Picture data

The data of a BPicture is composed of instructions.

These instructions have a small header, which looks as follows:

int16	id	The instruction id
int32	size	The size of the data

After this header the data follows. There are two exceptions: EnterStateChange and EnterFontState. These are used to enclose state and font changes. For ExitStateChange and ExitFontState there are no instructions, this is not needed as we know the size of the instruction block in the header of the Enter* functions.

These are the known instructions at the moment:

Id	Name	Size	Data
0x0010	MovePenBy	4	BPoint where
0x0100	StrokeLine	16	BPoint start BPoint end
0x0101	StrokeRect	16	BRect rect
0x0102	FillRect	16	BRect rect
0x0103	StrokeRoundRect	24	BRect rect BPoint radii
0x0104	FillRoundRect	24	BRect rect BPoint radii
0x0105	StrokeBezier	32	BPoint[4] control
0x0106	FillBezier	32	BPoint[4] control
0x010B	StrokePolygon	4 + point data size + 1	int32 numPoints BPoint *points bool isClosed
0x010C	FillPolygon	4 + point data size	int32 numPoints BPoint *points
0x010D	StrokeShape	shape data size	shape data, see below
0x010E	FillShape	shape data size	shape data, see below
0x010F	DrawString	4 + string data size + 8	strlen char *string float deltax float deltay
0x0110	DrawPixels	52 + pixel data size	BRect src BRect dest int32 width int32 height int32 bytesPerRow int32 pixelFormat int32 flags pixel data
0x0112	DrawPicture	12	BPoint where? ????
0x0113	StrokeArc	24	BPoint center BPoint radii float startTheta float arcTheta
0x0114	FillArc	24	BPoint center BPoint radii float startTheta float arcTheta
0x0115	StrokeEllipse	16	BRect rect
0x0116	FillEllipse	16	BRect rect
0x0200	EnterStateChange	size of state instructions	state instructions
0x0201	SetClippingRects	16 + size of rects	clipping_rect bound clipping_rect *rect
0x0202	ClipToPicture	7 + 8 + 1	zero bytes BPoint pt bool clip_to_inverse_picture
0x0203	PushState	0
0x0204	PopState	0
0x0205	SetClippingRects	0	This is a shorter instruction for 0 clipping rects.
0x0300	SetOrigin	8	BPoint pt
0x0301	SetPenLocation	8	BPoint pt
0x0302	SetDrawingMode	2	drawing_mode mode
0x0303	SetLineMode	2 + 2 + 4	cap_mode capMode join_mode joinMode float miterLimit
0x0304	SetPenSize	4	float size
0x0305	SetScale	4	float scale
0x0306	SetForeColor	4	rgb_color color
0x0307	SetBackColor	4	rgb_color color
0x0308	SetStipplePattern	8	pattern p
0x0309	EnterFontState	size of font instructions	font instructions
0x030A	SetBlendingMode	4	source_alpha alphaSrcMode alpha_function alphaFncMode
0x0380	SetFontFamily	4 + string data size	strlen char *family
0x0381	SetFontStyle	4 + string data size	strlen char style
0x0382	SetFontSpacing	4	int32 spacing
0x0383	SetFontEncoding	4	int32 encoding
0x0384	SetFontFlags	4	int32 flags
0x0385	SetFontSize	4	float size
0x0386	SetFontRotate	4	float rotation
0x0387	SetFontShear	4	float shear(is 0 instead of 90?)
0x0389	SetFontFace	4	int32 flags

There are a few undocumented instructions:

0x0388

SetFontBPP

4

int32 bpp

Also, not all instructions where checked yet. The SetClippingRects and DrawPixels data has still to be documented.

Regarding DrawPicture and ClipToPicture, it seems the pictures to draw are not inside the flattened data, instead they are stored as messages in the BMessage in a field called "piclib".

Shape data

The shape data contained in a BPicture is stored as follows:

int32	instruction count
uint32 *instructions	Each instruction looks like: First byte is the instruction id The next three bytes is the amount of points used*
int32	point count
BPoint *points	points

Id	Name	Points*	Notes
0x80	MoveTo		A "MoveTo" instruction doesn't stand alone, but is OR-ed with a "LineTo" or "BezierTo" instruction
0x10	LineTo	point count in instruction	One "LineTo" instruction draws "count" lines
0x90	MoveTo LineTo	point count in instruction + 1	There is one extra point for the "MoveTo", which is not counted in the instruction.
0x20	BezierTo	point count in instruction	One "BezierTo" instruction draws "count" lines
0xA0	MoveTo BezierTo	point count in instruction + 1	There is one extra point for the "MoveTo", which is not counted in the instruction.
0x40	Close	0	"Close" can only follow a "LineTo" or "BezierTo" instruction If an instruction follows "Close", the new instruction is OR-ed with "Close" and replaces it instruction A shape never starts with "Close"