| Package | com.greensock |
| Class | public class BlitMask |
| Inheritance | BlitMask  flash.display.Sprite |
bitmapMode can be turned off to restore interactivity in the DisplayObject
whenever you want. When scrolling very large images or text blocks, a BlitMask can greatly improve
performance, especially on mobile devices that have weaker processors. update() the BlitMask and it syncs the pixels.
The BlitMask basically sits on top of the DisplayObject in the display list and you can
move it independently too if you want.scrollX and scrollY properties to move the
target DisplayObject inside the masked area. For example, to scroll from top to bottom over
the course of 2 seconds, simply do: myBlitMask.scrollY = 0;
TweenLite.to(myBlitMask, 2, {scrollY:1}); bitmapMode of course), as though the BlitMask is
filled with a grid of bitmap copies of the target.smoothing to false or
for maximum quality, set it to truebitmapMode to get either maximum performance or interactivity
in the target DisplayObject anytime. (some other solutions out there are only viable for
non-interactive bitmap content)
import com.greensock.*;
//create a 200x200 BlitMask positioned at x:20, y:50 to mask our "mc" object and turn smoothing on:
var blitMask:BlitMask = new BlitMask(mc, 20, 50, 200, 200, true);
//position mc at the top left of the BlitMask using the scrollX and scrollY properties
blitMask.scrollX = 0;
blitMask.scrollY = 0;
//tween the scrollY to make mc scroll to the bottom over the course of 3 seconds and then turn off bitmapMode so that mc becomes interactive:
TweenLite.to(blitMask, 3, {scrollY:1, onComplete:blitMask.disableBitmapMode});
//or simply position mc manually and then call update() to sync the display:
mc.x = 350;
blitMask.update();
target is being scaled or rotated
because it forces a flushing and recapture of the internal bitmap. BlitMasks are MUCH better when you are
simply changing x/y properties (scrolling) because it can reuse the same cached bitmap over and over.| Property | Defined by | ||
|---|---|---|---|
| autoUpdate : Boolean
If
true, the BlitMask will automatically watch the target to see if
its position/scale/rotation has changed on each frame (while bitmapMode is true)
and if so, it will update() to make sure the BlitMask always stays synced with the target. | BlitMask | ||
| bitmapMode : Boolean
When
true, the BlitMask optimizes itself for performance by setting the target's
visible property to false (greatly reducing the load on Flash's graphics rendering
routines) and uses its internally cached bitmap version of the target to redraw only the necessary
pixels inside the masked area. | BlitMask | ||
| fillColor : uint
The ARGB hexadecimal color that should fill the empty areas of the BlitMask.
| BlitMask | ||
| height : Number Height of the BlitMask
| BlitMask | ||
| rotation : Number [write-only] Rotation of the BlitMask (always 0 because BlitMasks can't be rotated!)
| BlitMask | ||
| scaleX : Number scaleX (warning: altering the scaleX won't actually change its value - instead, it affects the
width property accordingly) | BlitMask | ||
| scaleY : Number scaleY (warning: altering the scaleY won't actually change its value - instead, it affects the
height property accordingly) | BlitMask | ||
| scrollX : Number
Typically a value between 0 and 1 indicating the
target's position in relation to the BlitMask
on the x-axis where 0 is at the beginning, 0.5 is scrolled to exactly the halfway point, and 1 is scrolled
all the way. | BlitMask | ||
| scrollY : Number
Typically a value between 0 and 1 indicating the
target's position in relation to the BlitMask
on the y-axis where 0 is at the beginning, 0.5 is scrolled to exactly the halfway point, and 1 is scrolled
all the way. | BlitMask | ||
| smoothing : Boolean
If
false (the default), the bitmap (and the BlitMask's x/y coordinates)
will be rendered only on whole pixels which is faster in terms of processing. | BlitMask | ||
| target : DisplayObject The target DisplayObject that the BlitMask should mask
| BlitMask | ||
| width : Number Width of the BlitMask
| BlitMask | ||
| wrap : Boolean
If
true, the bitmap will be wrapped around to the opposite side when it scrolls off
one of the edges (only in bitmapMode of course), like the BlitMask is filled with a
grid of bitmap copies of the target. | BlitMask | ||
| wrapOffsetX : Number
When
wrap is true, wrapOffsetX controls how many pixels
along the x-axis the wrapped copies of the bitmap are spaced. | BlitMask | ||
| wrapOffsetY : Number
When
wrap is true, wrapOffsetY controls how many pixels
along the y-axis the wrapped copies of the bitmap are spaced. | BlitMask | ||
| x : Number x coordinate of the BlitMask (it will automatically be forced to whole pixel values if
smoothing is false). | BlitMask | ||
| y : Number y coordinate of the BlitMask (it will automatically be forced to whole pixel values if
smoothing is false). | BlitMask | ||
| Method | Defined by | ||
|---|---|---|---|
|
BlitMask(target:DisplayObject, x:Number = 0, y:Number = 0, width:Number = 100, height:Number = 100, smoothing:Boolean = false, autoUpdate:Boolean = false, fillColor:uint = 0x00000000, wrap:Boolean = false)
Constructor
| BlitMask | ||
|
disableBitmapMode(event:Event = null):void
Identical to setting
bitmapMode = false but this method simplifies adding that
functionality to tweens or using it as an event handler. | BlitMask | ||
|
dispose():void
Disposes of the BlitMask and its internal BitmapData instances, releasing them for garbage collection.
