FLTK 1.3.4
Drawing functions

FLTK global graphics and GUI drawing functions. More...

Macros

#define fl_clip   fl_push_clip
 Intersects the current clip region with a rectangle and pushes this new region onto the stack (deprecated). More...
 

Enumerations

enum  {
  FL_SOLID = 0, FL_DASH = 1, FL_DOT = 2, FL_DASHDOT = 3,
  FL_DASHDOTDOT = 4, FL_CAP_FLAT = 0x100, FL_CAP_ROUND = 0x200, FL_CAP_SQUARE = 0x300,
  FL_JOIN_MITER = 0x1000, FL_JOIN_ROUND = 0x2000, FL_JOIN_BEVEL = 0x3000
}
 

Functions

void Fl_Quartz_Graphics_Driver::copy_offscreen (int x, int y, int w, int h, Fl_Offscreen pixmap, int srcx, int srcy)
 see fl_copy_offscreen()
 
FL_EXPORT int fl_add_symbol (const char *name, void(*drawit)(Fl_Color), int scalable)
 Adds a symbol to the system. More...
 
void fl_arc (int x, int y, int w, int h, double a1, double a2)
 Draw ellipse sections using integer coordinates. More...
 
void fl_arc (double x, double y, double r, double start, double end)
 Adds a series of points to the current path on the arc of a circle. More...
 
void fl_begin_complex_polygon ()
 Starts drawing a complex filled polygon. More...
 
void fl_begin_line ()
 Starts drawing a list of lines.
 
void fl_begin_loop ()
 Starts drawing a closed sequence of lines.
 
void fl_begin_offscreen (Fl_Offscreen ctx)
 Send all subsequent drawing commands to this offscreen buffer. More...
 
void fl_begin_points ()
 Starts drawing a list of points. More...
 
void fl_begin_polygon ()
 Starts drawing a convex filled polygon.
 
FL_EXPORT char fl_can_do_alpha_blending ()
 Checks whether platform supports true alpha blending for RGBA images. More...
 
FL_EXPORT void fl_chord (int x, int y, int w, int h, double a1, double a2)
 fl_chord declaration is a place holder - the function does not yet exist
 
void fl_circle (double x, double y, double r)
 fl_circle() is equivalent to fl_arc(x,y,r,0,360), but may be faster. More...
 
int fl_clip_box (int x, int y, int w, int h, int &X, int &Y, int &W, int &H)
 Intersects the rectangle with the current clip region and returns the bounding box of the result. More...
 
void fl_clip_region (Fl_Region r)
 Replaces the top of the clipping stack with a clipping region of any shape. More...
 
Fl_Region fl_clip_region ()
 Returns the current clipping region.
 
void fl_copy_offscreen (int x, int y, int w, int h, Fl_Offscreen pixmap, int srcx, int srcy)
 Copy a rectangular area of the given offscreen buffer into the current drawing destination. More...
 
Fl_Offscreen fl_create_offscreen (int w, int h)
 Creation of an offscreen graphics buffer. More...
 
FL_EXPORT void fl_cursor (Fl_Cursor)
 Sets the cursor for the current window to the specified shape and colors. More...
 
FL_EXPORT void fl_cursor (Fl_Cursor, Fl_Color fg, Fl_Color bg=FL_WHITE)
 
void fl_curve (double X0, double Y0, double X1, double Y1, double X2, double Y2, double X3, double Y3)
 Adds a series of points on a Bezier curve to the path. More...
 
void fl_delete_offscreen (Fl_Offscreen ctx)
 Deletion of an offscreen graphics buffer. More...
 
FL_EXPORT void fl_draw (const char *str, int x, int y)
 Draws a nul-terminated UTF-8 string starting at the given x, y location. More...
 
FL_EXPORT void fl_draw (int angle, const char *str, int x, int y)
 Draws a nul-terminated UTF-8 string starting at the given x, y location and rotating angle degrees counter-clockwise. More...
 
void fl_draw (const char *str, int n, int x, int y)
 Draws starting at the given x, y location a UTF-8 string of length n bytes.
 
void fl_draw (int angle, const char *str, int n, int x, int y)
 Draws at the given x, y location a UTF-8 string of length n bytes rotating angle degrees counter-clockwise. More...
 
FL_EXPORT void fl_draw (const char *str, int x, int y, int w, int h, Fl_Align align, Fl_Image *img=0, int draw_symbols=1)
 Fancy string drawing function which is used to draw all the labels. More...
 
FL_EXPORT void fl_draw (const char *str, int x, int y, int w, int h, Fl_Align align, void(*callthis)(const char *, int, int, int), Fl_Image *img=0, int draw_symbols=1)
 The same as fl_draw(const char*,int,int,int,int,Fl_Align,Fl_Image*,int) with the addition of the callthis parameter, which is a pointer to a text drawing function such as fl_draw(const char*, int, int, int) to do the real work.
 
FL_EXPORT void fl_draw_box (Fl_Boxtype, int x, int y, int w, int h, Fl_Color)
 Draws a box using given type, position, size and color. More...
 
void fl_draw_image (const uchar *buf, int X, int Y, int W, int H, int D=3, int L=0)
 Draws an 8-bit per color RGB or luminance image. More...
 
void fl_draw_image (Fl_Draw_Image_Cb cb, void *data, int X, int Y, int W, int H, int D=3)
 Draws an image using a callback function to generate image data. More...
 
void fl_draw_image_mono (const uchar *buf, int X, int Y, int W, int H, int D=1, int L=0)
 Draws a gray-scale (1 channel) image. More...
 
void fl_draw_image_mono (Fl_Draw_Image_Cb cb, void *data, int X, int Y, int W, int H, int D=1)
 Draws a gray-scale image using a callback function to generate image data. More...
 
