Agar 1.7 Manual



#include <agar/core.h>
#include <agar/gui.h>


ScreenshotAG_Button is a push-button displaying a text label or an image. It can trigger events and/or control a boolean value.


AG_Object(3)-> AG_Widget(3)-> AG_Button.


AG_Button * AG_ButtonNew (AG_Widget *parent, Uint flags, const char *format, ...)

AG_Button * AG_ButtonNewS (AG_Widget *parent, Uint flags, const char *label)

AG_Button * AG_ButtonNewFn (AG_Widget *parent, Uint flags, const char *label, void (*fn)(AG_Event *), const char *fnArgs, ...)

AG_Button * AG_ButtonNewInt (AG_Widget *parent, Uint flags, const char *label, int *p)

AG_Button * AG_ButtonNewUint (AG_Widget *parent, Uint flags, const char *label, Uint *p)

AG_Button * AG_ButtonNewFlag (AG_Widget *parent, Uint flags, const char *label, Uint *p, Uint bitmask)

void AG_ButtonSetInverted (AG_Button *button, int enable)

void AG_ButtonSetFocusable (AG_Button *button, int enable)

void AG_ButtonSetSticky (AG_Button *button, int enable)

void AG_ButtonJustify (AG_Button *button, enum ag_text_justify justify)

void AG_ButtonValign (AG_Button *button, enum ag_text_valign valign)

void AG_ButtonSetRepeatMode (AG_Button *button, int enable)

void AG_ButtonSurface (AG_Button *button, const AG_Surface *su)

void AG_ButtonSurfaceNODUP (AG_Button *button, AG_Surface *su)

void AG_ButtonText (AG_Button *button, const char *format, ...)

void AG_ButtonTextS (AG_Button *button, const char *label)

int AG_ButtonGetState (AG_Button *button)

int AG_ButtonSetState (AG_Button *button, int stateNew)

int AG_ButtonToggle (AG_Button *button)

The AG_ButtonNew() function allocates, initializes, and attaches an AG_Button. If label is non-NULL, it sets the initial text label. For a list of acceptable option flags refer to BUTTON FLAGS below.

The AG_ButtonNewFn() variant creates a button and also specifies a callback routine to run whenever it is pressed. Contrary to AG_ButtonNew(), it implies AG_BUTTON_EXCL (unless AG_BUTTON_NOEXCL is passed).

The AG_ButtonNewInt() shorthand creates a button and also sets its state binding to the natural integer at memory location p.

The AG_ButtonNewFlag() shorthand creates a button and also sets its state binding to the value of the bit(s) indicated by bitmask contained within the natural integer at memory location p.

AG_ButtonSetInverted() inverts the interpretation of the "state" binding (sets the AG_BUTTON_INVERTED flag).

AG_ButtonSetFocusable() sets whether the button is allowed to receive focus (0 = No, 1 = Yes). Default is Yes (see AG_WidgetFocus(3)).

AG_ButtonSetSticky() sets the behavior of the button when pressed (0 = Momentary, 1 = Sticky). In Momentary mode, the button springs back to its former state when released. Default is Sticky.

AG_ButtonJustify() sets the justification mode for the text label. The justify argument can be AG_TEXT_LEFT, AG_TEXT_CENTER or AG_TEXT_RIGHT.

AG_ButtonValign() sets the vertical alignment for the text label. The valign argument can be AG_TEXT_TOP, AG_TEXT_MIDDLE or AG_TEXT_BOTTOM.

AG_ButtonSetRepeatMode() enables or disables Repeat mode. Repeat mode causes multiple button-pushed events to be posted periodically for as long as the button is triggered (with an interval of agMouseSpinIval ms).

AG_ButtonSurface() sets the button label to a copy of the given surface. AG_ButtonSurfaceNODUP() uses the given surface as source without copying (potentially unsafely). If a label is currently set, it is replaced.

AG_ButtonText() sets the label of the button from the specified text string. If a surface is currently set, it is removed.

