QuickShow: Animate animated images :^)

With a little help (read: copy & paste) from ImageWidget, QuickShow will
now cycle through the frames of animated images - enjoy the cat GIFs!

Future improvement: cache decoded images like LibWeb's ImageResource to
waste less CPU - the same applies to LibGUI though, maybe we can put
something shared in LibGfx.

Closes #5837.

Userland/Applications/QuickShow/QSWidget.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Linus Groh <mail@linusgroh.de>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -25,16 +26,18 @@
  */
 
 #include "QSWidget.h"
+#include <AK/MappedFile.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/DirIterator.h>
+#include <LibCore/Timer.h>
 #include <LibGUI/MessageBox.h>
 #include <LibGUI/Painter.h>
-#include <LibGUI/Window.h>
 #include <LibGfx/Bitmap.h>
 #include <LibGfx/Orientation.h>
 #include <LibGfx/Palette.h>
 
 QSWidget::QSWidget()
+    : m_timer(Core::Timer::construct())
 {
     set_fill_with_background_color(false);
 }
@@ -244,12 +247,31 @@ void QSWidget::mousewheel_event(GUI::MouseEvent& event)
 
 void QSWidget::load_from_file(const String& path)
 {
-    auto bitmap = Gfx::Bitmap::load_from_file(path);
-    if (!bitmap) {
+    auto show_error = [&] {
         GUI::MessageBox::show(window(), String::formatted("Failed to open {}", path), "Cannot open image", GUI::MessageBox::Type::Error);
+    };
+
+    auto file_or_error = MappedFile::map(path);
+    if (file_or_error.is_error()) {
+        show_error();
+        return;
+    }
+
+    auto& mapped_file = *file_or_error.value();
+    m_image_decoder = Gfx::ImageDecoder::create((const u8*)mapped_file.data(), mapped_file.size());
+    auto bitmap = m_image_decoder->bitmap();
+    if (!bitmap) {
+        show_error();
         return;
     }
 
+    if (m_image_decoder->is_animated() && m_image_decoder->frame_count() > 1) {
+        const auto& first_frame = m_image_decoder->frame(0);
+        m_timer->set_interval(first_frame.duration);
+        m_timer->on_timeout = [this] { animate(); };
+        m_timer->start();
+    }
+
     m_path = path;
     m_bitmap = bitmap;
     m_scale = -1;
@@ -287,3 +309,31 @@ void QSWidget::reset_view()
     m_pan_origin = { 0, 0 };
     set_scale(100);
 }
+
+void QSWidget::set_bitmap(const Gfx::Bitmap* bitmap)
+{
+    if (m_bitmap == bitmap)
+        return;
+    m_bitmap = bitmap;
+    update();
+}
+
+// Same as ImageWidget::animate(), you probably want to keep any changes in sync
+void QSWidget::animate()
+{
+    m_current_frame_index = (m_current_frame_index + 1) % m_image_decoder->frame_count();
+
+    const auto& current_frame = m_image_decoder->frame(m_current_frame_index);
+    set_bitmap(current_frame.image);
+
+    if (current_frame.duration != m_timer->interval()) {
+        m_timer->restart(current_frame.duration);
+    }
+
+    if (m_current_frame_index == m_image_decoder->frame_count() - 1) {
+        ++m_loops_completed;
+        if (m_loops_completed > 0 && m_loops_completed == m_image_decoder->loop_count()) {
+            m_timer->stop();
+        }
+    }
+}

Userland/Applications/QuickShow/QSWidget.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Linus Groh <mail@linusgroh.de>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,12 +27,12 @@
 
 #pragma once
 
+#include <LibCore/Timer.h>
 #include <LibGUI/Frame.h>
 #include <LibGfx/Bitmap.h>
+#include <LibGfx/ImageDecoder.h>
 #include <LibGfx/Point.h>
 
-class QSLabel;
-
 class QSWidget final : public GUI::Frame {
     C_OBJECT(QSWidget)
 public:
@@ -72,18 +73,25 @@ private:
     virtual void mousewheel_event(GUI::MouseEvent&) override;
     virtual void drop_event(GUI::DropEvent&) override;
 
+    void set_bitmap(const Gfx::Bitmap* bitmap);
+
     void relayout();
     void resize_window();
     void reset_view();
+    void animate();
 
     String m_path;
     RefPtr<Gfx::Bitmap> m_bitmap;
-    int m_toolbar_height { 28 };
-
     Gfx::IntRect m_bitmap_rect;
+
+    RefPtr<Gfx::ImageDecoder> m_image_decoder;
+    size_t m_current_frame_index { 0 };
+    size_t m_loops_completed { 0 };
+    NonnullRefPtr<Core::Timer> m_timer;
+
     int m_scale { -1 };
+    int m_toolbar_height { 28 };
     Gfx::FloatPoint m_pan_origin;
-
     Gfx::IntPoint m_click_position;
     Gfx::FloatPoint m_saved_pan_origin;
     Vector<String> m_files_in_same_dir;

Userland/Libraries/LibGUI/ImageWidget.cpp

@@ -71,6 +71,7 @@ void ImageWidget::set_auto_resize(bool value)
         set_fixed_size(m_bitmap->size());
 }
 
+// Same as QSWidget::animate(), you probably want to keep any changes in sync
 void ImageWidget::animate()
 {
     m_current_frame_index = (m_current_frame_index + 1) % m_image_decoder->frame_count();