FL_EXPORT int fl_draw_pixmap (char *const *data, int x, int y, Fl_Color=FL_GRAY)
 Draw XPM image data, with the top-left corner at the given position. More...
 
FL_EXPORT int fl_draw_pixmap (const char *const *cdata, int x, int y, Fl_Color=FL_GRAY)
 Draw XPM image data, with the top-left corner at the given position. More...
 
FL_EXPORT int fl_draw_symbol (const char *label, int x, int y, int w, int h, Fl_Color)
 Draw the named symbol in the given rectangle using the given color. More...
 
void fl_end_complex_polygon ()
 Ends complex filled polygon, and draws.
 
void fl_end_line ()
 Ends list of lines, and draws.
 
void fl_end_loop ()
 Ends closed sequence of lines, and draws.
 
void fl_end_offscreen ()
 Quit sending drawing commands to the current offscreen buffer.
 
void fl_end_points ()
 Ends list of points, and draws.
 
void fl_end_polygon ()
 Ends convex filled polygon, and draws.
 
FL_EXPORT const char * fl_expand_text (const char *from, char *buf, int maxbuf, double maxw, int &n, double &width, int wrap, int draw_symbols=0)
 Copy from to buf, replacing control characters with ^X. More...
 
FL_EXPORT void fl_frame (const char *s, int x, int y, int w, int h)
 Draws a series of line segments around the given box. More...
 
FL_EXPORT void fl_frame2 (const char *s, int x, int y, int w, int h)
 Draws a series of line segments around the given box. More...
 
void fl_gap ()
 Call fl_gap() to separate loops of the path. More...
 
void fl_line (int x, int y, int x1, int y1)
 Draws a line from (x,y) to (x1,y1)
 
void fl_line (int x, int y, int x1, int y1, int x2, int y2)
 Draws a line from (x,y) to (x1,y1) and another from (x1,y1) to (x2,y2)
 
void fl_line_style (int style, int width=0, char *dashes=0)
 Sets how to draw lines (the "pen"). More...
 
void fl_loop (int x, int y, int x1, int y1, int x2, int y2)
 Outlines a 3-sided polygon with lines.
 
void fl_loop (int x, int y, int x1, int y1, int x2, int y2, int x3, int y3)
 Outlines a 4-sided polygon with lines.
 
FL_EXPORT void fl_measure (const char *str, int &x, int &y, int draw_symbols=1)
 Measure how wide and tall the string will be when printed by the fl_draw() function with align parameter. More...
 
FL_EXPORT int fl_measure_pixmap (char *const *data, int &w, int &h)
 Get the dimensions of a pixmap. More...
 
FL_EXPORT int fl_measure_pixmap (const char *const *cdata, int &w, int &h)
 Get the dimensions of a pixmap. More...
 
void fl_mult_matrix (double a, double b, double c, double d, double x, double y)
 Concatenates another transformation onto the current one. More...
 
int fl_not_clipped (int x, int y, int w, int h)
 Does the rectangle intersect the current clip region? More...
 
FL_EXPORT unsigned int fl_old_shortcut (const char *s)
 Emulation of XForms named shortcuts. More...
 
FL_EXPORT void fl_overlay_clear ()
 Erase a selection rectangle without drawing a new one.
 
FL_EXPORT void fl_overlay_rect (int x, int y, int w, int h)
 Draws a selection rectangle, erasing a previous one by XOR'ing it first.
 
void fl_pie (int x, int y, int w, int h, double a1, double a2)
 Draw filled ellipse sections using integer coordinates. More...
 
void fl_point (int x, int y)
 Draws a single pixel at the given coordinates.
 
void fl_polygon (int x, int y, int x1, int y1, int x2, int y2)
 Fills a 3-sided polygon. More...
 
void fl_polygon (int x, int y, int x1, int y1, int x2, int y2, int x3, int y3)
 Fills a 4-sided polygon. More...
 
void fl_pop_clip ()
 Restores the previous clip region. More...
 
void fl_pop_matrix ()
 Restores the current transformation matrix from the stack.
 
void fl_push_clip (int x, int y, int w, int h)
 Intersects the current clip region with a rectangle and pushes this new region onto the stack. More...
 
void fl_push_matrix ()
 Saves the current transformation matrix on the stack. More...
 
void fl_push_no_clip ()
 Pushes an empty clip region onto the stack so nothing will be clipped.
 
FL_EXPORT ucharfl_read_image (uchar *p, int X, int Y, int W, int H, int alpha=0)
 Reads an RGB(A) image from the current window or off-screen buffer. More...
 
void fl_rect (int x, int y, int w, int h)
 Draws a 1-pixel border inside the given bounding box. More...
 
void fl_rect (int x, int y, int w, int h, Fl_Color c)
 Draws with passed color a 1-pixel border inside the given bounding box.
 
void fl_rectf (int x, int y, int w, int h)
 Colors with current color a rectangle that exactly fills the given bounding box.
 
void fl_rectf (int x, int y, int w, int h, Fl_Color c)
 Colors with passed color a rectangle that exactly fills the given bounding box.
 
