widgets: split view and image

This will make implementing a more comprehensive photo view simpler.

data/gtk/image_view.ui

@@ -8,7 +8,7 @@
       <object class="GtkOverlay">
         <property name="hexpand">True</property>
         <child>
-          <object class="GtkPicture" id="picture">
+          <object class="IvImage" id="picture">
             <property name="halign">center</property>
             <property name="valign">center</property>
           </object>

src/meson.build

@@ -14,6 +14,7 @@ run_command(
 
 rust_sources = files(
   'widgets/image_view.rs',
+  'widgets/image.rs',
   'widgets/mod.rs',
   'application.rs',
   'config.rs',

src/widgets/image.rs

@@ -0,0 +1,208 @@
+// image.rs
+//
+// Copyright 2021 Christopher Davis <christopherdavis@gnome.org>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+use gdk::prelude::*;
+use gio::subclass::prelude::*;
+use gtk::{graphene, prelude::*, subclass::prelude::*};
+
+use once_cell::sync::Lazy;
+
+use std::cell::{Cell, RefCell};
+
+mod imp {
+    use super::*;
+
+    #[derive(Debug, Default)]
+    pub struct IvImage {
+        pub file: RefCell<Option<gio::File>>,
+        pub image_width: Cell<i32>,
+        pub image_height: Cell<i32>,
+        pub texture: RefCell<Option<gdk::Texture>>,
+    }
+
+    #[glib::object_subclass]
+    impl ObjectSubclass for IvImage {
+        const NAME: &'static str = "IvImage";
+        type ParentType = gtk::Widget;
+        type Type = super::IvImage;
+
+        fn new() -> Self {
+            Self {
+                file: RefCell::default(),
+                image_width: Cell::default(),
+                image_height: Cell::default(),
+                texture: RefCell::default(),
+            }
+        }
+    }
+
+    impl ObjectImpl for IvImage {
+        fn properties() -> &'static [glib::ParamSpec] {
+            static PROPERTIES: Lazy<Vec<glib::ParamSpec>> = Lazy::new(|| {
+                vec![glib::ParamSpec::new_object(
+                    "file",
+                    "File",
+                    "The current file",
+                    gio::File::static_type(),
+                    glib::ParamFlags::READWRITE,
+                )]
+            });
+
+            PROPERTIES.as_ref()
+        }
+
+        fn property(&self, obj: &Self::Type, _id: usize, pspec: &glib::ParamSpec) -> glib::Value {
+            match pspec.name() {
+                "file" => obj.file().to_value(),
+                _ => unimplemented!(),
+            }
+        }
+
+        fn set_property(
+            &self,
+            obj: &Self::Type,
+            _id: usize,
+            value: &glib::Value,
+            pspec: &glib::ParamSpec,
+        ) {
+            match pspec.name() {
+                "file" => obj.set_file(&value.get().unwrap()),
+                _ => unimplemented!(),
+            }
+        }
+
+        fn constructed(&self, obj: &Self::Type) {
+            obj.set_hexpand(true);
+            obj.set_vexpand(true);
+        }
+    }
+
+    impl WidgetImpl for IvImage {
+        fn snapshot(&self, widget: &Self::Type, snapshot: &gtk::Snapshot) {
+            if let Some(texture) = self.texture.borrow().as_ref() {
+                let width = widget.width() as f64;
+                let height = widget.height() as f64;
+                let ratio = texture.intrinsic_aspect_ratio();
+
+                if ratio == 0.0 {
+                    texture.snapshot(snapshot.upcast_ref(), width, height);
+                } else {
+                    let pic_ratio = width / height;
+
+                    let (snapshot_width, snapshot_height) = if ratio > pic_ratio {
+                        (width, width / ratio)
+                    } else {
+                        (height * ratio, height)
+                    };
+
+                    let x = (width - snapshot_width.ceil()) / 2.0;
+                    let y = (height - snapshot_height.ceil()).floor() / 2.0;
+
+                    snapshot.save();
+                    snapshot.translate(&graphene::Point::new(x as f32, y as f32));
+                    texture.snapshot(snapshot.upcast_ref(), snapshot_width, snapshot_height);
+                    snapshot.restore();
+                }
+            }
+        }
+
+        fn request_mode(&self, _widget: &Self::Type) -> gtk::SizeRequestMode {
+            gtk::SizeRequestMode::HeightForWidth
+        }
+
+        fn measure(
+            &self,
+            _widget: &Self::Type,
+            orienation: gtk::Orientation,
+            for_size: i32,
+        ) -> (i32, i32, i32, i32) {
+            if let Some(texture) = self.texture.borrow().as_ref() {
+                let default_size = 16.0; // Fall back to default icon size; Just a guess since the API GtkPicture uses is private
+                let measurement = if for_size < 0 { 0 } else { for_size };
+                let (min_width, min_height): (f64, f64) = (0.0, 0.0);
+
+                let (min, nat) = if orienation == gtk::Orientation::Horizontal {
+                    let size = texture.compute_concrete_size(
+                        0.0,
+                        measurement.into(),
+                        default_size,
+                        default_size,
+                    );
+                    let nat_width = size.0;
+
+                    (min_width.ceil(), nat_width.ceil())
+                } else {
+                    let size = texture.compute_concrete_size(
+                        measurement.into(),
+                        0.0,
+                        default_size,
+                        default_size,
+                    );
+                    let nat_height = size.1;
+
+                    (min_height.ceil(), nat_height.ceil())
+                };
+
+                (min as i32, nat as i32, -1, -1)
+            } else {
+                (0, 0, -1, -1)
+            }
+        }
+    }
+}
+
+glib::wrapper! {
+    pub struct IvImage(ObjectSubclass<imp::IvImage>) @extends gtk::Widget;
+}
+
+impl IvImage {
+    pub fn file(&self) -> Option<gio::File> {
+        let imp = imp::IvImage::from_instance(self);
+
+        imp.file.borrow().clone()
+    }
+
+    pub fn set_file(&self, file: &gio::File) {
+        let imp = imp::IvImage::from_instance(self);
+
+        match gdk::Texture::from_file(file) {
+            Ok(texture) => {
+                imp.image_width.set(texture.width());
+                imp.image_height.set(texture.height());
+                imp.file.replace(Some(file.clone()));
+                imp.texture.replace(Some(texture));
+            }
+            Err(e) => log::error!("Could not load a valid image from this file: {}", e),
+        };
+
+        self.queue_draw();
+        self.queue_resize();
+        imp.image_height.get();
+    }
+
+    pub fn image_width(&self) -> i32 {
+        let imp = imp::IvImage::from_instance(&self);
+        imp.image_width.get()
+    }
+
+    pub fn image_height(&self) -> i32 {
+        let imp = imp::IvImage::from_instance(&self);
+        imp.image_height.get()
+    }
+}

