I have been working in Flex for about 3 months now. I am writing a geometry tool that allows user to create points, line segments, circle and polygons, as well as constraints between these objects (e.g., distance, angle, perpendicular, etc.). Initially, I created a (subclass of) ApplicationControlBar and (a subclass) of Canvas. Tools in the app control bar and objects (by which I mean geometric shapes) in the canvas.
My canvas listeners for Event.RENDER and then, provided it's been told that something has changed, calls its draw() method - which, essentially, loops through objects, drawing them to the graphics object - after having cleared the graphics object. Similarly, the canvas listeners for various MouseEvents and KeyboardEvents, and traverses the list of objects doing hit tests. This was okay until I needed to render text (for distances and angles). Apparently there are ways around that - by rendering text to a bitmap and adding bitmap to graphics command stack (though I have yet to actually get this working). There are other concerns that I have about my approach thus far. But switching over to a model where each geometric object is a Sprite or a Shape raises some questions, too. Currently, I can highlight points, edges and angles of polygons are the mouse moves over them. I have no idea how I would accomplish this with Sprite or Shape, as neither appears to have a draw() or paint() method... Would I need to add Shapes for "selected look" for each point, line segment, etc. and toggle visible property appropriately? Is this something that skins might be used for? If so, how? I realize that this is a somewhat open-ended question, and I am hesitant asking it. I have done a fair amount of reading (books, blogs, docs), but I think that I am missing something here. If you have pointers or advice, I would be most grateful. Thanks. -Eric
