From adac558aabb64e292eb13937b51a8bbd07433e45 Mon Sep 17 00:00:00 2001
From: Alex Xu <alexkurosakimh3@gmail.com>
Date: Wed, 26 Aug 2026 13:05:14 -0700
Subject: [PATCH] shift click label spreads for HQ preview (#1427)

---
 gui/KCC.ui                      |  3 +++
 kindlecomicconverter/KCC_gui.py | 30 +++++++++++++++++++-----------
 kindlecomicconverter/KCC_ui.py  |  3 +++
 3 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/gui/KCC.ui b/gui/KCC.ui
index acfe7a60..25d0c401 100644
--- a/gui/KCC.ui
+++ b/gui/KCC.ui
@@ -779,6 +779,9 @@ Keeping this file may crash some readers like the Kobo native CBZ reader.</strin
            <height>30</height>
           </size>
          </property>
+         <property name="toolTip">
+          <string>Hold shift while clicking for a higher quality preview.</string>
+         </property>
          <property name="text">
           <string>Label Spreads</string>
          </property>
diff --git a/kindlecomicconverter/KCC_gui.py b/kindlecomicconverter/KCC_gui.py
index d9dff252..c3f24078 100644
--- a/kindlecomicconverter/KCC_gui.py
+++ b/kindlecomicconverter/KCC_gui.py
@@ -671,6 +671,9 @@ class KCCGUI(KCC_ui.Ui_mainWindow):
                     GUI.jobList.scrollToBottom()
 
     def labelSpreadsStart(self):
+        low_quality_preview = True
+        if QApplication.keyboardModifiers() == Qt.ShiftModifier:
+            low_quality_preview = False
         currentJobs = []
         # TODO: make this a function since it's copy pasted
         for i in range(GUI.jobList.count()):
@@ -704,29 +707,34 @@ class KCCGUI(KCC_ui.Ui_mainWindow):
                         continue 
                     # TODO: with statements
                     # TODO: ignore 1% of top and bottom too?
-                    im1 = Image.open(os.path.join(root, files[i])).convert('1', dither=Dither.NONE)
+                    im1 = Image.open(os.path.join(root, files[i]))
                     size1 = im1.size
-                    crop1 = im1.crop((0, 0, 0.2*size1[0], size1[1]))
-                    crop11 = im1.crop((0.01*size1[0], 0, 0.04*size1[0], size1[1]))
+                    preview_crop1 = im1.crop((0, 0, 0.2*size1[0], size1[1]))
+                    if low_quality_preview:
+                        preview_crop1 = preview_crop1.convert('1', dither=Dither.NONE)
+                    calculation_crop1 = im1.crop((0.01*size1[0], 0, 0.04*size1[0], size1[1])).convert('1', dither=Dither.NONE)
                     #crop1 = crop11
-                    im2 = Image.open(os.path.join(root, files[i+1])).convert('1', dither=Dither.NONE)
+                    im2 = Image.open(os.path.join(root, files[i+1]))
                     size2 = im2.size
-                    crop2 = im2.crop((0.8*size2[0], 0, size2[0], size2[1]))
-                    crop22 = im2.crop((0.96*size2[0], 0, .99* size2[0], size2[1]))
+                    preview_crop2 = im2.crop((0.8*size2[0], 0, size2[0], size2[1]))
+                    if low_quality_preview:
+                        preview_crop2 = preview_crop2.convert('1', dither=Dither.NONE)
+                    calculation_crop2 = im2.crop((0.96*size2[0], 0, .99* size2[0], size2[1])).convert('1', dither=Dither.NONE)
                     #crop2 = crop22
                     # dst = Image.new('1', (im1.width + im2.width, im1.height))
                     # dst.paste(im2, (0, 0))
                     # dst.paste(im1, (im1.width, 0))
-                    hist1 = crop11.histogram()
-                    hist2 = crop22.histogram()
+                    hist1 = calculation_crop1.histogram()
+                    hist2 = calculation_crop2.histogram()
                     # TODO: small percentage instead of zero
                     if hist1[0] == 0 or hist1[-1] == 0 or hist2[0] == 0 or hist2[-1] == 0:
                         continue
 
-                    dst = Image.new('1', (crop1.width + crop2.width, crop1.height))
+                    preview_mode = '1' if low_quality_preview else 'RGB'
+                    dst = Image.new(preview_mode, (preview_crop1.width + preview_crop2.width, preview_crop1.height))
 
-                    dst.paste(crop2, (0, 0))
-                    dst.paste(crop1, (crop1.width, 0))
+                    dst.paste(preview_crop2, (0, 0))
+                    dst.paste(preview_crop1, (preview_crop1.width, 0))
                     dst.save(os.path.join(workdir, f'label-{i:04}.png'))
                     images.append(os.path.join(workdir, f'label-{i:04}.png'))
 
diff --git a/kindlecomicconverter/KCC_ui.py b/kindlecomicconverter/KCC_ui.py
index 9c777dac..6a726de2 100644
--- a/kindlecomicconverter/KCC_ui.py
+++ b/kindlecomicconverter/KCC_ui.py
@@ -860,6 +860,9 @@ class Ui_mainWindow(object):
         self.editorButton.setText(QCoreApplication.translate("mainWindow", u"Metadata Editor", None))
         self.humbleButton.setText(QCoreApplication.translate("mainWindow", u"Humble Bundle Referral", None))
         self.kofiButton.setText(QCoreApplication.translate("mainWindow", u"Support me on Ko-fi", None))
+#if QT_CONFIG(tooltip)
+        self.labelSpreadsButton.setToolTip(QCoreApplication.translate("mainWindow", u"Hold shift while clicking for a higher quality preview.", None))
+#endif // QT_CONFIG(tooltip)
         self.labelSpreadsButton.setText(QCoreApplication.translate("mainWindow", u"Label Spreads", None))
 #if QT_CONFIG(tooltip)
         self.chunkSizeWidget.setToolTip(QCoreApplication.translate("mainWindow", u"<html><head/><body><p>Warning: chunk size greater than default may cause<br/>performance/battery issues, especially on older devices.</p></body></html>", None))