Coordinate Transformations
Suppose you need to draw an object such as an automobile. You know, from the manufacturer's specifications, the height, wheelbase, and total length. You could, of course, figure out all pixel positions, assuming some number of pixels per meter. However, there is an easier way: You can ask the graphics context to carry out the conversion for you.
g2.scale(pixelsPerMeter, pixelsPerMeter);g2.draw(new Line2D.Double(coordinates in meters)); // converts to pixels and draws scaled line
The scale method of the Graphics2D class sets the coordinate transformation of the graphics context to a scaling transformation. That transformation changes user coordinates (user-specified units) to device coordinates (pixels). Figure 7-18 ...
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