Added preview of output image quality.

png-to-jpeg/convert.py

@@ -1,7 +1,9 @@
 import logging
 import os
+from io import BytesIO
 
 from PIL import Image
+from PyQt5 import QtGui
 
 
 def convert_png_to_jpeg(file_paths: list, destination_folder: str, quality: int):
@@ -46,3 +48,18 @@ def get_file_list_from_folder(folder_to_check: str) -> list:
             file_path_list.append(abs_path)
 
     return file_path_list
+
+
+def get_preview_pixmap(filepath: str, quality: int) -> QtGui.QPixmap:
+    """
+    Returns a QPixmap showing the result of a conversion of the given file and given quality.
+    :param filepath: Path to the PNG file being converted.
+    :param quality: Quality of the output JPEG file
+    :return: QPixmap of converted JPEG
+    """
+
+    im = Image.open(filepath)
+    rgb_im = im.convert('RGB')
+    output = BytesIO()
+    rgb_im.save(output, format="JPEG", quality=quality)
+    return QtGui.QPixmap.fromImage(QtGui.QImage.fromData(output.getvalue()))

png-to-jpeg/view.py

@@ -1,8 +1,8 @@
 import os
 
-from PyQt5 import QtWidgets, QtCore
+from PyQt5 import QtWidgets, QtCore, QtGui
 
-from convert import get_file_list_from_folder, convert_png_to_jpeg
+from convert import get_file_list_from_folder, convert_png_to_jpeg, get_preview_pixmap
 
 
 class MainPage(QtWidgets.QMainWindow):
@@ -55,6 +55,11 @@ def __init__(self):
         button_convert = QtWidgets.QPushButton("Convert")
         button_convert.clicked.connect(self.on_convert_clicked)
 
+        # Selected image preview
+        layout_preview = QtWidgets.QLabel("Quality preview")
+        self.quality_preview_label = QtWidgets.QLabel()
+        self.quality_preview_label.setMaximumSize(250, 250)
+
         # Add widgets to the left panel
         layout_left_panel.addWidget(label_browse_files)
         layout_left_panel.addWidget(button_browse_files)
@@ -64,6 +69,8 @@ def __init__(self):
         layout_left_panel.addWidget(label_choose_destination)
         layout_left_panel.addWidget(widget_output_location)
         layout_left_panel.addWidget(button_convert)
+        layout_left_panel.addWidget(layout_preview)
+        layout_left_panel.addWidget(self.quality_preview_label)
 
         # Create right panel
         right_panel = QtWidgets.QWidget()
@@ -73,6 +80,7 @@ def __init__(self):
         # Found items listview
         label_found_files = QtWidgets.QLabel("Files to convert")
         self.list_found_files = QtWidgets.QListWidget()
+        self.list_found_files.clicked.connect(self.refresh_preview)
 
         # Add widgets to right panel
         layout_right_panel.addWidget(label_found_files)
@@ -82,6 +90,11 @@ def __init__(self):
         central_layout.addWidget(right_panel)
         self.setCentralWidget(central_widget)
 
+    def refresh_preview(self):
+        if self.list_found_files.currentRow() >= 0:
+            pixmap = get_preview_pixmap(self.file_list[self.list_found_files.currentRow()], self.slider_quality.value())
+            self.quality_preview_label.setPixmap(pixmap)
+
     def on_browse_clicked(self):
         filepath = QtWidgets.QFileDialog.getExistingDirectory(self, "Open Directory")
         if filepath != '':
@@ -94,6 +107,7 @@ def on_browse_clicked(self):
 
     def on_slider_updated(self, value):
         self.label_quality.setText(str(value))
+        self.refresh_preview()
 
     def on_output_clicked(self):
         filepath = QtWidgets.QFileDialog.getExistingDirectory(self, "Open Directory")