--- a/python/hexedit.py	Mon Jan 21 21:12:36 2013 +0100
+++ b/python/hexedit.py	Wed Jan 23 21:54:14 2013 +0100
@@ -3,7 +3,16 @@
 from PyQt4.QtGui import *
 
 BYTES_PER_LINE = 8
-GAP = 16
+GAP = 12
+
+def clamp(minimum, x, maximum):
+   return max(minimum, min(x, maximum))
+
+def asciiChar(v):
+   if v < 0x20 or v > 0x7e:
+      return '.'
+   else:
+      return chr(v)
 
 class BinViewer(QWidget):
    """ The view has an address, hex byte and ascii column """
@@ -13,10 +22,10 @@
       self.setFont(QFont('Courier', 18))
       self.setFocusPolicy(Qt.StrongFocus)
       self.blinkcursor = False
-      self.cursorX = 0
-      self.cursorY = 0
+      self.cursorX = self.cursorY = 0
       self.scrollArea = scrollArea
       self.Data = bytearray()
+      self.Offset = 0
       t = QTimer(self)
       t.timeout.connect(self.updateCursor)
       t.setInterval(500)
@@ -25,59 +34,57 @@
       self.blinkcursor = not self.blinkcursor
       self.update(self.cursorX, self.cursorY, self.charWidth, self.charHeight)
    def setCursorPosition(self, position):
-      position = int(position)
-      if position > len(self.Data) * 2 - 1:
-         position = len(self.Data) * 2 - 1
-      if position < 0:
-         position = 0
+      position = clamp(0, int(position), len(self.Data) * 2 - 1)
       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.cursorY = int(position / (2 * BYTES_PER_LINE)) * self.charHeight + 2
       self.blinkcursor = True
       self.update()
    def getCursorPosition(self):
       return self.cursorPosition
    CursorPosition = property(getCursorPosition, setCursorPosition)
+   def getOffset(self):
+      return self.offset
+   def setOffset(self, off):
+      self.offset = off
+      self.update()
+   Offset = property(getOffset, setOffset)
    def paintEvent(self, event):
+      # Helper variables:
+      er = event.rect()
+      chw, chh = self.charWidth, self.charHeight
       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.gray)
+      painter.fillRect(er, self.palette().color(QPalette.Base))
+      painter.fillRect(QRect(self.xposAddr, er.top(), 8 * chw, er.bottom() + 1), Qt.gray)
       painter.setPen(Qt.gray)
       x = self.xposAscii - (GAP / 2)
-      painter.drawLine(x, event.rect().top(), x, self.height())
-
-      painter.setPen(Qt.black)
+      painter.drawLine(x, er.top(), x, er.bottom())
+      x = self.xposEnd - (GAP / 2)
+      painter.drawLine(x, er.top(), x, er.bottom())
       # 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
-
+      firstIndex = max((int(er.top() / chh) - chh) * BYTES_PER_LINE, 0)
+      lastIndex = max((int(er.bottom() / chh) + chh) * BYTES_PER_LINE, 0)
+      yposStart = int(firstIndex / BYTES_PER_LINE) * chh + chh
+      # Draw contents:
+      painter.setPen(Qt.black)
       ypos = yposStart
       for index in range(firstIndex, lastIndex, BYTES_PER_LINE):
-         painter.drawText(self.xposAddr, ypos, '{0:08X}'.format(index))
-         
+         painter.drawText(self.xposAddr, ypos, '{0:08X}'.format(index + self.Offset))
          xpos = self.xposHex
-         xposA = self.xposAscii
+         xposAscii = self.xposAscii
          for colIndex in range(BYTES_PER_LINE):
             if index + colIndex < len(self.Data):
                b = self.Data[index + colIndex]
-               bhex = '{0:02X}'.format(b)
-               ba = chr(b)
-               painter.drawText(xpos, ypos, bhex)
-               painter.drawText(xposA, ypos, ba)
-               xpos += 2 * self.charWidth
-               xposA += self.charWidth
-         ypos += self.charHeight
-
+               painter.drawText(xpos, ypos, '{0:02X}'.format(b))
+               painter.drawText(xposAscii, ypos, asciiChar(b))
+               xpos += 2 * chw
+               xposAscii += chw
+         ypos += chh
       # cursor
       if self.blinkcursor:
-         painter.fillRect(self.cursorX, self.cursorY + self.charHeight - 2, self.charWidth, 2, Qt.black)
+         painter.fillRect(self.cursorX, self.cursorY + chh - 2, chw, 2, Qt.black)
    def keyPressEvent(self, event):
       if event.matches(QKeySequence.MoveToNextChar):
          self.CursorPosition += 1
@@ -87,6 +94,12 @@
          self.CursorPosition += 2 * BYTES_PER_LINE
       if event.matches(QKeySequence.MoveToPreviousLine):
          self.CursorPosition -= 2 * BYTES_PER_LINE
+      if event.matches(QKeySequence.MoveToNextPage):
+         rows = int(self.scrollArea.viewport().height() / self.charHeight)
+         self.CursorPosition += (rows - 1) * 2 * BYTES_PER_LINE
+      if event.matches(QKeySequence.MoveToPreviousPage):
+         rows = int(self.scrollArea.viewport().height() / self.charHeight)
+         self.CursorPosition -= (rows - 1) * 2 * BYTES_PER_LINE
       char = event.text().lower()
       if char and char in '0123456789abcdef':
          i = int(self.CursorPosition / 2)
@@ -113,12 +126,15 @@
    def adjust(self):
       self.charHeight = self.fontMetrics().height()
       self.charWidth = self.fontMetrics().width('x')
-      self.xposAddr = 2
+      self.xposAddr = GAP
       self.xposHex = self.xposAddr + 8 * self.charWidth + GAP
-      self.xposAscii = self.xposHex + (BYTES_PER_LINE * 2) * self.charWidth + GAP
-      self.setMinimumWidth(self.xposAscii + self.charWidth * BYTES_PER_LINE)
-      self.scrollArea.setMinimumWidth(self.xposAscii + self.charWidth * BYTES_PER_LINE)
+      self.xposAscii = self.xposHex + BYTES_PER_LINE * 2 * self.charWidth + GAP
+      self.xposEnd = self.xposAscii + self.charWidth * BYTES_PER_LINE + GAP
+      self.setMinimumWidth(self.xposEnd)
+      sbw = self.scrollArea.verticalScrollBar().width()
+      self.scrollArea.setMinimumWidth(self.xposEnd + sbw + 5)
       self.setMinimumHeight((int(len(self.Data) / BYTES_PER_LINE) + 1) * self.charHeight)
+      self.scrollArea.setMinimumHeight(self.charHeight * 8)
       self.update()
    def getData(self):
       return self.data
@@ -134,6 +150,7 @@
       self.bv = BinViewer(self)
       self.setWidget(self.bv)
       self.setWidgetResizable(True)
+      self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
       self.setFocusPolicy(Qt.NoFocus)
 
 if __name__ == '__main__':