c - TextLayer 不显示

Question

初学者，试图修改 Pebble 提供的示例应用程序之一，但我失去了理智。

在下面的代码中，我无法让 TextLayer *s_weather_label 实际呈现在屏幕上。不知道为什么……没有出现错误，应用程序编译正常。

#include "simple_analog.h"
#include "pebble.h"

static Window *window;
static Layer *s_simple_bg_layer, *s_date_layer, *s_hands_layer;
static BitmapLayer *s_background_layer;

static GBitmap *s_background_bitmap;
static TextLayer *s_day_label, *s_num_label, *s_weather_label;

static GPath *s_tick_paths[NUM_CLOCK_TICKS];
static GPath *s_minute_arrow, *s_hour_arrow;
static char s_num_buffer[4], s_day_buffer[6];

static void bg_update_proc(Layer *layer, GContext *ctx) {
  graphics_context_set_fill_color(ctx, GColorBlack);
  graphics_fill_rect(ctx, layer_get_bounds(layer), 0, GCornerNone);
  graphics_context_set_fill_color(ctx, GColorWhite);
  for (int i = 0; i < NUM_CLOCK_TICKS; ++i) {
    gpath_draw_filled(ctx, s_tick_paths[i]);
  }
}

static void hands_update_proc(Layer *layer, GContext *ctx) {
  GRect bounds = layer_get_bounds(layer);
  GPoint center = grect_center_point(&bounds);
  int16_t second_hand_length = bounds.size.w / 2;

  time_t now = time(NULL);
  struct tm *t = localtime(&now);
  int32_t second_angle = TRIG_MAX_ANGLE * t->tm_sec / 60;
  GPoint second_hand = {
    .x = (int16_t)(sin_lookup(second_angle) * (int32_t)second_hand_length / TRIG_MAX_RATIO) + center.x,
    .y = (int16_t)(-cos_lookup(second_angle) * (int32_t)second_hand_length / TRIG_MAX_RATIO) + center.y,
  };

  // second hand
  graphics_context_set_stroke_color(ctx, GColorWhite);
  graphics_draw_line(ctx, second_hand, center);

  // minute/hour hand
  graphics_context_set_fill_color(ctx, GColorWhite);
  graphics_context_set_stroke_color(ctx, GColorBlack);

  gpath_rotate_to(s_minute_arrow, TRIG_MAX_ANGLE * t->tm_min / 60);
  gpath_draw_filled(ctx, s_minute_arrow);
  gpath_draw_outline(ctx, s_minute_arrow);

  gpath_rotate_to(s_hour_arrow, (TRIG_MAX_ANGLE * (((t->tm_hour % 12) * 6) + (t->tm_min / 10))) / (12 * 6));
  gpath_draw_filled(ctx, s_hour_arrow);
  gpath_draw_outline(ctx, s_hour_arrow);

  // dot in the middle
  graphics_context_set_fill_color(ctx, GColorBlack);
  graphics_fill_rect(ctx, GRect(bounds.size.w / 2 - 1, bounds.size.h / 2 - 1, 3, 3), 0, GCornerNone);
}

static void date_update_proc(Layer *layer, GContext *ctx) {
  time_t now = time(NULL);
  struct tm *t = localtime(&now);

  strftime(s_day_buffer, sizeof(s_day_buffer), "%a", t);
  text_layer_set_text(s_day_label, s_day_buffer);

  strftime(s_num_buffer, sizeof(s_num_buffer), "%d", t);
  text_layer_set_text(s_num_label, s_num_buffer);
}

static void handle_second_tick(struct tm *tick_time, TimeUnits units_changed) {
  layer_mark_dirty(window_get_root_layer(window));
}

static void window_load(Window *window) {
  Layer *window_layer = window_get_root_layer(window);
  GRect bounds = layer_get_bounds(window_layer);

