chickadee » canvas-draw

Canvas Draw

Description

Bindings to the CanvasDraw graphics library

See the original C library

Author

Thomas Chust

Documentation

See the official API docs.

Here is a condensed version to be usable with the online and offline Chicken documentation.

main Module

Usage

(require-extension canvas-draw)

This module re-exports most bindings from the base, play and primitives modules.

To create canvasses you also have to import bindings from at least one of the context modules: iup, native, gl, clipboard, printer, picture, server, client, pdf, ps, svg, metafile, debug, cgm, dgn, dxf, emf, wmf.

The foreign types and conversion procedures defined in base are not re-exported.

base Module

Usage

(require-extension canvas-draw-base)

Basic CD library support. Initializes the CD library when loaded.

Data Types
(canvas? [v any/c]) -> boolean? procedure

Check whether a value is a CD canvas.

(context? [v any/c]) -> boolean? procedure

Check whether a value is a CD driver context.

(state? [v any/c]) -> boolean? procedure

Check whether a value is a CD canvas state.

Canvas Management
(context-capabilities [context context?]) -> (listof symbol?) procedure

Returns a list of flags describing the capabilities supported by the given context.

The following flags may show up in the list:

  • 'flush
  • 'clear
  • 'play
  • 'y-axis
  • 'clip-area
  • 'clip-polygon
  • 'region
  • 'rectangle
  • 'chord
  • 'image/rgb
  • 'image/rgba
  • 'image/map
  • 'get-image/rgb
  • 'image/server
  • 'background
  • 'background-opacity
  • 'write-mode
  • 'line-style
  • 'line-width
  • 'fprimtives
  • 'hatch
  • 'stipple
  • 'pattern
  • 'font
  • 'font-dimensions
  • 'text-size
  • 'text-orientation
  • 'palette
  • 'line-cap
  • 'line-join
  • 'path
  • 'bezier

[use-context+ (parameter/c any)]

A parameter determining whether calls to make-canvas should use extended variants of the passed context drivers.

Defaults to #f.

(make-canvas [context context?] [data (or/c string? pointer?)]) -> canvas? procedure

Creates a new canvas with the given driver context. The data is context specific and is either a string describing the setup of the new canvas or a pointer to some native data object. e.g., to create a canvas from an iup canvas, use (make-canvas context:iup iup-canvas)

(call-with-canvas [canvas canvas?] [proc (-> canvas? any)]) -> any procedure
(call-with-canvas [context context?] [data (or/c string? pointer?)] [proc (-> canvas? any)]) -> any procedure

Calls the given procedure with the given canvas and makes sure the canvas is synchronized with external resources around the call.

If called in the three argument form, a fresh canvas is created using the given context and is automatically destroyed upon return from the given procedure.

(canvas-context [canvas canvas?]) -> context? procedure

Retrieves the context from a given canvas.

(canvas-simulate! [canvas canvas?] [flags (listof symbol?)]) -> (listof symbol?) procedure

Sets flags determining which operations should be simulated by the given canvas. Returns the previous set of flags.

The following flags may show up in the list:

  • 'line
  • 'rectangle
  • 'box
  • 'arc
  • 'sector
  • 'chord
  • 'polyline
  • 'polygon
  • 'text
  • 'all
  • 'lines
  • 'fills
(canvas-attribute [canvas canvas?] [name (or/c symbol? string?)]) -> (or/c string? #f) procedure

Retrieves the value of a context specific canvas attribute.

(canvas-attribute-set! [canvas canvas?] [name (or/c symbol? string?)] [value (or/c string? #f)]) -> void? procedure

Alternatively (set! (canvas-attribute [canvas canvas?] [name (or/c symbol? string?)]) [value (or/c string? #f)]) -> void?

Sets the value of a context specific canvas attribute.

(canvas-state [canvas canvas?]) -> state? procedure

Extracts a representation of the current state from a canvas.

