From b1d1d547cfa9f922f1b0125316d5c0709e3385fd Mon Sep 17 00:00:00 2001
From: Sophie Herold <sophie@hemio.de>
Date: Thu, 4 Jan 2024 14:33:23 +0100
Subject: [PATCH] image/zoom: Force zoom to center for buttons

Before, using buttons on touchscreen could zoom to the cursor position.
---
 src/application.rs                  |  4 +-
 src/widgets/image/input_handling.rs |  2 +-
 src/widgets/image/zoom.rs           | 72 +++++++++++++++++++++--------
 src/widgets/image_view.rs           | 12 -----
 src/widgets/image_view.ui           |  4 +-
 src/window.rs                       | 46 ++++++++++++++----
 6 files changed, 94 insertions(+), 46 deletions(-)

diff --git a/src/application.rs b/src/application.rs
index ec0ab52..3764e0d 100644
--- a/src/application.rs
+++ b/src/application.rs
@@ -170,7 +170,7 @@ impl LpApplication {
         );
         self.set_accels_for_action("win.zoom-best-fit", &["0", "KP_0", "<Ctrl>0", "<Ctrl>KP_0"]);
         self.set_accels_for_action(
-            "win.zoom-in",
+            "win.zoom-in-cursor",
             &[
                 "<Ctrl>plus",
                 "plus",
@@ -181,7 +181,7 @@ impl LpApplication {
             ],
         );
         self.set_accels_for_action(
-            "win.zoom-out",
+            "win.zoom-out-cursor",
             &["<Ctrl>minus", "minus", "<Ctrl>KP_Subtract", "KP_Subtract"],
         );
 
diff --git a/src/widgets/image/input_handling.rs b/src/widgets/image/input_handling.rs
index bde5588..02eb6a3 100644
--- a/src/widgets/image/input_handling.rs
+++ b/src/widgets/image/input_handling.rs
@@ -85,7 +85,7 @@ impl imp::LpImage {
             if animated {
                 obj.zoom_to(zoom);
             } else {
-                obj.imp().zoom_to_full(zoom, false, false);
+                obj.imp().zoom_to_full(zoom, false, false, false);
             }
 
             // do not propagate event to scrolled window
diff --git a/src/widgets/image/zoom.rs b/src/widgets/image/zoom.rs
index 5b01631..9d31eee 100644
--- a/src/widgets/image/zoom.rs
+++ b/src/widgets/image/zoom.rs
@@ -126,7 +126,8 @@ impl imp::LpImage {
         (x, y)
     }
 
-    /// Required adjustment to put image coordinate under the cursor at this zoom level
+    /// Required adjustment to put image coordinate under the cursor at this
+    /// zoom level
     fn adj_for_position(
         &self,
         (cur_x, cur_y): (f64, f64),
@@ -216,8 +217,14 @@ impl imp::LpImage {
         }
     }
 
-    pub(super) fn zoom_to_full(&self, mut zoom: f64, animated: bool, snap_best_fit: bool) {
-        let obj = self.obj();
+    pub(super) fn zoom_to_full(
+        &self,
+        mut zoom: f64,
+        animated: bool,
+        snap_best_fit: bool,
+        force_cursor_center: bool,
+    ) {
+        let obj = self.obj().to_owned();
 
         let max_zoom = self.max_zoom();
         if zoom >= max_zoom {
@@ -254,16 +261,26 @@ impl imp::LpImage {
         }
 
         if animated {
-            let animation: &adw::TimedAnimation = self.zoom_animation();
+            let animation = self.zoom_animation();
 
