LibGUI: Add min/max sizes to GUI::Widget

This patch adds min_size and max_size properties to GUI::Widget. These
can also be accessed as min_width/min_height and max_width/max_height.

Layouts will respect these constraints and size widgets accordingly.

Libraries/LibGUI/BoxLayout.cpp

@@ -61,8 +61,6 @@ void BoxLayout::run(Widget& widget)
     if (should_log)
         dbgprintf("BoxLayout:  Starting with available size: %s\n", available_size.to_string().characters());
 
-    Optional<size_t> last_entry_with_automatic_size;
-
     for (size_t i = 0; i < m_entries.size(); ++i) {
         auto& entry = m_entries[i];
         if (entry.type == Entry::Type::Spacer) {
@@ -83,8 +81,6 @@ void BoxLayout::run(Widget& widget)
             if (should_log)
                 dbgprintf("BoxLayout:     Available size  after: %s\n", available_size.to_string().characters());
             ++number_of_entries_with_fixed_size;
-        } else {
-            last_entry_with_automatic_size = i;
         }
         available_size -= { spacing(), spacing() };
     }
@@ -102,21 +98,21 @@ void BoxLayout::run(Widget& widget)
         dbgprintf("BoxLayout:   available_size=%s, fixed=%d, fill=%d\n", available_size.to_string().characters(), number_of_entries_with_fixed_size, number_of_entries_with_automatic_size);
 
     Gfx::IntSize automatic_size;
-    Gfx::IntSize automatic_size_for_last_entry;
+
+    int remaining_size = 0;
+    int number_of_entries_with_automatic_size_remaining = number_of_entries_with_automatic_size;
 
     if (number_of_entries_with_automatic_size) {
         if (m_orientation == Orientation::Horizontal) {
             automatic_size.set_width(available_size.width() / number_of_entries_with_automatic_size);
             automatic_size.set_height(widget.height());
 
-            automatic_size_for_last_entry.set_width(available_size.width() - (number_of_entries_with_automatic_size - 1) * automatic_size.width());
-            automatic_size_for_last_entry.set_height(widget.height());
+            remaining_size = available_size.width();
         } else {
             automatic_size.set_width(widget.width());
             automatic_size.set_height(available_size.height() / number_of_entries_with_automatic_size);
 
-            automatic_size_for_last_entry.set_width(widget.width());
-            automatic_size_for_last_entry.set_height(available_size.height() - (number_of_entries_with_automatic_size - 1) * automatic_size.height());
+            remaining_size = available_size.height();
         }
     }
 
@@ -131,6 +127,7 @@ void BoxLayout::run(Widget& widget)
         if (entry.type == Entry::Type::Spacer) {
             current_x += automatic_size.width();
             current_y += automatic_size.height();
+            continue;
         }
 
         if (!entry.widget)
@@ -144,36 +141,71 @@ void BoxLayout::run(Widget& widget)
         }
         ASSERT(entry.widget);
 
-        if (last_entry_with_automatic_size.has_value() && i == last_entry_with_automatic_size.value()) {
-            rect.set_size(automatic_size_for_last_entry);
+        if (entry.widget->size_policy(Orientation::Vertical) == SizePolicy::Fixed) {
+            rect.set_width(widget.width());
+            rect.set_height(entry.widget->preferred_size().height());
         } else {
-            rect.set_size(automatic_size);
+            if (orientation() == Orientation::Horizontal)
+                rect.set_height(widget.height());
+            else
+                rect.set_height(remaining_size / number_of_entries_with_automatic_size_remaining);
         }
 
-        if (entry.widget->size_policy(Orientation::Vertical) == SizePolicy::Fixed)
-            rect.set_height(entry.widget->preferred_size().height());
-
-        if (entry.widget->size_policy(Orientation::Horizontal) == SizePolicy::Fixed)
+        if (entry.widget->size_policy(Orientation::Horizontal) == SizePolicy::Fixed) {
             rect.set_width(entry.widget->preferred_size().width());
+            rect.set_height(widget.height());
+        } else {
+            if (orientation() == Orientation::Horizontal)
+                rect.set_width(remaining_size / number_of_entries_with_automatic_size_remaining);
+            else
+                rect.set_width(widget.width());
+        }
 
         if (orientation() == Orientation::Horizontal) {
             if (entry.widget->size_policy(Orientation::Vertical) == SizePolicy::Fill)
                 rect.set_height(widget.height() - margins().top() - margins().bottom());
-            rect.center_vertically_within(widget.rect());
         } else {
             if (entry.widget->size_policy(Orientation::Horizontal) == SizePolicy::Fill)
                 rect.set_width(widget.width() - margins().left() - margins().right());
-            rect.center_horizontally_within(widget.rect());
         }
 