(canvas-state-set! [canvas canvas?] [state state?]) -> void? procedure

Alternatively (set! (canvas-state [canvas canvas?]) [state state?]) -> void?

Restores the given state of a canvas.

(canvas-clear! [canvas canvas?]) -> void? procedure

Clears a canvas to the background color.

(canvas-flush [canvas canvas?]) -> void? procedure

Flushes all pending drawing operations in a canvas to its backend.

Coordinate System
(canvas-size [canvas canvas?]) -> (values integer? integer? real? real?) procedure

Retrieves the width and height of the given canvas in pixels and millimeters.

(canvas-mm->px [canvas canvas?] [x/mm real?] [y/mm real?]) -> (values integer? integer?) procedure

Converts a position given in millimeters into a pixel position in the given canvas.

(canvas-px->mm [canvas canvas?] [x/px integer?] [y/px integer?]) -> (values real? real?) procedure

Converts a position given in pixels into a physical position in the given canvas.

(canvas-origin [canvas canvas?]) -> (values integer? integer?) procedure

Retrieves the position of the canvas' origin.

(canvas-origin-set! [canvas canvas?] [x integer?] [y integer?]) -> void? procedure

Defines the position of the canvas' origin.

(canvas-transform [canvas canvas?]) -> (or/c (-> real? real? (values integer? integer?)) #f) procedure

Retrieves the active coordinate transformation of the given canvas.

(canvas-transform-set! [canvas canvas?] [proc (or/c (-> real? real? (values integer? integer?)) #f)]) -> void? procedure

Alternatively (set! (canvas-transform [canvas canvas?]) [proc (or/c (-> real? real? (values integer? integer?)) #f)]) -> void?

Defines the active coordinate transformation for the given canvas. The given procedure must represent a linear transformation.

(canvas-transform-compose! [canvas canvas?] [proc (-> real? real? (values integer? integer?))]) -> void? procedure

Modifies the active coordinate transformation for the given canvas by left-multiplication with the given transformation. The given procedure must represent a linear transformation.

(canvas-transform-translate! [canvas canvas?] [dx real?] [dy real?]) -> void? procedure

Modifies the active coordinate transformation for the given canvas applying a translation.

(canvas-transform-scale! [canvas canvas?] [sx real?] [sy real?]) -> void? procedure

Modifies the active coordinate transformation for the given canvas applying a scaling.

(canvas-transform-rotate! [canvas canvas?] [alpha real?]) -> void? procedure

Modifies the active coordinate transformation for the given canvas applying a rotation around the origin.

General Attributes
(canvas-foreground [canvas canvas?]) -> integer? procedure

Retrieves the foreground color of the given canvas.

(canvas-foreground-set! [canvas canvas?] [color integer?]) -> void? procedure

Alternatively (set! (canvas-foreground [canvas canvas?]) [color integer?]) -> void?

Sets the foreground color of the given canvas.

(canvas-background [canvas canvas?]) -> integer? procedure

Retrieves the background color of the given canvas.

(canvas-background-set! [canvas canvas?] [color integer?]) -> void? procedure

Alternatively (set! (canvas-background [canvas canvas?]) [color integer?]) -> void?

Sets the background color of the given canvas.

(canvas-write-mode [canvas canvas?]) -> symbol? procedure

Retrieves the write mode of the given canvas.

The mode may be one of the following symbols:

  • 'replace
  • 'xor
  • 'not-xor
(canvas-write-mode-set! [canvas canvas?] [mode symbol?]) -> void? procedure

Alternatively (set! (canvas-write-mode [canvas canvas?]) [mode symbol?]) -> void?

Sets the write mode of the given canvas.

Clipping
(canvas-clip-mode [canvas canvas?]) -> (or/c symbol? #f) procedure

Retrieves the clipping mode of the given canvas.

The mode may be one of the following values:

  • 'area
  • 'polygon
  • 'region
  • #f

In fact, #t is never returned but may be used when setting the clipping mode.

