The Baby X Panel object

BBX_Panel *bbx_panel(BABYX *bbx, BBX_Panel *parent, char *tag, void (*changesize)(void *ptr, int width, int height), void *ptr);

You can then create child elements off it. It takes a callback for when it changes size, or is initially mapped. You should lay out child elements in response to this callback. As usual, it passes back a context pointer. The tag isn't strictly necessary, but is useful for when the panel is a widget. It allows higher level code to check that the panel has indeed been created with the correct higher level function.

void bbx_panel_kill(BBX_Panel *pan); char *bbx_panel_gettag(BBX_Panel *pan); void bbx_panel_setbackground(BBX_Panel *obj, BBX_RGBA col); void *bbx_panel_getptr(BBX_Panel *pan);

The panel has a destructor - you should destroy the children before calling this destructor -and an access function to the tag. You shouldn't use this to modify the returned pointer. There is also a function to set the background which works as expected, excapt that panels with alpha are not supported. There is also an access function for the context pointer. You can and sometimes should use this to change internals.

void bbx_panel_setmousefunc(BBX_Panel *pan, void (*mousefunc)(void *ptr, int action, int x, int y, int buttons), void *ptr); void bbx_panel_setkeyfunc(BBX_Panel *pan, void (*keyfunc)(void *ptr, int ch), void *ptr); int bbx_panel_gotmouse(BBX_Panel *pan, int *x, int *y);

What makes the Baby X panel special are its mouse and key callbacks. These take context pointers for consistency with the rest of the Baby X interface, but there is only one context pointer per panel. So all the context pointers passed to panel functions should be the same.

The mouse function passes back the action (BBX_MOUSE_CLICK, BBX_MOUSE_MOVE, BBX_MOUSE_RELEASE) together with the x, y (in panel co-ordinates) and the button states, a logical OR of BBX_MOUSE_BUTTON1, BBX_MOUSE_BUTTON2, BBX_MOUSE_BUTTON3. Button 1 is usually the left mouse button, button 2 the right, and button 3 the middle. You can detect dragging because a button is set. There is also a function to check if the mouse cursor is within the boundaries of the panel. It doesn't check for a captured mouse.

The key callback passes back the ASCII or Unicode value of the character entered at the keyboard. We also pass back some special keys, which have all negative codes.

#define BBX_KEY_BACKSPACE -100 #define BBX_KEY_DELETE -101 #define BBX_KEY_ESCAPE -102 #define BBX_KEY_HOME -103 #define BBX_KEY_LEFT -104 #define BBX_KEY_UP -105 #define BBX_KEY_RIGHT -106 #define BBX_KEY_DOWN -107 #define BBX_KEY_END -108

Using panels to create your own widgets

Most Baby X widgets are panels internally. You construct a widget out of a panel and, usually, a canvas. You might have other elements as well, depending on how complicated your widget is going to be. You then set the panel tag to the widget type, and typedef a BBX_Panel to your widget type.

An example is the BBX_Button type. It consists of a panel, and a BBX_Canvas that covers the whole area of the panel. It then attaches an internal "BUTTON" structure to the panel which stores its string, its callback, and so on, plus the canvas child element.