Canvas

Description

Drawing board for shapes and images.

Canvas is a drawing board. It is a support library for working with graphical surfaces and images. The sCanvas structure is a set of parameters that describe the graphical surface, for use in drawing functions. A graphical surface can be either a graphical frame buffer or an image, even in Flash. To draw in a graphical surface, first attach a canvas to it as a definition describing the structure of the area. Likewise, if you want to draw an image to the surface, first create a canvas for the image with its parameters. The parameters are a pointer to the image data, the image dimensions, and the format. The drawing area can be a graphic area with a depth of 1, 2, 4, 8 bits or with attributes. In the case of drawing an image to a canvas, the source and target canvas must have the same format. In the case of transformation matrices, only an 8-bit graphic format can be drawn.

Note

In PicoVGA, a default canvas Canvas is available. A graphic frame buffer is automatically attached to it when initialized with the Video() function. Otherwise, it can be used arbitrarily in the program.

Data Structures
struct	sCanvas
	Canvas descriptor. More...
class	cMat2Df
	2D Transformation Matrix More...

Macros
#define	CANVAS_8   0
	8-bit pixels
#define	CANVAS_4   1
	4-bit pixels
#define	CANVAS_2   2
	2-bit pixels
#define	CANVAS_1   3
#define	CANVAS_PLANE2   4
	4 colors on 2 planes
#define	CANVAS_ATTRIB8   5

Enumerations
enum	{   DRAWIMG_WRAP , DRAWIMG_NOBORDER , DRAWIMG_CLAMP , DRAWING_COLOR ,   DRAWIMG_TRANSP , DRAWIMG_PERSP }
	DrawImgMat mode. More...

Functions
void	DrawRect (sCanvas *canvas, int x, int y, int w, int h, u8 col)
	Draw rectangle. More...
void	DrawFrame (sCanvas *canvas, int x, int y, int w, int h, u8 col)
	Draw frame of 1 pixel thickness. More...
void	DrawClear (sCanvas *canvas)
	Clear canvas (fill with black color) More...
void	DrawPoint (sCanvas *canvas, int x, int y, u8 col)
	Draw a pixel. More...
void	DrawLine (sCanvas *canvas, int x1, int y1, int x2, int y2, u8 col)
	Draw a line. More...
void	DrawFillCircle (sCanvas *canvas, int x0, int y0, int r, u8 col, u8 mask=0xff)
	Draw filled circle. More...
void	DrawCircle (sCanvas *canvas, int x0, int y0, int r, u8 col, u8 mask=0xff)
	Draw circle. More...
void	DrawText (sCanvas *canvas, const char *text, int x, int y, u8 col, const void *font, int fontheight=8, int scalex=1, int scaley=1)
	Draw text (transparent background) More...
void	DrawTextBg (sCanvas *canvas, const char *text, int x, int y, u8 col, u8 bgcol, const void *font, int fontheight=8, int scalex=1, int scaley=1)
	Draw text with background color. More...
void	DrawImg (sCanvas *canvas, sCanvas *src, int xd, int yd, int xs, int ys, int w, int h)
	Draw image (without transparency) More...
void	DrawBlit (sCanvas *canvas, sCanvas *src, int xd, int yd, int xs, int ys, int w, int h, u8 col)
	Draw image with transparency. More...
void	DrawImgMat (sCanvas *canvas, const sCanvas *src, int x, int y, int w, int h, const class cMat2Df *m, u8 mode, u8 color)
	Draw 8-bit image with 2D transformation matrix. More...
void	DrawTileMap (sCanvas *canvas, const sCanvas *src, const u8 *map, int mapwbits, int maphbits, int tilebits, int x, int y, int w, int h, const cMat2Df *mat, u8 horizon)
	Draw tile map using perspective projection. More...
void	DrawImgLine (sCanvas *canvas, sCanvas *src, int xd, int yd, int xs, int ys, int wd, int ws)
	Draw image line interpolated. More...