-            // Set new point in image that should remain under the cursor while zooming if
-            // there isn't one already
-            if self.zoom_cursor_target.get().is_none() {
-                let img_pos = self
-                    .pointer_position
-                    .get()
-                    .map(|x| self.widget_to_img_coord(x));
-                self.zoom_cursor_target.set(img_pos);
+            if force_cursor_center {
+                animation.set_target(&adw::CallbackAnimationTarget::new(
+                    glib::clone!(@weak obj => move |zoom| {
+                        obj.imp().set_zoom_aiming(zoom, None);
+                    }),
+                ));
+            } else {
+                // Set new point in image that should remain under the cursor while zooming if
+                // there isn't one already
+                if self.zoom_cursor_target.get().is_none() {
+                    let img_pos = self
+                        .pointer_position
+                        .get()
+                        .map(|x| self.widget_to_img_coord(x));
+                    self.zoom_cursor_target.set(img_pos);
+                }
+
+                animation.set_target(&adw::PropertyAnimationTarget::new(&obj, "zoom"));
             }
 
             animation.set_value_from(obj.zoom());
@@ -283,7 +300,6 @@ impl imp::LpImage {
             let animation = adw::TimedAnimation::builder()
                 .duration(ZOOM_ANIMATION_DURATION)
                 .widget(&*obj)
-                .target(&adw::PropertyAnimationTarget::new(&*obj, "zoom"))
                 .build();
 
             animation.connect_done(glib::clone!(@weak obj => move |_| {
@@ -300,20 +316,38 @@ impl imp::LpImage {
 impl LpImage {
     /// Zoom in a step with animation
     ///
-    /// Used by buttons
-    pub fn zoom_in(&self) {
+    /// Used by keyboard shortcuts
+    pub fn zoom_in_cursor(&self) {
         let zoom = self.imp().zoom_target.get() * ZOOM_FACTOR_BUTTON;
 
         self.zoom_to(zoom);
     }
 
+    /// Zoom in a step with animation
+    ///
+    /// Used by buttons
+    pub fn zoom_in_center(&self) {
+        let zoom = self.imp().zoom_target.get() * ZOOM_FACTOR_BUTTON;
+
+        self.imp().zoom_to_full(zoom, true, true, true);
+    }
+
+    /// Zoom out a step with animation
+    ///
+    /// Used by keyboard shortcuts
+    pub fn zoom_out_cursor(&self) {
+        let zoom = self.imp().zoom_target.get() / ZOOM_FACTOR_BUTTON;
+
+        self.zoom_to(zoom);
+    }
+
     /// Zoom out a step with animation
     ///
     /// Used by buttons
-    pub fn zoom_out(&self) {
+    pub fn zoom_out_center(&self) {
         let zoom = self.imp().zoom_target.get() / ZOOM_FACTOR_BUTTON;
 
-        self.zoom_to(zoom);
+        self.imp().zoom_to_full(zoom, true, true, true);
     }
 
     /// Zoom to best fit
@@ -325,14 +359,14 @@ impl LpImage {
 
     /// Zoom to specific level with animation
     pub fn zoom_to(&self, zoom: f64) {
-        self.imp().zoom_to_full(zoom, true, true);
+        self.imp().zoom_to_full(zoom, true, true, false);
     }
 
     /// Zoom to specific level with animation not snapping to best-fit
     ///
     /// Used for zooming to 100% or 200%
     pub fn zoom_to_exact(&self, zoom: f64) {
-        self.imp().zoom_to_full(zoom, true, false);
+        self.imp().zoom_to_full(zoom, true, false, false);
     }
 
     pub fn is_best_fit(&self) -> bool {
diff --git a/src/widgets/image_view.rs b/src/widgets/image_view.rs
index 005d6f7..80afb03 100644
--- a/src/widgets/image_view.rs
+++ b/src/widgets/image_view.rs
@@ -632,18 +632,6 @@ impl LpImageView {
         self.imp().fullscreen_button.set_icon_name(icon);
     }
 