    // Create GBitmap, then set to created BitmapLayer
    s_background_bitmap = gbitmap_create_with_resource(RESOURCE_ID_IMAGE_BACKGROUND);
    s_background_layer = bitmap_layer_create(GRect(0, 0, 144, 168));
    bitmap_layer_set_bitmap(s_background_layer, s_background_bitmap);
    layer_add_child(window_get_root_layer(window), bitmap_layer_get_layer(s_background_layer));

  s_date_layer = layer_create(bounds);
  layer_set_update_proc(s_date_layer, date_update_proc);
  layer_add_child(window_layer, s_date_layer);

  s_day_label = text_layer_create(GRect(4, 146, 27, 20));
  text_layer_set_text(s_day_label, s_day_buffer);
  text_layer_set_background_color(s_day_label, GColorClear);
  text_layer_set_text_color(s_day_label, GColorWhite);
  text_layer_set_font(s_day_label, fonts_get_system_font(FONT_KEY_GOTHIC_18));

  layer_add_child(s_date_layer, text_layer_get_layer(s_day_label));

  s_num_label = text_layer_create(GRect(30, 146, 18, 20));
  text_layer_set_text(s_num_label, s_num_buffer);
  text_layer_set_background_color(s_num_label, GColorClear);
  text_layer_set_text_color(s_num_label, GColorWhite);
  text_layer_set_font(s_num_label, fonts_get_system_font(FONT_KEY_GOTHIC_18));

  // Create temperature Layer
  s_weather_label = text_layer_create(GRect(50, 146, 50, 20));
  text_layer_set_text(s_weather_label, "Loading...");
  text_layer_set_background_color(s_weather_label, GColorClear);
  text_layer_set_text_color(s_weather_label, GColorWhite);
  text_layer_set_font(s_weather_label, fonts_get_system_font(FONT_KEY_GOTHIC_18));

  layer_add_child(s_date_layer, text_layer_get_layer(s_num_label));

  s_hands_layer = layer_create(bounds);
  layer_set_update_proc(s_hands_layer, hands_update_proc);
  layer_add_child(window_layer, s_hands_layer);

}

static void window_unload(Window *window) {
  // Destroy GBitmap
  gbitmap_destroy(s_background_bitmap);

  // Destroy BitmapLayer
  bitmap_layer_destroy(s_background_layer);

  layer_destroy(s_date_layer);

  text_layer_destroy(s_day_label);
  text_layer_destroy(s_num_label);
  text_layer_destroy(s_weather_label);

  layer_destroy(s_hands_layer);
}

static void init() {
  window = window_create();
  window_set_window_handlers(window, (WindowHandlers) {
    .load = window_load,
    .unload = window_unload,
  });
  window_stack_push(window, true);

  s_day_buffer[0] = '\0';
  s_num_buffer[0] = '\0';

  // init hand paths
  s_minute_arrow = gpath_create(&MINUTE_HAND_POINTS);
  s_hour_arrow = gpath_create(&HOUR_HAND_POINTS);

  Layer *window_layer = window_get_root_layer(window);
  GRect bounds = layer_get_bounds(window_layer);
  GPoint center = grect_center_point(&bounds);
  gpath_move_to(s_minute_arrow, center);
  gpath_move_to(s_hour_arrow, center);

  for (int i = 0; i < NUM_CLOCK_TICKS; ++i) {
    s_tick_paths[i] = gpath_create(&ANALOG_BG_POINTS[i]);
  }

  tick_timer_service_subscribe(SECOND_UNIT, handle_second_tick);
}

static void deinit() {
  gpath_destroy(s_minute_arrow);
  gpath_destroy(s_hour_arrow);

  for (int i = 0; i < NUM_CLOCK_TICKS; ++i) {
    gpath_destroy(s_tick_paths[i]);
  }

  tick_timer_service_unsubscribe();
  window_destroy(window);
}

int main() {
  init();
  app_event_loop();
  deinit();
}

Answer 1

您需要将您的s_weather_label 图层添加到另一个图层。现在它已创建但未添加到任何内容。

我想只是添加:

layer_add_child(window_layer, text_layer_get_layer(s_weather_label));

会做你想做的事!