Macro Definition Documentation

CANVAS_ATTRIB8

#define CANVAS_ATTRIB8   5

2x4 bit color attributes per 8x8 pixel sample draw functions: bit 0..3 = draw color bit 4 = draw color is background color

Enumeration Type Documentation

anonymous enum

anonymous enum

DrawImgMat mode.

Enumerator
DRAWIMG_WRAP	Wrap image.
DRAWIMG_NOBORDER	No border (transparent border)
DRAWIMG_CLAMP	Clamp image (use last pixel as border)
DRAWING_COLOR	Color border.
DRAWIMG_TRANSP	Transparent image with key color.
DRAWIMG_PERSP	Perspective floor.

Function Documentation

DrawRect()

void DrawRect	(	sCanvas *	canvas,
		int	x,
		int	y,
		int	w,
		int	h,
		u8	col
	)

Draw rectangle.

Parameters

canvas	Canvas
x	Horizontal position
y	Veritical position
w	Width
h	Height
col	Color

DrawFrame()

void DrawFrame	(	sCanvas *	canvas,
		int	x,
		int	y,
		int	w,
		int	h,
		u8	col
	)

Draw frame of 1 pixel thickness.

Parameters

canvas	Canvas
x	Horizontal position
y	Veritical position
w	Width
h	Height
col	Color

DrawClear()

void DrawClear

(

sCanvas *

canvas

)

Clear canvas (fill with black color)

Parameters

canvas

Canvas

DrawPoint()

void DrawPoint	(	sCanvas *	canvas,
		int	x,
		int	y,
		u8	col
	)

Draw a pixel.

Parameters

canvas	Canvas
x	Horizontal position
y	Veritical position
col	Color

DrawLine()

void DrawLine	(	sCanvas *	canvas,
		int	x1,
		int	y1,
		int	x2,
		int	y2,
		u8	col
	)

Draw a line.

Parameters

canvas	Canvas
x1	Horizontal start position
y1	Veritical start position
x2	Horizontal end position
y2	Veritical end position
col	Color

DrawFillCircle()

void DrawFillCircle	(	sCanvas *	canvas,
		int	x0,
		int	y0,
		int	r,
		u8	col,
		u8	mask = 0xff
	)

Draw filled circle.

Parameters

canvas	Canvas
x0	Horizontal center coordinate
y0	Veritical center coordinate
r	Radius
col	Color (with CANVAS_ATTRIB8 format: bit 0..3 = draw color, bit 4 = draw color is background color)
mask	Mask. Specifies, using bits 0 to 7, which eighths of the circle are drawn. . B2|B1 . B3 . | . B0 ------o------ B4 . | . B7 . B5|B6 .

DrawCircle()

void DrawCircle	(	sCanvas *	canvas,
		int	x0,
		int	y0,
		int	r,
		u8	col,
		u8	mask = 0xff
	)

Draw circle.

Parameters

canvas	Canvas
x0	Horizontal center coordinate
y0	Veritical center coordinate
r	Radius
col	Color (with CANVAS_ATTRIB8 format: bit 0..3 = draw color, bit 4 = draw color is background color)
mask	Mask. Specifies, using bits 0 to 7, which eighths of the circle are drawn. . B2|B1 . B3 . | . B0 ------o------ B4 . | . B7 . B5|B6 .

DrawText()

void DrawText	(	sCanvas *	canvas,
		const char *	text,
		int	x,
		int	y,
		u8	col,
		const void *	font,
		int	fontheight = 8,
		int	scalex = 1,
		int	scaley = 1
	)

Draw text (transparent background)

Parameters

canvas	Canvas
text	C string to draw
x	Horizontal position
y	Verticle position
col	Text color
font	Pointer to 1-bit font
fontheight	Height of font in pixels (default 8)
scalex	Magnification scale in X dimension
scaley	Magnification scale in Y dimension

DrawTextBg()

void DrawTextBg	(	sCanvas *	canvas,
		const char *	text,
		int	x,
		int	y,
		u8	col,
		u8	bgcol,
		const void *	font,
		int	fontheight = 8,
		int	scalex = 1,
		int	scaley = 1
	)

Draw text with background color.

