Draw2D

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Functions

void	draw2d_start (void)
void	draw2d_finish (void)
const Image*	resid_image (...)

Types and Constants

enum	pixformat_t
enum	codec_t
enum	fstyle_t
enum	linecap_t
enum	linejoin_t
enum	fillwrap_t
enum	drawop_t
enum	align_t
enum	ellipsis_t
struct	color_t
struct	DCtx
struct	Draw
struct	Palette
struct	Pixbuf
struct	Image
struct	Font

The Draw2D library integrates all the functionality necessary to create two dimensions vector graphics. It depends directly on Geom2D (Figure 1) and, as we will see later, drawing does not imply having a graphical user interface in the program. It is possible to generate images using an internal memory buffer, without displaying the result in a window.

2D Contexts.
Drawing primitives.
Colors and Palettes.
Pixel Buffer and Images.
Fonts.

Dependencies tree of the draw2d library. — Figure 1: Dependencies of *draw2d*. See NAppGUI API.

This library connects directly to the native technologies of each operating system: GDI+ on Windows systems, Quartz2D on macOS and Cairo on Linux. In essence, draw2d offers a common and light interface so that the code is portable, delegating the final work in each of them. With this we guarantee three things:

Efficiency: These APIs have been tested for years and are maintained by system manufacturers.
Presence: They are integrated as stardard in all computers, so it is not necessary to install additional software.
Performance: The programs are smaller since they do not require linking with special routines for handling graphics, typography or images.

enum pixformat_t

Pixel format in an image. Number of bits per pixel and color model.

enum pixformat_t
{
    ekINDEX1,
    ekINDEX2,
    ekINDEX4,
    ekINDEX8,
    ekGRAY8,
    ekRGB24,
    ekRGBA32,
    ekFIMAGE
};

ekINDEX1	1 bit per pixel. 2 colors, indexed.
ekINDEX2	2 bits per pixel. 4 colors, indexed.
ekINDEX4	4 bits per pixel. 16 colors, indexed.
ekINDEX8	8 bits per pixel. 256 colors, indexed.
ekGRAY8	8 bits per pixel in grayscale. 256 shades of gray.
ekRGB24	24 bits per RGB pixel. 8 bits per channel (red, green, blue). The lowest order byte corresponds to the red one and the highest one to the blue one.
ekRGBA32	32 bits per pixel RGBA. 8 bits per channel (red, green, blue, alpha). The lowest order byte corresponds to the red one and the highest one to alpha (transparency).
ekFIMAGE	Represents the original format of the image. Only valid at image_pixels.

enum codec_t

Image encoding and compression format.

enum codec_t
{
    ekJPG,
    ekPNG,
    ekBMP,
    ekGIF
};

ekJPG	Joint Photographic Experts Group.
ekPNG	Portable Network Graphics.
ekBMP	BitMaP.
ekGIF	Graphics Interchange Format.

enum fstyle_t

Style in typographic fonts. Multiple values can be combined with the OR operator ('|').

enum fstyle_t
{
    ekFNORMAL,
    ekFBOLD,
    ekFITALIC,
    ekFSTRIKEOUT,
    ekFUNDERLINE,
    ekFSUBSCRIPT,
    ekFSUPSCRIPT,
    ekFPIXELS,
    ekFPOINTS
};

ekFNORMAL	Normal font, no style. Also called Regular.
ekFBOLD	Bold font.
ekFITALIC	Italic font.
ekFSTRIKEOUT	~~Crossed out~~ font.
ekFUNDERLINE	Underlined font.
ekFSUBSCRIPT	Subscript. See textview_fstyle.
ekFSUPSCRIPT	Superscript. See textview_fstyle
ekFPIXELS	Font sizes will be indicated in pixels.
ekFPOINTS	Font sizes will be indicated in points. Size in points.

enum linecap_t

Line end style.

enum linecap_t
{
    ekLCFLAT,
    ekLCSQUARE,
    ekLCROUND
};

ekLCFLAT	Flat termination at the last point of the line.
ekLCSQUARE	Termination in a box, whose center is the last point of the line.
ekLCROUND	Termination in a circle, whose center is the last point of the line.

enum linejoin_t

Line junction style.

enum linejoin_t
{
    ekLJMITER,
    ekLJROUND,
    ekLJBEVEL
};

ekLJMITER	Union at an angle. In very closed angles it is trimmed.
ekLJROUND	Rounded union.
ekLJBEVEL	Beveled union.

enum fillwrap_t

Behavior of the fill pattern in the limits.

enum fillwrap_t
{
    ekFCLAMP,
    ekFTILE,
    ekFFLIP
};

ekFCLAMP	The last limit value is used to fill the outside area.
ekFTILE	Pattern is repeated.
ekFFLIP	The pattern is repeated, reversing the order.

enum drawop_t

Operation to be performed on graphic primitives.

enum drawop_t
{
    ekSTROKE,
    ekFILL,
    ekSKFILL,
    ekFILLSK
};

ekSTROKE	Draw the outline of the figure with the default line style.
ekFILL	Fill the figure area with the default color or pattern.
ekSKFILL	First draw the outline and then fill in.
ekFILLSK	First fill in and then draw the outline.

enum align_t

Alignment values.

enum align_t
{
    ekLEFT,
    ekTOP,
    ekCENTER,
    ekRIGHT,
    ekBOTTOM,
    ekJUSTIFY
};

ekLEFT	Alignment to the left margin.
ekTOP	Alignment to the upper margin.
ekCENTER	Centered alignment.
ekRIGHT	Alignment to the right margin.
ekBOTTOM	Alignment to the lower margin.
ekJUSTIFY	Justification or expansion of content.

enum ellipsis_t

Position of the ellipsis (...) when clipping a text.

enum ellipsis_t
{
    ekELLIPNONE,
    ekELLIPBEGIN,
    ekELLIPMIDDLE,
    ekELLIPEND,
    ekELLIPMLINE
};

ekELLIPNONE	Without ellipsis.
ekELLIPBEGIN	Ellipsis at the beginning of the text.
ekELLIPMIDDLE	Ellipsis in the center of the text.
ekELLIPEND	Ellipsis at the end of the text.
ekELLIPMLINE	Multi-line text (without ellipsis).

struct color_t

32-bit integer representing an RGBA color. The lowest order byte corresponds to the red channel (Red) and the highest order to the Alpha channel (transparency). Colors.

struct color_t;

struct DCtx

2D drawing context, recipient for drawing commands. It is also known as canvas or surface. 2D Contexts.

struct DCtx;

struct Draw

Drawing geometric entities.

struct Drawf;

struct Drawd;

template<typename real>
struct Draw;

struct Palette

Color palette, usually related to indexed Pixbuf. Palettes.

struct Palette;

struct Pixbuf

In-memory buffer with pixel information. Pixel Buffer.

struct Pixbuf;

struct Image

Represents a bitmap image, composed of pixels. Images.

struct Image;

struct Font

Represents a typographic family, size and style with which the texts will be drawn. Fonts.

struct Font;

draw2d_start ()

Start the draw2d library, reserving space for global internal structures. Internally call core_start. In desktop applications, osmain call this function when starting the program.

void
draw2d_start(void);

draw2d_finish ()

Ends the draw2d library, freeing up the space of the global internal structures. Internally call core_finish. In desktop applications, osmain call this function when exiting the program.

void
draw2d_finish(void);

resid_image ()

Makes a casting ResId-Image.

const Image*
resid_image(const ResId id);

id	The resource Id.

Return

The Image Id.