| BlitMask | ||
|
enableBitmapMode(event:Event = null):void
Identical to setting
bitmapMode = true but this method simplifies adding that
functionality to tweens or using it as an event handler. | BlitMask | ||
|
normalizePosition():void
Repositions the
target so that it is visible within the BlitMask, as though wrap
was enabled (this method is called automatically when bitmapMode is disabled while wrap
is true). | BlitMask | ||
|
setSize(width:Number, height:Number):void
Sets the width and height of the BlitMask.
| BlitMask | ||
|
update(event:Event = null, forceRecaptureBitmap:Boolean = false):void
Updates the BlitMask's internal bitmap to reflect the
target's current position/scale/rotation. | BlitMask | ||
| autoUpdate | property |
autoUpdate:Boolean [read-write]
If true, the BlitMask will automatically watch the target to see if
its position/scale/rotation has changed on each frame (while bitmapMode is true)
and if so, it will update() to make sure the BlitMask always stays synced with the target.
This is the easiest way to use BlitMask but it is slightly less efficient than manually calling update()
whenever you need to. Keep in mind that if you're tweening with TweenLite or TweenMax, you can simply set
its onUpdate to the BlitMask's update() method to keep things synced.
Like onUpdate:myBlitMask.update.
public function get autoUpdate():Boolean
public function set autoUpdate(value:Boolean):void
| bitmapMode | property |
bitmapMode:Boolean [read-write]
When true, the BlitMask optimizes itself for performance by setting the target's
visible property to false (greatly reducing the load on Flash's graphics rendering
routines) and uses its internally cached bitmap version of the target to redraw only the necessary
pixels inside the masked area. Since only a bitmap version of the target is shown while in bitmapMode,
the target won't be interactive. So if you have buttons and other objects that normally react to
MouseEvents, they won't while in bitmapMode. If you need the interactivity, simply set bitmapMode
to false and then it will turn the target's visible property back to true
and its mask property to the BlitMask itself. Typically it is best to turn bitmapMode on at least when you're
animating the target or the BlitMask itself, and then when the tween/animation is done and you need
interactivity, set bitmapMode back to false. For example:
var bm:BlitMask = new BlitMask(mc, 0, 0, 300, 200, true);
TweenLite.to(mc, 3, {x:200, onUpdate:bm.update, onComplete:completeHandler});
function completeHandler():void {
bm.bitmapMode = false;
}
public function get bitmapMode():Boolean
public function set bitmapMode(value:Boolean):void
See also
| fillColor | property |
fillColor:uint [read-write]
The ARGB hexadecimal color that should fill the empty areas of the BlitMask. By default,
it is transparent (0x00000000). If you wanted a red color, for example, it would be
0xFFFF0000.
public function get fillColor():uint
public function set fillColor(value:uint):void
| height | property |
height:Number [read-write]Height of the BlitMask
Implementation public function get height():Number
public function set height(value:Number):void
| rotation | property |
rotation:Number [write-only]Rotation of the BlitMask (always 0 because BlitMasks can't be rotated!)
