Feature: Enhanced Editing, Hex Inspector, Color Shortcuts

- Enhanced Editing: Auto-create packets, Enter key support.
- Cursor: Fixed visibility (composition mode), click-to-move, immediate redraw.
- Hex Inspector: Added Hex Value display and input panel.
- Shortcuts: Added Color Insert buttons.
- Fixes: Resolved Hamming encoding for save, fixed duplicate spaces bug, fixed IndentationError.

src/teletext/io.py

@@ -62,24 +62,74 @@ def load_t42(file_path: str) -> TeletextService:
 
     return service
 
+
+def encode_hamming_8_4(value):
+    # Value is 4 bits (0-15)
+    d1 = (value >> 0) & 1
+    d2 = (value >> 1) & 1
+    d3 = (value >> 2) & 1
+    d4 = (value >> 3) & 1
+    
+    # Parity bits (Odd parity default? Or standard Hamming?)
+    # Teletext spec: 
+    # P1 = 1 + D1 + D2 + D4 (mod 2) -> Inverse of even parity check?
+    # Actually, simpler to look up or calculate. 
+    # Let's match typical implementation:
+    # P1 (b0) covers 1,3,7 (D1, D2, D4)
+    # P2 (b2) covers 1,5,7 (D1, D3, D4)
+    # P3 (b4) covers 3,5,7 (D2, D3, D4)
+    # P4 (b6) covers all.
+    # Teletext uses ODD parity for the hamming bits usually?
+    # "Hamming 8/4 with odd parity"
+    
+    p1 = 1 ^ d1 ^ d2 ^ d4
+    p2 = 1 ^ d1 ^ d3 ^ d4
+    p3 = 1 ^ d2 ^ d3 ^ d4
+    
+    res = (p1 << 0) | (d1 << 1) | \
+          (p2 << 2) | (d2 << 3) | \
+          (p3 << 4) | (d3 << 5) | \
+          (d4 << 7)
+          
+    # P4 (bit 6) makes total bits odd
+    # Count set bits so far
+    set_bits = bin(res).count('1')
+    p4 = 1 if (set_bits % 2 == 0) else 0
+    
+    res |= (p4 << 6)
+    
+    return res
+
 def save_t42(file_path: str, service: TeletextService):
     with open(file_path, 'wb') as f:
-        # User requirement: "without rearranging the order of the packets"
-        # Implies we should iterate the original list.
-        # However, if we edit data, we modify the Packet objects in place.
-        # If we Add/Delete packets, we need to handle that.
-        
         for packet in service.all_packets:
-            # Reconstruct the 42 bytes from the packet fields
-            # The packet.data (bytearray) should be mutable and edited by the UI.
-            # packet.original_data (first 2 bytes) + packet.data
+            # Reconstruct header bytes from packet.magazine and packet.row
+            # Byte 1: M1 M2 M3 R1
+            # Byte 2: R2 R3 R4 R5
             
-            # Note: If we changed Magazine or Row, we'd need to re-encode the first 2 bytes.
-            # For now, assume we primarily edit content (bytes 2-41).
+            mag = packet.magazine
+            if mag == 8: mag = 0 # 0 encoded as 8
             
-            header = packet.original_data[:2] # Keep original address for now
-            # TODO: regenerating header if Mag/Row changed
+            # Bits:
+            # B1 data: M1(0) M2(1) M3(2) R1(3)
+            m1 = (mag >> 0) & 1
+            m2 = (mag >> 1) & 1
+            m3 = (mag >> 2) & 1
+            r1 = (packet.row >> 0) & 1
             
+            b1_val = m1 | (m2 << 1) | (m3 << 2) | (r1 << 3)
+            b1_enc = encode_hamming_8_4(b1_val)
+            
+            # B2 data: R2(0) R3(1) R4(2) R5(3)
+            r2 = (packet.row >> 1) & 1
+            r3 = (packet.row >> 2) & 1
+            r4 = (packet.row >> 3) & 1
+            r5 = (packet.row >> 4) & 1
+            
+            b2_val = r2 | (r3 << 1) | (r4 << 2) | (r5 << 3)
+            b2_enc = encode_hamming_8_4(b2_val)
+            
+            header = bytes([b1_enc, b2_enc])
             f.write(header + packet.data)
 
 def decode_hamming_8_4(byte_val):

src/teletext/renderer.py

@@ -6,6 +6,40 @@ from PyQt6.QtCore import Qt, QRect, QSize, pyqtSignal
 from .models import Page, Packet
 from .charsets import get_char
 
