Brush up the mandelbrot example

Port qtbase/0e69349f6f8e9445877ea5b2105973115ad79cf7:

The example refines the image by running a number of passes
with increasing number of iterations, which is not really
visible to the user. Set an informational text string on
the generated image which provides this information
along with the elapsed time.
The idea is to do the same to the corresponding
Qt for Python example to have some sort of speed comparison
for number crunching.

Add a command line option for the number of passes.

Make the window a bit larger to accommodate the
information.

Task-number: PYSIDE-1112
Change-Id: I9313f860947386123166f794b80b541bc057be2c
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

1 files changed, 47 insertions, 8 deletions

diff --git a/examples/corelib/threads/mandelbrot.py b/examples/corelib/threads/mandelbrot.py
index b9d9ad681..e184d6529 100644
--- a/examples/corelib/threads/mandelbrot.py
+++ b/examples/corelib/threads/mandelbrot.py
@@ -42,8 +42,12 @@
 
 """PySide6 port of the corelib/threads/mandelbrot example from Qt v5.x, originating from PyQt"""
 
-from PySide6.QtCore import (Signal, QMutex, QMutexLocker, QPointF, QSize, Qt,
-        QThread, QWaitCondition)
+from argparse import ArgumentParser, RawTextHelpFormatter
+import sys
+
+from PySide6.QtCore import (Signal, QMutex, QElapsedTimer, QMutexLocker,
+                            QPoint, QPointF, QSize, Qt, QThread,
+                            QWaitCondition)
 from PySide6.QtGui import QColor, QImage, QPainter, QPixmap, qRgb
 from PySide6.QtWidgets import QApplication, QWidget
 
@@ -57,6 +61,16 @@ ZOOM_OUT_FACTOR = 1 / ZOOM_IN_FACTOR
 SCROLL_STEP = 20
 
 
+NUM_PASSES = 8
+
+
+INFO_KEY = 'info'
+
+
+HELP = "Use mouse wheel or the '+' and '-' keys to zoom. Press and " \
+       "hold left mouse button to scroll."
+
+
 class RenderThread(QThread):
     colormap_size = 512
 
@@ -102,6 +116,8 @@ class RenderThread(QThread):
             self.condition.wakeOne()
 
     def run(self):
+        timer = QElapsedTimer()
+
         while True:
             self.mutex.lock()
             resultSize = self._result_size
@@ -114,10 +130,10 @@ class RenderThread(QThread):
             half_height = resultSize.height() // 2
             image = QImage(resultSize, QImage.Format_RGB32)
 
-            NUM_PASSES = 8
             curpass = 0
 
             while curpass < NUM_PASSES:
+                timer.restart()
                 max_iterations = (1 << (2 * curpass + 6)) + 32
                 LIMIT = 4
                 all_black = True
@@ -164,6 +180,13 @@ class RenderThread(QThread):
                     curpass = 4
                 else:
                     if not self.restart:
+                        elapsed = timer.elapsed();
+                        unit = 'ms'
+                        if elapsed > 2000:
+                            elapsed /= 1000
+                            unit = 's'
+                        text = f"Pass {curpass+1}/{NUM_PASSES}, max iterations: {max_iterations}, time: {elapsed}{unit}"
+                        image.setText(INFO_KEY, text);
                         self.rendered_image.emit(image, scale_factor)
                     curpass += 1
 
@@ -227,7 +250,7 @@ class MandelbrotWidget(QWidget):
 
         self.setWindowTitle("Mandelbrot")
         self.setCursor(Qt.CrossCursor)
-        self.resize(550, 400)
+        self._info = ''
 
     def paintEvent(self, event):
         painter = QPainter(self)
@@ -256,8 +279,9 @@ class MandelbrotWidget(QWidget):
             painter.drawPixmap(exposed, self.pixmap, exposed)
             painter.restore()
 
-        text = "Use mouse wheel or the '+' and '-' keys to zoom. Press and " \
-                "hold left mouse button to scroll."
+        text = HELP
+        if self._info:
+            text += ' ' + self._info
         metrics = painter.fontMetrics()
         text_width = metrics.horizontalAdvance(text)
 
@@ -285,6 +309,8 @@ class MandelbrotWidget(QWidget):
             self.scroll(0, -SCROLL_STEP)
         elif event.key() == Qt.Key_Up:
             self.scroll(0, +SCROLL_STEP)
+        elif event.key() == Qt.Key_Q:
+            self.close()
         else:
             super(MandelbrotWidget, self).keyPressEvent(event)
 
@@ -318,6 +344,7 @@ class MandelbrotWidget(QWidget):
         if not self._last_drag_pos.isNull():
             return
 
+        self._info = image.text(INFO_KEY)
         self.pixmap = QPixmap.fromImage(image)
         self._pixmap_offset = QPointF()
         self._last_drag_position = QPointF()
@@ -339,11 +366,23 @@ class MandelbrotWidget(QWidget):
 
 
 if __name__ == '__main__':
-
-    import sys
+    parser = ArgumentParser(description='Qt Mandelbrot Example',
+                            formatter_class=RawTextHelpFormatter)
+    parser.add_argument('--passes', '-p', type=int, help='Number of passes (1-8)')
+    options = parser.parse_args()
+    if options.passes:
+        NUM_PASSES = int(options.passes)
+        if NUM_PASSES < 1 or NUM_PASSES > 8:
+            print(f'Invalid value: {options.passes}')
+            sys.exit(-1)
 
     app = QApplication(sys.argv)
     widget = MandelbrotWidget()
+    geometry = widget.screen().availableGeometry()
+    widget.resize((2 * geometry.size()) / 3)
+    pos = (geometry.size() - widget.size()) / 2
+    widget.move(geometry.topLeft() + QPoint(pos.width(), pos.height()))
+
     widget.show()
     r = app.exec_()
     widget.thread.stop()