import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *

BYTES_PER_LINE = 8
GAP = 16

class BinViewer(QWidget):
   """ The view has an address, hex byte and ascii column """
   def __init__(self, scrollArea):
      super().__init__()
      self.setFont(QFont('Courier', 10))
      self.setFocusPolicy(Qt.StrongFocus)
      self.blinkcursor = False
      self.cursorX = 0
      self.cursorY = 0
      self.scrollArea = scrollArea
      self.Data = bytearray()
      t = QTimer(self)
      t.timeout.connect(self.updateCursor)
      t.setInterval(500)
      t.start()
   def updateCursor(self):
      self.blinkcursor = not self.blinkcursor
      self.update(self.cursorX, self.cursorY, self.charWidth, self.charHeight)
   def setCursorPosition(self, position):
      if position > len(self.Data) * 2 - 1:
         position = len(self.Data) * 2 - 1
      if position < 0:
         position = 0
      self.cursorPosition = position
      x = position % (2 * BYTES_PER_LINE)
      self.cursorX = self.xposHex + x * self.charWidth
      self.cursorY = int(position / (2 * BYTES_PER_LINE)) * self.charHeight + 4
      self.blinkcursor = True
      self.update()
   def paintEvent(self, event):
      painter = QPainter(self)
      # Background:
      painter.fillRect(event.rect(), self.palette().color(QPalette.Base))
      painter.fillRect(QRect(self.xposAddr, event.rect().top(), self.xposHex, self.height()), Qt.yellow)

      painter.setPen(Qt.black)
      # first and last index
      firstIndex = (int(event.rect().top() / self.charHeight) - self.charHeight) * BYTES_PER_LINE
      if firstIndex < 0:
         firstIndex = 0
      lastIndex = (int(event.rect().bottom() / self.charHeight) + self.charHeight) * BYTES_PER_LINE
      if lastIndex < 0:
         lastIndex = 0
      yposStart = int(firstIndex / BYTES_PER_LINE) * self.charHeight + self.charHeight

      ypos = yposStart
      for index in range(firstIndex, lastIndex, BYTES_PER_LINE):
         painter.drawText(self.xposAddr, ypos, '{0:08X}'.format(index))
         
         xpos = self.xposHex
         for colIndex in range(BYTES_PER_LINE):
            if index + colIndex < len(self.Data):
               b = '{0:02X}'.format(self.Data[index + colIndex])
               painter.drawText(xpos, ypos, b)
               xpos += 2 * self.charWidth
         ypos += self.charHeight

      # cursor
      if self.blinkcursor:
         painter.fillRect(self.cursorX, self.cursorY + self.charHeight - 2, self.charWidth, 2, Qt.blue)
   def keyPressEvent(self, event):
      if event.matches(QKeySequence.MoveToNextChar):
         self.setCursorPosition(self.cursorPosition + 1)
      if event.matches(QKeySequence.MoveToPreviousChar):
         self.setCursorPosition(self.cursorPosition - 1)
      if event.matches(QKeySequence.MoveToNextLine):
         self.setCursorPosition(self.cursorPosition + 2 * BYTES_PER_LINE)
      if event.matches(QKeySequence.MoveToPreviousLine):
         self.setCursorPosition(self.cursorPosition - 2 * BYTES_PER_LINE)
      self.ensureVisible()
      self.update()
   def ensureVisible(self):
      self.scrollArea.ensureVisible(self.cursorX, self.cursorY + self.charHeight, 3, self.charHeight / 2 + 2)
   def adjust(self):
      self.charHeight = self.fontMetrics().height()
      self.charWidth = self.fontMetrics().width('x')
      self.xposAddr = 2
      self.xposHex = self.xposAddr + 8 * self.charWidth + GAP
      self.xposAscii = self.xposHex + (BYTES_PER_LINE * 3 - 1) * self.charWidth + GAP
      self.setMinimumWidth(self.xposAscii + self.charWidth * BYTES_PER_LINE)
      self.setMinimumHeight((int(len(self.Data) / BYTES_PER_LINE) + 1) * self.charHeight)
      self.update()
   def getBytes(self, offset):
      return bytes()
   def setHexFile(self, hf):
      self.hexfile = hf
      self.update()
   def getData(self):
      return self.data
   def setData(self, d):
      self.data = d
      self.adjust()
      self.setCursorPosition(0)
   Data = property(getData, setData)

class HexEdit(QScrollArea):
   def __init__(self):
      super().__init__()
      self.setWidgetResizable(True)
      self.bv = BinViewer(self)
      self.setWidget(self.bv)
      self.setFocusPolicy(Qt.NoFocus)

if __name__ == '__main__':
   app = QApplication(sys.argv)
   he = HexEdit()
   he.show()
   he.bv.Data = bytearray(range(100)) * 8
   app.exec()