android.graphics.Picture
A picture records drawing calls (via the canvas returned by beginRecording)
and can then play them back (via picture.draw(canvas) or canvas.drawPicture).
The picture's contents can also be written to a stream, and then later
restored to a new picture (via writeToStream / createFromStream). For most
content (esp. text, lines, rectangles), drawing a sequence from a picture can
be faster than the equivalent API calls, since the picture performs its
playback without incurring any java-call overhead.
Summary
Public Constructors
Public Methods
Protected Methods
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
Details
Public Constructors
public
Picture(Picture src)
Create a picture by making a copy of what has already been recorded in
src. The contents of src are unchanged, and if src changes later, those
changes will not be reflected in this picture.
Public Methods
public
Canvas
beginRecording(int width, int height)
To record a picture, call beginRecording() and then draw into the Canvas
that is returned. Nothing we appear on screen, but all of the draw
commands (e.g. drawRect(...)) will be recorded. To stop recording, call
endRecording(). At this point the Canvas that was returned must no longer
be referenced, and nothing should be drawn into it.
public
static
Picture
createFromStream(InputStream stream)
Create a new picture (already recorded) from the data in the stream. This
data was generated by a previous call to writeToStream().
public
void
draw(Canvas canvas)
Draw this picture on the canvas. The picture may have the side effect
of changing the matrix and clip of the canvas.
Parameters
canvas
| The picture is drawn to this canvas
|
public
void
endRecording()
Call endRecording when the picture is built. After this call, the picture
may be drawn, but the canvas that was returned by beginRecording must not
be referenced anymore. This is automatically called if Picture.draw() or
Canvas.drawPicture() is called.
public
int
getHeight()
Get the height of the picture as passed to beginRecording. This
does not reflect (per se) the content of the picture.
public
int
getWidth()
Get the width of the picture as passed to beginRecording. This
does not reflect (per se) the content of the picture.
public
void
writeToStream(OutputStream stream)
Write the picture contents to a stream. The data can be used to recreate
the picture in this or another process by calling createFromStream.
Protected Methods
protected
void
finalize()
Called by the virtual machine when there are no longer any (non-weak)
references to the receiver. Subclasses can use this facility to guarantee
that any associated resources are cleaned up before the receiver is
garbage collected. Uncaught exceptions which are thrown during the
running of the method cause it to terminate immediately, but are
otherwise ignored.
Note: The virtual machine assumes that the implementation in class Object
is empty.