Add screenshot capture via Joy-Con Capture button

- source/screenshot.c, screenshot.h: take_screenshot() saves framebuffer as BMP
- Path: sd:/switch/screenshot/omninx_installer_YYYYMMDD_HHMMSS.bmp (RTC timestamp)
- 3s cooldown, backlight flash on capture; TegraExplorer-style BGR flip
- main.c: call take_screenshot() when jc->cap in all joycon poll loops

Made-with: Cursor

source/main.c

@@ -35,6 +35,7 @@
 #include "fs.h"
 #include "version.h"
 #include "install.h"
+#include "screenshot.h"
 
 // Configuration
 #define PAYLOAD_PATH      "sd:/bootloader/update.bin"
@@ -264,12 +265,16 @@ void ipl_main(void) {
                 break;
             }
             
-            // Check joycon A button
+            // Check joycon A button; Capture = screenshot
             jc_gamepad_rpt_t *jc = joycon_poll();
-            if (jc && jc->a) {
+            if (jc) {
+                if (jc->cap)
+                    take_screenshot();
+                if (jc->a) {
                     button_pressed = true;
                     break;
                 }
+            }
             
             msleep(50); // Small delay to avoid busy-waiting
         }
@@ -345,6 +350,9 @@ void ipl_main(void) {
             jc_gamepad_rpt_t *jc = joycon_poll();
             u8 btn = btn_read();
             
+            if (jc && jc->cap)
+                take_screenshot();
+            
             // D-pad or Vol+ / Vol- for selection (Vol+ = up, Vol- = down)
             bool cur_up = false, cur_down = false;
             if (jc) {
@@ -402,10 +410,14 @@ void ipl_main(void) {
         bool user_cancelled = false;
         while (batt_pct < BATT_LOW_THRESHOLD && !bq24193_charger_connected() && !user_cancelled) {
             jc_gamepad_rpt_t *jc = joycon_poll();
-            if (jc && jc->plus && jc->minus) {
+            if (jc) {
+                if (jc->cap)
+                    take_screenshot();
+                if (jc->plus && jc->minus) {
                     user_cancelled = true;
                     break;
                 }
+            }
             if (max17050_get_property(MAX17050_RepSOC, &batt_raw) == 0) {
                 batt_pct = batt_raw >> 8;
             }
@@ -468,7 +480,11 @@ void ipl_main(void) {
             u8 btn_state = btn_read();
             if (btn_state & BTN_POWER) acknowledged = true;
             jc_gamepad_rpt_t *jc = joycon_poll();
-            if (jc && jc->a) acknowledged = true;
+            if (jc) {
+                if (jc->cap)
+                    take_screenshot();
+                if (jc->a) acknowledged = true;
+            }
             msleep(50);
         }
         // Wait for A and Power to be released so the same press doesn't start the install
@@ -530,9 +546,11 @@ void ipl_main(void) {
             break;
         }
         
-        // Check joycon buttons
+        // Check joycon buttons; Capture = screenshot
         jc_gamepad_rpt_t *jc = joycon_poll();
         if (jc) {
+            if (jc->cap)
+                take_screenshot();
             if (jc->a) {
                 button_pressed = true;
                 break;
@@ -578,6 +596,7 @@ void ipl_main(void) {
     
     // Wait 3 seconds before clearing screen to allow errors to be visible
     msleep(3000);
+    // take_screenshot(); // Take a screenshot of the installation summary
 
     // Clear screen for final summary to ensure it's visible
     gfx_clear_grey(0x1B);
@@ -630,12 +649,16 @@ void ipl_main(void) {
             break;
         }
         
-        // Check joycon A button
+        // Check joycon A button; Capture = screenshot
         jc_gamepad_rpt_t *jc = joycon_poll();
-        if (jc && jc->a) {
+        if (jc) {
+            if (jc->cap)
+                take_screenshot();
+            if (jc->a) {
                 button_pressed = true;
                 break;
             }
+        }
         
         msleep(50); // Small delay to avoid busy-waiting
     }
@@ -672,10 +695,14 @@ void ipl_main(void) {
             }
             
             jc_gamepad_rpt_t *jc = joycon_poll();
-            if (jc && jc->a) {
+            if (jc) {
+                if (jc->cap)
+                    take_screenshot();
+                if (jc->a) {
                     button_pressed = true;
                     break;
                 }
+            }
             
