simplify construction of the recovery progress bar

Instead of six separate images for the left end, right end, and tiled
center portion of the full and empty progress bars, just use two
images:  a full bar and an empty bar.  Draw the left side of the full
bar and the right side of the empty one, moving the boundary rightward
to "fill" the bar.  This makes recovery trivially smaller, and allows
fancier images to be used as progress bars.

Support paletted PNG images as resources.

minui/resources.c

@@ -97,9 +97,10 @@ int res_create_surface(const char* name, gr_surface* pSurface) {
     int color_type = info_ptr->color_type;
     int bit_depth = info_ptr->bit_depth;
     int channels = info_ptr->channels;
-    if (bit_depth != 8 || (channels != 3 && channels != 4) ||
-        (color_type != PNG_COLOR_TYPE_RGB &&
-         color_type != PNG_COLOR_TYPE_RGBA)) {
+    if (!(bit_depth == 8 &&
+          ((channels == 3 && color_type == PNG_COLOR_TYPE_RGB) ||
+           (channels == 4 && color_type == PNG_COLOR_TYPE_RGBA) ||
+           (channels == 1 && color_type == PNG_COLOR_TYPE_PALETTE)))) {
         return -7;
         goto exit;
     }
@@ -118,6 +119,10 @@ int res_create_surface(const char* name, gr_surface* pSurface) {
     surface->format = (channels == 3) ?
             GGL_PIXEL_FORMAT_RGBX_8888 : GGL_PIXEL_FORMAT_RGBA_8888;
 
+    if (color_type == PNG_COLOR_TYPE_PALETTE) {
+      png_set_palette_to_rgb(png_ptr);
+    }
+
     int y;
     if (channels == 3) {
         for (y = 0; y < height; ++y) {

ui.c

@@ -38,13 +38,11 @@
 #define PROGRESSBAR_INDETERMINATE_STATES 6
 #define PROGRESSBAR_INDETERMINATE_FPS 15
 
-enum { LEFT_SIDE, CENTER_TILE, RIGHT_SIDE, NUM_SIDES };
-
 static pthread_mutex_t gUpdateMutex = PTHREAD_MUTEX_INITIALIZER;
 static gr_surface gBackgroundIcon[NUM_BACKGROUND_ICONS];
 static gr_surface gProgressBarIndeterminate[PROGRESSBAR_INDETERMINATE_STATES];
-static gr_surface gProgressBarEmpty[NUM_SIDES];
-static gr_surface gProgressBarFill[NUM_SIDES];
+static gr_surface gProgressBarEmpty;
+static gr_surface gProgressBarFill;
 
 static const struct { gr_surface* surface; const char *name; } BITMAPS[] = {
     { &gBackgroundIcon[BACKGROUND_ICON_INSTALLING], "icon_installing" },
@@ -59,12 +57,8 @@ static const struct { gr_surface* surface; const char *name; } BITMAPS[] = {
     { &gProgressBarIndeterminate[3],    "indeterminate4" },
     { &gProgressBarIndeterminate[4],    "indeterminate5" },
     { &gProgressBarIndeterminate[5],    "indeterminate6" },
-    { &gProgressBarEmpty[LEFT_SIDE],    "progress_bar_empty_left_round" },
-    { &gProgressBarEmpty[CENTER_TILE],  "progress_bar_empty" },
-    { &gProgressBarEmpty[RIGHT_SIDE],   "progress_bar_empty_right_round" },
-    { &gProgressBarFill[LEFT_SIDE],     "progress_bar_left_round" },
-    { &gProgressBarFill[CENTER_TILE],   "progress_bar_fill" },
-    { &gProgressBarFill[RIGHT_SIDE],    "progress_bar_right_round" },
+    { &gProgressBarEmpty,               "progress_empty" },
+    { &gProgressBarFill,                "progress_fill" },
     { NULL,                             NULL },
 };
 
@@ -123,8 +117,8 @@ static void draw_progress_locked()
     if (gProgressBarType == PROGRESSBAR_TYPE_NONE) return;
 
     int iconHeight = gr_get_height(gBackgroundIcon[BACKGROUND_ICON_INSTALLING]);
-    int width = gr_get_width(gProgressBarIndeterminate[0]);
-    int height = gr_get_height(gProgressBarIndeterminate[0]);
+    int width = gr_get_width(gProgressBarEmpty);
+    int height = gr_get_height(gProgressBarEmpty);
 
     int dx = (gr_fb_width() - width)/2;
     int dy = (3*gr_fb_height() + iconHeight - 2*height)/4;
@@ -137,18 +131,12 @@ static void draw_progress_locked()
         float progress = gProgressScopeStart + gProgress * gProgressScopeSize;
         int pos = (int) (progress * width);
 
-        gr_surface s = (pos ? gProgressBarFill : gProgressBarEmpty)[LEFT_SIDE];
-        gr_blit(s, 0, 0, gr_get_width(s), gr_get_height(s), dx, dy);
-
-        int x = gr_get_width(s);
-        while (x + (int) gr_get_width(gProgressBarEmpty[RIGHT_SIDE]) < width) {
-            s = (pos > x ? gProgressBarFill : gProgressBarEmpty)[CENTER_TILE];
-            gr_blit(s, 0, 0, gr_get_width(s), gr_get_height(s), dx + x, dy);
-            x += gr_get_width(s);
+        if (pos > 0) {
+          gr_blit(gProgressBarFill, 0, 0, pos, height, dx, dy);
+        }
+        if (pos < width-1) {
+          gr_blit(gProgressBarEmpty, pos, 0, width-pos, height, dx+pos, dy);
         }
-
-        s = (pos > x ? gProgressBarFill : gProgressBarEmpty)[RIGHT_SIDE];
-        gr_blit(s, 0, 0, gr_get_width(s), gr_get_height(s), dx + x, dy);
     }
 
     if (gProgressBarType == PROGRESSBAR_TYPE_INDETERMINATE) {