puzzles: dynamic text size via custom font pack

Up to now, we'd just ignore whatever font size the puzzle asked for,
and instead just go with either the UI font or system font regardless
of their size, which led to some horrible-looking puzzles. This patch
adds the ability to automatically load fonts of the proper size when
they are available, which makes text-based puzzles such as Pattern and
Slant function correctly with any UI font.

The font pack, which should be extracted to the system-wide fonts
directory consists of 3 small bitmap fonts from 7px to 10px and then
anti-aliased Deja Vu fonts from 10px to 36px. It is available in the
source tree (apps/plugins/puzzles/fonts.zip), or from
<http://download.rockbox.org/useful/sgt-fonts.zip>.

Change-Id: I05c8fe7bd6d867e14de9b941deb91e8c642ee4a8

apps/plugins/puzzles/SOURCES

@@ -2,8 +2,6 @@ rockbox.c
 rbwrappers.c
 rbmalloc.c
 
-help.c
-
 src/combi.c
 src/divvy.c
 src/drawing.c

apps/plugins/puzzles/help.c

@@ -1,14 +0,0 @@
-#include "help.h"
-#include "lib/simple_viewer.h"
-
-void full_help(const char *name)
-{
-    unsigned old_bg = rb->lcd_get_background();
-
-    rb->lcd_set_foreground(LCD_WHITE);
-    rb->lcd_set_background(LCD_BLACK);
-
-    view_text(name, help_text);
-
-    rb->lcd_set_background(old_bg);
-}

apps/plugins/puzzles/help.h

@@ -2,6 +2,3 @@
 
 extern const char help_text[];
 extern const char quick_help_text[];
-
-/* in help.c */
-void full_help(const char *name);

apps/plugins/puzzles/rockbox.c

@@ -30,7 +30,9 @@
 #ifndef COMBINED
 #include "lib/playback_control.h"
 #endif
+#include "lib/simple_viewer.h"
 #include "lib/xlcd.h"
+
 #include "fixedpoint.h"
 
 /* how many ticks between timer callbacks */
@@ -131,6 +133,118 @@ static void rb_color(int n)
     rb->lcd_set_foreground(colors[n]);
 }
 
