Initial working pointer commit

include/pointer.h

@@ -0,0 +1,25 @@
+#ifndef POINTER_H
+#define POINTER_H
+
+#include <TFT_eSPI.h>
+#include <Arduino.h>
+
+// Max/min value for integer input (0 = 0 degrees, 100 = 180 degrees)
+#define MAX_VALUE 100
+#define MIN_VALUE 0
+
+// Pointer color and length
+#define POINTER_COLOR TFT_RED
+#define POINTER_LENGTH 60
+
+#define BG_COLOR TFT_BLACK // background color
+
+extern TFT_eSPI tft;
+
+void begin();
+
+void updatePointerAngle(double theta);
+
+void updatePointer(int value);
+
+#endif

src/main.cpp

@@ -1,5 +1,6 @@
 #include <Arduino.h>
 #include "display.h"
+#include "pointer.h"
 
 void setup() {
   Serial.begin(115200);
@@ -17,4 +18,20 @@ void loop() {
   // drawSdJpeg("/test.jpg", 0, 0);
 
   // HeapAnim();
+
+  // pointer loop
+  // if (Serial.available()) {
+  //       String input = Serial.readStringUntil('\n');
+  //       input.trim();
+
+  //       if (input.startsWith("a")) {                          // ex: use a10 to set to 10 degrees
+  //           double angle = input.substring(1).toDouble();
+  //           updatePointerAngle(angle);
+  //           Serial.printf("set to angle: %.2f deg\n", angle);
+  //       } else {
+  //           int value = input.toInt();                        // otherwise use integer method
+  //           updatePointer(value);
+  //           Serial.printf("set to value: %d\n", value);
+  //       }
+  //   }
 }

src/pointer.cpp

@@ -0,0 +1,60 @@
+#include "pointer.h"
+#include <Arduino.h>
+#include <math.h>
+
+TFT_eSPI tft = TFT_eSPI();
+
+static int pivotX = 0;                  // x coord of pivot point
+static int pivotY = 0;                  // y coord of pivot point
+static int length = POINTER_LENGTH;     // length of pointer
+static double currentTheta = 0.0;       // current angle in degrees
+
+// erases pointer by painting background colored line over old line
+static void erasePointer() {
+    int oldX = pivotX + length * cos(currentTheta * DEG_TO_RAD);
+    int oldY = pivotY + length * sin(currentTheta * DEG_TO_RAD);
+    tft.drawLine(pivotX, pivotY, oldX, oldY, BG_COLOR);
+}
+
+// initializes and sets up pointer
+void begin() {
+    tft.init();
+    tft.setRotation(1);                 // needed for some reason (see display.cpp initDisplay)
+    tft.fillScreen(BG_COLOR);           // fills screen with background color
+
+    // pulls screen width and height
+    int screenW = tft.width();
+    int screenH = tft.height();
+
+    // sets pivot point at middle of screen
+    pivotX = screenW / 2; 
+    pivotY = screenH / 2;
+
+    // sets pointer to 0 degrees
+    currentTheta = 0.0;
+    updatePointerAngle(0.0);
+
+    Serial.println("begin");
+}
+
+// updates pointer given an angle in degrees
+void updatePointerAngle(double theta) {
+    erasePointer();                                             // erases old point
+    currentTheta = theta;                                       // sets new degree to input
+
+    int newX =  pivotX + length * cos(theta * DEG_TO_RAD);      // calculates new x endpoint
+    int newY = pivotY + length * sin(theta * DEG_TO_RAD);       // calculates new y endpoint
+
+    tft.drawLine(pivotX, pivotY, newX, newY, POINTER_COLOR);    // draws new line
+}
+
+// updates pointer given a integer value defined in pointer.h
+void updatePointer(int value) {
+    // checks that value is between min and max values
+    if (value < MIN_VALUE) value = MIN_VALUE;
+    if (value > MAX_VALUE) value = MAX_VALUE;
+
+    // converts to degrees and calls angle method
+    double theta = 180.0 * value / MAX_VALUE;
+    updatePointerAngle(theta);
+}