+# Helper to create a blank packet
+def create_blank_packet(magazine: int, row: int) -> Packet:
+    # 42 bytes
+    # Bytes 0-1: Address (Hamming encoded)
+    # We need to compute Hamming for M and R.
+    # For now, let's just make a placeholder that "looks" okay or use 0x00 and let a future saver fix it.
+    # But wait, `Packet` expects 42 bytes input.
+    
+    # Ideally we should implement the hamming encoder from `io.py` or similar.
+    # For now, we will create a Packet with dummy address bytes and correct mag/row properties set manually if needed,
+    # OR we just construct the bytes.
+    
+    # Let's rely on the Packet class parsing... which is annoying if we can't easily encode.
+    # Hack: default to 0x00 0x00, then manually set .magazine and .row
+    
+    data = bytearray(42)
+    # Set spaces
+    data[2:] = b'\x20' * 40
+    
+    p = Packet(bytes(data))
+    # Override
+    p.magazine = magazine
+    p.row = row
+    p.data = bytearray(b'\x20' * 40)
+    
+    # We really should set the address bytes correctly so saving works "naturally".
+    # But `save_t42` uses `packet.original_data[:2]`.
+    # So we MUST encode properly or `save_t42` needs to regenerate headers.
+    
+    # Let's defer proper Hamming encoding to the Save step (as noted in TODO in io.py).
+    # For in-memory editing, this is fine.
+    return p
+
+
 # Teletext Palette
 COLORS = [
     QColor(0, 0, 0),       # Black
@@ -19,8 +53,11 @@ COLORS = [
 ]
 
 class TeletextCanvas(QWidget):
+    cursorChanged = pyqtSignal(int, int, int) # x, y, byte_val
+
     def __init__(self, parent=None):
         super().__init__(parent)
+        self.setMouseTracking(True) # Just in case
         self.setMinimumSize(480, 500) # 40x12 * 25x20 approx
         self.page: Page = None
         self.subset_idx = 0 # Default English
@@ -48,15 +85,57 @@ class TeletextCanvas(QWidget):
         self.cursor_visible = True
         # Blinking cursor timer could be added, for now static inverted is fine or toggle on timer elsewhere
 
+    def get_byte_at(self, x, y):
+        if not self.page: return 0
+        
+        # Row 0 special logic (header) - returning what is displayed or raw?
+        # User probably wants RAW byte for editing.
+        
+        packet = None
+        for p in self.page.packets:
+            if p.row == y:
+                packet = p
+                break
+        
+        if packet and 0 <= x < 40:
+             return packet.data[x]
+        return 0
+
+    def emit_cursor_change(self):
+        val = self.get_byte_at(self.cursor_x, self.cursor_y)
+        self.cursorChanged.emit(self.cursor_x, self.cursor_y, val)
+
     def set_cursor(self, x, y):
         self.cursor_x = max(0, min(self.cols - 1, x))
         self.cursor_y = max(0, min(self.rows - 1, y))
+        self.redraw()
         self.update()
+        self.emit_cursor_change()
 
     def move_cursor(self, dx, dy):
         self.cursor_x = max(0, min(self.cols - 1, self.cursor_x + dx))
         self.cursor_y = max(0, min(self.rows - 1, self.cursor_y + dy))
+        self.redraw()
         self.update()
+        self.emit_cursor_change()
+
+    def set_byte_at_cursor(self, byte_val):
+        if not self.page: return
+        
+        packet = None
+        for p in self.page.packets:
+            if p.row == self.cursor_y:
+                packet = p
+                break
+        
+        if packet:
+            if 0 <= self.cursor_x < 40:
+                packet.data[self.cursor_x] = byte_val
+                self.redraw()
+                self.emit_cursor_change()
+        else:
+            # Create packet if missing
+            self.handle_input(chr(byte_val)) # Lazy reuse or duplicate create logic
     
