feat(fltk): ViperFLProject 链接 libfltk_theme.a + Theme 按钮演示（base/Dark/Metro 主题切换）

ViperFLProject/App/main2.vp

@@ -17,6 +17,7 @@ import fltk
 term_ptr: t.CPtr = None
 status_ptr: t.CPtr = None
 scheme_idx: int = 0
+theme_idx: int = 0
 
 
 def on_btn_click(w: bytes, data: bytes):
@@ -79,6 +80,21 @@ def on_style(w: bytes, data: bytes):
     fltk.Fl_Output_set_value(status_ptr, f"Scheme: {fltk.Fl.scheme_string()}")
 
 
+def on_theme(w: bytes, data: bytes):
+    """Fl_Theme 主题切换：base→Dark→Metro 循环"""
+    global theme_idx
+    theme_idx = theme_idx + 1
+    if theme_idx == 1:
+        fltk.Fl.set_theme_dark()
+    elif theme_idx == 2:
+        fltk.Fl.set_theme_metro()
+    else:
+        fltk.Fl.set_scheme("base")
+        fltk.Fl.reload_scheme()
+        theme_idx = 0
+    fltk.Fl_Output_set_value(status_ptr, f"Theme: {theme_idx}")
+
+
 def on_tick(w: bytes, data: bytes):
     """定时器回调：每秒终端打印一次并续订"""
     fltk.Fl_Terminal_append(term_ptr, "tick\n")
@@ -95,10 +111,11 @@ def main() -> int:
     btn = fltk.Fl_Button(10, 70, 120, 30, "Click Me")
     check = fltk.Fl_Check_Button(150, 70, 100, 30, "Enable")
     slider = fltk.Fl_Slider(280, 70, 200, 30)
-    input_ = fltk.Fl_Input(10, 110, 240, 30, "Type here")
-    go = fltk.Fl_Button(260, 110, 60, 30, "Go")
-    style = fltk.Fl_Button(330, 110, 60, 30, "Style")
-    spinner = fltk.Fl_Spinner(400, 110, 120, 30)
+    input_ = fltk.Fl_Input(10, 110, 210, 30, "Type here")
+    go = fltk.Fl_Button(230, 110, 55, 30, "Go")
+    style = fltk.Fl_Button(295, 110, 55, 30, "Style")
+    theme = fltk.Fl_Button(360, 110, 55, 30, "Theme")
+    spinner = fltk.Fl_Spinner(425, 110, 100, 30)
     browser = fltk.Fl_Browser(10, 150, 280, 140)
     tree = fltk.Fl_Tree(300, 150, 280, 140)
     term = fltk.Fl_Terminal(10, 300, 570, 120, "Terminal")
@@ -118,6 +135,7 @@ def main() -> int:
     slider.set_callback(on_slider, 0)
     go.set_callback(on_go, input_._ptr)
     style.set_callback(on_style, 0)
+    theme.set_callback(on_theme, 0)
 
     # 数值微调框
     spinner.set_minimum(0.0)

ViperFLProject/project.vpj

@@ -34,6 +34,7 @@
         ],
         "static_libs": [
             "../includes/fltk/cfltk/build/libcfltk2.a",
+            "../includes/fltk/cfltk/build/libfltk_theme.a",
             "../includes/fltk/cfltk/build/fltk/lib/libfltk_images.a",
             "../includes/fltk/cfltk/build/fltk/lib/libfltk.a",
             "../includes/fltk/cfltk/build/fltk/lib/libfltk_png.a",