Plot elements of specific size
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I'm plotting a polygon made of edges and vertices. I'd like to plot these elements at a specific size or proportion: whether the polygon has 10 or 1000 vertices, I'd like the elements to be drawn at the same size. When zooming in and out of the vector image, element size would remain static. For example, define a canvas of 100inx100in and draw lines .1in thick (and save to a pdf).
Currently, it seems impossible since, e.g., the LineWidth and MarkerSize are relative to the screen instead of the canvas. This means that when you zoom into the figure, the elements keep their size wrt screen. One option is to scale their size according to the zoom level. However, then the large polygon wouldn't necessarily fit the screen.
There are two ways that I see to resolve this, both seem impossible:
- Define the size properties wrt the canvas and not the screen.
- Go to the proper zoom level, and draw all elements even if they aren't in the figure clip region (save to a pdf).
Questions on the subject asked about specific elements such as lines or markers. The suggested solutions were to draw with alternative functions such as patch() and rectangle().
In that case, I'll forsake matlab's clanky drawing mechanism altogether, export the data, and draw in svg. But it would be a shame since matlab has powerful tools such as different marker shapes or a force graph.
Am I missing something fundamental or is this the worst design I've seen lately?
Since stackoverflow uses CC-BY-SA 4.0 and Answers uses CC-BY-SA 3.0, I took the liberty of copying the actual content of the question from the originally posted link.
Original question:
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7 个评论
Rik
2021-10-23
It sounds like you want the result from functions like patch, but want to use line objects to achieve that. There is probably a way to get that to work, but I question the underlying assumption.
You could probably use a listener to increase the MarkerSize etc as a response to zooming in or out.
Rik
2021-10-23
So the rescaling on zoom should happen in the pdf?
It still sounds as if you want line art to behave like patches. That sounds like an XY problem to me. Can you confirm that is what you want? Or am I not understanding you correctly?
Walter Roberson
2021-10-23
If you look around a bit you can find some functions for creating UDF, which is interactive PDF.
Walter Roberson
2021-10-23
Drawing of lines and of the dot marker (specifically) are "primitives" handled by OpenGL. MATLAB did not invent this behaviour.
Zohar
2021-10-23
采纳的回答
First, I don't care about interactive zooming. I'd like to save a pdf.
If the zooming is happening only after the pdf conversion, I don't see why you can't just set the LineWidth and MarkerSize to your preference when the whole drawing is in view, and then convert.
If it's a problem of calculating the conversion factor from data units to points (the units that LineWidth and MarkerSize are measured in, 1 point = 1/72 inch), that can be done as follows:
set(gcf,'Units','points'); %change this back later, if needed
DU=diff(xlim); %width of figure in data units
P=hfig.Position(3); %width of figure in points
conversionFactor=P/DU; %conversion factor, data units to points
7 个评论
Zohar
2021-10-23
if I have a large drawing and I need to zoom in to the right scale, then not everything would fit in the screen--specifically, the figure window
Again, you sometimes speak as if you intend to be zooming in Matlab and elsewhere say that you only plan to be zooming a pdf print of the figure. Which is it?
Matlab saves to a pdf only what you see on the screen, right?
Yes, but you would print only after zooming out so that the full figure is in view. You would also set the MarkerSize and LineWidth when the full figure is in view. I don't see how the selection of the MarkerSize and LineWidth requires any zooming. Aren't you pre-selecting them in proportion to the dimensions of your polygon?
Is the issue that you want to be able to zoom the Matlab figure to verify the proportions of the LineWidths and MarkerSizes? If so, it is not an ad hoc matter to rescale the Markers to keep them in the same proportion. The code I proposed above systematically calculates the proportionality factor that you need given the current axes limits. You could put it in a function and re-execute it every time you zoom in and zoom out. As Rik pointed out, this could be further automated with listeners or, if you have R2021a, with a LimitsChangedFcn:
Zohar
2021-10-24
Now, it's a big polygon with a lot of tiny details which can't be captured using the screen pixel resolution: either nothing would be drawn, or elements would be scaled (out of proportion) to be the size of at least one pixel (the latter is matlab's behavior).
That may be true of how Matlab renders line objects on the screen, but I think internally, they are vectorized and, when exporting to PDF, are also sent in vectorized format by default. As a simple test, I generated a plot with MarkerSize=0.1. I can't see the marker in the Matlab figure no matter how much I zoom, but when I export the same figure to PDF, I can zoom down by a factor 6400 and see a very sharp, well-defined circular marker.
Further evidence of this is in the documentation for the new exportgraphics() command, which has specific options to let you export to PDF in vectorized format.
Matt J
2021-10-24
Are you saying that this new function allows me to draw in any resolution, and even though I won't be able to render it to a figure, I'll be able to save it to an offline pdf?
I think you should try it. I'm not sure you need to upgrade to a Matlab version which has exportgraphics(). I just used saveas().
Zohar
2021-10-24
更多回答（1 个）
You could probably use a listener to increase the MarkerSize etc as a response to zooming in or out.
The code below is an implementation of @Rik's suggestion. All line objects in the specified axis will have their MarkerSize and LineWidth properties auto-zoomed in proportion to changes in the axis x-limits.
plot(exp(1:3),'-o');
lockSizes(gca)
function updateSize(ax)
if ~nargin
ax=gca;
end
h=findobj(ax,'Type','line','-or','Type','functionline');
DU=diff(xlim);
factor=h(1).UserData.DU./DU;
for i=1:numel(h)
h(i).MarkerSize=h(i).MarkerSize*factor;
h(i).LineWidth=h(i).LineWidth*factor;
h(i).UserData.refSize=h(i).MarkerSize;
h(i).UserData.refWidth=h(i).LineWidth;
h(i).UserData.DU=DU;
end
end
function lockSizes(ax)
if ~nargin
ax=gca;
end
h=findobj(ax,'Type','line','-or','Type','functionline');
DU=diff(xlim);
for i=1:numel(h)
h(i).UserData.refSize=h(i).MarkerSize;
h(i).UserData.refWidth=h(i).LineWidth;
h(i).UserData.DU=DU;
end
addlistener(ax.XRuler,'MarkedClean',@(~,~) updateSize(ax));
end
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