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POLetter partially disappearing when exporting text using CairoPNG
 

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  1. POLetter partially disappearing when exporting text using CairoPNG
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    <p>I'm trying to construct a chart using ggplot which I am then saving to PNG image using the Cairo package's CairoPNG function.</p> <p>The problem is that the resulting image file seems to be missing chunks of the letter J on the x axis. This is a bit of an issue when I'm using month name as the x axis label.</p> <p>This only seems to happen when the text size is set to a whole number (such as 12). If I set it to 11.5 or 12.5 then the letters display fine.</p> <p>So, I can fix it by altering the font size but it feels like a bit of a hack. Does anyone know why it's behaving like this?</p> <p><img src="https://i.stack.imgur.com/4h87e.png" alt="enter image description here"></p> <p>Code is as follows:</p> <pre><code>library("ggplot2") library("scales") library("Cairo") # Set chart values line.width = 1 font.size = 12 # Generate some random data start.date &lt;- as.Date("2011-07-01") x.month &lt;-seq.Date(start.date, by = "month", length.out = 24) end.date &lt;- max(x.month) x.value &lt;- rnorm(24,mean=50,sd=2) # Combine into dataframe x.data &lt;- data.frame( "Month" = x.month, "Value" = x.value ) # Build chart p &lt;- ggplot(data=x.data, aes(Month, Value)) + geom_line(size=line.width) p &lt;- p + theme_bw() p &lt;- p + ggtitle("Test Chart\n") p &lt;- p + scale_y_continuous(limits = c(40, 60)) p &lt;- p + scale_x_date(limits=c(start.date+20,end.date-20), breaks = "1 month",labels = date_format("%b-%y")) p &lt;- p + theme(axis.text.x=element_text(angle=90, hjust=1, vjust=0.5, size=font.size), axis.text.y=element_text(size=font.size), axis.title.x=element_blank(), axis.title.y=element_blank()) # Export chart CairoPNG("c:\\temp\\temp1.png", width=500, height = 250) p dev.off() </code></pre> <hr> <p><strong>Edit 1</strong> I tried the following code suggested by baptiste but the letters seem to come through fine:</p> <pre><code>CairoPNG("test.png"); grid::grid.text("The disappearing J"); dev.off() </code></pre> <p><img src="https://i.stack.imgur.com/JhksJ.png" alt="enter image description here"></p> <hr> <p><strong>Edit 2</strong></p> <p>Issue isolated courtesy of baptiste. It really doesn't seem to like rotating capital Js!</p> <pre><code>CairoPNG("c:\\temp\\test.png",width=60, height=300); grid::grid.text("Rejoicefully Juxtaposing Jelly with Jam\nabcdefghijklmnopqrstuvwxyz\nABCDEFGHIJKLMNOPQRSTUVWXYZ", rot=90); dev.off() </code></pre> <p><img src="https://i.stack.imgur.com/WLHjj.png" alt="enter image description here"></p>
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    1. COI'd suggest you test the letter J on its own; this probably has nothing to do with ggplot2. Try `CairoPNG("test.png"); grid::grid.text("The disappearing J"); dev.off()`.
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      1. USbaptiste
    2. COHmm, I've updated my question with the results but that doesn't replicate the error. I wonder if it's a combination of the rotation of the text with CairoPNG. If I use the basic png function then I don't get the same problem.
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      1. USTumbledown
    3. COand if you rotate the letter, ie `grid.text("J", rot=90)`?
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      1. USbaptiste
 

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