ScrolledWindow sticking to edges

examples/ScrolledWindowViewport.cpp

@@ -38,6 +38,9 @@ int main() {
 	// Set the ScrolledWindow to always show the horizontal scrollbar
 	// and only show the vertical scrollbar when needed.
 	scrolledwindow->SetScrollbarPolicy( sfg::ScrolledWindow::HORIZONTAL_ALWAYS | sfg::ScrolledWindow::VERTICAL_AUTOMATIC );
+
+    // Set sticking ON
+    scrolledwindow->SetStick(sfg::ScrolledWindow::ScrollbarSticking::YES);
 
 	// Add the ScrolledWindow box to the ScrolledWindow
 	// and create a new viewport automatically.

include/SFGUI/Adjustment.hpp

@@ -25,9 +25,10 @@ class SFGUI_API Adjustment : public Object, public std::enable_shared_from_this<
 		 * @param minor_step Minor change value (such as clicking on arrow button).
 		 * @param major_step Major change value (such as clicking on the scroll area).
 		 * @param page_size Page size (how many entries are visible / slider size).
+         * @param stick True if the adjustment should stick to the maximum value.
 		 * @return Adjustment.
 		 */
-		static Ptr Create( float value = .0f, float lower = .0f, float upper = .0f, float minor_step = 1.f, float major_step = 5.f, float page_size = .0f );
+		static Ptr Create( float value = .0f, float lower = .0f, float upper = .0f, float minor_step = 1.f, float major_step = 5.f, float page_size = .0f, bool stick = false );
 
 		/** Assignment operator
 		 * @param adjustment Adjustment whose values are to be assigned to this one.
@@ -65,6 +66,21 @@ class SFGUI_API Adjustment : public Object, public std::enable_shared_from_this<
 		 */
 		void SetUpper( float new_upper );
 
+        /** Get Adjustment stick setting
+         * @return Adjustment stick setting
+         */
+        bool GetStick() const;
+
+        /** Set Adjustment stick setting
+         * @param new_stick new stick setting
+         */
+        void SetStick(bool new_stick);
+
+        /** Check if value is set to maximum
+         * @return True is Value at Upper
+         */
+        bool IsAtUpper() const;
+
 		/** Get Adjustment minor step
 		 * @return Adjustment minor step
 		 */
@@ -102,8 +118,9 @@ class SFGUI_API Adjustment : public Object, public std::enable_shared_from_this<
 		 * @param new_minor_step Minor change value (such as clicking on arrow button).
 		 * @param new_major_step Major change value (such as clicking on the scroll area).
 		 * @param new_page_size Page size (how many entries are visible / slider size).
+         * @param stick True if the adjustment should stick to the maximum value.
 		 */
-		void Configure( float new_value, float new_lower, float new_upper, float new_minor_step, float new_major_step, float new_page_size );
+		void Configure( float new_value, float new_lower, float new_upper, float new_minor_step, float new_major_step, float new_page_size, bool new_stick);
 
 		/** Increment current value
 		 */
@@ -132,15 +149,17 @@ class SFGUI_API Adjustment : public Object, public std::enable_shared_from_this<
 		 * @param minor_step Minor change value (such as clicking on arrow button).
 		 * @param major_step Major change value (such as clicking on the scroll area).
 		 * @param page_size Page size (how many entries are visible / slider size).
+         * @param stick True if the adjustment should stick to the maximum value.
 		 */
-		Adjustment( float value, float lower, float upper, float minor_step, float major_step, float page_size );
+		Adjustment( float value, float lower, float upper, float minor_step, float major_step, float page_size, bool new_stick);
 
 		float m_value;
 		float m_lower;
 		float m_upper;
 		float m_minor_step;
 		float m_major_step;
-		float m_page_size;
+        float m_page_size;
+        float m_stick;
 };
 
