contour colorscale doesn't support alpha

Author: cpsievert

R/plotly_build.R

@@ -416,6 +416,10 @@ map_color <- function(traces, title = "", na.color = "transparent") {
         colorObj[["showscale"]] <- TRUE
         traces[[i]] <- modify_list(colorObj, traces[[i]])
         traces[[i]]$colorscale <- as_df(traces[[i]]$colorscale)
+        # sigh, contour colorscale doesn't support alpha
+        if (traces[[i]][["type"]] == "contour") {
+          traces[[i]]$colorscale[, 2] <- strip_alpha(traces[[i]]$colorscale[, 2])
+        }
         next
       }
       colorObj$color <- color[[i]]

R/toRGB.R

@@ -39,3 +39,15 @@ rgb2hex <- function(string = "rgba(255,255,255,1)") {
     do.call(grDevices::rgb, c(x, list(maxColorValue = 255)))
   })
 }
+
+#convert rgba() to rgb()
+strip_alpha <- function(string = "rgba(255,255,255,1)", warn = TRUE) {
+  if (length(string) == 0) return(string)
+  if (warn) {
+    if (any(!grepl(",1\\)$", string))) {
+      warning("Removing an alpha value lower than 1")
+    }
+  }
+  string <- sub(",1\\)$", ")", string)
+  sub("^rgba", "rgb", string)
+}