From b99fb35727812fd8079589af6730ca4c09435c01 Mon Sep 17 00:00:00 2001
From: Andreas Huber <andreas.huber@lucares.de>
Date: Sun, 24 Oct 2021 20:02:11 +0200
Subject: [PATCH] scroll by wheel

---
 bigtext.py      | 13 ++++++++++-
 logFileModel.py | 62 ++++++++++++++++++++++++++++++++++++-------------
 2 files changed, 58 insertions(+), 17 deletions(-)

diff --git a/bigtext.py b/bigtext.py
index 4212cf0..b3afda2 100644
--- a/bigtext.py
+++ b/bigtext.py
@@ -20,6 +20,7 @@ from settings import Settings
 class BigText(QWidget):
     _byte_offset = 0
     _left_offset = 0
+    scroll_lines = 0
 
     highlights: [Highlight] = []
 
@@ -42,6 +43,14 @@ class BigText(QWidget):
     def paintEvent(self, event: QPaintEvent) -> None:
         self.draw()
 
+    def wheelEvent(self, event: QWheelEvent):
+        direction = 1 if event.angleDelta().y() > 0 else -1
+        #print("wheel event fired :) %s" % (direction))
+        self.scroll_lines = direction * 3
+        self.update()
+        #self.draw(direction * 3)
+        #self._vscrollbar.setValue(self._byte_offset)
+
     def mousePressEvent(self, e: QMouseEvent) -> None:
         if e.buttons() == Qt.MouseButton.LeftButton:
             offset = self.to_byte_offset(e)
@@ -80,7 +89,9 @@ class BigText(QWidget):
         self.update_font_metrics(painter)
 
         lines_to_show = self.height() / (self.fontMetrics().height())
-        self.lines = self.model.data(self._byte_offset, lines_to_show)
+        self.lines = self.model.data(self._byte_offset, self.scroll_lines, lines_to_show)
+        self.scroll_lines=0
+        self._byte_offset = self.lines[0].byte_offset()
 
         # draw hightlights first - some characters may overlap to the next line
         # by drawing the background hightlights first we prevent that the hightlight
diff --git a/logFileModel.py b/logFileModel.py
index 2594cd4..ab0139b 100644
--- a/logFileModel.py
+++ b/logFileModel.py
@@ -1,3 +1,4 @@
+import threading
 from typing import List
 import os
 from line import Line
@@ -6,27 +7,56 @@ from settings import Settings
 
 
 class LogFileModel:
+    _lock = threading.RLock()
+
     def __init__(self, file):
         self._file = file
 
-    def data(self, byte_offset:int, lines: int) -> List[Line]:
-        result : List[Line] = []
+    def data(self, byte_offset, scroll_lines, lines) -> List[Line]:
+        #print("data(%s, %s, %s)" % (byte_offset, scroll_lines, lines))
+        lines_before_offset: List[Line] = []
+        lines_after_offset: List[Line] = []
+        result: List[Line] = []
+        lines_to_find = lines  # + -1 * scroll_lines
 
-        # TODO handle lines longer than 4096 bytes
-        with open(self._file, 'r') as f:
-            offset = max(0, byte_offset - Settings.max_line_length())
-            offset = offset - offset % Settings.max_line_length() # align to blocks of 4kb
-            f.seek(offset)
-            while l := f.readline():
-                new_offset = f.tell()
-                if offset >= byte_offset:
-                    line = Line(offset, new_offset-1, l)
-                    result.append(line)
-                offset = new_offset
-                if len(result) >= lines:
-                    break
+        with self._lock:
+            # TODO handle lines longer than 4096 bytes
+            with open(self._file, 'rb') as f:
+                offset = min(byte_offset, self.byte_count())
+                offset = max(0, offset - Settings.max_line_length())
 
-        return result
+                #print("offset: %s" % (offset))
+
+                eof_reached = True
+                f.seek(offset)
+                while l := f.readline():
+                    new_offset = f.tell()
+                    line = Line(offset, new_offset, l.decode("utf8").replace("\r", "").replace("\n", ""))
+                    # print("%s %s" %(line.byte_offset(), line.line()))
+                    if offset < byte_offset:
+                        lines_before_offset.append(line)
+                    else:
+                        lines_after_offset.append(line)
+                    offset = f.tell()
+                    if len(lines_after_offset) >= lines_to_find:
+                        eof_reached = False
+                        break
+
+            if scroll_lines > 0:
+                result = result + lines_before_offset[-scroll_lines:]
+                result = result + lines_after_offset
+            elif eof_reached:
+                # we always return the number of requested lines even if we reach the end of the file
+                lines_to_return_from_before_offset = int(lines_to_find - len(lines_after_offset));
+                print(lines_to_return_from_before_offset)
+                if lines_to_return_from_before_offset > 0:
+                    result = result + lines_before_offset[-lines_to_return_from_before_offset:]
+                result = result + lines_after_offset
+            else:
+                result = result + lines_after_offset[-scroll_lines:]
+
+            #print("returning %s lines" % (len(result)))
+            return result
 
     def byte_count(self) -> int:
         return os.stat(self._file).st_size
\ No newline at end of file