Implementation public function set rotation(value:Number):void
| scaleX | property |
scaleX:Number [read-write] scaleX (warning: altering the scaleX won't actually change its value - instead, it affects the width property accordingly)
public function get scaleX():Number
public function set scaleX(value:Number):void
| scaleY | property |
scaleY:Number [read-write] scaleY (warning: altering the scaleY won't actually change its value - instead, it affects the height property accordingly)
public function get scaleY():Number
public function set scaleY(value:Number):void
| scrollX | property |
scrollX:Number [read-write]
Typically a value between 0 and 1 indicating the target's position in relation to the BlitMask
on the x-axis where 0 is at the beginning, 0.5 is scrolled to exactly the halfway point, and 1 is scrolled
all the way. This makes it very easy to animate the scroll. For example, to scroll from beginning to end
over 5 seconds, you could do:
myBlitMask.scrollX = 0;
TweenLite.to(myBlitMask, 5, {scrollX:1});
public function get scrollX():Number
public function set scrollX(value:Number):void
See also
| scrollY | property |
scrollY:Number [read-write]
Typically a value between 0 and 1 indicating the target's position in relation to the BlitMask
on the y-axis where 0 is at the beginning, 0.5 is scrolled to exactly the halfway point, and 1 is scrolled
all the way. This makes it very easy to animate the scroll. For example, to scroll from beginning to end
over 5 seconds, you could do:
myBlitMask.scrollY = 0;
TweenLite.to(myBlitMask, 5, {scrollY:1});
public function get scrollY():Number
public function set scrollY(value:Number):void
See also
| smoothing | property |
smoothing:Boolean [read-write]
If false (the default), the bitmap (and the BlitMask's x/y coordinates)
will be rendered only on whole pixels which is faster in terms of processing. However,
for the best quality and smoothest animation, set smoothing to true.
public function get smoothing():Boolean
public function set smoothing(value:Boolean):void
| target | property |
target:DisplayObject [read-write]The target DisplayObject that the BlitMask should mask
Implementation public function get target():DisplayObject
public function set target(value:DisplayObject):void
| width | property |
width:Number [read-write]Width of the BlitMask
Implementation public function get width():Number
public function set width(value:Number):void
| wrap | property |
wrap:Boolean [read-write]
If true, the bitmap will be wrapped around to the opposite side when it scrolls off
one of the edges (only in bitmapMode of course), like the BlitMask is filled with a
grid of bitmap copies of the target. Use the wrapOffsetX and wrapOffsetY
properties to affect how far apart the copies are from each other. You can reposition the
target anywhere and BlitMask will align the copies accordingly.
public function get wrap():Boolean
public function set wrap(value:Boolean):void
See also
| wrapOffsetX | property |
wrapOffsetX:Number [read-write]
When wrap is true, wrapOffsetX controls how many pixels
along the x-axis the wrapped copies of the bitmap are spaced. It is essentially the gap between
the copies (although you can use a negative value or 0 to avoid any gap).
public function get wrapOffsetX():Number
public function set wrapOffsetX(value:Number):void
See also
| wrapOffsetY | property |
wrapOffsetY:Number [read-write]
When wrap is true, wrapOffsetY controls how many pixels
along the y-axis the wrapped copies of the bitmap are spaced. It is essentially the gap between
the copies (although you can use a negative value or 0 to avoid any gap).
public function get wrapOffsetY():Number
public function set wrapOffsetY(value:Number):void
See also
| x | property |
x:Number [read-write] x coordinate of the BlitMask (it will automatically be forced to whole pixel values if smoothing is false).
public function get x():Number
public function set x(value:Number):void
| y | property |
y:Number [read-write] y coordinate of the BlitMask (it will automatically be forced to whole pixel values if smoothing is false).
public function get y():Number
public function set y(value:Number):void
| BlitMask | () | constructor |
public function BlitMask(target:DisplayObject, x:Number = 0, y:Number = 0, width:Number = 100, height:Number = 100, smoothing:Boolean = false, autoUpdate:Boolean = false, fillColor:uint = 0x00000000, wrap:Boolean = false)Constructor
Parameterstarget:DisplayObject — The DisplayObject that will be masked by the BlitMask
|
|
x:Number (default = 0)smoothing is false, the x coordinate will be rounded to the closest integer.