(canvas-clip-mode-set! [canvas canvas?] [mode (or/c symbol? #f)]) -> void? procedure

(set! (canvas-clip-mode [canvas canvas?]) [mode (or/c symbol? #f)]) -> void?

Sets the clipping mode of the given canvas.

(canvas-clip-area [canvas canvas?]) -> (values real? real? real? real?) procedure

Retrieves the current rectangular clipping area of the given canvas.

(canvas-clip-area-set! [canvas canvas?] [x0 double?] [x1 double?] [y0 double?] [y1 double?]) -> void? procedure

Sets the current rectangular clipping area of the given canvas.

The base module only exports checking type conversion functions instead of foreign types since the latter cannot be exported. To define the types canvas, nonnull-canvas, context, nonnull-context, state and nonnull-state in your own module, include the file "canvas-draw-types.scm".

((canvas->pointer [nonnull? any/c]) [canvas (or/c canvas? #f)]) -> (or/c pointer? #f) procedure

Checking conversion from canvasses to pointers.

Not re-exported from the main module.

((pointer->canvas [nonnull? any/c]) [canvas (or/c pointer? #f)]) -> (or/c canvas? #f) procedure

Checking conversion from pointers to canvasses.

Not re-exported from the main module.

((context->pointer [nonnull? any/c]) [context (or/c context? #f)]) -> (or/c pointer? #f) procedure

Checking conversion from contexts to pointers.

Not re-exported from the main module.

((pointer->context [nonnull? any/c]) [context (or/c pointer? #f)]) -> (or/c context? #f) procedure

Checking conversion from pointers to contexts.

Not re-exported from the main module.

((state->pointer [nonnull? any/c]) [state (or/c state? #f)]) -> (or/c pointer? #f) procedure

Checking conversion from states to pointers.

Not re-exported from the main module.

((pointer->state [nonnull? any/c]) [state (or/c pointer? #f)]) -> (or/c state? #f) procedure

Checking conversion from pointers to states.

Not re-exported from the main module.

play Module

Usage

(require-extension canvas-draw-play)

Replay functionality.

Context Content Replay
(canvas-play! [canvas canvas?] [context context?] [x0 integer?] [x1 integer?] [y0 integer?] [y1 integer?] [data (or/c string? pointer?)]) procedure

-> void?

Replays the drawing contained in the context withe the given data in the given canvas.

primitives Module

Usage

(require-extension canvas-draw-primitives)

Drawing primitives.

Points
(canvas-pixel! [canvas canvas?] [x integer?] [y integer?] [color integer? (canvas-foreground canvas)]) -> void? procedure

Draws a single pixel of the given color on the given canvas.

(canvas-mark! [canvas canvas?] [x integer?] [y integer?]) -> void? procedure

Draws a marker symbol on the given canvas.

(canvas-mark-type [canvas canvas?]) -> symbol? procedure

Retrieves the current marker symbol type for the given canvas. Possible values are

  • '+ or 'plus
  • '* or 'star
  • '0 or 'circle
  • 'O or 'hollow-circle
  • 'X or 'x
  • 'box
  • 'hollow-box
  • 'diamond
  • 'hollow-diamond
(canvas-mark-type-set! [canvas canvas?] [mark-type symbol?]) -> void? procedure

Alternatively (set! (canvas-mark-type [canvas canvas?]) [mark-type symbol?]) -> void?

Sets the current marker symbol type for the given canvas.

(canvas-mark-size [canvas canvas?]) -> integer? procedure

Retrieves the current marker symbol size for the given canvas.

(canvas-mark-size-set! [canvas canvas?] [size integer?]) -> void? procedure

Alternatively (set! (canvas-mark-size [canvas canvas?]) [size integer?]) -> void?

Sets the current marker symbol size for the given canvas.

Lines
(canvas-line! [canvas canvas?] [x0 real?] [y0 real?] [x1 real?] [y1 real?]) -> void? procedure

Draws a line on the given canvas.

