LibWeb: Implement <input type=submit> without using LibGUI

Following in the footsteps of <input type=checkbox>, this patch adds
LayoutButton which implements a basic push button using LibGfx styling
primitives.

Libraries/LibWeb/CMakeLists.txt

@@ -132,6 +132,7 @@ set(SOURCES
     Layout/LayoutBlock.cpp
     Layout/LayoutBox.cpp
     Layout/LayoutBreak.cpp
+    Layout/LayoutButton.cpp
     Layout/LayoutCanvas.cpp
     Layout/LayoutCheckBox.cpp
     Layout/LayoutDocument.cpp

Libraries/LibWeb/Forward.h

@@ -136,6 +136,8 @@ namespace Web {
 class EventHandler;
 class Frame;
 class LayoutBlock;
+class LayoutButton;
+class LayoutCheckBox;
 class LayoutDocument;
 class LayoutNode;
 class LayoutNodeWithStyle;

Libraries/LibWeb/HTML/HTMLInputElement.cpp

@@ -31,6 +31,7 @@
 #include <LibWeb/HTML/HTMLFormElement.h>
 #include <LibWeb/HTML/HTMLInputElement.h>
 #include <LibWeb/InProcessWebView.h>
+#include <LibWeb/Layout/LayoutButton.h>
 #include <LibWeb/Layout/LayoutCheckBox.h>
 #include <LibWeb/Layout/LayoutWidget.h>
 #include <LibWeb/Page/Frame.h>
@@ -46,6 +47,19 @@ HTMLInputElement::~HTMLInputElement()
 {
 }
 
+void HTMLInputElement::did_click_button(Badge<LayoutButton>)
+{
+    dispatch_event(DOM::Event::create("click"));
+
+    if (type().equals_ignoring_case("submit")) {
+        if (auto* form = first_ancestor_of_type<HTMLFormElement>()) {
+            // FIXME: Remove this const_cast once we have a non-const first_ancestor_of_type.
+            form->submit(this);
+        }
+        return;
+    }
+}
+
 RefPtr<LayoutNode> HTMLInputElement::create_layout_node(const CSS::StyleProperties* parent_style)
 {
     ASSERT(document().frame());
@@ -59,47 +73,27 @@ RefPtr<LayoutNode> HTMLInputElement::create_layout_node(const CSS::StyleProperti
     if (style->display() == CSS::Display::None)
         return nullptr;
 
-    RefPtr<GUI::Widget> widget;
-    if (type() == "submit") {
-        auto& button = page_view.add<GUI::Button>(value());
-        int text_width = Gfx::Font::default_font().width(value());
-        button.set_relative_rect(0, 0, text_width + 20, 20);
-        button.on_click = [this](auto) {
-            if (auto* form = first_ancestor_of_type<HTMLFormElement>()) {
-                // FIXME: Remove this const_cast once we have a non-const first_ancestor_of_type.
-                const_cast<HTMLFormElement*>(form)->submit(this);
-            }
-        };
-        widget = button;
-    } else if (type() == "button") {
-        auto& button = page_view.add<GUI::Button>(value());
-        int text_width = Gfx::Font::default_font().width(value());
-        button.set_relative_rect(0, 0, text_width + 20, 20);
-        button.on_click = [this](auto) {
-            const_cast<HTMLInputElement*>(this)->dispatch_event(DOM::Event::create("click"));
-        };
-        widget = button;
-    } else if (type() == "checkbox") {
-        return adopt(*new LayoutCheckBox(document(), *this, move(style)));
-    } else {
-        auto& text_box = page_view.add<GUI::TextBox>();
-        text_box.set_text(value());
-        text_box.on_change = [this] {
-            auto& widget = downcast<LayoutWidget>(layout_node())->widget();
-            const_cast<HTMLInputElement*>(this)->set_attribute(HTML::AttributeNames::value, static_cast<const GUI::TextBox&>(widget).text());
-        };
-        int text_width = Gfx::Font::default_font().width(value());
-        auto size_value = attribute(HTML::AttributeNames::size);
-        if (!size_value.is_null()) {
-            auto size = size_value.to_uint();
-            if (size.has_value())
-                text_width = Gfx::Font::default_font().glyph_width('x') * size.value();
-        }
-        text_box.set_relative_rect(0, 0, text_width + 20, 20);
-        widget = text_box;
-    }
+    if (type().equals_ignoring_case("submit") || type().equals_ignoring_case("button"))
+        return adopt(*new LayoutButton(document(), *this, move(style)));
 
