Type GroupObject Object SnapshotObject Library display.* Revision 2017.3083 Keywords canvas See also display.newSnapshot() snapshot:invalidate()
This group is a special offscreen group that enables you to draw on the snapshot's texture without redrawing the objects in snapshot.group.
Normally, snapshot invalidates causes the texture to be cleared prior to rendering the snapshot group's children to a texture.
In contrast, when the canvas is invalidated, they render to the texture without clearing the texture first.
To invalidate the canvas, simply pass the
"canvas" parameter to snapshot:invalidate() as shown in the example below.
Properties of the canvas will be ignored and will not effect on the rendered result.
Instead, for rendering purposes, the properties of snapshot.group will be used instead.
For example, properties like position (or rotation, scale, alpha, etc) will be taken from the snapshot's group property, instead of from the canvas property.
In addition, changes to the
snapshot.canvas will be reset to the corresponding value of snapshot.group just prior to when the canvas objects are drawn.
The canvas group behaves just like a normal group except:
local w,h = display.contentWidth,display.contentHeight local snapshot = display.newSnapshot( w, h ) local brush = display.newImage( "brush.png" ) snapshot.canvas:insert( brush ) snapshot:invalidate( "canvas" )