From be70bdafe504f3209dc44c8e2343cc83aa9bc8f3 Mon Sep 17 00:00:00 2001
From: Christopher Davis <christopherdavis@gnome.org>
Date: Mon, 27 Dec 2021 15:03:31 -0800
Subject: [PATCH] window: Implement drag and drop

The main page is no longer a lie.
---
 Cargo.toml         |  1 +
 data/gtk/window.ui |  5 +++++
 src/application.rs |  2 +-
 src/util.rs        | 25 ++++++++++++++++++-------
 src/window.rs      | 45 ++++++++++++++++++++++++++++++++++++++++++---
 5 files changed, 67 insertions(+), 11 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index e5094ed..562e554 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -20,6 +20,7 @@ features = ["feature_gtk4"]
 [dependencies.gtk]
 package = "gtk4"
 git = "https://github.com/gtk-rs/gtk4-rs"
+features = ["v4_6"]
 
 [dependencies.adw]
 package = "libadwaita"
diff --git a/data/gtk/window.ui b/data/gtk/window.ui
index 682a9a4..510d42f 100644
--- a/data/gtk/window.ui
+++ b/data/gtk/window.ui
@@ -61,6 +61,11 @@
             <child>
               <object class="LpImageView" id="image_view"/>
             </child>
+            <child>
+              <object class="GtkDropTarget" id="drop_target">
+                <property name="actions">copy</property>
+              </object>
+            </child>
           </object>
         </property>
         <style>
diff --git a/src/application.rs b/src/application.rs
index e3d8796..4a5f0e5 100644
--- a/src/application.rs
+++ b/src/application.rs
@@ -81,7 +81,7 @@ mod imp {
         fn open(&self, application: &Self::Type, files: &[gio::File], _hint: &str) {
             for file in files {
                 let win = LpWindow::new(application);
-                win.set_image_from_file(file);
+                win.set_image_from_file(file, true);
                 win.show();
             }
         }
diff --git a/src/util.rs b/src/util.rs
index 7b10fc0..e91a626 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -13,13 +13,24 @@ pub fn utf8_collate_key_for_filename(filename: &str) -> String {
 }
 
 pub fn get_file_display_name(file: &gio::File) -> Option<String> {
-    let info = file
-        .query_info(
-            *gio::FILE_ATTRIBUTE_STANDARD_DISPLAY_NAME,
-            gio::FileQueryInfoFlags::empty(),
-            gio::Cancellable::NONE,
-        )
-        .ok()?;
+    let info = query_attributes(file, vec![&gio::FILE_ATTRIBUTE_STANDARD_DISPLAY_NAME]).ok()?;
 
     Some(info.display_name().to_string())
 }
+
+pub fn query_attributes(
+    file: &gio::File,
+    attributes: Vec<&str>,
+) -> Result<gio::FileInfo, glib::Error> {
+    let mut attributes = attributes;
+    let mut attr_str = String::from(attributes.remove(0));
+    for attr in attributes {
+        attr_str.push_str(&format!(",{}", attr));
+    }
+
+    file.query_info(
+        &attr_str,
+        gio::FileQueryInfoFlags::empty(),
+        gio::Cancellable::NONE,
+    )
+}
diff --git a/src/window.rs b/src/window.rs
index ff4cfdc..7187c89 100644
--- a/src/window.rs
+++ b/src/window.rs
@@ -26,6 +26,7 @@ use gtk::subclass::prelude::*;
 use gtk::CompositeTemplate;
 
 use crate::config;
+use crate::util;
 use crate::widgets::LpImageView;
 
 mod imp {
@@ -65,6 +66,8 @@ mod imp {
         pub status_page: TemplateChild<adw::StatusPage>,
         #[template_child]
         pub image_view: TemplateChild<LpImageView>,
+        #[template_child]
+        pub drop_target: TemplateChild<gtk::DropTarget>,
     }
 
     #[glib::object_subclass]
@@ -135,6 +138,39 @@ mod imp {
                     }
                 }),
             );
+
+            self.drop_target.set_types(&[gdk::FileList::static_type()]);
+            self.drop_target.connect_drop(
+                clone!(@weak obj => @default-return false, move |_, value, _, _| {
+                    // Here we use a GValue, which is a dynamic object that can hold different types,
+                    // e.g. strings, numbers, or in this case objects. In order to get the GdkFileList
+                    // from the GValue, we need to use the `get()` method.
+                    //
+                    // We've added type annotations here, and written it as `let list: gdk::FileList = ...`,
+                    // but you might also see places where type arguments are used.
+                    // This line could have been written as `let list = value.get::<gdk::FileList>().unwrap()`.
+                    let list: gdk::FileList = value.get().unwrap();
+
+                    // TODO: Handle this like EOG and make a "directory" out of the given files
+                    let file = list.files().get(0).unwrap().clone();
+                    let info = util::query_attributes(
+                        &file,
+                        vec![&gio::FILE_ATTRIBUTE_STANDARD_CONTENT_TYPE])
+                        .expect("Could not query file info");
+
+                    if info
+                        .content_type()
+                        .map(|t| t.to_string())
+                        .filter(|t| t.starts_with("image/"))
+                        .is_some() {
+                        obj.set_image_from_file(&file, false);
+                    } else {
+                        log::debug!("{} was not a valid image.", file.uri().to_string());
+                    }
+
+                    true
+                }),
+            );
         }
     }
 
@@ -201,7 +237,7 @@ impl LpWindow {
             clone!(@weak self as win, @strong chooser => move |_, resp| {
                 if resp == gtk::ResponseType::Accept {
                     if let Some(file) = chooser.file() {
-                        win.set_image_from_file(&file);
+                        win.set_image_from_file(&file, true);
                     }
                 }
             }),
@@ -239,13 +275,16 @@ impl LpWindow {
         }
     }
 
-    pub fn set_image_from_file(&self, file: &gio::File) {
+    pub fn set_image_from_file(&self, file: &gio::File, resize: bool) {
         let imp = imp::LpWindow::from_instance(self);
 
         log::debug!("Loading file: {}", file.uri().to_string());
         match imp.image_view.set_image_from_file(file) {
             Ok((width, height)) => {
-                self.resize_from_dimensions(width, height);
+                if resize {
+                    self.resize_from_dimensions(width, height);
+                }
+
                 imp.stack.set_visible_child(&*imp.image_view);
                 imp.image_view.grab_focus();
                 self.set_actions_enabled(true)