Class SpriteSheetBuilder
The SpriteSheetBuilder allows you to generate sprite sheets at run time from any display object. This can allow
you to maintain your assets as vector graphics (for low file size), and render them at run time as sprite sheets
for better performance.
Sprite sheets can be built either synchronously, or asynchronously, so that large sprite sheets can be generated
without locking the UI.
Note that the "images" used in the generated sprite sheet are actually canvas elements, and that they will be sized
to the nearest power of 2 up to the value of maxWidth or maxHeight.
Properties
The scale to apply when drawing all frames to the sprite sheet. This is multiplied against any scale specified
in the addFrame call. This can be used, for example, to generate a sprite sheet at run time that is tailored to
the a specific device resolution (ex. tablet vs mobile).
Default Value: 1
The maximum height for the images (not individual frames) in the generated sprite sheet. It is recommended to use
a power of 2 for this value (ex. 1024, 2048, 4096). If the frames cannot all fit within the max dimensions, then
additional images will be created as needed.
Default Value: 2048
The maximum width for the images (not individual frames) in the generated sprite sheet. It is recommended to use
a power of 2 for this value (ex. 1024, 2048, 4096). If the frames cannot all fit within the max dimensions, then
additional images will be created as needed.
Default Value: 2048
The padding to use between frames. This is helpful to preserve antialiasing on drawn vector content.
Default Value: 1
The sprite sheet that was generated. This will be null before a build is completed successfully.
Methods
protected
void
_endBuild
(
)
protected
Number
_fillRow
(
)
- Returns:
Number
- The width & height of the row.
protected
void
_startBuild
(
)
Number
addFrame
(
source
,
sourceRect
,
scale
,
setupFunction
,
setupParams
,
setupScope
)
Adds a frame to the sprite sheet. Note that the frame will not be drawn until you call build. The optional
setup params allow you to have a function run immediately before the draw occurs. For example, this allows you to
add a single source multiple times, but manipulate it or it's children to change it to generate different frames.
Note that the source's transformations (x,y,scale,rotate,alpha) will be ignored, except for regX/Y. To apply
transforms to a source object and have them captured in the sprite sheet, simply place it into a Container
and pass in the Container as the source.
- Parameters:
-
source
<DisplayObject>
The source display object to draw as the frame.
-
sourceRect
<Rectangle>
Optional. A rectangle defining the portion of the source to draw to the frame. If
not specified, it will look for a getBounds method, bounds property, or nominalBounds property on the source to use.
If one is not found, the frame will be skipped.
-
scale
<Number>
Optional. The scale to draw this frame at. Default is 1.
-
setupFunction
<Function>
Optional. A function to call immediately before drawing this frame.
-
setupParams
<Array>
Optional. Parameters to pass to the setup function.
-
setupScope
<Object>
Optional. The scope to call the setupFunction in.
- Returns:
Number
- The index of the frame that was just added, or null if a sourceRect could not be determined.
void
addMovieClip
(
source
,
sourceRect
,
scale
)
This will take a MovieClip, and add its frames and labels to this builder. Labels will be added as an animation
running from the label index to the next label. For example, if there is a label named "foo" at frame 0 and a label
named "bar" at frame 10, in a MovieClip with 15 frames, it will add an animation named "foo" that runs from frame
index 0 to 9, and an animation named "bar" that runs from frame index 10 to 14.
Note that this will iterate through the full MovieClip with actionsEnabled set to false, ending on the last frame.
- Parameters:
-
source
<MovieClip>
The source MovieClip to add to the sprite sheet.
-
sourceRect
<Rectangle>
Optional. A rectangle defining the portion of the source to draw to the frame. If
not specified, it will look for a getBounds method, frameBounds array, bounds property, or nominalBounds property
on the source to use. If one is not found, the MovieClip will be skipped.
-
scale
<Number>
Optional. The scale to draw the movie clip at. Default is 1.
- Returns:
void
build
(
)
Builds a SpriteSheet instance based on the current frames.
void
buildAsync
(
callback
,
timeSlice
)
Asynchronously builds a SpriteSheet instance based on the current frames. It will run 20 times per second, using
an amount of time defined by timeSlice. When it is complete it will call the specified callback.
- Parameters:
-
callback
<Function>
Optional. The function to call when the build operation completes. It will be called
with a single parameter providing a reference back to the builder.
-
timeSlice
<Number>
Optional. A number from 0.01 to 1 that indicates what percentage of time the builder can use. This can be
thought of as the number of seconds per second the builder will use. For example, with a timeSlice value of 0.3,
the builder will run 20 times per second, using approximately 15ms per build (30% of available time, or 0.3s per second).
Defaults to 0.3.
- Returns:
void
void
clone
(
)
SpriteSheetBuilder instances cannot be cloned.
protected
void
initialize
(
)
Initialization method.
void
stopAsync
(
)
Stops the current asynchronous build.
String
toString
(
)
Returns a string representation of this object.
- Returns:
String
- a string representation of the instance.