Newton Developer Technical Information: Newton Programmer's Guide: 2.1 OS Addendum /

Chapter 2 - Newton Works Draw Application / Using the Drawing Application Interface

The Canvas and Its Methods

The canvas view provides methods to programmatically add a shape to it, and a number of methods that manipulate the set of currently selected shapes. If you are writing code for a tool in the tool bar, simply send these methods to self. Otherwise, use the *GetCanvas method described in "Draw Application Methods".

The current drawing style is stored in the canvas' currentDrawStyle slot. You may change the values in this style frame programmatically; the user can also set some of these slot through the user interface.

The *AddShape method adds a new shape to the canvas. The canvas provides a *DirtyShape method to redraw the part of the canvas where the new shape was added. Simply pass the same shape to both functions, as in:

 local shape := MakeRect (0,0,100,100);

:AddShape(shape,nil,nil);
 :DirtyShape(shape);

A number of functions exist to select shapes, and manipulate them. You can programmatically call many of the methods the user accesses though the Edit and Arrange pickers. See "The Canvas".