     def set_page(self, page: Page):
         self.page = page
@@ -64,6 +143,7 @@ class TeletextCanvas(QWidget):
         self.cursor_y = 0
         self.redraw()
         self.update()
+        self.emit_cursor_change()
 
     def handle_input(self, text):
         if not self.page:
@@ -96,10 +176,24 @@ class TeletextCanvas(QWidget):
                     self.redraw()
                     self.move_cursor(1, 0)
         else:
-            # Create a packet if it doesn't exist for this row?
-            # Creating new packets in a T42 stream is tricky (insertion).
-            # For now, only edit existing rows.
-            pass
+            # Create a packet if it doesn't exist for this row
+            if 0 <= self.cursor_x < 40:
+                 # Check if we should create it
+                 # Only if input is valid char?
+                if len(text) == 1:
+                     # Create new packet
+                     new_packet = create_blank_packet(self.page.magazine, self.cursor_y)
+                     self.page.packets.append(new_packet)
+                     # Sort packets by row? Or just append. Renderer handles unordered.
+                     # But for sanity, let's just append.
+                     
+                     # Write the char
+                     byte_val = ord(text)
+                     if byte_val > 255: byte_val = 0x3F
+                     new_packet.data[self.cursor_x] = byte_val
+                     
+                     self.redraw()
+                     self.move_cursor(1, 0)
         
     def redraw(self):
         self.buffer.fill(Qt.GlobalColor.black)
@@ -223,11 +317,48 @@ class TeletextCanvas(QWidget):
             # Draw Cursor
             # Invert the cell at cursor position
             if self.cursor_visible and c == self.cursor_x and row == self.cursor_y:
-                 painter.setCompositionMode(QPainter.CompositionMode.RasterOp_NotSourceXorDestination)
-                 # XOR with white (creates inversion)
+                 painter.setCompositionMode(QPainter.CompositionMode.CompositionMode_Difference)
+                 # Difference with white creates inversion
                  painter.fillRect(x, y, self.cell_w, self.cell_h, QColor(255, 255, 255))
                  painter.setCompositionMode(QPainter.CompositionMode.CompositionMode_SourceOver)
 
+    def mousePressEvent(self, event):
+        self.setFocus()
+        # Calculate cell from mouse position
+        # Need to account for scaling? 
+        # The widget sizes to fit, but we render to a fixed buffer then scale up.
+        # paintEvent scales buffer to self.rect().
+        
+        # This is a bit tricky because paintEvent uses aspect-ratio scaling and centering.
+        # We need to reverse the mapping.
+        
+        target_rect = self.rect()
+        # Re-calc scale and offset
+        # Note: This logic duplicates paintEvent, commonize?
+        
+        # Simple approximation for MVP:
+        # If the window is roughly aspect ratio correct, direct mapping works.
+        # If not, we need offset.
+        
+        # Let's get the exact rect used in paintEvent
+        scale_x = target_rect.width() / self.img_w
+        scale_y = target_rect.height() / self.img_h
+        scale = min(scale_x, scale_y)
+        
+        dw = self.img_w * scale
+        dh = self.img_h * scale
+        
+        ox = (target_rect.width() - dw) / 2
+        oy = (target_rect.height() - dh) / 2
+        
+        mx = event.pos().x() - ox
+        my = event.pos().y() - oy
+        
+        if 0 <= mx < dw and 0 <= my < dh:
+             col = int(mx / (self.cell_w * scale))
+             row = int(my / (self.cell_h * scale))
+             self.set_cursor(col, row)
+             
     def draw_mosaic(self, painter, x, y, char_code, color, contiguous):
         val = char_code & 0x7F
         bits = 0

src/teletext/ui.py

@@ -1,7 +1,10 @@
 
-import os
 from PyQt6.QtWidgets import (QMainWindow, QWidget, QVBoxLayout, QHBoxLayout, 
-                             QListWidget, QListWidgetItem, QComboBox, QLabel, QFileDialog, QMenuBar, QMenu, QMessageBox)
+                             QListWidget, QListWidgetItem, QComboBox, QLabel, QLineEdit, QPushButton, QFileDialog, QMenuBar, QMenu, QMessageBox)
+
+# ... (imports remain)
+
+# ... (imports remain)
 from PyQt6.QtGui import QAction, QKeyEvent
 from PyQt6.QtCore import Qt
 