(canvas-rectangle! [canvas canvas?] [x0 real?] [x1 real?] [y0 real?] [y1 real?]) -> void? procedure

Draws a hollow rectangle on the given canvas.

(canvas-arc! [canvas canvas?] [x real?] [y real?] [width real?] [height real?] [alpha0 real?] [alpha1 real?]) -> void? procedure

Draws a hollow ellipsis segment on the given canvas.

(canvas-line-style [canvas canvas?]) -> symbol? procedure

Retrieves the current line style of the given canvas. Possible values are

  • 'continuous
  • 'dashed
  • 'dotted
  • 'dash-dotted
  • 'dash-dot-dotted
  • 'custom
(canvas-line-style-set! [canvas canvas?] [line-style (or/c symbol? list?)]) -> symbol? procedure

Alternatively (set! (canvas-line-style [canvas canvas?]) [line-style (or/c symbol? list?)]) -> symbol?

Sets the current line style of the given canvas and returns the previous value.

In addition to the possible return values of canvas-line-style a custom line-style can be fully specified using the form (list 'custom [len integer?] ...).

(canvas-line-width [canvas canvas?]) -> integer? procedure

Retrieves the current line width of the given canvas.

(canvas-line-width-set! [canvas canvas?] [line-width integer?]) -> integer? procedure

Alternatively (set! (canvas-line-width [canvas canvas?]) [line-width integer?]) -> integer?

Sets the current line width of the given canvas and returns the previous value.

(canvas-line-join [canvas canvas?]) -> symbol? procedure

Retrieves the current line join style of the given canvas. Possible values are

  • 'miter
  • 'bevel
  • 'round
(canvas-line-join-set! [canvas canvas?] [line-join symbol?]) -> symbol? procedure

Alternatively (set! (canvas-line-join [canvas canvas?]) [line-join symbol?]) -> symbol?

Sets the current line join style of the given canvas and returns the previous value.

(canvas-line-cap [canvas canvas?]) -> symbol? procedure

Retrieves the current line cap style of the given canvas.

  • 'flat
  • 'square
  • 'round
(canvas-line-cap-set! [canvas canvas?] [line-cap symbol?]) -> symbol? procedure

Alternatively (set! (canvas-line-cap [canvas canvas?]) [line-cap symbol?]) -> symbol?

Sets the current line cap style of the given canvas and returns the previous value.

Filled Areas
(canvas-box! [canvas canvas?] [x0 real?] [x1 real?] [y0 real?] [y1 real?]) -> void? procedure

Draws a filled rectangle on the given canvas.

(canvas-sector! [canvas canvas?] [x real?] [y real?] [width real?] [height real?] [alpha0 real?] [alpha1 real?]) -> void? procedure

Draws a filled ellipsis sector on the given canvas.

(canvas-chord! [canvas canvas?] [x real?] [y real?] [width real?] [height real?] [alpha0 real?] [alpha1 real?]) -> void? procedure

Draws a filled ellipsis arc on the given canvas.

(canvas-background-opacity [canvas canvas?]) -> symbol? procedure

Retrieves the current background opacity of the given canvas. Possible values are

  • 'transparent
  • 'opaque
(canvas-background-opacity-set! [canvas canvas?] [background-opacity symbol?]) -> symbol? procedure

(set! (canvas-background-opacity-set! [canvas canvas?]) [background-opacity symbol?]) -> symbol?

Sets the current background opacity of the given canvas and returns the previous value.

(canvas-fill-mode [canvas canvas?]) -> symbol? procedure

Retrieves the current polygon fill mode of the given canvas. Possible values are

  • 'even-odd
  • 'winding
(canvas-fill-mode-set! [canvas canvas?] [fill-mode symbol?]) -> symbol? procedure

Alternatively (set! (canvas-fill-mode [canvas canvas?]) [fill-mode symbol?]) -> symbol?

