Examples

All examples live in examples/ and can be built with make examples. Each example also compiles as a loadable .gem (make gems) and can be run under orion-shell. See Gem Plugin System for details.

The imageeditor, taskmanager, and formeditor examples all follow the MDI application pattern — the recommended architecture for full Orion apps. See MDI Application Architecture for the complete guide.

Hello World (helloworld.c)

The minimal Orion program: one window, one label, one button.

./build/bin/helloworld

Key patterns shown:

• ui_init_graphics / ui_shutdown_graphics
• create_window + show_window
• get_message / dispatch_message / repost_messages loop
• evPaint → fill_rect + draw_text_small
• evCommand → button click handling

File Manager (filemanager.c)

A two-pane file browser using win_reportview.

./build/bin/filemanager

Key patterns shown:

• win_reportview with RVM_ADDITEM / RVM_CLEAR
• RVN_SELCHANGE / RVN_DBLCLK notifications
• evStatusBar for path display
• Directory traversal with opendir / readdir / stat

Image Editor (imageeditor.c)

A MacPaint-inspired MDI raster image editor with PNG open/save.

./build/bin/imageeditor

Demonstrates the full framework surface:

Feature	API used
MDI document windows	create_window with WINDOW_TOOLBAR \| WINDOW_STATUSBAR
Floating tool palette	WINDOW_ALWAYSONTOP top-level window
Floating colour palette	WINDOW_ALWAYSONTOP, left/right click = FG/BG colour
Menu bar (File menu)	win_menubar, kMenuBarMessageSetMenus, chained proc
Canvas rendering	OpenGL texture (glTexImage2D / glTexSubImage2D) + draw_rect
Drawing tools	Pencil, brush, eraser, flood-fill (BFS)
File picker dialog	Modal dialog with win_reportview
PNG I/O	load_image / save_image_png (stb_image, built into the framework)

Running at larger size

By default Orion uses 2x window scaling. Build without it for a larger logical canvas:

make examples CFLAGS="-DUI_WINDOW_SCALE=1"
./build/bin/imageeditor

Mouse coordinate note for canvas children

Child windows discovered via evHitTest receive absolute logical coordinates in wparam. Convert to child-local coords with:

window_t *root = get_root_window(win);
int lx = (int16_t)LOWORD(wparam) - root->frame.x - win->frame.x;
int ly = (int16_t)HIWORD(wparam) - root->frame.y - win->frame.y;

Browser MVP (browser/main.c)

A minimal browser-style example focused on fast HTML-to-text viewing.

Key patterns shown:

• Toolbar navigation (Back, Forward, Home, Refresh) + address bar
• File menu actions (New Window, Save Page HTML, Load Page HTML, Quit)
• Help menu About action
• Async HTTP fetching and completion handling (evHttpDone)
• HTML-to-text conversion via libxml2
• Local HTML loading via file:// URL support

Keyboard shortcuts:

• Ctrl+N new window
• Ctrl+S save page HTML
• Ctrl+O load page HTML
• Ctrl+Q quit

Writing Your Own Example

1. Create examples/myapp.c and #include "../ui.h"
2. Implement your window procedure(s)
3. In main():

   ui_init_graphics(0, "My App", 800, 600);
   window_t *w = create_window("My App", 0, MAKERECT(50,50,700,500),
                                NULL, my_proc, NULL);
   show_window(w, true);
   ui_event_t e;
   while (ui_is_running()) {
     while (get_message(&e)) dispatch_message(&e);
     repost_messages();
   }
   ui_shutdown_graphics();
   

4. Add a Makefile rule if your example needs extra libraries:

   $(BIN_DIR)/myapp$(EXE_EXT): examples/myapp.c $(STATIC_LIB) | $(BIN_DIR)
       $(CC) $(CFLAGS) -o $@ $< $(STATIC_LIB) $(LDFLAGS) $(LDFLAGS_EXAMPLE) $(LIBS)