proc deletehover {canvas graphics} {
  global kbbitmap dirty
  $graphics clip [lrange $dirty 0 1] [lrange $dirty 2 3]
  $graphics image $kbbitmap [list 0 0]
  $canvas flush  [lindex $dirty 0] [lindex $dirty 1] 100 100
  #[lindex $dirty 0] [lindex $dirty 1] [lindex $dirty 2] [lindex $dirty 3]
}

proc displayletter {canvas graphics x y} {
  global unshifted_letters letter kbbitmap lname2char dirty lastletter
  foreach {l xl yl xr yr} $unshifted_letters {
    if { < $xl $x } {
      if { < $yl $y } {
        if { < $x $xr } {
          if { < $y $yr } {
            if { eq $lastletter $l } {
              break
            }
            set lastletter $l
            
            deletehover $canvas $graphics
            
            $graphics clip [list 0 0] [list 239 319]
            set kbitmap [lcdui.image -resource [append "keys/" $l] ]
            $graphics image $kbitmap [list $xl [- 185 $yr] ]
            set dirty [list $xl [- 185 $yr] 24 62 ]
            $canvas flush 
            #[lindex $dirty 0] [lindex $dirty 1] 100 100
            
            # special handling for special keys
            if { eq $letter delete } {
              break
            } elseif { eq $letter ok } {
              break
            } elseif { eq $letter upshift } {
              break
            } elseif { eq $letter downshift } {
              break
            }
            
            # look up names of punctuation
            if { hcontains $lname2char $l } {
              set letter [hget $lname2char $l]
              break
            }

            # not punctuation, must be a letter
            set letter $l
            break
          }
        }
      }
    }
  }
}

proc canvasEvents {canvas event} {

  set reason [$event cget -reason]
  set x [$event cget -x]
  set y [- [$event cget -y] 105]
  
  set graphics [$canvas graphics]
  if { eq $reason 2 } {
    displayletter $canvas $graphics $x $y
  }
  if { eq $reason 4 } {
    displayletter $canvas $graphics $x $y
  }
  if { eq $reason 3 } {
    global letter text lastletter

    # special handling for special keys
    if { eq $letter delete } {
      if { > [strlen $text] 0 } {
        set text [strrange $text 0 [- [strlen $text] 2 ] ]
      }
    } elseif { eq $letter ok } {
    } elseif { eq $letter upshift } {
    } elseif { eq $letter downshift } {
    } else {
      append $text $letter
    }
    
    $graphics color white
    $graphics frect [list 0 185] [list 239 135]
    $graphics color black
    $graphics string [list 0 220] $text
    deletehover $canvas $graphics
    $canvas flush
    set letter ""
    set lastletter ""
  }
}

set canvas [lcdui.canvas -title "Test Canvas" -eventhandler canvasEvents  -suppresskeys 1]

set kbbitmap [lcdui.image -resource /lowercase_keyboard.png]
set graphics [$canvas graphics]
$graphics image $kbbitmap [list 0 0]

set unshifted_letters %%UNSHIFTEDLETTERS%%
set shifted_letters %%SHIFTEDLETTERS%%
set letter ""
set text ""
set lastletter ""
set dirty [list 0 0 0 0]
set lname2char [hash {exclamation ! speech "\"" pound £ dollar $ percent % caret ^ ampersand & asterisk * openbracket ( closebracket ) openangle < closeangle > semicolon ; space " " plus "+" colon : hash "\#" dot . comma , at @ apostrophe ' }]


$canvas setcurrent