SWF Button (swf_button)

struct swf_button {
	char align;
	unsigned		f_button_reserved : 2;
	if(version >= 8) {
		unsigned		f_button_blend_mode : 1;
		unsigned		f_button_filter_list : 1;
	}
	else {
		unsigned		f_button_reserved : 2;
	}
	unsigned		f_button_state_hit_test : 1;
	unsigned		f_button_state_down : 1;
	unsigned		f_button_state_over : 1;
	unsigned		f_button_state_up : 1;
	if(any f_button_state_... != 0) {
		unsigned short		f_button_id_ref;
		unsigned short		f_button_layer;
		swf_matrix		f_matrix;
		if(f_tag == DefineButton2) {
			swf_color_transform		f_color_transform;
		}
		if(f_button_filter_list) {
			unsigned char		f_filter_count;
			swf_any_filter		f_filter;
		}
		if(f_button_blend_mode) {
			unsigned char		f_blend_mode;
		}
	}
};

A button structure defines a state and a corresponding shape reference. The shape will be affected by the specified matrix whenever used.

There are many acceptable combinations. The object which is referenced is drawn when its state matches the current state of the button. If only the f_button_state_hit_test is set, then the shape is always displayed.

In order to define the area where the button can be clicked, it is necessary to set the f_button_state_hit_test flag to 1. Also, when this flag is set, only a shape can be referenced (no edit text, sprite or text object will work in this case).

When the f_button_state_hit_test is set, the square used to delimit the referenced shape will be used to determine whether the mouse is over the button or not.

Shapes referenced with the f_button_state_down flag set are drawn when a mouse button is being pushed over this button.

Shapes referenced with the f_button_state_up flag set are drawn when no mouse button is being pushed over this button. When neither up or down is specified, up us assumed.

Shapes referenced with the f_button_state_over flag set are drawn when the mouse is moved over this button.

The f_button_layer is used like a depth parameter. The smallest layer is drawn first (behind) and the highest layer is drawn last (on top of all the other shapes).

Though four flags allow for 16 different states, you are likely to only use a few. The hit test can appear on each state. The down and up won't usually be used together, though, if they are the shape will be drawn when the button is clicked or not.

Since version 8, this structure supports blending modes and a list of filters.

The structure is always aligned to a byte. If all of the f_button_state_... flags are zeroes, then the entry is an EOB (End Of Buttons) entry.