-    pub fn zoom_out(&self) {
-        if let Some(current_page) = self.current_page() {
-            current_page.image().zoom_out();
-        }
-    }
-
-    pub fn zoom_in(&self) {
-        if let Some(current_page) = self.current_page() {
-            current_page.image().zoom_in();
-        }
-    }
-
     pub fn rotate_image(&self, angle: f64) {
         if let Some(current_page) = self.current_page() {
             current_page.image().rotate_by(angle);
diff --git a/src/widgets/image_view.ui b/src/widgets/image_view.ui
index 829255e..1a0d7a0 100644
--- a/src/widgets/image_view.ui
+++ b/src/widgets/image_view.ui
@@ -59,7 +59,7 @@
             <child>
               <object class="GtkButton" id="zoom_out">
                 <property name="icon-name">zoom-out-symbolic</property>
-                <property name="action-name">win.zoom-out</property>
+                <property name="action-name">win.zoom-out-center</property>
                 <property name="tooltip-text" translatable="yes">Zoom Out</property>
                 <style>
                   <class name="osd" />
@@ -70,7 +70,7 @@
             <child>
               <object class="GtkButton" id="zoom_in">
                 <property name="icon-name">zoom-in-symbolic</property>
-                <property name="action-name">win.zoom-in</property>
+                <property name="action-name">win.zoom-in-center</property>
                 <property name="tooltip-text" translatable="yes">Zoom In</property>
                 <style>
                   <class name="osd" />
diff --git a/src/window.rs b/src/window.rs
index 74c3326..f8cac62 100644
--- a/src/window.rs
+++ b/src/window.rs
@@ -180,12 +180,20 @@ mod imp {
                 win.imp().image_view.jump(Position::Last);
             });
 
-            klass.install_action("win.zoom-out", None, move |win, _, _| {
-                win.zoom_out();
+            klass.install_action("win.zoom-out-cursor", None, move |win, _, _| {
+                win.zoom_out_cursor();
             });
 
-            klass.install_action("win.zoom-in", None, move |win, _, _| {
-                win.zoom_in();
+            klass.install_action("win.zoom-out-center", None, move |win, _, _| {
+                win.zoom_out_center();
+            });
+
+            klass.install_action("win.zoom-in-cursor", None, move |win, _, _| {
+                win.zoom_in_cursor();
+            });
+
+            klass.install_action("win.zoom-in-center", None, move |win, _, _| {
+                win.zoom_in_center();
             });
 
             klass.install_action("win.zoom-to-exact", Some("d"), move |win, _, level| {
@@ -485,12 +493,28 @@ impl LpWindow {
         self.set_fullscreened(fullscreen);
     }
 
-    fn zoom_out(&self) {
-        self.imp().image_view.zoom_out();
+    fn zoom_out_cursor(&self) {
+        if let Some(image) = self.imp().image_view.current_image() {
+            image.zoom_out_cursor();
+        }
     }
 
-    fn zoom_in(&self) {
-        self.imp().image_view.zoom_in();
+    fn zoom_out_center(&self) {
+        if let Some(image) = self.imp().image_view.current_image() {
+            image.zoom_out_center();
+        }
+    }
+
+    fn zoom_in_cursor(&self) {
+        if let Some(image) = self.imp().image_view.current_image() {
+            image.zoom_in_cursor();
+        }
+    }
+
+    fn zoom_in_center(&self) {
+        if let Some(image) = self.imp().image_view.current_image() {
+            image.zoom_in_center();
+        }
     }
 
     fn zoom_to_exact(&self, level: f64) {
@@ -870,8 +894,10 @@ impl LpWindow {
             .map(|image| !image.is_max_zoom())
             .unwrap_or_default();
 
-        self.action_set_enabled("win.zoom-out", can_zoom_out);
-        self.action_set_enabled("win.zoom-in", can_zoom_in);
+        self.action_set_enabled("win.zoom-out-cursor", can_zoom_out);
+        self.action_set_enabled("win.zoom-out-center", can_zoom_out);
+        self.action_set_enabled("win.zoom-in-cursor", can_zoom_in);
+        self.action_set_enabled("win.zoom-in-center", can_zoom_in);
     }
 
     fn on_fullscreen_changed(&self) {