From efe9a1b99507d742b8c685495480d4934196a59e Mon Sep 17 00:00:00 2001
From: Igor Kushnir <igorkuo@gmail.com>
Date: Wed, 10 Mar 2021 14:59:36 +0200
Subject: [PATCH] MagnifyingGlass: get rid of C-style casts to Viewer*

qobject_cast<const Viewer *> improves const correctness.
QLabel::pixmap() is const-qualified => make Viewer::pixmap() const too.

Return non-const QPixmap from Viewer::pixmap() to let compiler move the
return value at the function's call sites.

Introduce a named constant maxRelativeDimension. Change its type from
float to double, which usually multiplies faster on x86-64.

Remove redundant parentheses to improve readability.
---
 YACReader/magnifying_glass.cpp | 13 ++++++-------
 YACReader/viewer.cpp           |  2 +-
 YACReader/viewer.h             |  2 +-
 3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/YACReader/magnifying_glass.cpp b/YACReader/magnifying_glass.cpp
index d2b8f458..839b1b6c 100644
--- a/YACReader/magnifying_glass.cpp
+++ b/YACReader/magnifying_glass.cpp
@@ -36,7 +36,7 @@ void MagnifyingGlass::updateImage(int x, int y)
     // image section augmented
     int zoomWidth = static_cast<int>(width() * zoomLevel);
     int zoomHeight = static_cast<int>(height() * zoomLevel);
-    auto p = (Viewer *)parent();
+    auto *const p = qobject_cast<const Viewer *>(parentWidget());
     int currentPos = p->verticalScrollBar()->sliderPosition();
     const QPixmap image = p->pixmap();
     int iWidth = image.width();
@@ -191,10 +191,11 @@ void MagnifyingGlass::zoomOut()
     }
 }
 
+static constexpr auto maxRelativeDimension = 0.9;
+
 void MagnifyingGlass::sizeUp()
 {
-    auto p = (Viewer *)parent();
-    if (width() < (p->width() * 0.90f))
+    if (width() < parentWidget()->width() * maxRelativeDimension)
         resizeAndUpdate(width() + 30, height() + 15);
 }
 
@@ -206,8 +207,7 @@ void MagnifyingGlass::sizeDown()
 
 void MagnifyingGlass::heightUp()
 {
-    auto p = (Viewer *)parent();
-    if (height() < (p->height() * 0.90f))
+    if (height() < parentWidget()->height() * maxRelativeDimension)
         resizeAndUpdate(width(), height() + 15);
 }
 
@@ -219,8 +219,7 @@ void MagnifyingGlass::heightDown()
 
 void MagnifyingGlass::widthUp()
 {
-    auto p = (Viewer *)parent();
-    if (width() < (p->width() * 0.90f))
+    if (width() < parentWidget()->width() * maxRelativeDimension)
         resizeAndUpdate(width() + 30, height());
 }
 
diff --git a/YACReader/viewer.cpp b/YACReader/viewer.cpp
index edda73de..4a942df2 100644
--- a/YACReader/viewer.cpp
+++ b/YACReader/viewer.cpp
@@ -748,7 +748,7 @@ void Viewer::mouseMoveEvent(QMouseEvent *event)
     }
 }
 
-const QPixmap Viewer::pixmap()
+QPixmap Viewer::pixmap() const
 {
 #if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     return content->pixmap();
diff --git a/YACReader/viewer.h b/YACReader/viewer.h
index ee5bbda9..e86562d5 100644
--- a/YACReader/viewer.h
+++ b/YACReader/viewer.h
@@ -181,7 +181,7 @@ private:
 public:
     Viewer(QWidget *parent = nullptr);
     ~Viewer();
-    const QPixmap pixmap();
+    QPixmap pixmap() const;
     // Comic * getComic(){return comic;}
     const BookmarksDialog *getBookmarksDialog() { return bd; }
     // returns the current index starting in 1 [1,nPages]