FL_EXPORT void fl_rectf (int x, int y, int w, int h, uchar r, uchar g, uchar b)
 Colors a rectangle with "exactly" the passed r,g,b color. More...
 
FL_EXPORT void fl_reset_spot (void)
 
void fl_restore_clip ()
 Undoes any clobbering of clip done by your program.
 
void fl_rotate (double d)
 Concatenates rotation transformation onto the current one. More...
 
void fl_rtl_draw (const char *str, int n, int x, int y)
 Draws a UTF-8 string of length n bytes right to left starting at the given x, y location.
 
void fl_scale (double x, double y)
 Concatenates scaling transformation onto the current one. More...
 
void fl_scale (double x)
 Concatenates scaling transformation onto the current one. More...
 
FL_EXPORT void fl_scroll (int X, int Y, int W, int H, int dx, int dy, void(*draw_area)(void *, int, int, int, int), void *data)
 Scroll a rectangle and draw the newly exposed portions. More...
 
FL_EXPORT void fl_set_spot (int font, int size, int X, int Y, int W, int H, Fl_Window *win=0)
 
FL_EXPORT void fl_set_status (int X, int Y, int W, int H)
 
FL_EXPORT const char * fl_shortcut_label (unsigned int shortcut)
 Get a human-readable string from a shortcut value. More...
 
FL_EXPORT const char * fl_shortcut_label (unsigned int shortcut, const char **eom)
 Get a human-readable string from a shortcut value. More...
 
double fl_transform_dx (double x, double y)
 Transforms distance using current transformation matrix. More...
 
double fl_transform_dy (double x, double y)
 Transforms distance using current transformation matrix. More...
 
double fl_transform_x (double x, double y)
 Transforms coordinate using the current transformation matrix. More...
 
double fl_transform_y (double x, double y)
 Transforms coordinate using the current transformation matrix. More...
 
void fl_transformed_vertex (double xf, double yf)
 Adds coordinate pair to the vertex list without further transformations. More...
 
void fl_translate (double x, double y)
 Concatenates translation transformation onto the current one. More...
 
void fl_vertex (double x, double y)
 Adds a single vertex to the current path. More...
 
void fl_xyline (int x, int y, int x1)
 Draws a horizontal line from (x,y) to (x1,y)
 
void fl_xyline (int x, int y, int x1, int y2)
 Draws a horizontal line from (x,y) to (x1,y), then vertical from (x1,y) to (x1,y2)
 
void fl_xyline (int x, int y, int x1, int y2, int x3)
 Draws a horizontal line from (x,y) to (x1,y), then a vertical from (x1,y) to (x1,y2) and then another horizontal from (x1,y2) to (x3,y2)
 
void fl_yxline (int x, int y, int y1)
 Draws a vertical line from (x,y) to (x,y1)
 
void fl_yxline (int x, int y, int y1, int x2)
 Draws a vertical line from (x,y) to (x,y1), then a horizontal from (x,y1) to (x2,y1)
 
void fl_yxline (int x, int y, int y1, int x2, int y3)
 Draws a vertical line from (x,y) to (x,y1) then a horizontal from (x,y1) to (x2,y1), then another vertical from (x2,y1) to (x2,y3)
 

Variables

const int stack_max = 16
 

Detailed Description

FLTK global graphics and GUI drawing functions.

These functions are declared in <FL/fl_draw.H>, and in <FL/x.H> for offscreen buffer-related ones.

Macro Definition Documentation

#define fl_clip   fl_push_clip

Intersects the current clip region with a rectangle and pushes this new region onto the stack (deprecated).

Parameters
[in]x,y,w,hposition and size
Deprecated:
fl_clip(int, int, int, int) is deprecated and will be removed from future releases. Please use fl_push_clip(int x, int y, int w, int h) instead.

Enumeration Type Documentation

anonymous enum
Enumerator
FL_SOLID 

line style: ___________

FL_DASH 

line style: _ _ _ _ _ _

FL_DOT 

line style: . . . . . .

FL_DASHDOT 

line style: _ . _ . _ .

FL_DASHDOTDOT 

line style: _ . . _ . .

FL_CAP_FLAT 

cap style: end is flat

FL_CAP_ROUND 

cap style: end is round

FL_CAP_SQUARE 

cap style: end wraps end point

FL_JOIN_MITER 

join style: line join extends to a point

FL_JOIN_ROUND 

join style: line join is rounded

FL_JOIN_BEVEL 

join style: line join is tidied

Function Documentation

FL_EXPORT int fl_add_symbol ( const char *  name,
void(*)(Fl_Color drawit,
int  scalable 
)

Adds a symbol to the system.

Parameters
[in]namename of symbol (without the "@")
[in]drawitfunction to draw symbol
[in]scalableset to 1 if drawit uses scalable vector drawing
Returns
1 on success, 0 on failure
void fl_arc ( int  x,
int  y,
int  w,
int  h,
double  a1,
double  a2 
)
inline

Draw ellipse sections using integer coordinates.

These functions match the rather limited circle drawing code provided by X and WIN32. The advantage over using fl_arc with floating point coordinates is that they are faster because they often use the hardware, and they draw much nicer small circles, since the small sizes are often hard-coded bitmaps.

If a complete circle is drawn it will fit inside the passed bounding box. The two angles are measured in degrees counter-clockwise from 3 o'clock and are the starting and ending angle of the arc, a2 must be greater or equal to a1.

fl_arc() draws a series of lines to approximate the arc. Notice that the integer version of fl_arc() has a different number of arguments than the double version fl_arc(double x, double y, double r, double start, double end)

Parameters
[in]x,y,w,hbounding box of complete circle
[in]a1,a2start and end angles of arc measured in degrees counter-clockwise from 3 o'clock. a2 must be greater than or equal to a1.
void fl_arc ( double  x,
double  y,
double  r,
double  start,
double  end 
)
inline

Adds a series of points to the current path on the arc of a circle.

You can get elliptical paths by using scale and rotate before calling fl_arc().

Parameters
[in]x,y,rcenter and radius of circular arc
[in]start,endangles of start and end of arc measured in degrees counter-clockwise from 3 o'clock. If end is less than start then it draws the arc in a clockwise direction.

Examples:

// Draw an arc of points
fl_arc(100.0, 100.0, 50.0, 0.0, 180.0);
// Draw arc with a line
fl_arc(200.0, 100.0, 50.0, 0.0, 180.0);
// Draw filled arc
fl_arc(300.0, 100.0, 50.0, 0.0, 180.0);
void fl_begin_complex_polygon ( )
inline

Starts drawing a complex filled polygon.

The polygon may be concave, may have holes in it, or may be several disconnected pieces. Call fl_gap() to separate loops of the path.

To outline the polygon, use fl_begin_loop() and replace each fl_gap() with fl_end_loop();fl_begin_loop() pairs.

Note
For portability, you should only draw polygons that appear the same whether "even/odd" or "non-zero" winding rules are used to fill them. Holes should be drawn in the opposite direction to the outside loop.
void fl_begin_offscreen ( Fl_Offscreen  ctx)

Send all subsequent drawing commands to this offscreen buffer.

Parameters
ctxthe offscreen buffer.
void fl_begin_points ( )
inline

Starts drawing a list of points.

Points are added to the list with fl_vertex()

FL_EXPORT char fl_can_do_alpha_blending ( )

Checks whether platform supports true alpha blending for RGBA images.

Returns
1 if true alpha blending supported by platform
0 not supported so FLTK will use screen door transparency
void fl_circle ( double  x,
double  y,
double  r 
)
inline

fl_circle() is equivalent to fl_arc(x,y,r,0,360), but may be faster.

It must be the only thing in the path: if you want a circle as part of a complex polygon you must use fl_arc()

Parameters
[in]x,y,rcenter and radius of circle
int fl_clip_box ( int  x,
int  y,
int  w,
int  h,
int &  X,
int &  Y,
int &  W,
int &  H 
)
inline

Intersects the rectangle with the current clip region and returns the bounding box of the result.

Returns non-zero if the resulting rectangle is different to the original. This can be used to limit the necessary drawing to a rectangle. W and H are set to zero if the rectangle is completely outside the region.

Parameters
[in]x,y,w,hposition and size of rectangle
[out]X,Y,W,Hposition and size of resulting bounding box.
Returns
Non-zero if the resulting rectangle is different to the original.
void fl_clip_region ( Fl_Region  r)
inline

Replaces the top of the clipping stack with a clipping region of any shape.

Fl_Region is an operating system specific type.

Parameters
[in]rclipping region
void fl_copy_offscreen ( int  x,
int  y,
int  w,
int  h,
Fl_Offscreen  pixmap,
int  srcx,
int  srcy 
)

Copy a rectangular area of the given offscreen buffer into the current drawing destination.

Parameters
x,yposition where to draw the copied rectangle
w,hsize of the copied rectangle
pixmapoffscreen buffer containing the rectangle to copy
srcx,srcyorigin in offscreen buffer of rectangle to copy
Fl_Offscreen fl_create_offscreen ( int  w,
int  h 
)

Creation of an offscreen graphics buffer.

Parameters
w,hwidth and height in pixels of the buffer.
Returns
the created graphics buffer.
FL_EXPORT void fl_cursor ( Fl_Cursor  c)

Sets the cursor for the current window to the specified shape and colors.

The cursors are defined in the <FL/Enumerations.H> header file.

void fl_curve ( double  X0,
double  Y0,
double  X1,
double  Y1,
double  X2,
double  Y2,
double  X3,
double  Y3 
)
inline

Adds a series of points on a Bezier curve to the path.

The curve ends (and two of the points) are at X0,Y0 and X3,Y3.

Parameters
[in]X0,Y0curve start point
[in]X1,Y1curve control point
[in]X2,Y2curve control point
[in]X3,Y3curve end point
void fl_delete_offscreen ( Fl_Offscreen  ctx)

Deletion of an offscreen graphics buffer.

Parameters
ctxthe buffer to be deleted.
FL_EXPORT void fl_draw ( const char *  str,
int  x,
int  y 
)

Draws a nul-terminated UTF-8 string starting at the given x, y location.

Text is aligned to the left and to the baseline of the font. To align to the bottom, subtract fl_descent() from y. To align to the top, subtract fl_descent() and add fl_height(). This version of fl_draw provides direct access to the text drawing function of the underlying OS. It does not apply any special handling to control characters.

FL_EXPORT void fl_draw ( int  angle,
const char *  str,
int  x,
int  y 
)

Draws a nul-terminated UTF-8 string starting at the given x, y location and rotating angle degrees counter-clockwise.

