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Starting tomorrow, Jun 23, 2012, many countries are to celebrate the centeray birth year of Alan Turing. Alan created the Turing machine concepts and formalized algorithm and computation that are now in use in all our computers (including your portable phone and your electronic watch.)

He actually participated to the creation of the first electronic computer during second world war in England. His algorithms and knowledge of cryptography gave him the necessary skills to crack the encoding of the German Enigma Machine (a form of printer that would encode messages with a level of complexity too ...

Pop a target (sprite, movie, thread) name s₁.

Pop a first Boolean b₂, which, when true, means that the mouse pointer is locked to the center of the object being dragged.

Pop a second Boolean b3, which when true means that the mouse pointer is constrained to the specified rectangle1 (n₄ to n₇, representing y₂, x₂, y₁, x₁.)

Once this function was called, the object attached to the mouse pointer will follow the mouse until a Stop Drag action is applied or another object is defined as the object being dragged with another Start Drag.

• 1. The rectangle is not defined when b₃ is false.

struct swf_definescalinggrid {
	swf_tag				f_tag;		/* 78 */
	unsigned short			f_button_id_ref;
	swf_rect			f_rect;
};

This definition is used so the scaling factors applied on an object affects only the center of the object fully. The borders are only affected in one direction and the corners are not scaled (note, restrictions apply, see below.) This is quite useful to draw a scalable button or window.

Fig 1 — Sample button being scaled with a scaling grid

struct swf_defineedittext {
	swf_tag			f_tag;		/* 37 */
	unsigned short		f_edit_id;
	swf_rect		f_rect;
	unsigned		f_edit_has_text : 1;
	unsigned		f_edit_word_wrap : 1;
	unsigned		f_edit_multiline : 1;
	unsigned		f_edit_password : 1;
	unsigned		f_edit_readonly : 1;
	unsigned		f_edit_has_color : 1;
	unsigned		f_edit_has_max_length : 1;
	unsigned		f_edit_has_font : 1;
	if(version >= 6) {
		unsigned		f_edit_reserved : 1;
		unsigned		f_edit_auto_size : 1;
	}
	else {
		unsigned		f_edit_reserved : 2;
	}
	unsigned		f_edit_has_layout : 1;
	unsigned		f_edit_no_select : 1;
	unsigned		f_edit_border : 1;
	unsigned		f_edit_reserved : 1;
	unsigned		f_edit_html : 1;
	unsigned		f_edit_use_outlines : 1;
	if(f_edit_has_font) {
		unsigned short		f_edit_font_id_ref;
		unsigned short		f_edit_font_height;
	}
	if(f_edit_has_color) {
		swf_rgba		f_edit_color;
	}
	if(f_edit_has_max_length) {
		unsigned short		f_edit_max_length;
	}
	if(f_edit_has_layout) {
		unsigned char		f_edit_align;
		unsigned short		f_edit_left_margin;
		unsigned short		f_edit_right_margin;
		signed short		f_edit_indent;
		signed short		f_edit_leading;
	}
	string			f_edit_variable_name;
	if(f_edit_has_text) {
		string			f_edit_initial_text;
	}
};

Additional interactivity has been added in V4.0 of the SWF format. This is given by the use of edit boxes offering the end users a way to enter text as if the SWF movie was in fact an interactive form.

The text is defined in a variable (accessible in action scripts). It can be dynamically assigned and retrieved. It is legal to have an empty string as the variable name (not dynamically accessible).

Since version 8, the text drawn by a DefineEditText tag can be tweaked by adding a CSMTextSettings tag.

The f_edit_word_wrap flag will be set to true (1) in order to have words going beyond the ...

When appropriate, images can also be included in SWF files. All the images can be full color and also have an alpha channel.

Edges are used to define a shape vector based and also coordinates where images need to be drawn. The edges are always coordinates from where ever your last point was to where ever you want the next point to be (a little like a turtle in LOGO).

/* the filter type */
struct swf_filter_type {
	unsigned char	f_type;
};

struct swf_filter_glow {
	swf_filter_type	f_type;		/* 0, 2, 3, 4 or 7 */
	if(f_type == GradientGlow || f_type == GradientBevel) {
		unsigned char		f_count;
	}
	else {
		f_count = 1;
	}
	swf_rgba		f_rgba[f_count];
	if(f_type == Bevel) {
		swf_rgba		f_highlight_rgba[f_count];
	}
	if(f_type == GradientGlow || f_type == GradientBevel) {
		unsigned char		f_position[f_count];
	}
	signed long fixed	f_blur_horizontal;
	signed long fixed	f_blur_vertical;
	if(f_type != Glow) {
		signed long fixed	f_radian_angle;
		signed long fixed	f_distance;
	}
	signed short fixed	f_strength;
	unsigned		f_inner_shadow : 1;
	unsigned		f_knock_out : 1;
	unsigned		f_composite_source : 1;
	if(f_type == Bevel) {
		unsigned		f_on_top : 1;
	}
	else {
		unsigned		f_reserved : 1;
	}
	if(f_type == GradientGlow || f_type == GradientBevel) {
		unsigned		f_passes : 4;
	}
	else {
		unsigned		f_reserved : 4;
	}
};

struct swf_filter_blur {
	swf_filter_type		f_type;	/* 1 */
	unsigned long fixed	f_blur_horizontal;
	unsigned long fixed	f_blur_vertical;
	unsigned		f_passes : 5;
	unsigned		f_reserved : 3;
};

struct swf_filter_convolution {
	swf_filter_type	f_type;		/* 5 */
	unsigned char	f_columns;
	unsigned char	f_rows;
	long float	f_divisor;
	long float	f_bias;
	long float	f_weights[f_columns × f_rows];
	swf_rgba	f_default_color;
	unsigned	f_reserved : 6;
	unsigned	f_clamp : 1;
	unsigned	f_preserve_alpha : 1;
};

struct swf_filter_colormatrix {
	swf_filter_type	f_type;		/* 6 */
	long float	f_matrix[20];
};

struct swf_any_filter {
	swf_filter_type			f_fitler_type;
	swf_filter_blur			f_filter_blur;
	swf_filter_colormatrix		f_filter_colormatrix;
	swf_filter_convolution		f_filter_convolution;
	swf_filter_glow			f_filter_glow;
};

A filter defines how to transform the objects it is attached to. The first byte is the filter type. The data following depend on the type. Because each filter is much different, they are defined in separate structures. You can attach a filter to an object using an ActionScript or the PlaceObject3 tag.

The following describes the different filters available since version 8.

... Value Name Version 0 Drop Shadow 8

struct swf_gradient {
	if(tag == DefineShape4) {
		unsigned		f_spread_mode : 2;
		unsigned		f_interpolation_mode : 2;
		unsigned		f_count : 4;
	}
	else {
		unsigned		f_pad : 4;
		unsigned		f_count : 4;
	}
	swf_gradient_record	f_gradient_record[f_count];
	/* f_type is defined in the swf_fill_style encompassing this gradient */
	if(f_type == 0x13) {
		signed short fixed	f_focal_point;
	}
};

This structure defines a gradient. This is a set of colors which are used to define an image with colors smoothly varying from one color to the next. The gradient can be radial (circular) or linear (rectangular).

The f_count field is limited depending on the tag used and the version of SWF as defined below: