RaphaelJS -- vector or not?

I'm trying to place a circle at 50% of the width of the paper using RaphaelJS, is this possible without first doing the math (.5 * pixel width)? I want to simply be able to place an element at 50% of its container's width, is this even possible with the current Raphael API?

Raphael claims开发者_如何学编程 to be able to draw vector graphics, and yet it seems everything in the API is pixel-based. How can you draw a vector image using pixels? That seems 100% contradictory.

Likewise, as I understand vector art, it retains the same dimensions regardless of actual size. Is this not one of the primary reasons to use vector graphics, that it doesn't matter if it's for screen, print or whatever, it will always be the same scale? Thus, I'm further confused by the need for something like ScaleRaphael; just seems like such functionality is part and parcel to creating vector graphics. But, perhaps I just don't understand vector graphics?

It just doesn't seem like an image that is created with absolute pixel dimensions and unable to be resized natively qualifies as a vector image. That, or I'm missing a very large chunk of the API here.

Thanks in advance for any help. I've attempted to post this twice now to the RaphaelJS Google Group, but I guess they are censoring it for whatever reason because I've been waiting for it to appear since last week and still no sign of my posts (although other new posts are showing up).

Using pixel values to define shape positions/dimensions does not make it a non-vector shape. Take for instance Adobe Illustrator - this is a vector product and yet you can still see that the properties for each object shows the positions and dimensions is pixels.

A basic explanation of vector graphics would be like this, taking a rectangle as an example:

A vector rectangle will have a number of properties such as x, y, width and height. These properties can be specified in pixels. The difference with vector (as opposed to raster) is that these pixel properties are only used to determine how the shape is drawn. So when the display is rendered (refreshed) the "system" can redrawn the shape using the same properties without effecting the quality of the resize.

A raster image however will hold a lot more information (i.e. the exact value of each pixel used to form the shape/rectangle)

If the word "pixel" makes you think it is contradictory, just remeber everything on a computer screen is rendered in pixels. Even vector graphics have to be converted to "raster" as some point in the graphics pipeline.

If you are worried about having to use a calculation (0.5 * width) then just remember that something has to do that calculation, and personally I would happily handle this simple step myself.

After all that, you should just calculate size and position in pixels based on the size of your "paper" element and feed those values in Raphael for creating the shape.