This version of fl_draw provides direct access to the text drawing function of the underlying OS and is supported by Xft, Win32 and MacOS fltk subsets.

void fl_draw ( int  angle,
const char *  str,
int  n,
int  x,
int  y 
)
inline

Draws at the given x, y location a UTF-8 string of length n bytes rotating angle degrees counter-clockwise.

Note
When using X11 (Unix, Linux, Cygwin et al.) this needs Xft to work. Under plain X11 (w/o Xft) rotated text is not supported by FLTK. A warning will be issued to stderr at runtime (only once) if you use this method with an angle other than 0.
FL_EXPORT void fl_draw ( const char *  str,
int  x,
int  y,
int  w,
int  h,
Fl_Align  align,
Fl_Image img,
int  draw_symbols 
)

Fancy string drawing function which is used to draw all the labels.

The string is formatted and aligned inside the passed box. Handles '\t' and '\n', expands all other control characters to '^X', and aligns inside or against the edges of the box. See Fl_Widget::align() for values of align. The value FL_ALIGN_INSIDE is ignored, as this function always prints inside the box. If img is provided and is not NULL, the image is drawn above or below the text as specified by the align value. The draw_symbols argument specifies whether or not to look for symbol names starting with the '@' character'

FL_EXPORT void fl_draw_box ( Fl_Boxtype  t,
int  x,
int  y,
int  w,
int  h,
Fl_Color  c 
)

Draws a box using given type, position, size and color.

Parameters
[in]tbox type
[in]x,y,w,hposition and size
[in]ccolor
void fl_draw_image ( const uchar buf,
int  X,
int  Y,
int  W,
int  H,
int  D = 3,
int  L = 0 
)
inline

Draws an 8-bit per color RGB or luminance image.

Parameters
[in]bufpoints at the "r" data of the top-left pixel. Color data must be in r,g,b order. Luminance data is only one gray byte.
[in]X,Yposition where to put top-left corner of image
[in]W,Hsize of the image
[in]Ddelta to add to the pointer between pixels. It may be any value greater than or equal to 1, or it can be negative to flip the image horizontally
[in]Ldelta to add to the pointer between lines (if 0 is passed it uses W * D), and may be larger than W * D to crop data, or negative to flip the image vertically

It is highly recommended that you put the following code before the first show() of any window in your program to get rid of the dithering if possible:

Fl::visual(FL_RGB);

Gray scale (1-channel) images may be drawn. This is done if abs(D) is less than 3, or by calling fl_draw_image_mono(). Only one 8-bit sample is used for each pixel, and on screens with different numbers of bits for red, green, and blue only gray colors are used. Setting D greater than 1 will let you display one channel of a color image.

Note:
The X version does not support all possible visuals. If FLTK cannot draw the image in the current visual it will abort. FLTK supports any visual of 8 bits or less, and all common TrueColor visuals up to 32 bits.
void fl_draw_image ( Fl_Draw_Image_Cb  cb,
void *  data,
int  X,
int  Y,
int  W,
int  H,
int  D = 3 
)
inline

Draws an image using a callback function to generate image data.

You can generate the image as it is being drawn, or do arbitrary decompression of stored data, provided it can be decompressed to individual scan lines easily.

Parameters
[in]cbcallback function to generate scan line data
[in]datauser data passed to callback function
[in]X,Yscreen position of top left pixel
[in]W,Himage width and height
[in]Ddata size in bytes (must be greater than 0)
See Also
fl_draw_image(const uchar* buf, int X,int Y,int W,int H, int D, int L)

The callback function cb is called with the void* data user data pointer to allow access to a structure of information about the image, and the x, y, and w of the scan line desired from the image. 0,0 is the upper-left corner of the image, not x, y. A pointer to a buffer to put the data into is passed. You must copy w pixels from scanline y, starting at pixel x, to this buffer.

Due to cropping, less than the whole image may be requested. So x may be greater than zero, the first y may be greater than zero, and w may be less than W. The buffer is long enough to store the entire W * D pixels, this is for convenience with some decompression schemes where you must decompress the entire line at once: decompress it into the buffer, and then if x is not zero, copy the data over so the x'th pixel is at the start of the buffer.

You can assume the y's will be consecutive, except the first one may be greater than zero.

If D is 4 or more, you must fill in the unused bytes with zero.

void fl_draw_image_mono ( const uchar buf,
int  X,
int  Y,
int  W,
int  H,
int  D = 1,
int  L = 0 
)
inline

Draws a gray-scale (1 channel) image.

See Also
fl_draw_image(const uchar* buf, int X,int Y,int W,int H, int D, int L)
void fl_draw_image_mono ( Fl_Draw_Image_Cb  cb,
void *  data,
int  X,
int  Y,
int  W,
int  H,
int  D = 1 
)
inline

Draws a gray-scale image using a callback function to generate image data.

See Also
fl_draw_image(Fl_Draw_Image_Cb cb, void* data, int X,int Y,int W,int H, int D)
FL_EXPORT int fl_draw_pixmap ( char *const *  data,
int  x,
int  y,
Fl_Color  bg 
)

Draw XPM image data, with the top-left corner at the given position.

The image is dithered on 8-bit displays so you won't lose color space for programs displaying both images and pixmaps.

Parameters
[in]datapointer to XPM image data
[in]x,yposition of top-left corner
[in]bgbackground color
Returns
0 if there was any error decoding the XPM data.
FL_EXPORT int fl_draw_pixmap ( const char *const *  cdata,
int  x,
int  y,
Fl_Color  bg 
)

Draw XPM image data, with the top-left corner at the given position.

