Android 10 關機充電字型 設定範例

BGM

Android 10 以來 關機充電在AOSP中隻顯示圖檔 無法顯示百分比

探讨

Android 9及 之前的解決方案 一般是講字型轉換為二進制頭檔案來加載 ，

Android 10中資源加載的邏輯改變 二進制檔案的解析 移植困難

思路

AOSP中 Recovery mode中使用的miui的字型。 可以在系統不啟動的時候加載字型

使用此種字型解析方案 可以更快的實作關機充電字型

參考源碼

bootable/recovery/minui/resources.cpp

PngHandler::PngHandler(const std::string& name) {
  std::string res_path = g_resource_dir + "/" + name + ".png";
  png_fp_.reset(fopen(res_path.c_str(), "rbe"));
  // Try to read from |name| if the resource path does not work.
  if (!png_fp_) {
    png_fp_.reset(fopen(name.c_str(), "rbe"));
  }

  if (!png_fp_) {
    error_code_ = -1;
    return;
  }

  uint8_t header[8];
  size_t bytesRead = fread(header, 1, sizeof(header), png_fp_.get());
  if (bytesRead != sizeof(header)) {
    error_code_ = -2;
    return;
  }

  if (png_sig_cmp(header, 0, sizeof(header))) {
    error_code_ = -3;
    return;
  }

  png_ptr_ = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
  if (!png_ptr_) {
    error_code_ = -4;
    return;
  }

  info_ptr_ = png_create_info_struct(png_ptr_);
  if (!info_ptr_) {
    error_code_ = -5;
    return;
  }

  if (setjmp(png_jmpbuf(png_ptr_))) {
    error_code_ = -6;
    return;
  }

  png_init_io(png_ptr_, png_fp_.get());
  png_set_sig_bytes(png_ptr_, sizeof(header));
  png_read_info(png_ptr_, info_ptr_);

  png_get_IHDR(png_ptr_, info_ptr_, &width_, &height_, &bit_depth_, &color_type_, nullptr, nullptr,
               nullptr);

  channels_ = png_get_channels(png_ptr_, info_ptr_);

  if (bit_depth_ == 8 && channels_ == 3 && color_type_ == PNG_COLOR_TYPE_RGB) {
    // 8-bit RGB images: great, nothing to do.
  } else if (bit_depth_ <= 8 && channels_ == 1 && color_type_ == PNG_COLOR_TYPE_GRAY) {
    // 1-, 2-, 4-, or 8-bit gray images: expand to 8-bit gray.
    png_set_expand_gray_1_2_4_to_8(png_ptr_);
  } else if (bit_depth_ <= 8 && channels_ == 1 && color_type_ == PNG_COLOR_TYPE_PALETTE) {
    // paletted images: expand to 8-bit RGB.  Note that we DON'T
    // currently expand the tRNS chunk (if any) to an alpha
    // channel, because minui doesn't support alpha channels in
    // general.
    png_set_palette_to_rgb(png_ptr_);
    channels_ = 3;
  } else {
    fprintf(stderr, "minui doesn't support PNG depth %d channels %d color_type %d\n", bit_depth_,
            channels_, color_type_);
    error_code_ = -7;
  }
}
           

總結

要熟悉關機充電的流程。合理利用已有機制