Applications: Add a very simple PDFViewer

Author: https://github.com/mattco98
Commit: https://github.com/SerenityOS/serenity/commit/f7ea1eb6101
Pull-request: https://github.com/SerenityOS/serenity/pull/7018
Reviewed-by: https://github.com/alimpfard
Reviewed-by: https://github.com/bcoles
Reviewed-by: https://github.com/tomuta

Base/home/anon/.config/LaunchServer.ini

@@ -16,6 +16,7 @@ txt=/bin/TextEditor
 font=/bin/FontEditor
 sheets=/bin/Spreadsheet
 gml=/bin/Playground
+pdf=/bin/PDFViewer
 *=/bin/TextEditor
 
 [Protocol]

Base/res/apps/PDFViewer.af

@@ -0,0 +1,4 @@
+[App]
+Name=PDFViewer
+Executable=/bin/PDFViewer
+Category=Graphics

Userland/Applications/CMakeLists.txt

@@ -16,6 +16,7 @@ add_subdirectory(KeyboardMapper)
 add_subdirectory(KeyboardSettings)
 add_subdirectory(Magnifier)
 add_subdirectory(MouseSettings)
+add_subdirectory(PDFViewer)
 add_subdirectory(Piano)
 add_subdirectory(PixelPaint)
 add_subdirectory(Run)

Userland/Applications/PDFViewer/CMakeLists.txt

@@ -0,0 +1,8 @@
+set(SOURCES
+    PDFViewer.cpp
+    PDFViewerWidget.cpp
+    main.cpp
+    )
+
+serenity_app(PDFViewer ICON app-pdf-viewer)
+target_link_libraries(PDFViewer LibGUI LibPDF)

Userland/Applications/PDFViewer/PDFViewer.cpp

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2021, Matthew Olsson <mattco@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "PDFViewer.h"
+#include <LibGUI/Action.h>
+#include <LibGUI/Painter.h>
+#include <LibPDF/Renderer.h>
+
+PDFViewer::PDFViewer()
+{
+    set_should_hide_unnecessary_scrollbars(true);
+    set_focus_policy(GUI::FocusPolicy::StrongFocus);
+    set_scrollbars_enabled(true);
+}
+
+PDFViewer::~PDFViewer()
+{
+}
+
+void PDFViewer::set_document(RefPtr<PDF::Document> document)
+{
+    m_document = document;
+    m_current_page_index = document->get_first_page_index();
+    update();
+}
+
+RefPtr<Gfx::Bitmap> PDFViewer::get_rendered_page(u32 index)
+{
+    auto existing_rendered_page = m_rendered_pages.get(index);
+    if (existing_rendered_page.has_value())
+        return existing_rendered_page.value();
+
+    auto rendered_page = render_page(m_document->get_page(index));
+    m_rendered_pages.set(index, rendered_page);
+    return rendered_page;
+}
+
+void PDFViewer::paint_event(GUI::PaintEvent& event)
+{
+    GUI::Frame::paint_event(event);
+
+    GUI::Painter painter(*this);
+    painter.add_clip_rect(widget_inner_rect());
+    painter.add_clip_rect(event.rect());
+    painter.fill_rect(event.rect(), Color(0x80, 0x80, 0x80));
+
+    if (!m_document)
+        return;
+
+    painter.translate(frame_thickness(), frame_thickness());
+    painter.translate(-horizontal_scrollbar().value(), -vertical_scrollbar().value());
+
+    auto page = get_rendered_page(m_current_page_index);
+
+    auto total_width = width() - frame_thickness() * 2;
+    auto total_height = height() - frame_thickness() * 2;
+    auto bitmap_width = page->width();
+    auto bitmap_height = page->height();
+
+    Gfx::IntPoint p { (total_width - bitmap_width) / 2, (total_height - bitmap_height) / 2 };
+
+    painter.blit(p, *page, page->rect());
+}
+
+void PDFViewer::mousewheel_event(GUI::MouseEvent& event)
+{
+    if (event.wheel_delta() > 0) {
+        if (m_current_page_index < m_document->get_page_count() - 1)
+            m_current_page_index++;
+    } else if (m_current_page_index > 0) {
+        m_current_page_index--;
+    }
+    update();
+}
+
+RefPtr<Gfx::Bitmap> PDFViewer::render_page(const PDF::Page& page)
+{
+    float page_width = page.media_box.upper_right_x - page.media_box.lower_left_x;
+    float page_height = page.media_box.upper_right_y - page.media_box.lower_left_y;
+    float page_scale_factor = page_height / page_width;
+
+    float width = 300.0f;
+    float height = width * page_scale_factor;
+    auto bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::BGRA8888, { width, height });
+
+    PDF::Renderer::render(*m_document, page, bitmap);
+    return bitmap;
+}

Userland/Applications/PDFViewer/PDFViewer.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2021, Matthew Olsson <mattco@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/HashMap.h>
+#include <LibGUI/AbstractScrollableWidget.h>
+#include <LibGfx/Bitmap.h>
+#include <LibPDF/Document.h>
+
+class PDFViewer : public GUI::AbstractScrollableWidget {
+    C_OBJECT(PDFViewer)
+
+public:
+    virtual ~PDFViewer() override;
+
+    void set_document(RefPtr<PDF::Document>);
+
+protected:
+    PDFViewer();
+
+    virtual void paint_event(GUI::PaintEvent&) override;
+    virtual void mousewheel_event(GUI::MouseEvent&) override;
+
+private:
+    RefPtr<Gfx::Bitmap> get_rendered_page(u32 index);
+    RefPtr<Gfx::Bitmap> render_page(const PDF::Page&);
+
+    RefPtr<PDF::Document> m_document;
+    u32 m_current_page_index { 0 };
+    HashMap<u32, RefPtr<Gfx::Bitmap>> m_rendered_pages;
+};

