Merge pull request #151 from quo/dft-check-group

Only use DFT button signal if it is from same group as position signal

Author: StollD

src/core/generic/dft.hpp

@@ -25,6 +25,7 @@ class DftStylus {
 
 	i32 m_real = 0;
 	i32 m_imag = 0;
+	std::optional<u32> m_group = std::nullopt;
 
 public:
 	DftStylus(Config config, std::optional<const ipts::Metadata> metadata)
@@ -95,6 +96,7 @@ class DftStylus {
 			 dft.y[0].real[IPTS_DFT_NUM_COMPONENTS / 2];
 		m_imag = dft.x[0].imag[IPTS_DFT_NUM_COMPONENTS / 2] +
 			 dft.y[0].imag[IPTS_DFT_NUM_COMPONENTS / 2];
+		m_group = dft.group;
 
 		f64 x = this->interpolate_position(dft.x[0]);
 		f64 y = this->interpolate_position(dft.y[0]);
@@ -159,6 +161,11 @@ class DftStylus {
 		if (dft.rows <= 0)
 			return;
 
+		// The position and button signals must be from the same group,
+		// otherwise the relative phase is meaningless.
+		if (!m_group.has_value() || m_group != dft.group)
+			return;
+
 		bool button = false;
 		bool rubber = false;
 

src/ipts/data.hpp

@@ -34,6 +34,7 @@ struct Heatmap {
 };
 
 struct DftWindow {
+	std::optional<u32> group = std::nullopt;
 	u8 rows = 0;
 	u8 type = 0;
 

src/ipts/parser.hpp

@@ -39,6 +39,7 @@ class Parser {
 private:
 	struct ipts_dimensions m_dim {};
 	struct ipts_timestamp m_time {};
+	struct ipts_pen_metadata m_pen_meta {};
 
 public:
 	/*!
@@ -231,6 +232,9 @@ class Parser {
 			case IPTS_REPORT_TYPE_HEATMAP:
 				this->parse_heatmap_data(sub);
 				break;
+			case IPTS_REPORT_TYPE_PEN_METADATA:
+				this->parse_pen_metadata(sub);
+				break;
 			case IPTS_REPORT_TYPE_PEN_DFT_WINDOW:
 				this->parse_dft_window(sub);
 				break;
@@ -426,6 +430,12 @@ class Parser {
 		dft.rows = window.num_rows;
 		dft.type = window.data_type;
 
+		if (window.seq_num == m_pen_meta.seq_num &&
+		    window.data_type == m_pen_meta.data_type) {
+			const auto g = m_pen_meta.group_counter;
+			dft.group = g;
+		}
+
 		dft.dim = m_dim;
 		dft.time = m_time;
 
@@ -434,6 +444,18 @@ class Parser {
 
 		this->on_dft(dft);
 	}
+
+	/*!
+	 * Parses a pen metadata report.
+	 *
+	 * A pen metadata report precedes each DFT report.
+
+	 * @param[in] reader The chunk of data allocated to the report.
+	 */
+	void parse_pen_metadata(Reader &reader)
+	{
+		m_pen_meta = reader.read<struct ipts_pen_metadata>();
+	}
 };
 
 } // namespace iptsd::ipts

src/ipts/protocol.hpp

@@ -157,6 +157,13 @@ struct [[gnu::packed]] ipts_heatmap_header {
 	u32 size;
 };
 
+struct [[gnu::packed]] ipts_pen_metadata {
+	u32 group_counter;
+	u8 seq_num;
+	u8 data_type;
+	u8 reserved[10]; // NOLINT(modernize-avoid-c-arrays,cppcoreguidelines-avoid-c-arrays)
+};
+
 struct [[gnu::packed]] ipts_pen_dft_window {
 	u32 timestamp; // counting at approx 8MHz
 	u8 num_rows;