dc: live VMU LCD preview in options + dt-based screensaver + label rename

- VMU options: when the icon row is selected and the user scrolls L/R
  through the BIOS presets, the picked shape is pushed to the physical
  VMU's LCD in real time. B (cancel) reverts the LCD to the VMU's
  committed icon (custom ICONDATA if any, else the preset); A on any
  other row (commit) leaves the previewed shape in place since the
  staged icon_shape gets written to the VMU anyway. Removing a custom
  icon also pushes the now-active preset shape so the LCD matches the
  card's new state immediately.
- Screensaver: motion was per-frame (x += dx) with dt ignored, so when
  the host frame rate climbed (e.g. Flycast without throttle) the logo
  flew across the screen. Switch to float position + pixel/sec velocity
  driven by dt in tick(), and convert the idle threshold to seconds.
  The original 2 px/frame at 60fps becomes a constant 120 px/s.
- VMU options label: "Custom BIOS color:" -> "VMU Color:" with the value
  column still aligned to "Real Mode (3D BIOS):".

Author: RobertDaleSmith

dc/src/modes/browser.c

@@ -579,6 +579,26 @@ static void push_icons_to_vmus(void)
     }
 }
 
+/* Live LCD preview while the user navigates the icon-shape selector or
+ * deletes a custom icon. Shape >= 124 falls back to our bundled icon. */
+static void push_preset_to_vmu_lcd(int port, int slot, uint8_t shape)
+{
+    if (!jt_ports[port].slots[slot].has_lcd) return;
+    const uint8_t *mono = (shape < 124) ? &bios_icons_mono[shape * 128]
+                                        : fallback_vmu_icon_mono;
+    jt_vmu_show_mono_bits(port, slot, mono);
+}
+
+/* Push the VMU's committed icon (custom ICONDATA if any, else preset
+ * shape) to its LCD. Used to undo the in-options live preview on cancel. */
+static void push_vmu_committed_to_lcd(const vmu_info_t *v)
+{
+    if (!jt_ports[v->port].slots[v->slot].has_lcd) return;
+    jt_icon_t icon;
+    build_base_icon(&icon, v);
+    jt_vmu_show_mono_bits(v->port, v->slot, icon.mono_bits);
+}
+
 /* Begin "change/set custom icon": stash the editor base, commit staged
  * option edits (so they survive the mode switch), set the apply target,
  * and open the Icon Library to pick -- or, if empty, the editor seeded
@@ -753,7 +773,13 @@ static void update_save_delete_confirm(uint32_t edges)
 
 static void update_options(uint32_t edges)
 {
-    if (edges & CONT_B) { view = VIEW_VMUS; return; }
+    if (edges & CONT_B) {
+        /* Cancel: revert the LCD to the committed icon so any preview
+         * pushed by the icon-shape selector goes away. */
+        push_vmu_committed_to_lcd(&vmus[vmu_sel]);
+        view = VIEW_VMUS;
+        return;
+    }
     if (edges & CONT_DPAD_UP)   if (opt_sel > 0) opt_sel--;
     if (edges & CONT_DPAD_DOWN) if (opt_sel < OPT_COUNT - 1) opt_sel++;
 
@@ -781,6 +807,11 @@ static void update_options(uint32_t edges)
                 if (n < 0)   n = 123;   /* wrap through the 124 shapes */
                 if (n > 123) n = 0;
                 staged_icon_shape = (uint8_t)n;
+                /* Live preview: push the picked shape onto the VMU's LCD
+                 * so the user can see it on the physical card. Reverted
+                 * on B (cancel); persisted on A-elsewhere (commit). */
+                vmu_info_t *v = &vmus[vmu_sel];
+                push_preset_to_vmu_lcd(v->port, v->slot, staged_icon_shape);
                 break;
             }
         }
@@ -834,6 +865,8 @@ static void update_icon_actions(uint32_t edges)
         } else if (action == 1) {         /* Remove */
             commit_staged_options();
             remove_custom_icon();
+            /* Card is now on its preset shape -- mirror that to the LCD. */
+            push_preset_to_vmu_lcd(v->port, v->slot, v->icon_shape);
             view = VIEW_OPTIONS;
         } else {                          /* Back */
             view = VIEW_OPTIONS;
@@ -1060,7 +1093,7 @@ static void draw_options(void)
         int ly = row_y[OPT_CUSTOM_COLOR];
         uint16_t fg = (opt_sel == OPT_CUSTOM_COLOR) ? JT_COL_YELLOW : JT_COL_WHITE;
         jt_text(x + 12, ly, fg, JT_COL_BLACK,
-                "Custom BIOS color:    %s", staged_custom_color ? "ON " : "off");
+                "VMU Color:            %s", staged_custom_color ? "ON " : "off");
     }
 
