Add example: AutoTouchRotation for multi-rotation touch calibration

examples/Generic/AutoTouchRotation/AutoTouchRotation.ino

@@ -0,0 +1,209 @@
+/*
+  This example demonstrates how to automatically apply the correct touch
+  calibration data for all four display rotations using the TFT_eSPI library.
+
+  The sketch shows how to:
+   - Store four sets of touch calibration data (one for each rotation)
+   - Automatically load the correct calibration when tft.setRotation() changes
+   - Keep touch alignment consistent with the display orientation
+
+  The display rotates automatically every 10 seconds (0→1→2→3).
+  Touch input is immediately available in the new orientation.
+
+  Calibration data is stored in SPIFFS for persistence across power cycles.
+
+  This example is based on the TFT_Button_Label_Datum example and works with
+  ESP32 modules using the XPT2046 touch controller.
+
+  Tested on:
+   - ESP32-32E with ST7796 display (HSPI)
+   - XPT2046 touch controller
+*/
+
+#include "FS.h"
+#include <SPI.h>
+#include <TFT_eSPI.h>
+
+TFT_eSPI tft = TFT_eSPI();
+TFT_eSPI_Button key;
+
+// This is the file name used to store the calibration data
+// You can change this to create new calibration files.
+// The SPIFFS file name must start with "/".
+#define CALIBRATION_FILE "/TouchCalData"
+
+// Set REPEAT_CAL to true instead of false to run calibration
+// again, otherwise it will only be done once.
+// Repeat calibration if you change the screen rotation.
+#define REPEAT_CAL false
+
+// Touch calibration data for each of the 4 rotations
+// Obtain these values using the Touch_calibrate example
+uint16_t calData0[5] = { 219, 3560, 230, 3662, 4 }; // rotation 0
+uint16_t calData1[5] = { 206, 3677, 204, 3544, 7 }; // rotation 1
+uint16_t calData2[5] = { 215, 3566, 229, 3674, 2 }; // rotation 2
+uint16_t calData3[5] = { 239, 3651, 218, 3553, 1 }; // rotation 3
+
+// Pointer table for easy access to calibration data sets
+uint16_t* calDataSets[4] = { calData0, calData1, calData2, calData3 };
+
+uint8_t currentRotation = 1; // Start in landscape mode
+bool touchscreen_calibrated = false;
+
+//---------------------------------------------------------------------------
+void setup(void)
+{
+  Serial.begin(115200);
+
+  tft.init();
+
+  // Set the rotation before we calibrate
+  tft.setRotation(currentRotation);
+
+  // call screen calibration
+  touch_calibrate();
+
+  // Display initial UI
+  drawUI();
+
+  Serial.println("\nAutoTouchRotation Example - TFT_eSPI");
+  Serial.println("Display rotates every 10 seconds");
+  Serial.printf("Current rotation: %d\n", currentRotation);
+}
+
+//---------------------------------------------------------------------------
+void loop()
+{
+  static unsigned long lastChange = 0;
+  uint16_t t_x = 0, t_y = 0;
+  bool pressed = false;
+
+  // Check for touch input
+  if (touchscreen_calibrated && tft.getTouch(&t_x, &t_y)) {
+    pressed = true;
+  }
+
+  // Handle button press/release
+  if (pressed && key.contains(t_x, t_y)) {
+    key.press(true);
+  } else {
+    key.press(false);
+  }
+
+  // Handle button just pressed
+  if (key.justPressed()) {
+    key.drawButton(true);
+    tft.fillRect(10, 30, 200, 20, TFT_BLACK);
+    tft.setTextColor(TFT_GREEN, TFT_BLACK);
+    tft.drawString("Button Pressed!", 10, 30);
+    Serial.printf("Pressed @ rotation %d\n", currentRotation);
+  }
+
+  // Handle button just released
+  if (key.justReleased()) {
+    key.drawButton();
+  }
+
+  // Demo: change rotation every 10 seconds
+  if (millis() - lastChange > 10000) {
+    currentRotation = (currentRotation + 1) % 4;
+    setRotationAndTouch(currentRotation);
+    drawUI();
+    lastChange = millis();
+  }
+
+  delay(20);
+}
+
+//---------------------------------------------------------------------------
+// Set display rotation and apply matching touch calibration data
+//---------------------------------------------------------------------------
+void setRotationAndTouch(uint8_t rot)
+{
+  if (rot > 3) rot = 0;
+
+  tft.setRotation(rot);
+  tft.setTouch(calDataSets[rot]);
+  touchscreen_calibrated = true;
+
+  Serial.printf("Rotation: %d, Touch cal data: { %d, %d, %d, %d, %d }\n",
+                rot,
+                calDataSets[rot][0], calDataSets[rot][1],
+                calDataSets[rot][2], calDataSets[rot][3],
+                calDataSets[rot][4]);
+}
+
+//---------------------------------------------------------------------------
+// Redraw user interface elements
+//---------------------------------------------------------------------------
+void drawUI(void)
+{
+  tft.fillScreen(TFT_BLACK);
+
+  key.initButtonUL(&tft, 60, 100, 120, 60, TFT_WHITE, TFT_BLUE, TFT_WHITE, "PRESS", 2);
+  key.drawButton();
+
+  tft.setTextColor(TFT_YELLOW, TFT_BLACK);
+  tft.drawString("Rotation: " + String(currentRotation), 10, 10);
+}
+
+//---------------------------------------------------------------------------
+// Touch screen calibration routine
+//---------------------------------------------------------------------------
+void touch_calibrate(void)
+{
+  uint16_t calData[5];
+  uint8_t calDataOK = 0;
+
+  // Calibration data is stored in SPIFFS
+  if (SPIFFS.begin()) {
+    if (SPIFFS.exists(CALIBRATION_FILE)) {
+      File f = SPIFFS.open(CALIBRATION_FILE, "r");
+      if (f) {
+        if (f.readBytes((char *)calData, 14) == 14)
+          calDataOK = 1;
+        f.close();
+      }
+    }
+  }
+
+  if (!calDataOK) {
+    // data not valid so run calibration again
+    tft.fillScreen(TFT_BLACK);
+    tft.setCursor(20, 0);
+    tft.setTextFont(2);
+    tft.setTextSize(1);
+    tft.setTextColor(TFT_WHITE, TFT_BLACK);
+
+    tft.println("Touch corners as indicated");
+
+    tft.setTextFont(1);
+    tft.println();
+
+    if (REPEAT_CAL) {
+      tft.println("Set REPEAT_CAL to false to skip this next time");
+    }
+
+    // conduct calibration
+    delay(2000);
+    tft.calibrateTouch(calData, TFT_MAGENTA, TFT_BLACK, 15);
+
+    // (Re)set the calibration data
+    tft.setTouch(calData);
+
+    // Store calibration data
+    if (SPIFFS.begin()) {
+      File f = SPIFFS.open(CALIBRATION_FILE, "w");
+      if (f) {
+        f.write((const unsigned char *)calData, 14);
+        f.close();
+      }
+      SPIFFS.end();
+    }
+  } else {
+    // Use stored calibration data
+    tft.setTouch(calData);
+  }
+
+  touchscreen_calibrated = true;
+}