From 773cd0f414bf917d150606b2b7b0166d60d98563 Mon Sep 17 00:00:00 2001
From: Clyde Stubbs <2366188+clydebarrow@users.noreply.github.com>
Date: Sun, 31 Dec 2023 21:01:16 +1100
Subject: [PATCH] GT911 touchscreen: Fix bug causing touch button release to
 fail (#6042)

* Fix bug causing gt911 touch button release to fail

* Cache button state and report changes only
---
 .../gt911/touchscreen/gt911_touchscreen.cpp       | 15 ++++++++-------
 .../gt911/touchscreen/gt911_touchscreen.h         |  1 +
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/esphome/components/gt911/touchscreen/gt911_touchscreen.cpp b/esphome/components/gt911/touchscreen/gt911_touchscreen.cpp
index 84854d5b0d..68ed66a89f 100644
--- a/esphome/components/gt911/touchscreen/gt911_touchscreen.cpp
+++ b/esphome/components/gt911/touchscreen/gt911_touchscreen.cpp
@@ -14,6 +14,7 @@ static const uint8_t GET_TOUCHES[2] = {0x81, 0x4F};
 static const uint8_t GET_SWITCHES[2] = {0x80, 0x4D};
 static const uint8_t GET_MAX_VALUES[2] = {0x80, 0x48};
 static const size_t MAX_TOUCHES = 5;  // max number of possible touches reported
+static const size_t MAX_BUTTONS = 4;  // max number of buttons scanned
 
 #define ERROR_CHECK(err) \
   if ((err) != i2c::ERROR_OK) { \
@@ -79,9 +80,6 @@ void GT911Touchscreen::update_touches() {
     return;
   }
 
-  if (num_of_touches == 0)
-    return;
-
   err = this->write(GET_TOUCHES, sizeof(GET_TOUCHES), false);
   ERROR_CHECK(err);
   // num_of_touches is guaranteed to be 0..5. Also read the key data
@@ -94,10 +92,13 @@ void GT911Touchscreen::update_touches() {
     uint16_t y = encode_uint16(data[i][4], data[i][3]);
     this->add_raw_touch_position_(id, x, y);
   }
-  auto keys = data[num_of_touches][0];
-  for (size_t i = 0; i != 4; i++) {
-    for (auto *listener : this->button_listeners_)
-      listener->update_button(i, (keys & (1 << i)) != 0);
+  auto keys = data[num_of_touches][0] & ((1 << MAX_BUTTONS) - 1);
+  if (keys != this->button_state_) {
+    this->button_state_ = keys;
+    for (size_t i = 0; i != MAX_BUTTONS; i++) {
+      for (auto *listener : this->button_listeners_)
+        listener->update_button(i, (keys & (1 << i)) != 0);
+    }
   }
 }
 
diff --git a/esphome/components/gt911/touchscreen/gt911_touchscreen.h b/esphome/components/gt911/touchscreen/gt911_touchscreen.h
index 44875de5f1..a9e1279ed3 100644
--- a/esphome/components/gt911/touchscreen/gt911_touchscreen.h
+++ b/esphome/components/gt911/touchscreen/gt911_touchscreen.h
@@ -26,6 +26,7 @@ class GT911Touchscreen : public touchscreen::Touchscreen, public i2c::I2CDevice
 
   InternalGPIOPin *interrupt_pin_{};
   std::vector<GT911ButtonListener *> button_listeners_;
+  uint8_t button_state_{0xFF};  // last button state. Initial FF guarantees first update.
 };
 
 }  // namespace gt911