From d8b2b04bb26e2069bbfd182dbee21d3bcc18bcaf Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Sat, 22 Jul 2023 12:33:19 -0500
Subject: [PATCH] Reuse pressure field in touch/pen events to provide hover
 distance

---
 src/Input.h       | 4 ++--
 src/InputStream.c | 8 ++++----
 src/Limelight.h   | 9 +++++++--
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/src/Input.h b/src/Input.h
index cacd411..29ab0b9 100644
--- a/src/Input.h
+++ b/src/Input.h
@@ -131,7 +131,7 @@ typedef struct _SS_TOUCH_PACKET {
     uint32_t pointerId;
     netfloat x;
     netfloat y;
-    netfloat pressure;
+    netfloat pressureOrDistance;
 } SS_TOUCH_PACKET, *PSS_TOUCH_PACKET;
 
 #define SS_PEN_MAGIC 0x55000003
@@ -143,7 +143,7 @@ typedef struct _SS_PEN_PACKET {
     uint8_t zero[1]; // Alignment/reserved
     netfloat x;
     netfloat y;
-    netfloat pressure;
+    netfloat pressureOrDistance;
     uint16_t rotation;
     uint8_t tilt;
     uint8_t zero2[1];
diff --git a/src/InputStream.c b/src/InputStream.c
index b45aa73..3bc75a2 100644
--- a/src/InputStream.c
+++ b/src/InputStream.c
@@ -1216,7 +1216,7 @@ int LiSendHScrollEvent(signed char scrollClicks) {
     return LiSendHighResHScrollEvent(scrollClicks * LI_WHEEL_DELTA);
 }
 
-int LiSendTouchEvent(uint8_t eventType, uint32_t pointerId, float x, float y, float pressure) {
+int LiSendTouchEvent(uint8_t eventType, uint32_t pointerId, float x, float y, float pressureOrDistance) {
     PPACKET_HOLDER holder;
     int err;
 
@@ -1247,7 +1247,7 @@ int LiSendTouchEvent(uint8_t eventType, uint32_t pointerId, float x, float y, fl
     memset(holder->packet.touch.zero, 0, sizeof(holder->packet.touch.zero));
     floatToNetfloat(x, holder->packet.touch.x);
     floatToNetfloat(y, holder->packet.touch.y);
-    floatToNetfloat(pressure, holder->packet.touch.pressure);
+    floatToNetfloat(pressureOrDistance, holder->packet.touch.pressureOrDistance);
 
     err = LbqOfferQueueItem(&packetQueue, holder, &holder->entry);
     if (err != LBQ_SUCCESS) {
@@ -1260,7 +1260,7 @@ int LiSendTouchEvent(uint8_t eventType, uint32_t pointerId, float x, float y, fl
 }
 
 int LiSendPenEvent(uint8_t eventType, uint8_t toolType, uint8_t penButtons,
-                   float x, float y, float pressure,
+                   float x, float y, float pressureOrDistance,
                    uint16_t rotation, uint8_t tilt) {
     PPACKET_HOLDER holder;
     int err;
@@ -1294,7 +1294,7 @@ int LiSendPenEvent(uint8_t eventType, uint8_t toolType, uint8_t penButtons,
     memset(holder->packet.pen.zero, 0, sizeof(holder->packet.pen.zero));
     floatToNetfloat(x, holder->packet.pen.x);
     floatToNetfloat(y, holder->packet.pen.y);
-    floatToNetfloat(pressure, holder->packet.pen.pressure);
+    floatToNetfloat(pressureOrDistance, holder->packet.pen.pressureOrDistance);
     holder->packet.pen.rotation = LE16(rotation);
     holder->packet.pen.tilt = tilt;
     memset(holder->packet.pen.zero2, 0, sizeof(holder->packet.pen.zero2));
diff --git a/src/Limelight.h b/src/Limelight.h
index c5820ff..c1bc7b2 100644
--- a/src/Limelight.h
+++ b/src/Limelight.h
@@ -595,6 +595,11 @@ int LiSendMouseMoveAsMousePositionEvent(short deltaX, short deltaY, short refere
 //
 // Sending a down/move event with a pressure of 0.0 indicates the actual pressure is unknown.
 //
+// For hover events, the pressure value is treated as a 1.0 to 0.0 range of distance from the touch
+// surface where 1.0 is the farthest measurable distance and 0.0 is actually touching the display
+// (which is invalid for a hover event). Reporting distance 0.0 for a hover event indicates the
+// actual distance is unknown.
+//
 // Pointer ID is an opaque ID that must uniquely identify each active touch on screen. It must
 // remain constant through any down/up/move/cancel events involved in a single touch interaction.
 //
@@ -607,7 +612,7 @@ int LiSendMouseMoveAsMousePositionEvent(short deltaX, short deltaY, short refere
 #define LI_TOUCH_EVENT_CANCEL      0x04
 #define LI_TOUCH_EVENT_BUTTON_ONLY 0x05
 #define LI_TOUCH_EVENT_HOVER_LEAVE 0x06
-int LiSendTouchEvent(uint8_t eventType, uint32_t pointerId, float x, float y, float pressure);
+int LiSendTouchEvent(uint8_t eventType, uint32_t pointerId, float x, float y, float pressureOrDistance);
 
 // This function is similar to LiSendTouchEvent() but allows additional parameters relevant for pen
 // input, including rotation, tilt, and buttons. Rotation is in degrees from vertical in Y dimension
@@ -625,7 +630,7 @@ int LiSendTouchEvent(uint8_t eventType, uint32_t pointerId, float x, float y, fl
 #define LI_ROT_UNKNOWN 0xFFFF
 #define LI_TILT_UNKNOWN 0xFF
 int LiSendPenEvent(uint8_t eventType, uint8_t toolType, uint8_t penButtons,
-                   float x, float y, float pressure,
+                   float x, float y, float pressureOrDistance,
                    uint16_t rotation, uint8_t tilt);
 
 // This function queues a mouse button event to be sent to the remote server.