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/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; }