CanvasOperationBeginLayer

Type

statement

Summary

Begin a new drawing layer on a canvas. mBounds:An expression which evaluates to a rectangle.

Syntax

begin layer [ with <mEffect> ] on <mCanvas>

Description

Begins a new layer on mCanvas to group drawing operations for which the opacity, blend mode, and optional effect are to be applied to as a whole rather than individually. The optional drawing bounds can be used to restrict the area to which the effect is applied, allowing the canvas library to optimize memory allocation & drawing operations for the new layer.

Parameters

Name	Type	Description
mCanvas		An expression which evaluates to a canvas.
mEffect		An expression which evaluates to an effect.

Examples

// Draw two overlapping rectangles grouped with half transparency
set the opacity of this canvas to 0.5
begin layer on this canvas
fill rectangle path of rectangle path [50,50,100,100] on this canvas
fill rectangle path of rectangle path [75,75,125,125] on this canvas
end layer on this canvas

// Create an effect for the new layer
variable tEffect as Effect
put outer shadow effect into tEffect

// Draw rectangle with an effect applied
begin layer with tEffect on this canvas
fill rectangle path of rectangle [50,50,100,100] on this canvas
end layer on this canvas