class Hud(object):
        # head up display - draws a semi-transparent text box.
        def __init__(self):
                self.showme = 0
                self.app = []
                self.strs = []
                self.fontbase = []
                self.ident = []
                self.strings1 = []
                self.strings2 = []
                self.string_lists = []
                self.formats = []
                self.messages = []
                self.pins = []

        def show(self, string):
                # only for legacy vismach models
                self.messages += [str(string)]

        def clear(self):
                # only for legacy vismach models
                self.messages = []

        def show_txt(self, string):
                # displays a string
                self.ident += ["txt"] 
                self.strings1 += [str(string)]
                self.strings2 += [None]
                self.string_lists += [None]
                self.pins += [None]
                self.formats += [None]

        def show_msg(self, string1, string_list, pin, string2=""):
                # displays the string 'string_list[val]'
                # where 'val' is a hal_pin with values 0,1,.... 
                # example usage:
                # myhud.show_msg("Kinematics ", ["IDENTITY","TCP"], "motion.switchkins-type", " active")
                self.ident += ["msg"] 
                self.strings1 += [str(string1)]
                self.strings2 += [str(string2)]
                self.string_lists += [string_list]
                self.pins += [pin]
                self.formats += [None]

        def show_pin(self, string1, pin, form, string2=""):
                # displays 'string1' followed by a hal_pin value 'val' and an optional 'string2' 
                # the value 'val' is formatted by a python format string
                # example usage: 
                # myhud.show_val("X : ", "joint.0.pos-fb", "{:8.3f}", "mm")
                self.showme = 1
                self.ident += ["pin"] 
                self.strings1 += [str(string1)]
                self.strings2 += [str(string2)]
                self.string_lists += [None]
                self.pins += [pin]
                self.formats += [form]

        def hide(self):
                self.showme = 0
                
        def draw(self):
                # update the lines to be displayed in the hud using the respective lists
                strs = []   
                for n in range(len(self.ident)):
                    if self.ident[n] == "msg":
                        strs += [self.strings1[n]
                                 + self.string_lists[n][int(hal.get_value( self.pins[n]))]
                                 + self.strings2[n] 
                                ]
                    elif self.ident[n] == "pin":
                         strs += [self.strings1[n] 
                                 + str(self.formats[n].format(hal.get_value( self.pins[n])))
                                 + self.strings2[n]
                                ]
                    else:
                         strs += [self.strings1[n]]

                drawtext = strs + self.messages
                self.lines = len(drawtext)
                #draw head-up-display
                #see axis.py for more font/color configurability
                if ((self.showme == 0) or (self.lines == 0)):
                        return
                
                glMatrixMode(GL_PROJECTION)
                glPushMatrix()
                glLoadIdentity()
                
                if not self.fontbase:
                        self.fontbase = int(self.app.loadbitmapfont("9x15"))
                char_width, char_height = 9, 15
                xmargin,ymargin = 5,5
                ypos = float(self.app.winfo_height())
                
                glOrtho(0.0, self.app.winfo_width(), 0.0, ypos, -1.0, 1.0)
                glMatrixMode(GL_MODELVIEW)
                glPushMatrix()
                glLoadIdentity()
                
                #draw the text box
                maxlen = max([len(p) for p in drawtext])
                box_width = maxlen * char_width
                glDepthFunc(GL_ALWAYS)
                glDepthMask(GL_FALSE)
                glDisable(GL_LIGHTING)
                glEnable(GL_BLEND)
                glEnable(GL_NORMALIZE)
                glBlendFunc(GL_ONE, GL_CONSTANT_ALPHA)
                glColor3f(0,0.2,0) # sets the color of the hud overlay
                glBlendColor(0,0,0,0.5) #rgba, sets the transparency of the overlay using the 'a' value 
                glBegin(GL_QUADS)
                glVertex3f(0, ypos, 1) #upper left
                glVertex3f(0, ypos - 2*ymargin - char_height*len(drawtext), 1) #lower left
                glVertex3f(box_width+2*xmargin, ypos - 2*ymargin - char_height*len(drawtext), 1) #lower right
                glVertex3f(box_width+2*xmargin,  ypos , 1) #upper right
                glEnd()
                glDisable(GL_BLEND)
                glEnable(GL_LIGHTING)
                
                #fill the box with text
                maxlen = 0
                ypos -= char_height+ymargin
                i=0
                glDisable(GL_LIGHTING)
                glColor3f(1,0.8,0.4) # sets the color of the text in the hud
                for string in drawtext:
                        maxlen = max(maxlen, len(string))
                        glRasterPos2i(xmargin, int(ypos))
                        for char in string:
                                glCallList(self.fontbase + ord(char))
                        ypos -= char_height
                        i = i + 1
                glDepthFunc(GL_LESS)
                glDepthMask(GL_TRUE)
                glEnable(GL_LIGHTING)
        
                glPopMatrix()
                glMatrixMode(GL_PROJECTION)
                glPopMatrix()
                glMatrixMode(GL_MODELVIEW)