1 files changed, 48 insertions, 0 deletions
diff --git a/src/tangara/ui/screenshot.cpp b/src/tangara/ui/screenshot.cpp
new file mode 100644
index 00000000..e4f9cc3f
--- /dev/null
+++ b/src/tangara/ui/screenshot.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2024 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#include "screenshot.hpp"
+#include <sys/_stdint.h>
+
+#include <string>
+
+#define LODEPNG_NO_COMPILE_CPP
+#include "libs/lodepng/lodepng.h"
+
+#include "esp_log.h"
+#include "lvgl.h"
+
+namespace ui {
+
+[[maybe_unused]] static constexpr char kTag[] = "screenshot";
+
+auto SaveScreenshot(lv_obj_t* obj, const std::string& path) -> void {
+  lv_draw_buf_t* buf = lv_snapshot_take(obj, LV_COLOR_FORMAT_RGB888);
+  if (!buf) {
+    return;
+  }
+
+  // LVGL appears to output BGR data instead. Not quite sure why, but swapping
+  // each pair is quite easy.
+  for (size_t i = 0; i < buf->data_size; i += 3) {
+    uint8_t temp = buf->data[i];
+    buf->data[i] = buf->data[i + 2];
+    buf->data[i + 2] = temp;
+  }
+
+  // The LVGL lodepng fork uses LVGL's file API, so an extra '/' is needed.
+  std::string fullpath = "//sdcard/" + path;
+
+  auto res = lodepng_encode_file(fullpath.c_str(), buf->data, buf->header.w,
+                                 buf->header.h, LCT_RGB, 8);
+
+  lv_draw_buf_destroy(buf);
+  if (res != 0) {
+    ESP_LOGE(kTag, "lodepng error: '%s'", lodepng_error_text(res));
+  }
+}
+
+}  // namespace ui