|
|
y:Number (default = 0) |
|
width:Number (default = 100) |
|
height:Number (default = 100) |
|
smoothing:Boolean (default = false)false (the default), the bitmap (and the BlitMask's x/y coordinates) will be rendered only on whole pixels which is faster in terms of processing. However, for the best quality and smoothest animation, set smoothing to true.
|
|
autoUpdate:Boolean (default = false)true, the BlitMask will automatically watch the target to see if its position/scale/rotation has changed on each frame (while bitmapMode is true) and if so, it will update() to make sure the BlitMask always stays synced with the target. This is the easiest way to use BlitMask but it is slightly less efficient than manually calling update() whenever you need to. Keep in mind that if you're tweening with TweenLite or TweenMax, you can simply set its onUpdate to the BlitMask's update() method to keep things synced. Like onUpdate:myBlitMask.update.
|
|
fillColor:uint (default = 0x00000000)0xFFFF0000.
|
|
wrap:Boolean (default = false)true, the bitmap will be wrapped around to the opposite side when it scrolls off one of the edges (only in bitmapMode of course), like the BlitMask is filled with a grid of bitmap copies of the target. Use the wrapOffsetX and wrapOffsetY properties to affect how far apart the copies are from each other.
|
| disableBitmapMode | () | method |
public function disableBitmapMode(event:Event = null):void
Identical to setting bitmapMode = false but this method simplifies adding that
functionality to tweens or using it as an event handler. For example, to enable bitmapMode at
the beginning of a tween and then disable it when the tween completes, you could do:
TweenLite.to(mc, 3, {x:400, onStart:myBlitMask.enableBitmapMode, onUpdate:myBlitMask.update, onComplete:myBlitMask.disableBitmapMode});
event:Event (default = null)addEventListener(MouseEvent.CLICK, myBlitMask.disableBitmapMode).
|
See also
| dispose | () | method |
public function dispose():voidDisposes of the BlitMask and its internal BitmapData instances, releasing them for garbage collection.
| enableBitmapMode | () | method |
public function enableBitmapMode(event:Event = null):void
Identical to setting bitmapMode = true but this method simplifies adding that
functionality to tweens or using it as an event handler. For example, to enable bitmapMode at
the beginning of a tween and then disable it when the tween completes, you could do:
TweenLite.to(mc, 3, {x:400, onStart:myBlitMask.enableBitmapMode, onUpdate:myBlitMask.update, onComplete:myBlitMask.disableBitmapMode});
event:Event (default = null)addEventListener(MouseEvent.CLICK, myBlitMask.enableBitmapMode).
|
See also
| normalizePosition | () | method |
public function normalizePosition():void
Repositions the target so that it is visible within the BlitMask, as though wrap
was enabled (this method is called automatically when bitmapMode is disabled while wrap
is true). For example, if you tween the target way off the edge of the BlitMask and
have wrap enabled, it will appear to come back in from the other side even though the raw coordinates
of the target would indicate that it is outside the BlitMask. If you want to force the coordinates to normalize
so that they reflect that wrapped position, simply call normalizePosition(). It will automatically
choose the coordinates that would maximize the visible portion of the target if a seam is currently showing.
| setSize | () | method |
public function setSize(width:Number, height:Number):void
Sets the width and height of the BlitMask.
Keep in mind that a BlitMask should not be rotated or scaled.
You can also directly set the width or height properties.
width:Number — The width of the BlitMask
|
|
height:Number — The height of the BlitMask
|
See also
| update | () | method |
public function update(event:Event = null, forceRecaptureBitmap:Boolean = false):void
Updates the BlitMask's internal bitmap to reflect the target's current position/scale/rotation.
This is a very important method that you'll need to call whenever visual or transformational changes are made
to the target so that the BlitMask remains synced with it.
event:Event (default = null)update() as an event handler. For example, you could addEventListener(Event.ENTER_FRAME, myBlitMask.update) to make sure it is updated on every frame (although it would be more efficient to simply set autoUpdate to true in this case).
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forceRecaptureBitmap:Boolean (default = false)target is only recaptured if its scale or rotation changed because doing so is rather processor-intensive, but you can force a full update (and regeneration of the cached bitmap) by setting forceRecaptureBitmap to true.
|