             msleep(50);
         }

source/screenshot.c

@@ -0,0 +1,111 @@
+/*
+ * Screenshot support for OmniNX Installer Payload
+ * Based on TegraExplorer (AllgemeinerProblemLoeser) TakeScreenshot implementation.
+ */
+
+#include "screenshot.h"
+#include "gfx.h"
+#include "nx_sd.h"
+#include <libs/fatfs/ff.h>
+#include <mem/heap.h>
+#include <display/di.h>
+#include <utils/util.h>
+#include <utils/sprintf.h>
+#include <rtc/max77620-rtc.h>
+#include <string.h>
+
+/* BMP file header (54 bytes), matching TegraExplorer tools.h */
+typedef struct __attribute__((packed)) _bmp_hdr_t
+{
+	u16 magic;
+	u32 size;
+	u32 rsvd;
+	u32 data_off;
+	u32 hdr_size;
+	u32 width;
+	u32 height;
+	u16 planes;
+	u16 pxl_bits;
+	u32 comp;
+	u32 img_size;
+	u32 res_h;
+	u32 res_v;
+	u64 rsvd2;
+} bmp_hdr_t;
+
+#define BMP_HEADER_SIZE  0x36
+#define FB_SIZE          0x384000   /* 1280 * 720 * 4 */
+#define SCREEN_W         1280
+#define SCREEN_H         720
+
+void take_screenshot(void)
+{
+	static u32 last_timer = 0;
+
+	if (!sd_get_card_mounted())
+		return;
+
+	/* 3-second cooldown (same as TegraExplorer) */
+	u32 now = get_tmr_s();
+	if (last_timer != 0 && now < last_timer + 3)
+		return;
+	last_timer = now;
+
+	const char basepath[] = "sd:/switch/screenshot";
+	char name[48];
+	char path[80];
+	rtc_time_t rtc;
+
+	max77620_rtc_get_time(&rtc);
+	s_printf(name, "omninx_installer_%04d%02d%02d_%02d%02d%02d.bmp",
+		(u32)rtc.year, (u32)rtc.month, (u32)rtc.day,
+		(u32)rtc.hour, (u32)rtc.min, (u32)rtc.sec);
+	s_printf(path, "%s/%s", basepath, name);
+
+	f_mkdir("sd:/switch");
+	f_mkdir(basepath);
+
+	const u32 file_size = BMP_HEADER_SIZE + FB_SIZE;
+	u8 *bitmap = (u8 *)malloc(file_size);
+	u32 *fb_copy = (u32 *)malloc(FB_SIZE);
+	if (!bitmap || !fb_copy) {
+		if (bitmap) free(bitmap);
+		if (fb_copy) free(fb_copy);
+		return;
+	}
+
+	/* Copy framebuffer with same coordinate flip as TegraExplorer (BGR layout) */
+	u32 *fb_ptr = gfx_ctxt.fb;
+	for (int x = SCREEN_W - 1; x >= 0; x--) {
+		for (int y = SCREEN_H - 1; y >= 0; y--)
+			fb_copy[y * SCREEN_W + x] = *fb_ptr++;
+	}
+
+	memcpy(bitmap + BMP_HEADER_SIZE, fb_copy, FB_SIZE);
+
+	bmp_hdr_t *bmp = (bmp_hdr_t *)bitmap;
+	bmp->magic    = 0x4D42;
+	bmp->size     = file_size;
+	bmp->rsvd     = 0;
+	bmp->data_off = BMP_HEADER_SIZE;
+	bmp->hdr_size = 40;
+	bmp->width    = SCREEN_W;
+	bmp->height   = SCREEN_H;
+	bmp->planes   = 1;
+	bmp->pxl_bits = 32;
+	bmp->comp     = 0;
+	bmp->img_size = FB_SIZE;
+	bmp->res_h    = 2834;
+	bmp->res_v    = 2834;
+	bmp->rsvd2    = 0;
+
+	sd_save_to_file(bitmap, file_size, path);
+
+	free(bitmap);
+	free(fb_copy);
+
+	/* Brief backlight flash (same as TegraExplorer) */
+	display_backlight_brightness(255, 1000);
+	msleep(100);
+	display_backlight_brightness(100, 1000);
+}

source/screenshot.h

@@ -0,0 +1,13 @@
+/*
+ * Screenshot support for OmniNX Installer Payload
+ * Based on TegraExplorer (AllgemeinerProblemLoeser) TakeScreenshot implementation.
+ */
+
+#pragma once
+
+#include <utils/types.h>
+
+/* Take a screenshot of the current framebuffer and save as BMP to SD.
+ * Triggered by Capture button (jc->cap). Uses 3-second cooldown.
+ * Saves to sd:/switch/screenshot/omninx_installer_YYYYMMDD_HHMMSS.bmp */
+void take_screenshot(void);