void ScreenRecoveryUI::Init()
{
gr_init();
gr_font_size(&char_width, &char_height);
text_col = text_row = 0;
text_rows = gr_fb_height() / char_height;
if (text_rows > kMaxRows) text_rows = kMaxRows;
text_top = 1;
text_cols = gr_fb_width() / char_width;
if (text_cols > kMaxCols - 1) text_cols = kMaxCols - 1;
LoadBitmap("icon_installing", &backgroundIcon[INSTALLING_UPDATE]);
backgroundIcon[ERASING] = backgroundIcon[INSTALLING_UPDATE];
LoadBitmap("icon_error", &backgroundIcon[ERROR]);
backgroundIcon[NO_COMMAND] = backgroundIcon[ERROR];
LoadBitmap("progress_empty", &progressBarEmpty);
LoadBitmap("progress_fill", &progressBarFill);
LoadLocalizedBitmap("installing_text", &backgroundText[INSTALLING_UPDATE]);
LoadLocalizedBitmap("erasing_text", &backgroundText[ERASING]);
LoadLocalizedBitmap("no_command_text", &backgroundText[NO_COMMAND]);
LoadLocalizedBitmap("error_text", &backgroundText[ERROR]);
int i;
progressBarIndeterminate = (gr_surface*)malloc(indeterminate_frames *
sizeof(gr_surface));
for (i = 0; i 0) {
installationOverlay = (gr_surface*)malloc(installing_frames *
sizeof(gr_surface));
for (i = 0; i
1、gr_init() 初始化图形设备，分配Pixelflinger库渲染的内存
2、gr_font_size() 将字体对应的surface长宽赋值给char_width和char_height
3、LoadBitmap() 将png生成surface, 每个png图片对应一个surface, 所有surface存放在一个数组中
4、LoadLocalizedBitmap() 将区域文字所在的图片中的text信息根据当前的locale提取出来，生成对应的surface, 所以
surface也存放在一个数组中
6、pthread_create(&progress_t, NULL, progress_thread, NULL)
创建一个线程，该线程的任务是一个死循环，在该循环中不停
地检测currentIcon以及progressBarType来决定是不是要更新进度条。
7、调用RecoveryUI的Init()，初始化输入事件处理。
void ScreenRecoveryUI::SetLocale(const char* locale) {
if (locale) {
char* lang = strdup(locale);
for (char* p = lang; *p; ++p) {
if (*p == '_') {
*p = '\0';
break;
}
}
// A bit cheesy: keep an explicit list of supported languages
// that are RTL.
if (strcmp(lang, "ar") == 0 || // Arabic
strcmp(lang, "fa") == 0 || // Persian (Farsi)
strcmp(lang, "he") == 0 || // Hebrew (new language code)
strcmp(lang, "iw") == 0 || // Hebrew (old language code)
strcmp(lang, "ur") == 0) { // Urdu
rtl_locale = true;
}
free(lang);
}
}
ScreenRecoveryUI类的SetLocale， 该函数根据locale判断所用的字体是否属于阿拉伯语系，阿拉伯语的书写习惯是从右到左，如果是阿拉伯语系的话，就设置一个标志，后面根据这个标志决定从右到左显示文字或进度条。SetLocale的参数locale赋值逻辑是这样的，先从command文件中读取, command文件中设置locale的命令如"--locale=zh_CN“，如果没有传入locale,初始化过程中会尝试从/cache/recovery/last_locale中读取locale, 如果该文件也没有，则locale不会被赋值，就默认用English. void ScreenRecoveryUI::SetBackground(Icon icon)
{
pthread_mutex_lock(&updateMutex);
// Adjust the offset to account for the positioning of the
// base image on the screen.
