QuickShow: Allow dropping an image file on the QuickShow window

We now try to open image files dropped on us from FileManager. :^)

The QuickShow code is not exactly well-factored, and should be fixes up
to not do the same thing twice, etc.

Applications/QuickShow/QSWidget.cpp

@@ -1,6 +1,9 @@
 #include "QSWidget.h"
-#include <LibGUI/GPainter.h>
+#include <AK/URL.h>
 #include <LibDraw/GraphicsBitmap.h>
+#include <LibGUI/GMessageBox.h>
+#include <LibGUI/GPainter.h>
+#include <LibGUI/GWindow.h>
 
 QSWidget::QSWidget(GWidget* parent)
     : GFrame(parent)
@@ -90,3 +93,38 @@ void QSWidget::mousewheel_event(GMouseEvent& event)
             on_scale_change(m_scale);
     }
 }
+
+void QSWidget::set_path(const String& path)
+{
+    m_path = path;
+}
+
+void QSWidget::drop_event(GDropEvent& event)
+{
+    event.accept();
+    window()->move_to_front();
+
+    if (event.data_type() == "url-list") {
+        auto lines = event.data().split_view('\n');
+        if (lines.is_empty())
+            return;
+        if (lines.size() > 1) {
+            GMessageBox::show("QuickShow can only open one file at a time!", "One at a time please!", GMessageBox::Type::Error, GMessageBox::InputType::OK, window());
+            return;
+        }
+        URL url(lines[0]);
+        auto bitmap = GraphicsBitmap::load_from_file(url.path());
+        if (!bitmap) {
+            GMessageBox::show(String::format("Failed to open %s", url.to_string().characters()), "Cannot open image", GMessageBox::Type::Error, GMessageBox::InputType::OK, window());
+            return;
+        }
+
+        m_path = url.path();
+        m_bitmap = bitmap;
+        m_scale = 100;
+        if (on_scale_change)
+            on_scale_change(m_scale);
+        relayout();
+        m_bitmap_rect.center_within(rect());
+    }
+}

Applications/QuickShow/QSWidget.h

@@ -11,6 +11,10 @@ public:
     virtual ~QSWidget() override;
 
     void set_bitmap(NonnullRefPtr<GraphicsBitmap>);
+    const GraphicsBitmap* bitmap() const { return m_bitmap.ptr(); }
+
+    void set_path(const String&);
+    const String& path() const { return m_path; }
 
     Function<void(int)> on_scale_change;
 
@@ -22,6 +26,7 @@ private:
     virtual void mouseup_event(GMouseEvent&) override;
     virtual void mousemove_event(GMouseEvent&) override;
     virtual void mousewheel_event(GMouseEvent&) override;
+    virtual void drop_event(GDropEvent&) override;
 
     void relayout();
 
@@ -30,4 +35,5 @@ private:
     int m_scale { 100 };
     Point m_pan_origin;
     Point m_pan_bitmap_origin;
+    String m_path;
 };

Applications/QuickShow/main.cpp

@@ -44,30 +44,32 @@ int main(int argc, char** argv)
     if (argc > 1)
         path = argv[1];
 
-    auto bitmap = load_png(path);
+    auto bitmap = GraphicsBitmap::load_from_file(path);
     if (!bitmap) {
         fprintf(stderr, "Failed to load %s\n", path);
         return 1;
     }
 
     auto window = GWindow::construct();
+    auto widget = QSWidget::construct();
+    widget->set_path(path);
+    widget->set_bitmap(*bitmap);
 
     auto update_window_title = [&](int scale) {
-        window->set_title(String::format("QuickShow: %s %s %d%%", path, bitmap->size().to_string().characters(), scale));
+        window->set_title(String::format("QuickShow: %s %s %d%%", widget->path().characters(), widget->bitmap()->size().to_string().characters(), scale));
     };
 
     window->set_double_buffering_enabled(true);
     update_window_title(100);
     window->set_rect(200, 200, bitmap->width(), bitmap->height());
 
-    auto widget = QSWidget::construct();
     widget->on_scale_change = [&](int scale) {
         update_window_title(scale);
     };
-    widget->set_bitmap(*bitmap);
     window->set_main_widget(widget);
 
     window->show();
 
+    bitmap = nullptr;
     return app.exec();
 }