mcap/src/app/screen_capture.jai

// Screen capture, as Snagit does it: PrintScreen on Windows, Cmd+Shift+2 on macOS (the capture_region
// global hotkey, from any app, even with mcap hidden in the tray) freezes every screen, and a rectangle
// dragged over them is taken (app/screen_capture_win32.jai, app/screen_capture_macos.jai). What is taken goes onto the clipboard at once,
// and into the library as an .mcap in the folder SCREEN_CAPTURE_FOLDER: the pixels as a PNG, with
// the window it was taken from in metadata.json, its title as WindowName and its program as AppName,
// as Snagit records them, so searches find it the same way. mcap then comes to the front showing
// it in the Capture window, and OCR and labels read it once they are free.
//
// The PNG is made and the file written on a thread of its own, as a large capture takes a second or
// so to compress. A screen recording (app/screen_record.jai) goes into the library through the same
// jobs.

SCREEN_CAPTURE_FOLDER :: "Screen Captures";   // in the library

Screen_Capture_Job :: struct {
  shot: Screen_Shot;
  date: string;        // CaptureDate; heap

  // A recording (app/screen_record.jai), not a still; its strings are heap.
  video: bool;
  recording: string;   // the MP4 recorded, deleted once in the library
  encoder: string;     // "h264_nvenc"
  source: string;      // how the screen was taken: Record_Stats.source
  dropped: s64;        // frames the encoder fell too far behind for
  paused_seconds: float64;   // left out of it
  audio: string;             // the sound's sources, "Speakers (...); Microphone (...)", or ""

  thread: Thread;
  busy: bool;          // cleared by the thread as it ends
  path: string;        // what it wrote; heap
  error: string;       // or why it could not; heap
}

screen_capture: struct {
  jobs: [..] *Screen_Capture_Job;
  scan_pending: [..] s32;      // captures OCR and labels have yet to read
  segment_pending: [..] s32;   // and then segmentation, when the folder is set to segment
}

// From app_frame when the hotkey fired, outside the ImGui frame: lets a region be chosen, copies it,
// and starts writing it into the library.
screen_capture_take :: () {
  if app_exit_shutdown_started()  return;
  date := import_calendar_text(to_calendar(current_time_consensus(), .LOCAL));
  start := current_time_monotonic();
  // While recording, the overlay's frozen screen would be in the recording: the screen under the
  // cursor is taken at once instead.
  shot, ok, error := platform_screen_capture_select(immediate = screen_record.recording);
  if !ok {
    if error { log_error("[capture] %.", error); toast_show(.Error, "Screen capture: %", error); }
    else       log("[capture] Cancelled.");
    return;
  }
  log("[capture] % x % at %, % (%) from \"%\" (%), chosen in % s.", shot.width, shot.height, shot.left, shot.top,
      ifx shot.whole_screen then "the whole screen" else "a region", shot.window_title, shot.app_name,
      FF(to_float64_seconds(current_time_monotonic() - start), 1));

  if !platform_copy_image_to_clipboard(shot.pixels, shot.width, shot.height)  log_error("[capture] Could not put the capture on the clipboard.");

  job := New(Screen_Capture_Job,, context.default_allocator);
  job.shot = shot;
  job.date = copy_string(date,, context.default_allocator);
  screen_capture_job_start(job);
}

// Writes the job into the library on a thread of its own; screen_capture_frame takes it from there.
// The job is freed when it cannot start.
screen_capture_job_start :: (job: *Screen_Capture_Job) -> bool {
  job.busy = true;
  if !thread_init(*job.thread, screen_capture_save_proc, temporary_storage_size = 1024 * 1024, name = "screen capture") {
    what := ifx job.video then "recording" else "capture";
    log_error("[capture] Could not start the thread to save the %.", what);
    toast_show(.Error, "The screen % could not be saved", what);
    screen_capture_job_free(job);
    return false;
  }
  thread_start(*job.thread, job);
  screen_capture.jobs.allocator = context.default_allocator;
  array_add(*screen_capture.jobs, job);
  return true;
}

// Every frame, even while hidden in the tray: the captures written, into the grid and the Capture
// window, and then read.
screen_capture_frame :: () {
  if app_exit_shutdown_started()  return;
  screen_record_frame();
  for job: screen_capture.jobs {
    if atomic_read(*job.busy)  continue;
    thread_is_done(*job.thread, -1);
    thread_deinit(*job.thread);
    what := ifx job.video then "recording" else "capture";
    if job.video  screen_record_saved(job.path, job.error);
    if job.error {
      log_error("[capture] Could not save the %: %", what, job.error);
      toast_show(.Error, "The screen % could not be saved: %", what, job.error);
    } else {
      log("[capture] Saved %.", job.path);
      index := viewer_add_capture(job.path);
      if index >= 0 {
        viewer_request_full(index);
        screen_capture.scan_pending.allocator = context.default_allocator;
        screen_capture.segment_pending.allocator = context.default_allocator;
        array_add(*screen_capture.scan_pending, index);
        if !job.video && library_folder_segments(SCREEN_CAPTURE_FOLDER)  array_add(*screen_capture.segment_pending, index);
      }
      app.restore_window_this_frame = true;
      if job.video  toast_show(.Success, "% x % recorded", job.shot.width, job.shot.height);
      else          toast_show(.Success, "% x % captured and copied to the clipboard", job.shot.width, job.shot.height);
    }
    screen_capture_job_free(job);
    remove job;
  }