 }

include/SFGUI/ResizableImage.hpp

@@ -189,7 +189,7 @@ namespace sfg
             if (m_KeepAspect)
             {
                 // Use same scale for both sides of the sprite
-                float lowerScale = std::min(scaleX, scaleY);
+                float lowerScale = scaleX < scaleY ? scaleX : scaleY;
 
                 tempSprite.scale(lowerScale, lowerScale);
 

include/SFGUI/ScrolledWindow.hpp

@@ -39,6 +39,14 @@ class SFGUI_API ScrolledWindow : public Container {
 			DEFAULT = HORIZONTAL_ALWAYS | VERTICAL_ALWAYS
 		};
 
+        /** Scrollbar sticking.
+         */
+        enum class ScrollbarSticking : char {
+            NO = 0, //!< Do not move scrollbar.
+            YES, //!< Keep scrollbar sticked to the bottom.
+            DEFAULT = NO
+        };
+
 		/** Create scrolled window.
 		 * @return ScrolledWindow.
 		 */
@@ -88,6 +96,11 @@ class SFGUI_API ScrolledWindow : public Container {
 		 */
 		void SetPlacement( Placement placement );
 
+        /** Set the scrollbar behaviour when the bottom child is expanding.
+         * @param stick new ScrollbarSticking.
+         */
+        void SetStick(ScrollbarSticking stick);
+
 		/** Get the allocation of the content area of this Scrolled Window
 		 * @return Allocation of the content area of this Scrolled Window
 		 */
@@ -146,7 +159,8 @@ class SFGUI_API ScrolledWindow : public Container {
 		std::shared_ptr<Viewport> m_viewport;
 
 		char m_policy;
-		Placement m_placement;
+        Placement m_placement;
+        ScrollbarSticking m_stick;
 };
 
 }

src/SFGUI/Adjustment.cpp

@@ -5,18 +5,19 @@ namespace sfg {
 // Signals.
 Signal::SignalID Adjustment::OnChange = 0;
 
-Adjustment::Adjustment( float value, float lower, float upper, float minor_step, float major_step, float page_size ) :
+Adjustment::Adjustment( float value, float lower, float upper, float minor_step, float major_step, float page_size, bool stick ) :
 	m_value( value ),
 	m_lower( lower ),
 	m_upper( upper ),
 	m_minor_step( minor_step ),
 	m_major_step( major_step ),
-	m_page_size( page_size )
+	m_page_size( page_size ),
+    m_stick ( stick )
 {
 }
 
-Adjustment::Ptr Adjustment::Create( float value, float lower, float upper, float minor_step, float major_step, float page_size ) {
-	return Adjustment::Ptr( new Adjustment( value, lower, upper, minor_step, major_step, page_size ) );
+Adjustment::Ptr Adjustment::Create( float value, float lower, float upper, float minor_step, float major_step, float page_size, bool stick ) {
+	return Adjustment::Ptr( new Adjustment( value, lower, upper, minor_step, major_step, page_size, stick) );
 }
 
 Adjustment& Adjustment::operator=( const Adjustment& adjustment ) {
@@ -25,7 +26,8 @@ Adjustment& Adjustment::operator=( const Adjustment& adjustment ) {
 	SetMinorStep( adjustment.m_minor_step );
 	SetMajorStep( adjustment.m_major_step );
 	SetPageSize( adjustment.m_page_size );
-	SetValue( adjustment.m_value );
+    SetValue( adjustment.m_value );
+    SetValue( adjustment.m_stick );
 
 	return *this;
 }
@@ -51,6 +53,10 @@ void Adjustment::SetValue( float new_value ) {
 	}
 }
 
+bool Adjustment::IsAtUpper() const {
+    return m_value + m_page_size >= m_upper;
+}
+
 float Adjustment::GetLower() const {
 	return m_lower;
 }
@@ -70,13 +76,25 @@ float Adjustment::GetUpper() const {
 }
 
 void Adjustment::SetUpper( float new_upper ) {
-	m_upper = new_upper;
+    if (m_upper != new_upper)
+    {
+        bool sticked = m_stick && IsAtUpper();
+        m_upper = new_upper;
 