See Also
fl_draw_pixmap(char* const* data, int x, int y, Fl_Color bg)
FL_EXPORT int fl_draw_symbol ( const char *  label,
int  x,
int  y,
int  w,
int  h,
Fl_Color  col 
)

Draw the named symbol in the given rectangle using the given color.

Parameters
[in]labelname of symbol
[in]x,yposition of symbol
[in]w,hsize of symbol
[in]colcolor of symbox
Returns
1 on success, 0 on failure
FL_EXPORT const char* fl_expand_text ( const char *  from,
char *  buf,
int  maxbuf,
double  maxw,
int &  n,
double &  width,
int  wrap,
int  draw_symbols 
)

Copy from to buf, replacing control characters with ^X.

Stop at a newline or if maxbuf characters written to buffer. Also word-wrap if width exceeds maxw. Returns a pointer to the start of the next line of characters. Sets n to the number of characters put into the buffer. Sets width to the width of the string in the current font.

FL_EXPORT void fl_frame ( const char *  s,
int  x,
int  y,
int  w,
int  h 
)

Draws a series of line segments around the given box.

The string s must contain groups of 4 letters which specify one of 24 standard grayscale values, where 'A' is black and 'X' is white. The order of each set of 4 characters is: top, left, bottom, right. The result of calling fl_frame() with a string that is not a multiple of 4 characters in length is undefined. The only difference between this function and fl_frame2() is the order of the line segments.

Parameters
[in]ssets of 4 grayscale values in top, left, bottom, right order
[in]x,y,w,hposition and size
FL_EXPORT void fl_frame2 ( const char *  s,
int  x,
int  y,
int  w,
int  h 
)

Draws a series of line segments around the given box.

The string s must contain groups of 4 letters which specify one of 24 standard grayscale values, where 'A' is black and 'X' is white. The order of each set of 4 characters is: bottom, right, top, left. The result of calling fl_frame2() with a string that is not a multiple of 4 characters in length is undefined. The only difference between this function and fl_frame() is the order of the line segments.

Parameters
[in]ssets of 4 grayscale values in bottom, right, top, left order
[in]x,y,w,hposition and size
void fl_gap ( )
inline

Call fl_gap() to separate loops of the path.

It is unnecessary but harmless to call fl_gap() before the first vertex, after the last vertex, or several times in a row.

void fl_line_style ( int  style,
int  width = 0,
char *  dashes = 0 
)
inline

Sets how to draw lines (the "pen").

If you change this it is your responsibility to set it back to the default using fl_line_style(0).

Parameters
[in]styleA bitmask which is a bitwise-OR of a line style, a cap style, and a join style. If you don't specify a dash type you will get a solid line. If you don't specify a cap or join type you will get a system-defined default of whatever value is fastest.
[in]widthThe thickness of the lines in pixels. Zero results in the system defined default, which on both X and Windows is somewhat different and nicer than 1.
[in]dashesA pointer to an array of dash lengths, measured in pixels. The first location is how long to draw a solid portion, the next is how long to draw the gap, then the solid, etc. It is terminated with a zero-length entry. A NULL pointer or a zero-length array results in a solid line. Odd array sizes are not supported and result in undefined behavior.
Note
Because of how line styles are implemented on Win32 systems, you must set the line style after setting the drawing color. If you set the color after the line style you will lose the line style settings.
The dashes array does not work under Windows 95, 98 or Me, since those operating systems do not support complex line styles.
FL_EXPORT void fl_measure ( const char *  str,
int &  w,
int &  h,
int  draw_symbols 
)

Measure how wide and tall the string will be when printed by the fl_draw() function with align parameter.

If the incoming w is non-zero it will wrap to that width.

The current font is used to do the width/height calculations, so unless its value is known at the time fl_measure() is called, it is advised to first set the current font with fl_font(). With event-driven GUI programming you can never be sure which widget was exposed and redrawn last, nor which font it used. If you have not called fl_font() explicitly in your own code, the width and height may be set to unexpected values, even zero!

Note: In the general use case, it's a common error to forget to set w to 0 before calling fl_measure() when wrap behavior isn't needed.

Parameters
[in]strnul-terminated string
[out]w,hwidth and height of string in current font
[in]draw_symbolsnon-zero to enable @symbol handling [default=1]
// Example: Common use case for fl_measure()
const char *s = "This is a test";
int wi=0, hi=0; // initialize to zero before calling fl_measure()
fl_font(FL_HELVETICA, 14); // set current font face/size to be used for measuring
fl_measure(s, wi, hi); // returns pixel width/height of string in current font
FL_EXPORT int fl_measure_pixmap ( char *const *  data,
int &  w,
int &  h 
)

Get the dimensions of a pixmap.

An XPM image contains the dimensions in its data. This function returns the width and height.

Parameters
[in]datapointer to XPM image data.
[out]w,hwidth and height of image
Returns
non-zero if the dimensions were parsed OK
0 if there were any problems
FL_EXPORT int fl_measure_pixmap ( const char *const *  cdata,
int &  w,
int &  h 
)

Get the dimensions of a pixmap.

See Also
fl_measure_pixmap(char* const* data, int &w, int &h)
void fl_mult_matrix ( double  a,
double  b,
double  c,
double  d,
double  x,
double  y 
)
inline

Concatenates another transformation onto the current one.

