add regression tests for "joins bug"; add NEWS item

pkg/inst/NEWS.rd

@@ -2,6 +2,16 @@
 \title{NEWS file for the vwline package}
 \encoding{UTF-8}
 
+\section{Changes in version 0.2-3}{
+  \itemize{
+    \item Fix for calculation of joins (outer corners) on closed lines.
+
+    The last corner was missing (reduced to bevel), which also produced some
+    crazy results for some orderings of vertices.
+
+    Thanks to James Ward for bug report.
+  }
+}
 \section{Changes in version 0.2-2}{
   \itemize{
     \item Tidying for submission to CRAN.

pkg/inst/regression-tests/bug-joins.R

@@ -0,0 +1,72 @@
+
+library(vwline)
+
+pdf("bug-joins.pdf", compress=FALSE)
+
+## The bug was that the last corner on a closed line was not being added
+## (was reduced to bevel).
+## For some orderings of vertices, this also produced weird artifacts.
+
+## make a line with a bend
+x <- c(.4, .6, .6)
+y <- c(.4, .4, .6)
+
+## define fixed line width
+w <- rep(0.04, length(x));
+
+## Bevel corners
+grid.newpage()
+grid.vwline(x=x, y=y, w=w,
+   linejoin="bevel",
+   open=FALSE, gp=grid::gpar(col="black", fill="darkorange"))
+
+## Round corners
+grid.newpage()
+grid.vwline(x=x, y=y, w=w,
+   linejoin="round",
+   open=FALSE, gp=grid::gpar(col="black", fill="darkorange"))
+
+## Reverse order of vertices (round corners)
+x2 <- rev(x);
+y2 <- rev(y);
+grid.newpage()
+grid.vwline(x=x2, y=y2, w=w,
+   linejoin="round",
+   open=FALSE, gp=grid::gpar(col="black", fill="darkorange"))
+
+## Open version(s)
+grid.newpage()
+grid.vwline(x=x, y=y, w=w,
+   linejoin="round",
+   open=TRUE, gp=grid::gpar(col="black", fill="darkorange"))
+
+grid.newpage()
+grid.vwline(x=x2, y=y2, w=w,
+   linejoin="round",
+   open=TRUE, gp=grid::gpar(col="black", fill="darkorange"))
+
+## Mitre corners
+grid.newpage()
+grid.vwline(x=x, y=y, w=w,
+   linejoin="mitre",
+   open=FALSE, gp=grid::gpar(col="black", fill="darkorange"))
+
+dev.off()
+
+savedPDF <- system.file("regression-tests", "bug-joins.save.pdf",
+                        package="vwline")
+diff <- tools::Rdiff("bug-joins.pdf", savedPDF)
+
+if (diff != 0L) {
+    ## If differences found, generate images of the differences and error out
+    system("pdfseparate bug-joins.pdf bug-joins-test-pages-%d.pdf")
+    system(paste0("pdfseparate ", savedPDF, " bug-joins-model-pages-%d.pdf"))
+    modelFiles <- list.files(pattern="bug-joins-model-pages-.*")
+    N <- length(modelFiles)
+    for (i in 1:N) {
+        system(paste0("compare bug-joins-model-pages-", i, ".pdf ",
+                      "bug-joins-test-pages-", i, ".pdf ",
+                      "bug-joins-diff-pages-", i, ".png"))
+    } 
+    stop("Regression testing detected differences")
+}