+/* font bundle size range */
+#define BUNDLE_MIN 7
+#define BUNDLE_MAX 36
+#define BUNDLE_COUNT (BUNDLE_MAX - BUNDLE_MIN + 1)
+
+static struct bundled_font {
+    int status; /* -3 = never tried loading, or unloaded, -2 = failed to load, >= -1: loaded successfully */
+    int last_use;
+} loaded_fonts[2*BUNDLE_COUNT]; /* monospace are first, then proportional */
+
+static int n_fonts, access_counter = -1;
+
+static void unload_fonts(void)
+{
+    for(int i = 0; i < 2 * BUNDLE_COUNT; ++i)
+        if(loaded_fonts[i].status > 0) /* don't unload FONT_UI */
+        {
+            rb->font_unload(loaded_fonts[i].status);
+            loaded_fonts[i].status = -3;
+        }
+    access_counter = -1;
+    rb->lcd_setfont(FONT_UI);
+}
+
+static void rb_setfont(int type, int size)
+{
+    if(access_counter < 0)
+    {
+        for(int i = 0; i < 2 * BUNDLE_COUNT; ++i)
+                loaded_fonts[i].status = -3;
+        access_counter = 0;
+        n_fonts = 0;
+    }
+
+    /* out of range */
+    if(BUNDLE_MAX < size)
+        size = BUNDLE_MAX;
+
+    int font_idx = (type == FONT_FIXED ? 0 : BUNDLE_COUNT) + size - BUNDLE_MIN;
+    switch(loaded_fonts[font_idx].status)
+    {
+    case -3:
+    {
+        /* never loaded */
+        char buf[MAX_PATH];
+        if(size < 10) /* Deja Vu only goes down to 10px, below that it's a giant blob */
+        {
+            if(size < 7)
+                size = 7; /* we're not going to force anyone to read 05-Tiny :P */
+            /* we also don't care about monospace/proportional at this point */
+            switch(size)
+            {
+            case 7:
+                rb->snprintf(buf, sizeof(buf), FONT_DIR "/07-Fixed.fnt");
+                break;
+            case 8:
+                rb->snprintf(buf, sizeof(buf), FONT_DIR "/08-Rockfont.fnt");
+                break;
+            case 9:
+                rb->snprintf(buf, sizeof(buf), FONT_DIR "/09-Fixed.fnt");
+                break;
+            default:
+                assert(false);
+            }
+        }
+        else
+            rb->snprintf(buf, sizeof(buf), FONT_DIR "/%02d-%s.fnt", size, type == FONT_FIXED ? "DejaVuSansMono" : "DejaVuSans");
+
+        if(n_fonts >= MAXUSERFONTS - 3) /* safety margin, FIXME */
+        {
+            /* unload an old font */
+            int oldest_use = -1, oldest_idx = -1;
+            for(int i = 0; i < 2 * BUNDLE_COUNT; ++i)
+            {
+                if((loaded_fonts[i].status >= 0 && loaded_fonts[i].last_use < oldest_use) || oldest_use < 0)
+                {
+                    oldest_use = loaded_fonts[i].last_use;
+                    oldest_idx = i;
+                }
+            }
+            assert(oldest_idx >= 0);
+            rb->font_unload(loaded_fonts[oldest_idx].status);
+            loaded_fonts[oldest_idx].status = -3;
+            n_fonts--;
+        }
+
+        loaded_fonts[font_idx].status = rb->font_load(buf);
+        if(loaded_fonts[font_idx].status < 0)
+            goto fallback;
+        loaded_fonts[font_idx].last_use = access_counter++;
+        n_fonts++;
+        rb->lcd_setfont(loaded_fonts[font_idx].status);
+        break;
+    }
+    case -2:
+    case -1:
+        goto fallback;
+    default:
+        loaded_fonts[font_idx].last_use = access_counter++;
+        rb->lcd_setfont(loaded_fonts[font_idx].status);
+        break;
+    }
+
+    return;
+
+fallback:
+
+    rb->lcd_setfont(type == FONT_FIXED ? FONT_SYSFIXED : FONT_UI);
+
+    return;
+}
+
 static void rb_draw_text(void *handle, int x, int y, int fonttype,
                          int fontsize, int align, int color, char *text)
 {
@@ -139,19 +253,7 @@ static void rb_draw_text(void *handle, int x, int y, int fonttype,
 
     offset_coords(&x, &y);
 
-    /* TODO: variable font size */
+    rb_setfont(fonttype, fontsize);
-    switch(fonttype)
-    {
-    case FONT_FIXED:
-        rb->lcd_setfont(FONT_SYSFIXED);
-        break;
-    case FONT_VARIABLE:
-        rb->lcd_setfont(FONT_UI);
-        break;
-    default:
-        fatal("bad font");
-        break;
-    }
 
     int w, h;
     rb->lcd_getstringsize(text, &w, &h);
@@ -1053,6 +1155,27 @@ static void quick_help(void)
     return;
 }
 
+static void full_help(const char *name)
+{
+    unsigned old_bg = rb->lcd_get_background();
+
+    bool orig_clipped = clipped;
+    if(orig_clipped)
+        rb_unclip(NULL);
+
+    rb->lcd_set_foreground(LCD_WHITE);
+    rb->lcd_set_background(LCD_BLACK);
+    unload_fonts();
+    rb->lcd_setfont(FONT_UI);
+
+    view_text(name, help_text);
+
+    rb->lcd_set_background(old_bg);
+
+    if(orig_clipped)
+        rb_clip(NULL, clip_rect.x, clip_rect.y, clip_rect.width, clip_rect.height);
+}
+
 static void init_default_settings(void)
 {
     settings.slowmo_factor = 1;
@@ -1663,6 +1786,7 @@ static char *init_for_game(const game *gm, int load_fd, bool draw)
 
 static void exit_handler(void)
 {
+    unload_fonts();
 #ifdef HAVE_ADJUSTABLE_CPU_FREQ
     rb->cpu_boost(false);
 #endif