if (backgroundIcon[icon] != NULL) {
gr_surface bg = backgroundIcon[icon];
gr_surface text = backgroundText[icon];
overlay_offset_x = install_overlay_offset_x + (gr_fb_width() - gr_get_width(bg)) / 2;
overlay_offset_y = install_overlay_offset_y +
(gr_fb_height() - (gr_get_height(bg) + gr_get_height(text) + 40)) / 2;
}
currentIcon = icon;
update_screen_locked();
pthread_mutex_unlock(&updateMutex);
} SetBackground函数比较简洁，关键部分在update_screen_locked，下面我们重点分析一下。 update_screen_locked和update_progress_locked是recovery的UI部分的关键函数，update_screen_locked用来更新背景, update_progress_locked用来更新进度条，因为显示的画面会一直在更新，所以这两个函数会在不同的地方被反复调用
void ScreenRecoveryUI::update_screen_locked()
{
draw_screen_locked();
gr_flip();
} update_screen_locked包含两个操作，一是更新screen, 二是切换前后buffer。 void ScreenRecoveryUI::draw_screen_locked()
{
draw_background_locked(currentIcon);
draw_progress_locked();
if (show_text) {
SetColor(TEXT_FILL);
gr_fill(0, 0, gr_fb_width(), gr_fb_height());
int y = 0;
int i = 0;
if (show_menu) {
SetColor(HEADER);
for (; i y+2 && count
draw_background_locked函数的实现代码中又出现了几个以gr_开头的函数，以gr_开头的函数来自minui库，minui库的代码在recovery源码下的minui目录下，minui提供的接口实现了图形的描绘以及固定大小的文字显示。
gr_color(unsigned char r, unsigned char g, unsigned char b, unsigned char a);
gr_fill(int x, int y, int w, int h);
gr_blit(gr_surface source, int sx, int sy, int w, int h, int dx, int dy);
draw_background_locked函数先将整个渲染buffer填充为黑色，然后计算背景surface的长宽，文字surface的长宽，再结合fb的长宽计算出背景surface以及文字surface显示的坐标，有长宽和坐标就可以调用Pixelflinger的接口在渲染buffer上进行渲染。
void ScreenRecoveryUI::draw_progress_locked()
{
if (currentIcon == ERROR) return;
if (currentIcon == INSTALLING_UPDATE || currentIcon == ERASING) {
draw_install_overlay_locked(installingFrame);
}
if (progressBarType != EMPTY) {
int iconHeight = gr_get_height(backgroundIcon[INSTALLING_UPDATE]);
int width = gr_get_width(progressBarEmpty);
int height = gr_get_height(progressBarEmpty);
int dx = (gr_fb_width() - width)/2;
int dy = (3*gr_fb_height() + iconHeight - 2*height)/4;
// Erase behind the progress bar (in case this was a progress-only update)
gr_color(0, 0, 0, 255);
gr_fill(dx, dy, width, height);
if (progressBarType == DETERMINATE) {
float p = progressScopeStart + progress * progressScopeSize;
int pos = (int) (p * width);
if (rtl_locale) {
// Fill the progress bar from right to left.
if (pos > 0) {
gr_blit(progressBarFill, width-pos, 0, pos, height, dx+width-pos, dy);
}
if (pos 0) {
gr_blit(progressBarFill, 0, 0, pos, height, dx, dy);
}
if (pos
draw_progress_locked函数的原理与 update_screen_locked函数类似， 最终是将进度条的surface输出到渲染buffer,
recovery中各个场景的画面，就是由背景、文字、进度条的重叠，不同的是所用的surface 以及surface的坐标。
recovery main函数中的UI代码基本上已经分析过了，最后一点主菜单的显示，就是通过上面介绍的这些接口将文字图片显示出来，因此就不再多讲。总的来说，recovery的UI显示部分难度不大，应用层调用minui库实现了图形的描绘以及固定大小的文字显示，minui库调用了Pixelflinger库来进行渲染。
附上minui部分接口的说明，供参考
int gr_init(void);
void gr_exit(void);
int gr_fb_width(void);
int gr_fb_height(void);
gr_pixel *gr_fb_data(void);
void gr_flip(void);
void gr_fb_blank(bool blank);
void gr_color(unsigned char r, unsigned char g, unsigned char b, unsigned char a);
void gr_fill(int x, int y, int w, int h);
int gr_text(int x, int y, const char *s);
int gr_measure(const char *s);
void gr_font_size(int *x, int *y);
void gr_blit(gr_surface source, int sx, int sy, int w, int h, int dx, int dy);
unsigned int gr_get_width(gr_surface surface);
unsigned int gr_get_height(gr_surface surface);
int res_create_surface(const char* name, gr_surface* pSurface);
void res_free_surface(gr_surface surface);