Parameters

canvas	Canvas
text	C string to draw
x	Horizontal position
y	Verticle position
col	Text color
bgcol	Background color
font	Pointer to 1-bit font
fontheight	Height of font in pixels (default 8)
scalex	Magnification scale in X dimension
scaley	Magnification scale in Y dimension

DrawImg()

void DrawImg	(	sCanvas *	canvas,
		sCanvas *	src,
		int	xd,
		int	yd,
		int	xs,
		int	ys,
		int	w,
		int	h
	)

Draw image (without transparency)

Parameters

canvas	Destination canvas
src	Source canvas
xd	Destination horizontal postion
yd	Destination vertical position
xs	Source horizontal position
ys	Source vertical position
w	Width
h	Height

DrawBlit()

void DrawBlit	(	sCanvas *	canvas,
		sCanvas *	src,
		int	xd,
		int	yd,
		int	xs,
		int	ys,
		int	w,
		int	h,
		u8	col
	)

Draw image with transparency.

Note

Source and destination must have same format. CANVAS_ATTRIB8 format replaced by DrawImg() function.

Parameters

canvas	Destination canvas
src	Source canvas
xd	Destination horizontal postion
yd	Destination vertical position
xs	Source horizontal position
ys	Source vertical position
w	Width
h	Height
col	Transparency key color

DrawImgMat()

void DrawImgMat	(	sCanvas *	canvas,
		const sCanvas *	src,
		int	x,
		int	y,
		int	w,
		int	h,
		const class cMat2Df *	m,
		u8	mode,
		u8	color
	)

Draw 8-bit image with 2D transformation matrix.

Note

To wrap and perspective mode: Width and height of source image must be power of 2.

Parameters

canvas	Destination canvas
src	Source canvas with image
x	Destination horizontal postion
y	Destination vertical position
w	Destination width
h	Destination height
m	Transformation matrix (should be prepared using cMat2Df::PrepDrawImg() function)
mode	Mode enum value
color	Key or border color

DrawTileMap()

void DrawTileMap	(	sCanvas *	canvas,
		const sCanvas *	src,
		const u8 *	map,
		int	mapwbits,
		int	maphbits,
		int	tilebits,
		int	x,
		int	y,
		int	w,
		int	h,
		const cMat2Df *	mat,
		u8	horizon
	)

Draw tile map using perspective projection.

Parameters

canvas	Destination canvas
src	Source canvas with column of 8-bit square tiles (width = tile size, must be power of 2)
map	Byte map of tile indices
mapwbits	Number of bits of map width (number of tiles; width must be power of 2)
maphbits	Number of bits of map height (number of tiles; height must be power of 2)
tilebits	Number of bits of tile size (e.g. 5 = tile 32x32 pixel)
x	Destination horizontal postion
y	Destination vertical position
w	Destination width
h	Destination height
mat	Transformation matrix (should be prepared using cMat2Df::PrepDrawImg() function)
horizon	Horizon offset (0 = do not use perspective projection)

DrawImgLine()

void DrawImgLine	(	sCanvas *	canvas,
		sCanvas *	src,
		int	xd,
		int	yd,
		int	xs,
		int	ys,
		int	wd,
		int	ws
	)

Draw image line interpolated.

Note

Overflow in X direction is not checked

Parameters

canvas	Destination canvas (8-bit pixel format)
src	Source canvas (source image in 8-bit pixel format)
xd	Destination horizontal postion
yd	Destination vertical position
xs	Source horizontal position
ys	Source vertical position
wd	Destination width
ws	Source width