From bf315e30cfc6aad25beb6ed09211bdcf813fd35c Mon Sep 17 00:00:00 2001
From: Eric Hung <naturalsmen@gmail.com>
Date: Mon, 25 Jul 2016 16:09:59 +0800
Subject: [PATCH] Refactor addMFI to follow skeleton_TA structure

Refactor addMFI to use skeleton_TA structure. chartMFI function is given
to create Money Flow Indicator based on skeleton_TA structure.
---
 R/addMFI.R | 94 +++++++++++++++++++++++++++++++++---------------------
 1 file changed, 58 insertions(+), 36 deletions(-)

diff --git a/R/addMFI.R b/R/addMFI.R
index 923877df..af3fb61b 100644
--- a/R/addMFI.R
+++ b/R/addMFI.R
@@ -7,45 +7,67 @@
 `addMFI` <-
 function (n = 14, ..., on = NA, legend = "auto") 
 {
-    lchob <- get.current.chob()
-    x <- as.matrix(lchob@xdata)
-    volume <- Vo(x)
-    x <- HLC(x)
-    x <- MFI(HLC = x, volume = volume, n = n)
-    yrange <- NULL
-    chobTA <- new("chobTA")
-    if (NCOL(x) == 1) {
-        chobTA@TA.values <- x[lchob@xsubset]
-    }
-    else chobTA@TA.values <- x[lchob@xsubset, ]
-    chobTA@name <- "chartTA"
-    if (any(is.na(on))) {
-        chobTA@new <- TRUE
-    }
-    else {
-        chobTA@new <- FALSE
-        chobTA@on <- on
+    lenv <- new.env()
+    lenv$chartMFI <- function(x, n, ..., on, legend) {
+      xdata <- lchob$Env$xdata
+      xsubset <- lchob$Env$xsubset
+      volume <- lchob$Env$vo
+      xdata <- HLC(xdata)
+      mfi <- MFI(HLC = xdata, volume = volume, n = n)[xsubset]
+      spacing <- x$Env$theme$spacing
+      x.pos <- 1 + spacing * (1:NROW(mfi) - 1)
+      xlim <- x$Env$xlim
+      ylim <- c(0,100)
+      theme <- x$Env$theme
+
+      lines(x.pos, mfi, col = 8, lwd = 1, lend = 2, ...)
     }
-    chobTA@call <- match.call()
-    legend.name <- gsub("^addMFI", "Money Flow Index ", deparse(match.call()))
-    gpars <- c(list(...), list(col = 8))[unique(names(c(list(col = 8), 
-        list(...))))]
-    chobTA@params <- list(xrange = lchob@xrange, yrange = yrange, 
-        colors = lchob@colors, color.vol = lchob@color.vol, multi.col = lchob@multi.col, 
-        spacing = lchob@spacing, width = lchob@width, bp = lchob@bp, 
-        x.labels = lchob@x.labels, time.scale = lchob@time.scale, 
-        isLogical = is.logical(x), legend = legend, legend.name = legend.name, 
-        pars = list(gpars))
-    if (is.null(sys.call(-1))) {
-        TA <- lchob@passed.args$TA
-        lchob@passed.args$TA <- c(TA, chobTA)
-        lchob@windows <- lchob@windows + ifelse(chobTA@new, 1, 
-            0)
-        do.call("chartSeries.chob", list(lchob))
-        invisible(chobTA)
+    if(!is.character(legend) || legend == "auto")
+      legend <- gsub("^addMFI", "Money Flow Index ", deparse(match.call()))
+    mapply(function(name, value) {
+      assign(name, value, envir = lenv)
+    }, names(list(n = n, ..., on = on, legend = legend)), 
+    list(n = n, ..., on = on, legend = legend))
+    exp <- parse(text = gsub("list", "chartMFI", as.expression(substitute(list(x = current.chob(), 
+                                                                                 n = n, ..., on = on, legend = legend)))), srcfile = NULL)
+    exp <- c(exp, expression(
+      lc <- xts:::legend.coords("topleft", xlim, c(0,100)),
+      legend(x = lc$x, y = lc$y, 
+             legend = c(paste(legend, ":"),
+                        paste(format(last(mfi),nsmall = 3L))),
+             text.col = c(theme$fg, 8), 
+             xjust = lc$xjust, 
+             yjust = lc$yjust, 
+             bty = "n", 
+             y.intersp=0.95)))
+    exp <- c(expression(
+      # add inbox color
+      rect(xlim[1], 0, xlim[2], 100, col=theme$fill),
+      # add grid lines and left-side axis labels
+      segments(xlim[1], y_grid_lines(c(0,100)), 
+               xlim[2], y_grid_lines(c(0,100)), 
+               col = theme$grid, lwd = x$Env$grid.ticks.lwd, lty = 3),
+      text(xlim[1], y_grid_lines(c(0,100)), y_grid_lines(c(0,100)), 
+           col = theme$labels, srt = theme$srt, 
+           offset = 0.5, pos = 2, cex = theme$cex.axis, xpd = TRUE),
+      # add border of plotting area
+      rect(xlim[1], 0, xlim[2], 100, border=theme$labels)), exp)
+    
+    lchob <- current.chob()
+    x <- lchob$Env$xdata
+    xsubset <- lchob$Env$xsubset
+    volume <- lchob$Env$vo
+    x <- HLC(x)
+    mfi <- MFI(HLC = x, volume = volume, n = n)[xsubset]
+    lchob$Env$mfi <- mfi
+    if(any(is.na(on))) {
+      lchob$add_frame(ylim=c(0,100),asp=1,fixed=TRUE)
+      lchob$next_frame()
     }
     else {
-        return(chobTA)
+      lchob$set_frame(sign(on)*(abs(on)+1L))
     }
+    lchob$replot(exp, env=c(lenv,lchob$Env), expr=TRUE)
+    lchob
 }