Android recovery UI实现分析

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

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[cpp] view%20plain copy void ScreenRecoveryUI::update_screen_locked()  {      draw_screen_locked();      gr_flip();  }   update_screen_locked包含两个操作，一是更新screen,%20二是切换前后buffer。 [cpp] view%20plain copy 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 < menu_top + menu_items; ++i) {                  if (i == menu_top) SetColor(MENU);                    if (i == menu_top + menu_sel) {                      // draw the highlight bar                      SetColor(MENU_SEL_BG);                      gr_fill(0, y-2, gr_fb_width(), y+char_height+2);                      // white text of selected item                      SetColor(MENU_SEL_FG);                      if (menu[i][0]) gr_text(4, y, menu[i], 1);                      SetColor(MENU);                  } else {                      if (menu[i][0]) gr_text(4, y, menu[i], i < menu_top);                  }                  y += char_height+4;              }              SetColor(MENU);              y += 4;              gr_fill(0, y, gr_fb_width(), y+2);              y += 4;              ++i;          }            SetColor(LOG);            // display from the bottom up, until we hit the top of the          // screen, the bottom of the menu, or we've displayed the          // entire text buffer.          int ty;          int row = (text_top+text_rows-1) % text_rows;          for (int ty = gr_fb_height() - char_height, count = 0;               ty > y+2 && count < text_rows;               ty -= char_height, ++count) {              gr_text(4, ty, text[row], 0);              --row;              if (row < 0) row = text_rows-1;          }      }  }   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%20char%20r,%20unsigned%20char%20g,%20unsigned%20char%20b,%20unsigned%20char%20a);%20 /*%20设置字体颜色%20*/%20 gr_fill(int%20x,%20int%20y,%20int%20w,%20int%20h);%20 /*%20填充矩形区域,参数分别代表起始坐标、矩形区域大小%20*/%20 gr_blit(gr_surface%20source,%20int%20sx,%20int%20sy,%20int%20w,%20int%20h,%20int%20dx,%20int%20dy);%20 /*%20填充由source指定的图片%20*/%20 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。 [cpp] view%20plain copy 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 < width-1) {                      gr_blit(progressBarEmpty, 0, 0, width-pos, height, dx, dy);                  }              } else {                  // Fill the progress bar from left to right.                  if (pos > 0) {                      gr_blit(progressBarFill, 0, 0, pos, height, dx, dy);                  }                  if (pos < width-1) {                      gr_blit(progressBarEmpty, pos, 0, width-pos, height, dx+pos, dy);                  }              }          }            if (progressBarType == INDETERMINATE) {              static int frame = 0;              gr_blit(progressBarIndeterminate[frame], 0, 0, width, height, dx, dy);              // in RTL locales, we run the animation backwards, which              // makes the spinner spin the other way.              if (rtl_locale) {                  frame = (frame + indeterminate_frames - 1) % indeterminate_frames;              } else {                  frame = (frame + 1) % indeterminate_frames;              }          }      }  }   draw_progress_locked函数的原理与 update_screen_locked函数类似，%20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%20以及surface的坐标。 recovery%20main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[html] view%20plain copy int gr_init(void);             /* 初始化图形显示,主要是打开设备、分配内存、初始化一些参数 */    void gr_exit(void);            /* 注销图形显示,关闭设备并释放内存 */        int gr_fb_width(void);         /* 获取屏幕的宽度 */    int gr_fb_height(void);        /* 获取屏幕的高度 */    gr_pixel *gr_fb_data(void);    /* 获取显示数据缓存的地址 */    void gr_flip(void);            /* 刷新显示内容 */    void gr_fb_blank(bool blank);  /* 清屏 */        void gr_color(unsigned char r, unsigned char g, unsigned char b, unsigned char a);  /* 设置字体颜色 */    void gr_fill(int x, int y, int w, int h);  /* 填充矩形区域,参数分别代表起始坐标、矩形区域大小 */    int gr_text(int x, int y, const char *s);  /* 显示字符串 */    int gr_measure(const char *s);             /* 获取字符串在默认字库中占用的像素长度 */    void gr_font_size(int *x, int *y);         /* 获取当前字库一个字符所占的长宽 */        void gr_blit(gr_surface source, int sx, int sy, int w, int h, int dx, int dy);  /* 填充由source指定的图片 */    unsigned int gr_get_width(gr_surface surface);   /* 获取图片宽度 */    unsigned int gr_get_height(gr_surface surface);  /* 获取图片高度 */    /* 根据图片创建显示资源数据,name为图片在mk文件指定的相对路径 */    int res_create_surface(const char* name, gr_surface* pSurface);    void res_free_surface(gr_surface surface);       /* 释放资源数据 */