Parameters
[in]a,b,c,d,x,ytransformation matrix elements such that X' = aX + cY + x and Y' = bX +dY + y
int fl_not_clipped ( int  x,
int  y,
int  w,
int  h 
)
inline

Does the rectangle intersect the current clip region?

Parameters
[in]x,y,w,hposition and size of rectangle
Returns
non-zero if any of the rectangle intersects the current clip region. If this returns 0 you don't have to draw the object.
Note
Under X this returns 2 if the rectangle is partially clipped, and 1 if it is entirely inside the clip region.
FL_EXPORT unsigned int fl_old_shortcut ( const char *  s)

Emulation of XForms named shortcuts.

Converts ascii shortcut specifications (eg. "^c") into the FLTK integer equivalent (eg. FL_CTRL+'c')

These ascii characters are used to specify the various keyboard modifier keys:

 # - Alt
 + - Shift
 ^ - Control
 ! - Meta
 @ - Command (Ctrl on linux/win, Meta on OSX)

These special characters can be combined to form chords of modifier keys. (See 'Remarks' below)

After the optional modifier key prefixes listed above, one can either specify a single keyboard character to use as the shortcut, or a numeric sequence in hex, decimal or octal.

Examples:

 "c"      -- Uses 'c' as the shortcut
 "#^c"    -- Same as FL_ALT|FL_CTRL|'c'
 "#^!c"   -- Same as FL_ALT|FL_CTRL|FL_META|'c'
 "@c"     -- Same as FL_COMMAND|'c' (see FL_COMMAND for platform specific behavior)
 "0x63"   -- Same as "c" (hex 63=='c')
 "99"     -- Same as "c" (dec 99=='c')
 "0143"   -- Same as "c" (octal 0143=='c')
 "^0x63"  -- Same as (FL_CTRL|'c'), or (FL_CTRL|0x63)
 "^99"    -- Same as (FL_CTRL|'c'), or (FL_CTRL|99)
 "^0143"  -- Same as (FL_CTRL|'c'), or (FL_CTRL|0143)
Remarks
Due to XForms legacy, there are some odd things to consider when using the modifier characters.
(1) You can use the special modifier keys for chords only if the modifiers are provided in this order: #, +, ^, !, @. Other ordering can yield undefined results.
So for instance, Ctrl-Alt-c must be specified as "#^c" (and not "^#c"), due to the above ordering rule.
(2) If you want to make a shortcut that uses one of the special modifier characters (as the character being modified), then to avoid confusion, specify the numeric equivalent, e.g.
 If you want..                    Then use..
 -----------------------------    ------------------------------
 '#' as the shortcut..            "0x23"  (instead of just "#").
 '+' as the shortcut..            "0x2b"  (instead of just "+").
 '^' as the shortcut..            "0x5e"  (instead of just "^").
 Alt-+ as the shortcut..          "#0x2b" (instead of "#+").
 Alt-^ as the shortcut..          "#0x5e" (instead of "#^").
 ..etc..
As a general rule that's easy to remember, unless the shortcut key to be modified is a single alpha-numeric character [A-Z,a-z,0-9), it's probably best to use the numeric equivalents.
Todo:
Fix these silly legacy issues in a future release to support more predictable behavior for the modifier keys.
void fl_pie ( int  x,
int  y,
int  w,
int  h,
double  a1,
double  a2 
)
inline

Draw filled ellipse sections using integer coordinates.

Like fl_arc(), but fl_pie() draws a filled-in pie slice. This slice may extend outside the line drawn by fl_arc(); to avoid this use w - 1 and h - 1.

Parameters
[in]x,y,w,hbounding box of complete circle
[in]a1,a2start and end angles of arc measured in degrees counter-clockwise from 3 o'clock. a2 must be greater than or equal to a1.
void fl_polygon ( int  x,
int  y,
int  x1,
int  y1,
int  x2,
int  y2 
)
inline

Fills a 3-sided polygon.

The polygon must be convex.

void fl_polygon ( int  x,
int  y,
int  x1,
int  y1,
int  x2,
int  y2,
int  x3,
int  y3 
)
inline

Fills a 4-sided polygon.

The polygon must be convex.

void fl_pop_clip ( )
inline

Restores the previous clip region.

You must call fl_pop_clip() once for every time you call fl_push_clip(). Unpredictable results may occur if the clip stack is not empty when you return to FLTK.

void fl_push_clip ( int  x,
int  y,
int  w,
int  h 
)
inline

Intersects the current clip region with a rectangle and pushes this new region onto the stack.

Parameters
[in]x,y,w,hposition and size
void fl_push_matrix ( )
inline

Saves the current transformation matrix on the stack.

The maximum depth of the stack is 32.

FL_EXPORT uchar* fl_read_image ( uchar p,
int  X,
int  Y,
int  W,
int  H,
int  alpha = 0 
)

Reads an RGB(A) image from the current window or off-screen buffer.

Parameters
[in]ppixel buffer, or NULL to allocate one
[in]X,Yposition of top-left of image to read
[in]W,Hwidth and height of image to read
[in]alphaalpha value for image (0 for none)
Returns
pointer to pixel buffer, or NULL if allocation failed.

The p argument points to a buffer that can hold the image and must be at least W*H*3 bytes when reading RGB images, or W*H*4 bytes when reading RGBA images. If NULL, fl_read_image() will create an array of the proper size which can be freed using delete[].