-    return adopt(*new LayoutWidget(document(), *this, *widget));
+    if (type() == "checkbox")
+        return adopt(*new LayoutCheckBox(document(), *this, move(style)));
+
+    auto& text_box = page_view.add<GUI::TextBox>();
+    text_box.set_text(value());
+    text_box.on_change = [this] {
+        auto& widget = downcast<LayoutWidget>(layout_node())->widget();
+        const_cast<HTMLInputElement*>(this)->set_attribute(HTML::AttributeNames::value, static_cast<const GUI::TextBox&>(widget).text());
+    };
+    int text_width = Gfx::Font::default_font().width(value());
+    auto size_value = attribute(HTML::AttributeNames::size);
+    if (!size_value.is_null()) {
+        auto size = size_value.to_uint();
+        if (size.has_value())
+            text_width = Gfx::Font::default_font().glyph_width('x') * size.value();
+    }
+    text_box.set_relative_rect(0, 0, text_width + 20, 20);
+    return adopt(*new LayoutWidget(document(), *this, text_box));
 }
 
 void HTMLInputElement::set_checked(bool checked)

Libraries/LibWeb/HTML/HTMLInputElement.h

@@ -48,6 +48,8 @@ public:
 
     bool enabled() const;
 
+    void did_click_button(Badge<LayoutButton>);
+
 private:
     bool m_checked { false };
 };

Libraries/LibWeb/Layout/LayoutButton.cpp

@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <LibGUI/Event.h>
+#include <LibGUI/Painter.h>
+#include <LibGfx/Font.h>
+#include <LibGfx/StylePainter.h>
+#include <LibWeb/DOM/Document.h>
+#include <LibWeb/Layout/LayoutButton.h>
+#include <LibWeb/Page/Frame.h>
+
+namespace Web {
+
+LayoutButton::LayoutButton(DOM::Document& document, HTML::HTMLInputElement& element, NonnullRefPtr<CSS::StyleProperties> style)
+    : LayoutReplaced(document, element, move(style))
+{
+}
+
+LayoutButton::~LayoutButton()
+{
+}
+
+void LayoutButton::layout(LayoutMode layout_mode)
+{
+    auto& font = specified_style().font();
+    set_intrinsic_width(font.width(node().value()) + 20);
+    set_has_intrinsic_width(true);
+
+    set_intrinsic_height(20);
+    set_has_intrinsic_height(true);
+    LayoutReplaced::layout(layout_mode);
+}
+
+void LayoutButton::paint(PaintContext& context, PaintPhase phase)
+{
+    if (!is_visible())
+        return;
+
+    LayoutReplaced::paint(context, phase);
+
+    if (phase == PaintPhase::Foreground) {
+        bool hovered = document().hovered_node() == &node();
+        Gfx::StylePainter::paint_button(context.painter(), enclosing_int_rect(absolute_rect()), context.palette(), Gfx::ButtonStyle::Normal, m_being_pressed, hovered, node().checked(), node().enabled());
+
+        auto text_rect = enclosing_int_rect(absolute_rect());
+        if (m_being_pressed)
+            text_rect.move_by(1, 1);
+        context.painter().draw_text(text_rect, node().value(), specified_style().font(), Gfx::TextAlignment::Center);
+    }
+}
+
+void LayoutButton::handle_mousedown(Badge<EventHandler>, const Gfx::IntPoint&, unsigned button, unsigned)
+{
+    if (button != GUI::MouseButton::Left || !node().enabled())
+        return;
+
+    m_being_pressed = true;
+    set_needs_display();
+
+    m_tracking_mouse = true;
+    frame().event_handler().set_mouse_event_tracking_layout_node(this);
+}
+
+void LayoutButton::handle_mouseup(Badge<EventHandler>, const Gfx::IntPoint& position, unsigned button, unsigned)
+{
+    if (!m_tracking_mouse || button != GUI::MouseButton::Left || !node().enabled())
+        return;
+
+    // NOTE: Handling the click may run arbitrary JS, which could disappear this node.
+    NonnullRefPtr protected_this = *this;
+    NonnullRefPtr protected_frame = frame();
+
+    bool is_inside = enclosing_int_rect(absolute_rect()).contains(position);
+    if (is_inside)
+        node().did_click_button({});
+
+    m_being_pressed = false;
+    m_tracking_mouse = false;
+
+    protected_frame->event_handler().set_mouse_event_tracking_layout_node(nullptr);
+}
+
+void LayoutButton::handle_mousemove(Badge<EventHandler>, const Gfx::IntPoint& position, unsigned, unsigned)
+{
+    if (!m_tracking_mouse || !node().enabled())
+        return;
+
+    bool is_inside = enclosing_int_rect(absolute_rect()).contains(position);
+    if (m_being_pressed == is_inside)
+        return;
+
+    m_being_pressed = is_inside;
+    set_needs_display();
+}
+
+}

