From 652b1fa57a82d9f9288e46e1d47bb4f9920fbd09 Mon Sep 17 00:00:00 2001
From: Johannes Lorenz <1042576+JohannesLorenz@users.noreply.github.com>
Date: Sun, 12 Nov 2023 02:21:51 +0100
Subject: [PATCH] SubWindow: Increase to respect child's sizeHint (#6956)

Before this commit, on creation, `SubWindow` gets resized to exactly the
children's `sizeHint`. This makes the child too small, since the
`SubWindow` already contains a title bar and borders.

With this commit, the `SubWindow` is calculated such that after
rendering, the child window gets exactly the `size` that its `sizeHint`
has previously suggested.

Most of LMMS widgets are not resizable, but the Lv2 help window is a
good example to test this out. The help windows now in most cases
contain enough space to fit the help text. In some cases, it still does
not fit, though debug prints show that the `size` matches the
`sizeHint`.
---
 include/SubWindow.h    |  2 ++
 src/gui/MainWindow.cpp | 10 +++++++++-
 src/gui/SubWindow.cpp  | 32 +++++++++++++++++++++++++++-----
 3 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/include/SubWindow.h b/include/SubWindow.h
index fdda6de42..d1cc6a7af 100644
--- a/include/SubWindow.h
+++ b/include/SubWindow.h
@@ -68,6 +68,8 @@ public:
 	void setActiveColor( const QBrush & b );
 	void setTextShadowColor( const QColor &c );
 	void setBorderColor( const QColor &c );
+	int titleBarHeight() const;
+	int frameWidth() const;
 
 protected:
 	// hook the QWidget move/resize events to update the tracked geometry
diff --git a/src/gui/MainWindow.cpp b/src/gui/MainWindow.cpp
index 145467ed7..6acaa4b86 100644
--- a/src/gui/MainWindow.cpp
+++ b/src/gui/MainWindow.cpp
@@ -562,13 +562,21 @@ void MainWindow::addSpacingToToolBar( int _size )
 								7, _size );
 }
 
+
+
+
 SubWindow* MainWindow::addWindowedWidget(QWidget *w, Qt::WindowFlags windowFlags)
 {
 	// wrap the widget in our own *custom* window that patches some errors in QMdiSubWindow
 	auto win = new SubWindow(m_workspace->viewport(), windowFlags);
 	win->setAttribute(Qt::WA_DeleteOnClose);
 	win->setWidget(w);
-	if (w && w->sizeHint().isValid()) {win->resize(w->sizeHint());}
+	if (w && w->sizeHint().isValid()) {
+		auto titleBarHeight = win->titleBarHeight();
+		auto frameWidth = win->frameWidth();
+		QSize delta(2* frameWidth, titleBarHeight + frameWidth);
+		win->resize(delta + w->sizeHint());
+	}
 	m_workspace->addSubWindow(win);
 	return win;
 }
diff --git a/src/gui/SubWindow.cpp b/src/gui/SubWindow.cpp
index 78e4f586c..dc6e49297 100644
--- a/src/gui/SubWindow.cpp
+++ b/src/gui/SubWindow.cpp
@@ -34,6 +34,7 @@
 #include <QMoveEvent>
 #include <QPainter>
 #include <QPushButton>
+#include <QStyleOption>
 
 #include "embed.h"
 
@@ -41,11 +42,11 @@ namespace lmms::gui
 {
 
 
-SubWindow::SubWindow( QWidget *parent, Qt::WindowFlags windowFlags ) :
-	QMdiSubWindow( parent, windowFlags ),
-	m_buttonSize( 17, 17 ),
-	m_titleBarHeight( 24 ),
-	m_hasFocus( false )
+SubWindow::SubWindow(QWidget *parent, Qt::WindowFlags windowFlags) :
+	QMdiSubWindow(parent, windowFlags),
+	m_buttonSize(17, 17),
+	m_titleBarHeight(titleBarHeight()),
+	m_hasFocus(false)
 {
 	// initialize the tracked geometry to whatever Qt thinks the normal geometry currently is.
 	// this should always work, since QMdiSubWindows will not start as maximized
@@ -240,6 +241,27 @@ void SubWindow::setBorderColor( const QColor &c )
 
 
 
+
+int SubWindow::titleBarHeight() const
+{
+	QStyleOptionTitleBar so;
+	so.titleBarState = Qt::WindowActive; // kThemeStateActiv
+	so.titleBarFlags = Qt::Window;
+	return style()->pixelMetric(QStyle::PM_TitleBarHeight, &so, this);
+}
+
+
+
+
+int SubWindow::frameWidth() const
+{
+	QStyleOptionFrame so;
+	return style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, &so, this);
+}
+
+
+
+
 /**
  * @brief SubWindow::moveEvent
  *