@@ -34,6 +37,19 @@ class MainWindow(QMainWindow):
         self.page_list.itemClicked.connect(self.on_page_selected)
         left_layout.addWidget(self.page_list)
         
+        # Hex Inspector
+        hex_layout = QVBoxLayout()
+        hex_label = QLabel("Hex Value:")
+        self.hex_input = QLineEdit()
+        self.hex_input.setMaxLength(2)
+        self.hex_input.setPlaceholderText("00")
+        self.hex_input.returnPressed.connect(self.on_hex_entered)
+        hex_layout.addWidget(hex_label)
+        hex_layout.addWidget(self.hex_input)
+        left_layout.addLayout(hex_layout)
+        
+        left_layout.addStretch()
+        
         self.layout.addLayout(left_layout)
         
         # Center Area Layout (Top Bar + Canvas)
@@ -51,8 +67,30 @@ class MainWindow(QMainWindow):
         
         center_layout.addLayout(top_bar)
         
+        # Color Shortcuts
+        color_layout = QHBoxLayout()
+        colors = [
+            ("Red", 0x01, "#FF0000"),
+            ("Green", 0x02, "#00FF00"),
+            ("Yellow", 0x03, "#FFFF00"),
+            ("Blue", 0x04, "#0000FF"),
+            ("Magenta", 0x05, "#FF00FF"),
+            ("Cyan", 0x06, "#00FFFF"),
+            ("White", 0x07, "#FFFFFF"),
+        ]
+        
+        for name, code, hex_color in colors:
+            btn = QPushButton(name)
+            btn.setStyleSheet(f"background-color: {hex_color}; font-weight: bold; color: black;")
+            btn.clicked.connect(lambda checked, c=code: self.insert_char(c))
+            color_layout.addWidget(btn)
+            
+        color_layout.addStretch()
+        center_layout.addLayout(color_layout)
+
         # Canvas
         self.canvas = TeletextCanvas()
+        self.canvas.cursorChanged.connect(self.on_cursor_changed)
         center_layout.addWidget(self.canvas, 1) # Expand
         
         self.layout.addLayout(center_layout, 1)
@@ -165,6 +203,28 @@ class MainWindow(QMainWindow):
             self.canvas.set_page(page)
             self.canvas.setFocus()
 
+    def insert_char(self, char_code):
+        self.canvas.set_byte_at_cursor(char_code)
+        # Advance cursor
+        self.canvas.move_cursor(1, 0)
+        self.canvas.setFocus()
+            
+    def on_cursor_changed(self, x, y, val):
+        self.hex_input.setText(f"{val:02X}")
+        
+    def on_hex_entered(self):
+        text = self.hex_input.text()
+        try:
+            val = int(text, 16)
+            if 0 <= val <= 255:
+                # Update canvas input
+                # We can call handle_input with char, OR set byte directly. 
+                # Direct byte set is safer for non-printable.
+                self.canvas.set_byte_at_cursor(val)
+                self.canvas.setFocus() # Return focus to canvas
+        except ValueError:
+            pass # Ignore invalid hex
+            
     # Input Handling (Editor Logic)
     def keyPressEvent(self, event: QKeyEvent):
         if not self.current_page:
@@ -182,6 +242,10 @@ class MainWindow(QMainWindow):
             self.canvas.move_cursor(-1, 0)
         elif key == Qt.Key.Key_Right:
             self.canvas.move_cursor(1, 0)
+        elif key == Qt.Key.Key_Return or key == Qt.Key.Key_Enter:
+            # Move to start of next line
+            self.canvas.cursor_x = 0
+            self.canvas.move_cursor(0, 1)
         else:
             # Typing
             # Filter non-printable