  // As an import's are, once the models are loaded and free: OCR and labels, then segmentation.
  if screen_capture.scan_pending.count && !ocr_ui.scan.running && ocr_ui_models_ready(labels_ui.scan_labels) && ocr_ui.engine {
    ocr_scan_start(screen_capture.scan_pending);
    array_reset_keeping_memory(*screen_capture.scan_pending);
  }
  // Once their catalog entries are in: the scan takes only images, and they say which.
  if screen_capture.segment_pending.count && !screen_capture.scan_pending.count && !ocr_ui.thread_busy && !ocr_ui.scan.running {
    catalogued := true;
    for screen_capture.segment_pending  if !viewer.captures[it].catalog && !viewer.captures[it].removed { catalogued = false; break; }
    if catalogued {
      segment_scan_start(screen_capture.segment_pending, quiet = true);
      array_reset_keeping_memory(*screen_capture.segment_pending);
    }
  }
}

// On the shutdown thread: a capture being written is finished, not lost.
screen_capture_shutdown :: () {
  screen_record_shutdown();   // a recording running is stopped and becomes a job, finished below
  for screen_capture.jobs  thread_is_done(*it.thread, -1);
}

screen_capture_job_free :: (job: *Screen_Capture_Job) {
  push_allocator(context.default_allocator);
  screen_shot_free(*job.shot);
  free(job.date);
  free(job.path);
  free(job.error);
  free(job.recording);
  free(job.encoder);
  free(job.source);
  free(job.audio);
  free(job);
}

screen_capture_save_proc :: (thread: *Thread) -> s64 {
  job := cast(*Screen_Capture_Job) thread.data;
  context.allocator = context.default_allocator;
  defer atomic_swap(*job.busy, false);
  path, error: string;
  if job.video  path, error = screen_record_write(job);
  else          path, error = screen_capture_write(job.shot, job.date);
  if error  job.error = copy_string(error);
  else      job.path = copy_string(path);
  return 0;
}

// Writes the capture into the library: its path, or why it could not be (temp).
screen_capture_write :: (shot: Screen_Shot, date: string) -> path: string, error: string {
  image := Image.{pixels = shot.pixels.data, width = shot.width, height = shot.height};
  png, _, _, png_ok, png_error := image_preview_png(image, max(shot.width, shot.height));   // at its own size
  if !png_ok  return "", png_error;
  preview, preview_width, preview_height, preview_ok, preview_error := image_preview_png(image, MCAP_PREVIEW_MAX_SIDE);
  if !preview_ok  return "", preview_error;
  hash := import_hash(png);

  doc := New(Capture_Document,, temp);
  capture_document_init(doc, temp);
  doc.comment = tprint("Captured by % %.", APP_NAME, VERSION);
  metadata := capture_add_file(doc, "metadata.json");
  import_add(doc, metadata, "AppName", import_text(shot.app_name));
  import_add(doc, metadata, "CaptureDate", date);
  import_add(doc, metadata, "WindowName", import_text(shot.window_title));
  info := capture_add_file(doc, "capture.json");
  import_add(doc, info, "Region", ifx shot.whole_screen then "screen" else "selection");
  import_add_number(doc, info, "Left", xx shot.left);
  import_add_number(doc, info, "Top", xx shot.top);
  import_add_number(doc, info, "Width", xx shot.width);
  import_add_number(doc, info, "Height", xx shot.height);
  if shot.app_path  import_add(doc, info, "AppPath", import_text(shot.app_path));
  import_add(doc, info, "ContentHash", import_hash_text(hash));
  import_add(doc, info, "Format", "PNG");

  name := import_out_name(date, hash);
  text, text_ok := import_document_text(doc, name);
  if !text_ok  return "", "its Capture Text does not read back cleanly (see the Event Log)";

  m: Mcap;
  m.text = text;
  m.preview = .{width = cast(u16) preview_width, height = cast(u16) preview_height, png = preview};
  m.original_name = tprint("%.png", path_strip_extension(name));
  m.original = png;
  m.rendered_kind = .NONE;
  serializer, serialized, serialize_error := mcap_serialize(m,, temp);
  if !serialized  return "", serialize_error;

  path, folder_error := screen_capture_out_path(name);
  if folder_error  return "", folder_error;
  written, write_error := mcap_write(path, cast([] u8) string.{serializer.count, serializer.data});
  if !written  return "", write_error;
  return path, "";
}

// Where a capture named name goes in SCREEN_CAPTURE_FOLDER, made if need be: name, or name_2 ... when
// another file has it. Temp.
screen_capture_out_path :: (name: string) -> path: string, error: string {
  folder := tprint("%/%", viewer_folder(), SCREEN_CAPTURE_FOLDER);
  if !make_directory_if_it_does_not_exist(folder, recursive = true)  return "", tprint("% could not be made", folder);
  path := tprint("%/%", folder, name);
  number := 2;
  while file_exists(path) {
    path = tprint("%/%_%.%", folder, path_strip_extension(name), number, MCAP_EXTENSION);
    number += 1;
  }
  return path, "";
}

#if OS == .LINUX {
  Screen_Shot :: struct {
    pixels: [] u8;
    width, height: s32;
    left, top: s32;
    whole_screen: bool;
    window_title, app_name, app_path: string;
  }

  screen_shot_free :: (shot: *Screen_Shot) {
    array_free(shot.pixels,, context.default_allocator);
    shot.* = .{};
  }

  platform_screen_capture_select :: (video := false, immediate := false) -> Screen_Shot, ok: bool, error: string {
    return .{}, false, "not available on this system yet";
  }

  platform_copy_image_to_clipboard :: (pixels: [] u8, width: s32, height: s32) -> bool {
    return false;
  }
}