draw qrcode for wlan connection

2 files changed, 96 insertions, 0 deletions

diff --git a/src/draw_qrcode.cpp b/src/draw_qrcode.cpp
new file mode 100644
index 0000000..594e47c
--- /dev/null
+++ b/src/draw_qrcode.cpp
@@ -0,0 +1,94 @@
+#include <GxEPD2_BW.h>
+#include <Fonts/FreeSansBold9pt7b.h>
+#include <Fonts/FreeSans9pt7b.h>
+#include <qrcode.h>
+
+#define BLOCK_WIDTH 4
+
+static uint16_t sizes[] = {
+	17, 32, 53, 78, 106, 134, 154, 192, 230,
+};
+
+static void escape_strings(String &text) {
+	text.replace("\\", "\\\\");
+	text.replace("\"", "\\\"");
+	text.replace(";", "\\;");
+	text.replace(",", "\\,");
+	text.replace(":", "\\:");
+}
+
+static int version_for_len(int length) {
+	/* assuming ECC_LOW byte qrcodes
+	   sizes taken from table in https://github.com/ricmoo/QRCode/blob/master/README.md */
+
+	for (int i = 0; i < sizeof(sizes)/sizeof(uint16_t); i++) {
+		if (length <= sizes[i])
+			return i + 1;
+	}
+	return -1;
+}
+
+int draw_qrcode(GxEPD2_GFX_BASE_CLASS &display, int16_t x, int16_t y, String &text) {
+	QRCode qrcode;
+	int version = version_for_len(text.length());
+	if (version <= 0)
+		return 0;
+
+	uint8_t bytes[qrcode_getBufferSize(version)];
+	qrcode_initText(&qrcode, bytes, version, ECC_LOW, text.c_str());
+
+	/* add quiet zone */
+	x += 4 * BLOCK_WIDTH;
+	y += 4 * BLOCK_WIDTH;
+
+	for (int row = 0; row < qrcode.size; row++) {
+		for (int col = 0; col < qrcode.size; col++) {
+			if (!qrcode_getModule(&qrcode, row, col)) {
+				continue;
+			}
+			display.fillRect(x + BLOCK_WIDTH * row, y + BLOCK_WIDTH * col, BLOCK_WIDTH, BLOCK_WIDTH, GxEPD_BLACK);
+		}
+	}
+	return qrcode.size * BLOCK_WIDTH + 8 * BLOCK_WIDTH;
+}
+
+void draw_qrcode_wlan(GxEPD2_GFX_BASE_CLASS &display, int16_t x, int16_t y, const char *ssid, const char *psk) {
+	String ssid_str = String(ssid);
+	String psk_str = String(psk);
+	escape_strings(ssid_str);
+	escape_strings(psk_str);
+
+	/* assuming WPA network; (H)idden attribute is kept at default */
+	String wifi_str = "WIFI:S:" + ssid_str;
+	if (psk_str.length() == 0) {
+		/* open network */
+		wifi_str += ";;;;";
+	} else {
+		wifi_str += ";P:" + psk_str + ";T:WPA;;";
+	}
+
+	int size = draw_qrcode(display, x, y, wifi_str);
+
+	/* draw text */
+	int16_t x2, y2;
+	uint16_t w, h;
+	String text_ssid = String("SSID:");
+	String text_psk = String("PSK:");
+
+	display.setFont(&FreeSansBold9pt7b);
+	display.getTextBounds(text_ssid, 0, 0, &x2, &y2, &w, &h);
+	display.setCursor(x, y + size + h);
+	display.print(text_ssid);
+	display.setFont(&FreeSans9pt7b);
+	display.setCursor(x + w, y + size + h);
+	display.print("  " + ssid_str);
+
+	if (psk_str.length() > 0) {
+		display.setFont(&FreeSansBold9pt7b);
+		display.setCursor(x, y + size + 2 * h + 10);
+		display.print(text_psk);
+		display.setFont(&FreeSans9pt7b);
+		display.setCursor(x + w, y + size + 2 * h + 10);
+		display.print("  " + psk_str);
+	}
+}
diff --git a/src/main.cpp b/src/main.cpp
index b8cb0c1..70f2559 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -4,6 +4,7 @@
 #include <WiFi.h>
 
 #include "calendar.h"
+#include "draw_qrcode.h"
 #include "secrets.h"
 
 /*
@@ -42,6 +43,7 @@ void draw() {
 	do {
 		display.fillScreen(GxEPD_WHITE);
 		draw_calendar(display, 30, 30);
+		draw_qrcode_wlan(display, 30, 200, wifi_ssid, wifi_psk);
 	} while(display.nextPage());
 }