     /* RGBA sliders. Bar = 16 cells x 14px = 224px wide. Each cell

dc/src/ui/screensaver.c

@@ -22,13 +22,19 @@
 #include "gen_logo.h"
 #include "../ports/ports.h"
 
-/* 30 seconds at 60 fps -- matches the PCE tester's threshold. */
-#define IDLE_FRAMES 1800
-
-static int  idle_counter = 0;
-static bool active = false;
-static int  x, y, dx, dy;
-static int  color_idx = 0;
+/* 30 seconds of idle before the screensaver kicks in. dt-based so the
+ * threshold doesn't depend on framerate (was IDLE_FRAMES = 30 * 60). */
+#define IDLE_SECONDS 30.0f
+
+static float idle_time = 0.0f;
+static bool  active = false;
+/* Position + velocity are dt-based: x/y in pixels (float so subpixel
+ * accumulation doesn't drop frames at high fps), vx/vy in pixels/sec.
+ * 120 px/s == the original 2 px/frame at 60 fps, but now constant regardless
+ * of the actual frame rate (which can spike on Flycast without throttle
+ * and was making the logo fly across the screen). */
+static float x, y, vx, vy;
+static int   color_idx = 0;
 static int  last_x = -1000;
 static int  last_y = -1000;
 /* Pending-wake flag: set the single frame we deactivate, consumed by
@@ -49,13 +55,13 @@ static const uint16_t cycle[7] = {
 
 void jt_screensaver_init(void)
 {
-    idle_counter = 0;
+    idle_time = 0.0f;
     active = false;
     color_idx = 0;
-    /* Start in the upper-left quadrant with a velocity that puts the
-     * logo on a diagonal trajectory at ~2 px/frame. */
-    x = 64; y = 80;
-    dx = 2;  dy = 2;
+    /* Upper-left start; diagonal at 120 px/s (matches the previous
+     * 2 px/frame at 60 fps). */
+    x = 64.0f; y = 80.0f;
+    vx = 120.0f; vy = 120.0f;
     last_x = -1000;
     last_y = -1000;
 }
@@ -116,38 +122,40 @@ static void blit_logo(int px, int py, uint16_t color)
 
 void jt_screensaver_tick(float dt)
 {
-    (void)dt;
     bool input = any_user_input();
 
     if (input) {
         if (active) {
             active = false;
-            idle_counter = 0;
+            idle_time = 0.0f;
             wake_pending = true;
         }
-        idle_counter = 0;
+        idle_time = 0.0f;
         return;
     }
 
-    idle_counter++;
-    if (!active && idle_counter >= IDLE_FRAMES) {
+    idle_time += dt;
+    if (!active && idle_time >= IDLE_SECONDS) {
         active = true;
     }
+
+    /* Step + bounce in tick so motion is dt-based: at any frame rate the
+     * logo moves at vx/vy pixels per second instead of vx/vy per frame.
+     * Each wall hit flips the relevant component and advances the cycle
+     * index. The back buffer is cleared every frame by main.c, so the
+     * draw side just blits at the current position. */
+    if (active) {
+        x += vx * dt;
+        y += vy * dt;
+        if (x < 0)                { x = 0;              vx = -vx; color_idx = (color_idx + 1) % 7; }
+        if (x + LOGO_W > 640)     { x = 640 - LOGO_W;   vx = -vx; color_idx = (color_idx + 1) % 7; }
+        if (y < 0)                { y = 0;              vy = -vy; color_idx = (color_idx + 1) % 7; }
+        if (y + LOGO_H > 480)     { y = 480 - LOGO_H;   vy = -vy; color_idx = (color_idx + 1) % 7; }
+    }
 }
 
 void jt_screensaver_draw(void)
 {
     if (!active) return;
-
-    /* Step + bounce. Each wall hit flips the relevant component and
-     * advances the cycle index. The back buffer is cleared every frame
-     * by main.c, so we just draw the logo at its new position. */
-    x += dx;
-    y += dy;
-    if (x < 0) { x = 0; dx = -dx; color_idx = (color_idx + 1) % 7; }
-    if (x + LOGO_W > 640) { x = 640 - LOGO_W; dx = -dx; color_idx = (color_idx + 1) % 7; }
-    if (y < 0) { y = 0; dy = -dy; color_idx = (color_idx + 1) % 7; }
-    if (y + LOGO_H > 480) { y = 480 - LOGO_H; dy = -dy; color_idx = (color_idx + 1) % 7; }
-
-    blit_logo(x, y, cycle[color_idx]);
+    blit_logo((int)x, (int)y, cycle[color_idx]);
 }