AG_ButtonGetState() returns the current boolean state of the button (1 = pressed, 0 = released). AG_ButtonSetState() sets the state to stateNew and returns the previous state. AG_ButtonToggle() atomically toggles the state of the button and returns the new state.


The following flags are provided:
AG_BUTTON_STICKYPrevent the button from springing back to its previous state following a click. Set on initialization or by AG_ButtonSetSticky().
AG_BUTTON_MOUSEOVERThe cursor is over the button area (read-only).
AG_BUTTON_REPEATRepeat mode is enabled (read-only, see AG_ButtonSetRepeatMode()).
AG_BUTTON_PRESSINGThe button is being activated (read-only).
AG_BUTTON_SETSet "state" to 1 when the button becomes visible.
AG_BUTTON_INVERTEDInvert the interpretation of the "state" binding (Default: 0=Released, 1=Pressed).
AG_BUTTON_EXCLDisable the test for redrawing the button upon external changes to the "state" binding.
AG_BUTTON_NO_FOCUSCannot gain focus (see AG_WidgetSetFocusable(3)).
AG_BUTTON_HFILLExpand horizontally in parent container.
AG_BUTTON_VFILLExpand vertically in parent container.
AG_BUTTON_ALIGN_LEFTAlign text horizontally to the left.
AG_BUTTON_ALIGN_CENTERCenter text horizontally (the default).
AG_BUTTON_ALIGN_LEFTAlign text horizontally to the right.
AG_BUTTON_VALIGN_TOPAlign text vertically to the top.
AG_BUTTON_VALIGN_MIDDLEAlign text vertically to the middle (the default).
AG_BUTTON_VALIGN_BOTTOMAlign text vertically to the bottom.


The AG_Button widget generates the following events:
button-pushed (int new_state)
The button was pressed. If using AG_BUTTON_STICKY, the new_state argument indicates the new state of the button.


The AG_Button widget provides the following bindings. In all cases, a value of 1 is considered boolean TRUE, and a value of 0 is considered boolean FALSE.
BOOL *state Value (1/0) of natural integer
INT *state Value (1/0) of natural integer
UINT *state Value (1/0) of natural integer
UINT8 *state Value (1/0) of 8-bit integer
UINT16 *state Value (1/0) of 16-bit integer
UINT32 *state Value (1/0) of 32-bit integer
FLAGS *state Bits in an int
FLAGS8 *state Bits in 8-bit word
FLAGS16 *state Bits in 16-bit word
FLAGS32 *state Bits in 32-bit word


The following code fragment creates a button and sets a handler function for the button-pushed event:
MyHandlerFn(AG_Event *event)
	AG_TextMsg(AG_MSG_INFO, "Hello, %s!", AG_STRING(1));

AG_ButtonNewFn(parent, 0, "Hello", MyHandlerFn, "%s", "world");

The following code fragment uses buttons to control specific bits in a 32-bit word:
Uint32 MyFlags = 0;

AG_ButtonNewFlag32(parent, 0, "Bit 1", &MyFlags, 0x01);
AG_ButtonNewFlag32(parent, 0, "Bit 2", &MyFlags, 0x02);

The following code fragment uses a button to control an int protected by a mutex device:
int MyInt = 0;
AG_Mutex MyMutex;
AG_Button *btn;

btn = AG_ButtonNew(parent, 0, "Mutex-protected flag");
AG_BindIntMp(btn, "state", &MyInt, &MyMutex);


AG_Event(3), AG_Intro(3), AG_Surface(3), AG_Toolbar(3), AG_Widget(3), AG_Window(3)


The AG_Button widget first appeared in Agar 1.0. As of Agar 1.6.0 the AG_ButtonSetPadding() call is now deprecated (replaced by AG_SetStyle(3) with "padding" attribute). Agar 1.6.0 also introduced AG_BUTTON_SET. ElectronTubeStore is © 2022 Julien Nadeau Carriere <>.
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