src/widgets/image_view.rs

@@ -32,6 +32,7 @@ use once_cell::sync::Lazy;
 use std::cell::{Cell, RefCell};
 
 use crate::util;
+use crate::widgets::IvImage;
 
 mod imp {
     use super::*;
@@ -40,7 +41,7 @@ mod imp {
     #[template(resource = "/org/gnome/Loupe/gtk/image_view.ui")]
     pub struct IvImageView {
         #[template_child]
-        pub picture: TemplateChild<gtk::Picture>,
+        pub picture: TemplateChild<IvImage>,
         #[template_child]
         pub controls: TemplateChild<gtk::Box>,
         #[template_child]
@@ -156,18 +157,16 @@ impl IvImageView {
         }
 
         self.set_parent_from_file(file);
-        let texture = gdk::Texture::from_file(file)?;
-        imp.picture.set_paintable(Some(&texture));
+        imp.picture.set_file(file);
         *imp.uri.borrow_mut() = Some(file.uri().to_string());
         self.notify("filename");
         self.update_action_state();
 
-        log::debug!(
-            "Image dimensions: {} x {}",
-            texture.width(),
-            texture.height()
-        );
-        Ok((texture.width(), texture.height()))
+        let width = imp.picture.image_width();
+        let height = imp.picture.image_height();
+
+        log::debug!("Image dimensions: {} x {}", width, height);
+        Ok((width, height))
     }
 
     fn set_parent_from_file(&self, file: &gio::File) {
@@ -241,7 +240,7 @@ impl IvImageView {
         );
 
         let file = gio::File::for_path(path);
-        imp.picture.set_file(Some(&file));
+        imp.picture.set_file(&file);
         *imp.uri.borrow_mut() = Some(file.uri().to_string());
         *imp.filename.borrow_mut() = util::get_file_display_name(&file);
         self.notify("filename");

src/widgets/mod.rs

@@ -17,6 +17,8 @@
 //
 // SPDX-License-Identifier: GPL-3.0-or-later
 
+mod image;
 mod image_view;
 
+pub use image::IvImage;
 pub use image_view::IvImageView;