The alpha parameter controls whether an alpha channel is created and the value that is placed in the alpha channel. If 0, no alpha channel is generated.

void fl_rect ( int  x,
int  y,
int  w,
int  h 
)
inline

Draws a 1-pixel border inside the given bounding box.

This function is meant for quick drawing of simple boxes. The behavior is undefined for line widths that are not 1.

FL_EXPORT void fl_rectf ( int  x,
int  y,
int  w,
int  h,
uchar  r,
uchar  g,
uchar  b 
)

Colors a rectangle with "exactly" the passed r,g,b color.

On screens with less than 24 bits of color this is done by drawing a solid-colored block using fl_draw_image() so that the correct color shade is produced.

FL_EXPORT void fl_reset_spot ( void  )
Todo:
provide user documentation for fl_reset_spot function
void fl_rotate ( double  d)
inline

Concatenates rotation transformation onto the current one.

Parameters
[in]d- rotation angle, counter-clockwise in degrees (not radians)
void fl_scale ( double  x,
double  y 
)
inline

Concatenates scaling transformation onto the current one.

Parameters
[in]x,yscale factors in x-direction and y-direction
void fl_scale ( double  x)
inline

Concatenates scaling transformation onto the current one.

Parameters
[in]xscale factor in both x-direction and y-direction
FL_EXPORT void fl_scroll ( int  X,
int  Y,
int  W,
int  H,
int  dx,
int  dy,
void(*)(void *, int, int, int, int)  draw_area,
void *  data 
)

Scroll a rectangle and draw the newly exposed portions.

Parameters
[in]X,Yposition of top-left of rectangle
[in]W,Hsize of rectangle
[in]dx,dypixel offsets for shifting rectangle
[in]draw_areacallback function to draw rectangular areas
[in]datapointer to user data for callback The contents of the rectangular area is first shifted by dx and dy pixels. The draw_area callback is then called for every newly exposed rectangular area.
FL_EXPORT void fl_set_spot ( int  font,
int  size,
int  X,
int  Y,
int  W,
int  H,
Fl_Window win = 0 
)
Todo:
provide user documentation for fl_set_spot function
FL_EXPORT void fl_set_status ( int  X,
int  Y,
int  W,
int  H 
)
Todo:
provide user documentation for fl_set_status function
FL_EXPORT const char* fl_shortcut_label ( unsigned int  shortcut)

Get a human-readable string from a shortcut value.

Unparse a shortcut value as used by Fl_Button or Fl_Menu_Item into a human-readable string like "Alt+N". This only works if the shortcut is a character key or a numbered function key. If the shortcut is zero then an empty string is returned. The return value points at a static buffer that is overwritten with each call.

Since
FLTK 1.3.4 modifier key names can be localized, but key names can not yet be localized. This may be added to a future FLTK version.

Modifier key names (human-readable shortcut names) can be defined with the following global const char * pointer variables:

  • fl_local_ctrl => name of FL_CTRL
  • fl_local_alt => name of FL_ALT
  • fl_local_shift => name of FL_SHIFT
  • fl_local_meta => name of FL_META
fl_local_ctrl = "Strg"; // German for "Ctrl"
fl_local_shift = "Umschalt"; // German for "Shift"

The shortcut name will be constructed by adding all modifier names in the order defined above plus the name of the key. A '+' character is added to each modifier name unless it has a trailing '\' or a trailing '+'.

Example:

Ctrl+Alt+Shift+Meta+F12

The default values for modifier key names are as given above for all platforms except Mac OS X. Mac OS X uses graphical characters that represent the typical OS X modifier names in menus, e.g. cloverleaf, saucepan, etc. You may, however, redefine Mac OS X modifier names as well.

Parameters
[in]shortcutthe integer value containing the ascii character or extended keystroke plus modifiers
Returns
a pointer to a static buffer containing human readable text for the shortcut
FL_EXPORT const char* fl_shortcut_label ( unsigned int  shortcut,
const char **  eom 
)

Get a human-readable string from a shortcut value.

Parameters
[in]shortcutthe integer value containing the ascii character or extended keystroke plus modifiers
[in]eomif this pointer is set, it will receive a pointer to the end of the modifier text
Returns
a pointer to a static buffer containing human readable text for the shortcut
See Also
fl_shortcut_label(unsigned int shortcut)
double fl_transform_dx ( double  x,
double  y 
)
inline

Transforms distance using current transformation matrix.

Parameters
[in]x,ycoordinate
double fl_transform_dy ( double  x,
double  y 
)
inline

Transforms distance using current transformation matrix.

Parameters
[in]x,ycoordinate
double fl_transform_x ( double  x,
double  y 
)
inline

Transforms coordinate using the current transformation matrix.

Parameters
[in]x,ycoordinate
double fl_transform_y ( double  x,
double  y 
)
inline

Transforms coordinate using the current transformation matrix.

Parameters
[in]x,ycoordinate
void fl_transformed_vertex ( double  xf,
double  yf 
)
inline

Adds coordinate pair to the vertex list without further transformations.

Parameters
[in]xf,yftransformed coordinate
void fl_translate ( double  x,
double  y 
)
inline

Concatenates translation transformation onto the current one.

Parameters
[in]x,ytranslation factor in x-direction and y-direction
void fl_vertex ( double  x,
double  y 
)
inline

Adds a single vertex to the current path.

Parameters
[in]x,ycoordinate