Sets the current polygon fill mode of the given canvas and returns the previous value.

(canvas-interior-style [canvas canvas?]) -> (or/c symbol? list?) procedure

Retrieves the current interior style of the given canvas. Possible values are

  • 'solid
  • '(hatch horizontal)
  • '(hatch vertical)
  • '(hatch forward-diagonal)
  • '(hatch backward-diagonal)
  • '(hatch cross)
  • '(hatch diagonal-cross)
  • (list 'stipple [width integer?] [height integer?] [data blob?])
  • (list 'pattern/rgb [width integer?] [height integer?] [data blob?])
  • (list 'pattern/rgba [width integer?] [height integer?] [data blob?])
  • #f
(canvas-interior-style-set! [canvas canvas?] [interior-style (or/c symbol? list?)]) -> void? procedure

Alternatively (set! (canvas-interior-style [canvas canvas?]) [interior-style (or/c symbol? list?)]) -> void?

Sets the current interior style of the given canvas and returns the previous value.

Text
(canvas-text! [canvas canvas?] [x real?] [y real?] [text string?]) -> void? procedure

Draws a string of text on the given canvas.

(canvas-font [canvas canvas?]) -> string? procedure

Retrieves the current font of the given canvas.

(canvas-font-set! [canvas canvas?] [font string?]) -> void? procedure

Alternatively (set! (canvas-font [canvas canvas?]) [font string?]) -> void?

Sets the current font of the given canvas and returns the previous value.

(canvas-text-alignment [canvas canvas?]) -> symbol? procedure

Retrieves the current text alignment of the given canvas. Possible values are

  • 'north
  • 'south
  • 'east
  • 'west
  • 'north-east
  • 'north-west
  • 'south-east
  • 'south-west
  • 'center
  • 'base-left
  • 'base-center
  • 'base-right
(canvas-text-alignment-set! [canvas canvas?] [text-alignment symbol?]) -> void? procedure

Alternatively (set! (canvas-text-alignment [canvas canvas?]) [text-alignment symbol?]) -> void?

Sets the current text alignment of the given canvas and returns the previous value.

(canvas-text-orientation [canvas canvas?]) -> real?

Retrieves the current text orientation of the given canvas.

(canvas-text-orientation-set! [canvas canvas?] [orientation real?]) -> void? procedure

Alternatively (set! (canvas-text-orientation [canvas canvas?]) [orientation real?]) -> void?

Sets the current text orientation of the given canvas and returns the previous value.

(canvas-font-dimensions [canvas canvas?]) -> (values integer? integer? integer? integer?) procedure

Returns the maximum width, height, ascent and descent of the current font of the given canvas.

(canvas-text-size [canvas canvas?] [text string?]) -> (values integer? integer?) procedure

Computes the width and height of the given text when drawn on the given canvas.

(canvas-text-box [canvas canvas?] [x integer?] [y integer?] [text string?]) -> (values integer? integer? integer? integer?) procedure

Computes the bounding box of the given text when drawn on the given canvas. Returns the minimum and maximum x and y coordinates.

Vertices
(call-with-canvas-in-mode [canvas canvas?] [mode symbol?] [proc (-> canvas? any)]) -> any procedure

Calls proc with the given canvas and ready to receive vertex data in the given mode. Returns whatever proc returns.

Possible modes are

  • 'open-lines
  • 'closed-lines
  • 'fill
  • 'clip
  • 'bezier
  • 'region
  • 'path
(canvas-path-set! [canvas canvas?] [path-action symbol?]) -> void? procedure

Configures the action between sequences of vertex data sent to the given canvas. Possible actions are

  • 'new
  • 'move-to
  • 'line-to
  • 'arc
  • 'curve-to
  • 'close
  • 'fill
  • 'stroke
  • 'fill+stroke
  • 'clip
(canvas-vertex! [canvas canvas?] [x real?] [y real?]) -> void? procedure

Sends a vertex to the given canvas.

License

BSD license

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