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1.17 class bitmap

A bitmap is a graphical that displays an image. Most of the behaviour to manipulate the pixels of a bitmaps thus can be found with class image.

Bitmaps (images) come in two flavours. If image<-kind = bitmap, the elements of the bitmap are regarded as booleans: boolean true (@on) is painted in the graphical<-colour of the bitmap and boolean false (@off) in the current background. If image<-kind is pixmap each individual pixel represents a colour.

Transparency comes from the image rather than from the bitmap: pixels that the image's alpha channel calls transparent are not painted, and the bitmap lets whatever is behind it show through. Use image->has_alpha to test whether an image has such pixels. Older versions had a bitmap<->transparent to say that the @off pixels of a bitmap-kind image should not be painted, and took it as the second argument of bitmap->initialise; both are gone.

A bitmap can show an animation: each frame of the animation is in turn its bitmap<-image. bitmap->play plays the animation and bitmap->frame shows a frame: 

new(BM, bitmap(animation('spinner.png'))),
send(BM, play).

Bugs:

Stencils are not implemented.

There are no means for scaling bitmaps: bitmap->geometry moves a bitmap but ignores the requested size. Scale the image instead, with image<-scale.

See also
- class image
- class animation
- bitmap-status

1.17.1 Instance variables

bitmap <- image: image
The image that contains the actual pixels. If the bitmap shows an bitmap<-animation, this is the frame shown.
bitmap <- animation: animation*
The animation whose frames are shown, or @nil.
bitmap <- frame: int
The index of the frame of bitmap<-animation shown, where the first frame is 1. 0 if there is no animation.
bitmap <- loops: int
How many times the animation was played to its end since bitmap->play.

1.17.2 Send methods

bitmap ->geometry: x=[int], y=[int], width=[int], height=[int]
Just moves the bitmap. In the current implementation bitmaps cannot be scaled.
bitmap ->image: image
Associate an image with a bitmap. Sets the width and height of the bitmap to the width and height of the image. If the image has bitmap<->access both and bitmap<->bitmap @nil, the bitmap<->bitmap variable of the image is filled with the bitmap. Subsequent changes to the image are forwarded to the bitmap.
See also
image-bitmap
bitmap ->initialise: image=[image|animation]
Create a bitmap for the given image object. The bitmap will be given the same graphical<-width and graphical<-height as the image. If the argument is an animation, the bitmap shows its first frame (see bitmap->animation).

Note that images are automatically converted from names (see image->initialise). Thus, the following displays XPCE's icon on a picture window: 

?- send(new(P, picture), open),
   send(P, display,
            bitmap('16x16/pce.xpm'), point(25, 25)).

By default, image objects are cached (i.e. remain in memory). If you have many or large ones, please study image->initialise and image->load.

bitmap ->animation: animation*
Show the frames of an animation. This stops playing the previous animation and shows the first frame. @nil leaves the bitmap showing the current frame as an ordinary image.
bitmap ->frame: int
Show the frame of bitmap<-animation at this index, where the first frame is 1. Fails if there is no such frame. If the animation is playing, it continues from this frame.
bitmap ->play:
Play bitmap<-animation from the current frame: show each frame for its animation<-delays and continue with the next. After the last frame it starts again, until it has played animation<-loop_count times; it then stops at the last frame. Fails if there is no animation or it has only one frame.
bitmap ->stop:
Stop playing. The current frame stays.
bitmap ->load: file, path=[char_array]
Load file in the associated image. XPCE searches for the file in the path described by the last argument. The default path is image.path.

Backward compatibility only. New code should manipulate the image directly.

Defaults: The default search path is determined by the resource bitmap.path. Its system defined value is 

.:~/lib/bitmaps:$PCEHOME/bitmaps:/usr/include/X11/bitmaps

Diagnostics: Fails silently on bad format or non-existing file.

See also
image->save

1.17.3 Get methods

bitmap <-contains: -> chain
Return a new chain object holding bitmap<-image.
bitmap <-playing: -> bool
@on while the animation plays.
bitmap <-convert: name -> bitmap
bitmap<-convert converts text of the form