myignore/textRect_rotate.R

In jonocarroll/ggeasy: Easy Access to 'ggplot2' Commands

tg_bounds <- function(tg,lab,theta){
  bounds <- grid:::grid.Call(grid:::L_textBounds, 
                             grDevices::as.graphicsAnnot(tg$label[lab]),
                             tg$x[lab],
                             tg$y[lab], 
                             resolveHJust(tg$just, tg$hjust), 
                             resolveVJust(tg$just,tg$vjust), 
                             tg$rot, theta)
  bounds <- unit(bounds, "inches")
  convertUnit(bounds,unitTo = attr(tg$x,'unit'),valueOnly = TRUE)
}

extend_bound <- function(bounds,rot,draw = FALSE){
  
  #left right center points
  xy <- rotatePoint(pivot = c(mean(bounds[c(180,360),1]),bounds[180,2]),
                    point = matrix(c(median(bounds[,1])-bounds[1,3],bounds[180,2],
                                     median(bounds[,1])+bounds[1,3],bounds[180,2]),
                                   ncol=2,byrow = TRUE),
                    rot = rot)
  
  #top/bottom left vertices
  xy_l <- rotatePoint(pivot = xy[1,],
                      point = matrix(c(xy[1,1],xy[1,2]+bounds1[1,4],
                                       xy[1,1],xy[1,2]-bounds1[1,4]),
                                     ncol=2,byrow = TRUE),
                      rot = rot)
  #top/bottom right vertices
  xy_r <- rotatePoint(pivot = xy[2,],
                      point = matrix(c(xy[2,1],xy[2,2]+bounds1[2,4],
                                       xy[2,1],xy[2,2]-bounds1[2,4]),
                                     ncol=2,byrow = TRUE),
                      rot = rot)
  
  ret <- rbind(xy_l,xy_r)
  
  if(draw)
    lines(ret[c(3,1,2,4,3),1],ret[c(3,1,2,4,3),2])
  
  ret <- ret[c(3,1,2,4),]
  
  return(ret)
}

rotatePoint <- function(pivot, point, rot) {
  # Rotate clockwise, angle in radians
  rad <- rot * pi / 180
  x <- (cos(rad) * (point[,1] - pivot[1])) - (sin(rad) * (point[,2] - pivot[2])) +pivot[1]
  y <- (sin(rad) * (point[,1] - pivot[1])) + (cos(rad) * (point[,2] - pivot[2])) + pivot[2]
  return(cbind(x, y))
}

txt <- c("Hi there","Hi there")
rot <- 0 #rotation for text boxes

this_tg <- textGrob(label = txt,x = c(0.25,0.4),y=c(0.5,0.5),rot = rot)

bounds1 <- do.call('rbind',lapply(seq(1,360,1),tg_bounds,tg = this_tg,lab = 1))
bounds2 <- do.call('rbind',lapply(seq(1,360,1),tg_bounds,tg = this_tg,lab = 2))

plot(bounds1[,c(1:2)],type='l',xlim=c(0,.6),ylim=c(0,.6))
xy <- extend_bound(bounds1,rot = rot,draw = TRUE)
lines(bounds2[,c(1:2)])
xy2 <- extend_bound(bounds2,rot = rot,draw = TRUE)