mag = 1000;
 	usize dft_freq_min_mag = 10000;
 	usize dft_tilt_min_mag = 10000;
-	usize dft_contact_min_mag = 10000;
 	usize dft_mpp2_button_min_mag = 50000;
 	usize dft_mpp2_contact_min_mag = 50000;
 	f64 dft_tilt_distance = 0.6;
diff --git a/src/core/linux/config-loader.hpp b/src/core/linux/config-loader.hpp
index 66007be..93eea34 100644
--- a/src/core/linux/config-loader.hpp
+++ b/src/core/linux/config-loader.hpp
@@ -172,7 +172,6 @@ class ConfigLoader {
 		this->get(ini, "DFT", "PositionMinAmp", m_config.dft_position_min_amp);
 		this->get(ini, "DFT", "PositionMinMag", m_config.dft_position_min_mag);
 		this->get(ini, "DFT", "PositionExp", m_config.dft_position_exp);
-		this->get(ini, "DFT", "ContactMinMag", m_config.dft_contact_min_mag);
 		this->get(ini, "DFT", "ButtonMinMag", m_config.dft_button_min_mag);
 		this->get(ini, "DFT", "FreqMinMag", m_config.dft_freq_min_mag);
 		this->get(ini, "DFT", "TiltMinMag", m_config.dft_tilt_min_mag);