+        // Apply min/max constraints to filled widgets.
+        if (entry.widget->size_policy(Orientation::Horizontal) == SizePolicy::Fill) {
+            if (entry.widget->min_size().width() >= 0)
+                rect.set_width(max(entry.widget->min_size().width(), rect.width()));
+            if (entry.widget->max_size().width() >= 0)
+                rect.set_width(min(entry.widget->max_size().width(), rect.width()));
+        }
+        if (entry.widget->size_policy(Orientation::Vertical) == SizePolicy::Fill) {
+            if (entry.widget->min_size().height() >= 0)
+                rect.set_height(max(entry.widget->min_size().height(), rect.height()));
+            if (entry.widget->max_size().height() >= 0)
+                rect.set_height(min(entry.widget->max_size().height(), rect.height()));
+        }
+
+        if (orientation() == Orientation::Horizontal)
+            rect.center_vertically_within(widget.rect());
+        else
+            rect.center_horizontally_within(widget.rect());
+
         if (should_log)
             dbgprintf("BoxLayout: apply, %s{%p} <- %s\n", entry.widget->class_name(), entry.widget.ptr(), rect.to_string().characters());
+
         entry.widget->set_relative_rect(rect);
 
-        if (orientation() == Orientation::Horizontal)
+        if (orientation() == Orientation::Horizontal) {
+            if (entry.widget->size_policy(Orientation::Horizontal) == SizePolicy::Fill) {
+                remaining_size -= rect.width();
+                --number_of_entries_with_automatic_size_remaining;
+            }
             current_x += rect.width() + spacing();
-        else
+        } else {
+            if (entry.widget->size_policy(Orientation::Vertical) == SizePolicy::Fill) {
+                remaining_size -= rect.height();
+                --number_of_entries_with_automatic_size_remaining;
+            }
             current_y += rect.height() + spacing();
+        }
     }
 }
 }

Libraries/LibGUI/Widget.cpp

@@ -138,6 +138,13 @@ Widget::Widget()
     REGISTER_SIZE_POLICY_PROPERTY("horizontal_size_policy", horizontal_size_policy, set_horizontal_size_policy);
     REGISTER_SIZE_POLICY_PROPERTY("vertical_size_policy", vertical_size_policy, set_vertical_size_policy);
 
+    REGISTER_SIZE_PROPERTY("min_size", min_size, set_min_size);
+    REGISTER_SIZE_PROPERTY("max_size", max_size, set_max_size);
+    REGISTER_INT_PROPERTY("min_width", min_width, set_min_width);
+    REGISTER_INT_PROPERTY("max_width", max_width, set_max_width);
+    REGISTER_INT_PROPERTY("min_height", min_height, set_min_height);
+    REGISTER_INT_PROPERTY("max_height", max_height, set_max_height);
+
     register_property(
         "focus_policy", [this]() -> JsonValue {
         auto policy = focus_policy();
@@ -659,6 +666,22 @@ bool Widget::global_cursor_tracking() const
     return win->global_cursor_tracking_widget() == this;
 }
 
+void Widget::set_min_size(const Gfx::IntSize& size)
+{
+    if (m_min_size == size)
+        return;
+    m_min_size = size;
+    invalidate_layout();
+}
+
+void Widget::set_max_size(const Gfx::IntSize& size)
+{
+    if (m_max_size == size)
+        return;
+    m_max_size = size;
+    invalidate_layout();
+}
+
 void Widget::set_preferred_size(const Gfx::IntSize& size)
 {
     if (m_preferred_size == size)

Libraries/LibGUI/Widget.h

@@ -120,6 +120,24 @@ public:
     void set_horizontal_size_policy(SizePolicy policy) { set_size_policy(policy, vertical_size_policy()); }
     void set_vertical_size_policy(SizePolicy policy) { set_size_policy(horizontal_size_policy(), policy); }
 
+    Gfx::IntSize min_size() const { return m_min_size; }
+    void set_min_size(const Gfx::IntSize&);
+    void set_min_size(int width, int height) { set_min_size({ width, height }); }
+
+    int min_width() const { return m_min_size.width(); }
+    int min_height() const { return m_min_size.height(); }
+    void set_min_width(int width) { set_min_size(width, min_height()); }
+    void set_min_height(int height) { set_min_size(min_width(), height); }
+
+    Gfx::IntSize max_size() const { return m_max_size; }
+    void set_max_size(const Gfx::IntSize&);
+    void set_max_size(int width, int height) { set_max_size({ width, height }); }
+
+    int max_width() const { return m_max_size.width(); }
+    int max_height() const { return m_max_size.height(); }
+    void set_max_width(int width) { set_max_size(width, max_height()); }
+    void set_max_height(int height) { set_max_size(max_width(), height); }
+
     Gfx::IntSize preferred_size() const { return m_preferred_size; }
     void set_preferred_size(const Gfx::IntSize&);
     void set_preferred_size(int width, int height) { set_preferred_size({ width, height }); }
@@ -365,6 +383,8 @@ private:
     SizePolicy m_horizontal_size_policy { SizePolicy::Fill };
     SizePolicy m_vertical_size_policy { SizePolicy::Fill };
     Gfx::IntSize m_preferred_size;
+    Gfx::IntSize m_min_size { -1, -1 };
+    Gfx::IntSize m_max_size { -1, -1 };
     Margins m_content_margins;
 
     bool m_fill_with_background_color { false };