Userland/Applications/PDFViewer/PDFViewerWidget.cpp

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2021, Matthew Olsson <mattco@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "PDFViewerWidget.h"
+#include <LibCore/File.h>
+#include <LibGUI/Action.h>
+#include <LibGUI/Application.h>
+#include <LibGUI/BoxLayout.h>
+#include <LibGUI/FilePicker.h>
+#include <LibGUI/Menu.h>
+#include <LibGUI/Menubar.h>
+
+PDFViewerWidget::PDFViewerWidget()
+{
+    set_fill_with_background_color(true);
+    set_layout<GUI::VerticalBoxLayout>();
+
+    m_viewer = add<PDFViewer>();
+}
+
+PDFViewerWidget::~PDFViewerWidget()
+{
+}
+
+void PDFViewerWidget::initialize_menubar(GUI::Menubar& menubar)
+{
+    auto& file_menu = menubar.add_menu("&File");
+    file_menu.add_action(GUI::CommonActions::make_open_action([&](auto&) {
+        Optional<String> open_path = GUI::FilePicker::get_open_filepath(window());
+        if (open_path.has_value())
+            open_file(open_path.value());
+    }));
+    file_menu.add_action(GUI::CommonActions::make_quit_action([](auto&) {
+        GUI::Application::the()->quit();
+    }));
+}
+
+void PDFViewerWidget::open_file(const String& path)
+{
+    window()->set_title(String::formatted("{} - PDFViewer", path));
+    auto file_result = Core::File::open(path, Core::OpenMode::ReadOnly);
+    VERIFY(!file_result.is_error());
+    m_buffer = file_result.value()->read_all();
+    m_viewer->set_document(adopt_ref(*new PDF::Document(m_buffer)));
+}

Userland/Applications/PDFViewer/PDFViewerWidget.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2021, Matthew Olsson <mattco@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include "PDFViewer.h"
+#include <LibGUI/Widget.h>
+
+class PDFViewer;
+
+class PDFViewerWidget final : public GUI::Widget {
+    C_OBJECT(PDFViewerWidget)
+public:
+    ~PDFViewerWidget() override;
+    void open_file(const String& path);
+    void initialize_menubar(GUI::Menubar&);
+
+private:
+    PDFViewerWidget();
+
+    RefPtr<PDFViewer> m_viewer;
+    ByteBuffer m_buffer;
+    RefPtr<GUI::Action> m_open_action;
+};

Userland/Applications/PDFViewer/main.cpp

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2021, Matthew Olsson <mattco@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "PDFViewerWidget.h"
+#include <LibGUI/Application.h>
+#include <LibGUI/Icon.h>
+#include <LibGUI/Menubar.h>
+#include <LibGUI/Window.h>
+
+int main(int argc, char** argv)
+{
+    auto app = GUI::Application::construct(argc, argv);
+    auto app_icon = GUI::Icon::default_icon("app-pdf-viewer");
+
+    auto window = GUI::Window::construct();
+    window->set_title("PDFViewer");
+    window->resize(640, 400);
+
+    auto& pdf_viewer_widget = window->set_main_widget<PDFViewerWidget>();
+
+    auto menubar = GUI::Menubar::construct();
+    pdf_viewer_widget.initialize_menubar(menubar);
+    window->set_menubar(menubar);
+    window->show();
+    window->set_icon(app_icon.bitmap_for_size(16));
+
+    if (argc >= 2)
+        pdf_viewer_widget.open_file(argv[1]);
+
+    return app->exec();
+}

Userland/Libraries/LibPDF/Document.cpp

@@ -115,23 +115,6 @@ Value Document::resolve(const Value& value)
     return obj;
 }
 
-template<IsValueType T>
-UnwrappedValueType<T> Document::resolve_to(const Value& value)
-{
-    auto resolved = resolve(value);
-
-    if constexpr (IsSame<T, bool>)
-        return resolved.as_bool();
-    if constexpr (IsSame<T, int>)
-        return resolved.as_int();
-    if constexpr (IsSame<T, float>)
-        return resolved.as_float();
-    if constexpr (IsObject<T>)
-        return object_cast<T>(resolved.as_object());
-
-    VERIFY_NOT_REACHED();
-}
-
 void Document::build_page_tree()
 {
     auto page_tree = m_catalog->get_dict(this, "Pages");

Userland/Libraries/LibPDF/Document.h

@@ -65,7 +65,21 @@ public:
     // Like resolve, but unwraps the Value into the given type. Accepts
     // any object type, and the three primitive Value types.
     template<IsValueType T>
-    UnwrappedValueType<T> resolve_to(const Value& value);
+    UnwrappedValueType<T> resolve_to(const Value& value)
+    {
+        auto resolved = resolve(value);
+
+        if constexpr (IsSame<T, bool>)
+            return resolved.as_bool();
+        if constexpr (IsSame<T, int>)
+            return resolved.as_int();
+        if constexpr (IsSame<T, float>)
+            return resolved.as_float();
+        if constexpr (IsObject<T>)
+            return object_cast<T>(resolved.as_object());
+
+        VERIFY_NOT_REACHED();
+    }
 
 private:
     // FIXME: Currently, to improve performance, we don't load any pages at Document