Libraries/LibWeb/Layout/LayoutButton.h

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <LibWeb/HTML/HTMLInputElement.h>
+#include <LibWeb/Layout/LayoutReplaced.h>
+
+namespace Web {
+
+class LayoutButton : public LayoutReplaced {
+public:
+    LayoutButton(DOM::Document&, HTML::HTMLInputElement&, NonnullRefPtr<CSS::StyleProperties>);
+    virtual ~LayoutButton() override;
+
+    virtual void layout(LayoutMode = LayoutMode::Default) override;
+    virtual void paint(PaintContext&, PaintPhase) override;
+
+    const HTML::HTMLInputElement& node() const { return static_cast<const HTML::HTMLInputElement&>(LayoutReplaced::node()); }
+    HTML::HTMLInputElement& node() { return static_cast<HTML::HTMLInputElement&>(LayoutReplaced::node()); }
+
+private:
+    virtual const char* class_name() const override { return "LayoutButton"; }
+    virtual bool is_button() const override { return true; }
+    virtual bool wants_mouse_events() const override { return true; }
+    virtual void handle_mousedown(Badge<EventHandler>, const Gfx::IntPoint&, unsigned button, unsigned modifiers) override;
+    virtual void handle_mouseup(Badge<EventHandler>, const Gfx::IntPoint&, unsigned button, unsigned modifiers) override;
+    virtual void handle_mousemove(Badge<EventHandler>, const Gfx::IntPoint&, unsigned buttons, unsigned modifiers) override;
+
+    bool m_being_pressed { false };
+    bool m_tracking_mouse { false };
+};
+
+}
+
+AK_BEGIN_TYPE_TRAITS(Web::LayoutButton)
+static bool is_type(const Web::LayoutNode& layout_node) { return layout_node.is_button(); }
+AK_END_TYPE_TRAITS()

Libraries/LibWeb/Layout/LayoutNode.h

@@ -93,6 +93,7 @@ public:
     virtual bool is_table_row_group() const { return false; }
     virtual bool is_break() const { return false; }
     virtual bool is_check_box() const { return false; }
+    virtual bool is_button() const { return false; }
     bool has_style() const { return m_has_style; }
 
     bool is_inline() const { return m_inline; }