Skip to main content

Font Management and GlyphVectors

Fonts and text are always a pain when drawing vector graphics!

After hitting myself over the head over a stupid bug in my zoom tests (like this:)
JButton inButton = new JButton("IN");
inButton.setActionCommand("IN");
JButton outButton = new JButton("OUT");
inButton.setActionCommand("OUT");
I got center scaling implemented in my branch. Which lets me test a different approach to managing fonts. I had tried to be clever and do something like:
GlyphVector glyphs = font.createGlyphVector("N");
ArrayList shapes = new ArrayList();
for (int i = 0; i < glyphs.getNumberOfGlyphs(); i++) {
shapes.add(affineTransform.getTransformedShape(glyphs.get(i)));
}
but letter shapes fill horribly with lots of missing pixels. Anyway, I eventually settled on just storing the Glyphs themselves. Less pure, but it works, and it allows the size of TextSymbols to be computed and used by the class in between drawing.

So, for fonts there had to be a way in my architecture to change the font size when the whole molecule is scaled. The nicer approach is the obvious one - just to transform the Graphics object. However, it turns out there are advantages to the more cumbersome approach. Here's an image:
which shows rings at various sizes, with the numbers at their centers showing the font size at that scale. An important one is the 'size' (9-5) - which is 4, but there is no readable size of font at that size. However, the FontManager class keeps track of how far below (or above) the minimum and maximum font sizes, and then returns to that size at the appropriate point.

Comments

Popular posts from this blog

Common Vertex Matrices of Graphs

There is an interesting set of papers out this year by Milan Randic et al (sorry about the accents - blogger seems to have a problem with accented 'c'...). I've looked at his work before here.

[1] Common vertex matrix: A novel characterization of molecular graphs by counting
[2] On the centrality of vertices of molecular graphs

and one still in publication to do with fullerenes. The central idea here (ho ho) is a graph descriptor a bit like path lengths called 'centrality'. Briefly, it is the count of neighbourhood intersections between pairs of vertices. Roughly this is illustrated here:


For the selected pair of vertices, the common vertices are those at the same distance from each - one at a distance of two and one at a distance of three. The matrix element for this pair will be the sum - 2 - and this is repeated for all pairs in the graph. Naturally, this is symmetric:


At the right of the matrix is the row sum (∑) which can be ordered to provide a graph invarian…

Generating Dungeons With BSP Trees or Sliceable Rectangles

So, I admit that the original reason for looking at sliceable rectangles was because of this gaming stackoverflow question about generating dungeon maps. The approach described there uses something called a binary split partition tree (BSP Tree) that's usually used in the context of 3D - notably in the rendering engine of the game Doom. Here is a BSP tree, as an example:



In the image, we have a sliced rectangle on the left, with the final rectangles labelled with letters (A-E) and the slices with numbers (1-4). The corresponding tree is on the right, with the slices as internal nodes labelled with 'h' for horizontal and 'v' for vertical. Naturally, only the leaves correspond to rectangles, and each internal node has two children - it's a binary tree.

So what is the connection between such trees and the sliceable dual graphs? Well, the rectangles are related in exactly the expected way:


Here, the same BSP tree is on the left (without some labels), and the slicea…

Signatures with user-defined edge colors

A bug in the CDK implementation of my signature library turned out to be due to the fact that the bond colors were hard coded to just recognise the labels {"-", "=", "#" }. The relevant code section even had an XXX above it!

Poor show, but it's finally fixed now. So that means I can handle user-defined edge colors/labels - consider the complete graph (K5) below:

So the red/blue colors here are simply those of a chessboard imposed on top of the adjacency matrix - shown here on the right. You might expect there to be at least two vertex signature classes here : {0, 2, 4} and {1, 3} where the first class has vertices with two blue and two red edges, and the second has three blue and two red.

Indeed, here's what happens for K4 to K7:

Clearly even-numbered complete graphs have just one vertex class, while odd-numbered ones have two (at least?). There is a similar situation for complete bipartite graphs:

Although I haven't explored any more of these…