-	if( m_upper < m_lower ) {
-		m_lower = m_upper;
-	}
+        if (m_upper < m_lower) {
+            m_lower = m_upper;
+        }
 
-	SetValue( GetValue() );
+        SetValue(sticked ? m_upper : GetValue());
+    }
+}
+
+bool Adjustment::GetStick() const {
+    return m_stick;
+}
+
+void Adjustment::SetStick(bool new_stick) {
+    m_stick = new_stick;
 }
 
 float Adjustment::GetMinorStep() const {
@@ -109,13 +127,14 @@ void Adjustment::SetPageSize( float new_page_size ) {
 	SetValue( GetValue() );
 }
 
-void Adjustment::Configure( float new_value, float new_lower, float new_upper, float new_minor_step, float new_major_step, float new_page_size ) {
+void Adjustment::Configure( float new_value, float new_lower, float new_upper, float new_minor_step, float new_major_step, float new_page_size, bool new_stick ) {
 	SetValue( new_value );
 	SetLower( new_lower );
 	SetUpper( new_upper );
 	SetMinorStep( new_minor_step );
 	SetMajorStep( new_major_step );
-	SetPageSize( new_page_size );
+    SetPageSize(new_page_size);
+    SetStick(new_stick);
 }
 
 void Adjustment::Increment() {

src/SFGUI/ListBox.cpp

@@ -543,7 +543,8 @@ void ListBox::UpdateScrollbarAdjustment() {
 		static_cast<float>( m_items.size() ),
 		1.f,
 		static_cast<float>( m_max_displayed_items_count ),
-		static_cast<float>( m_max_displayed_items_count )
+		static_cast<float>( m_max_displayed_items_count ), 
+        false // stick
 	);
 }
 

src/SFGUI/ScrolledWindow.cpp

@@ -14,7 +14,8 @@ ScrolledWindow::ScrolledWindow( Adjustment::Ptr horizontal_adjustment, Adjustmen
 	m_vertical_scrollbar(),
 	m_viewport(),
 	m_policy( ScrollbarPolicy::DEFAULT ),
-	m_placement( Placement::DEFAULT )
+	m_placement( Placement::DEFAULT ),
+    m_stick(ScrollbarSticking::DEFAULT)
 {
 	m_horizontal_scrollbar = Scrollbar::Create( horizontal_adjustment, Scrollbar::Orientation::HORIZONTAL );
 	m_vertical_scrollbar = Scrollbar::Create( vertical_adjustment, Scrollbar::Orientation::VERTICAL );
@@ -81,6 +82,15 @@ void ScrolledWindow::SetPlacement( Placement placement ) {
 	Invalidate();
 }
 
+void ScrolledWindow::SetStick(ScrollbarSticking stick) {
+    m_stick = stick;
+    GetHorizontalAdjustment()->SetStick(stick == ScrollbarSticking::YES);
+    GetVerticalAdjustment()->SetStick(stick == ScrollbarSticking::YES);
+
+    RecalculateContentAllocation();
+    Invalidate();
+}
+
 bool ScrolledWindow::IsHorizontalScrollbarVisible() const {
 	if( m_policy & HORIZONTAL_ALWAYS ) {
 		return true;

src/SFGUI/SpinButton.cpp

@@ -25,7 +25,7 @@ SpinButton::SpinButton() :
 
 SpinButton::Ptr SpinButton::Create( float minimum, float maximum, float step ) {
 	auto adjustment = Adjustment::Create();
-	adjustment->Configure( minimum, minimum, maximum, step, 0.f, 0.f );
+	adjustment->Configure( minimum, minimum, maximum, step, 0.f, 0.f, false /* stick */ );
 
 	auto ptr = Ptr( new SpinButton );
 	ptr->SetAdjustment( adjustment );