Added scroll zoom commands.

TODO/_current.md

@@ -28,11 +28,13 @@
 
 # Scroll
 
+* Click in thumb drag and release outside thumb causes it to stay pressed.
 * Implement touch scroll inertia.
 * Implement `ScrollMode::ZOOM`.
     - Touch gesture.
     - Scroll wheel zoom.
     - Commands.
+    - Scroll-to-fill.
 
 # Touch Events
 

examples/image.rs

@@ -461,8 +461,8 @@ fn center_viewport(msg: impl UiNode) -> impl UiNode {
         // the large images can take a moment to decode in debug builds, but the size
         // is already known after read, so the "loading.." message ends-up off-screen
         // because it is centered on the image.
-        x = zero_ui::widgets::scroll::SCROLL_HORIZONTAL_OFFSET_VAR.map(|&fct| Length::Relative(fct) - 1.vw() * fct);
-        y = zero_ui::widgets::scroll::SCROLL_VERTICAL_OFFSET_VAR.map(|&fct| Length::Relative(fct) - 1.vh() * fct);
+        x = zero_ui::widgets::scroll::SCROLL.horizontal_offset().map(|&fct| Length::Relative(fct) - 1.vw() * fct);
+        y = zero_ui::widgets::scroll::SCROLL.vertical_offset().map(|&fct| Length::Relative(fct) - 1.vh() * fct);
         zero_ui::core::widget_base::can_auto_hide = false;
         max_size = (1.vw(), 1.vh());
         child_align = Align::CENTER;

examples/scroll.rs

@@ -105,7 +105,7 @@ fn scroll_to_btn(target: WidgetId, mode: ScrollToMode) -> impl UiNode {
         child = Text!("Scroll To {} {}", target, if let ScrollToMode::Minimal{..} = &mode { "(minimal)" } else { "(center)" });
         enabled = cmd.is_enabled();
         on_click = hn!(|_| {
-            cmd.notify_param(commands::ScrollToRequest { widget_id: target, mode: mode.clone() });
+            cmd.notify_param(commands::ScrollToRequest { widget_id: target, mode: mode.clone(), zoom: None, });
         });
     }
 }

zero-ui/src/widgets/scroll.rs

@@ -102,7 +102,9 @@ fn on_build(wgt: &mut WidgetBuilding) {
         let child = with_context_var(child, SCROLL_HORIZONTAL_OFFSET_VAR, var(0.fct()));
 
         let child = with_context_var(child, OVERSCROLL_VERTICAL_OFFSET_VAR, var(0.fct()));
-        with_context_var(child, OVERSCROLL_HORIZONTAL_OFFSET_VAR, var(0.fct()))
+        let child = with_context_var(child, OVERSCROLL_HORIZONTAL_OFFSET_VAR, var(0.fct()));
+
+        with_context_var(child, SCROLL_SCALE_VAR, var(1.fct()))
     });
 }
 

zero-ui/src/widgets/scroll/commands.rs

@@ -165,7 +165,8 @@ command! {
         shortcut_filter: ShortcutFilter::FOCUSED | ShortcutFilter::CMD_ENABLED,
     };
 
-    /// Represents the action of scrolling until a child widget is fully visible.
+    /// Represents the action of scrolling until a child widget is fully visible, the command can
+    /// also adjust the zoom scale.
     ///
     /// # Metadata
     ///
@@ -178,6 +179,25 @@ command! {
     ///
     /// You can use the [`scroll_to`] function to invoke this command in all parent scrolls automatically.
     pub static SCROLL_TO_CMD;
+
+    /// Represents the **zoom in** action.
+    pub static ZOOM_IN_CMD = {
+        name: "Zoom In",
+        shortcut: shortcut!(CTRL+'+'),
+        shortcut_filter: ShortcutFilter::FOCUSED | ShortcutFilter::CMD_ENABLED,
+    };
+
+    /// Represents the **zoom out** action.
+    pub static ZOOM_OUT_CMD = {
+        name: "Zoom Out",
+        shortcut: shortcut!(CTRL+'-'),
+        shortcut_filter: ShortcutFilter::FOCUSED | ShortcutFilter::CMD_ENABLED,
+    };
+
+    /// Represents the **reset zoom** action.
+    pub static ZOOM_RESET_CMD = {
+        name: "Reset Zoom",
+    };
 }
 
 /// Parameters for the scroll and page commands.
@@ -250,6 +270,13 @@ pub struct ScrollToRequest {
 
     /// How much the scroll position will change to showcase the target widget.
     pub mode: ScrollToMode,
+
+    /// Optional zoom scale target.
+    ///
+    /// If set the offsets and scale will animate so that the `mode`
+    /// is fullfilled when this zoom factor is reached. If not set the scroll will happen in
+    /// the current zoom scale.
+    pub zoom: Option<Factor>,
 }
 impl ScrollToRequest {
     /// Pack the request into a command parameter.
@@ -265,6 +292,7 @@ impl ScrollToRequest {
             p.downcast_ref::<WidgetId>().map(|id| ScrollToRequest {
                 widget_id: *id,
                 mode: ScrollToMode::default(),
+                zoom: None,
             })
         }
     }
@@ -287,7 +315,8 @@ impl_from_and_into_var! {
     fn from(widget_id: WidgetId) -> ScrollToRequest {
         ScrollToRequest {
             widget_id,
-            mode: ScrollToMode::default()
+            mode: ScrollToMode::default(),
+            zoom: None,
         }
     }
 }
@@ -374,13 +403,12 @@ impl IntoValue<Option<ScrollToMode>> for ScrollToMode {}
 ///
 /// [`is_scroll`]: WidgetInfoExt::is_scroll
 pub fn scroll_to(target: impl Into<WidgetId>, mode: impl Into<ScrollToMode>) {
-    let target = target.into();
-    for w in crate::core::window::WINDOWS.widget_trees() {
-        if let Some(target) = w.get(target) {
-            scroll_to_info(&target, mode.into());
-            break;
-        }
-    }
+    scroll_to_impl(target.into(), mode.into(), None)
+}
+
+/// Like [`scroll_to`], but also adjusts the zoom scale.
+pub fn scroll_to_zoom(target: impl Into<WidgetId>, mode: impl Into<ScrollToMode>, zoom: impl Into<Factor>) {
+    scroll_to_impl(target.into(), mode.into(), Some(zoom.into()))
 }
 
 /// Scroll all parent [`is_scroll`] widgets of `target` so that it becomes visible.
@@ -389,13 +417,31 @@ pub fn scroll_to(target: impl Into<WidgetId>, mode: impl Into<ScrollToMode>) {
 ///
 /// [`is_scroll`]: WidgetInfoExt::is_scroll
 pub fn scroll_to_info(target: &crate::core::widget_info::WidgetInfo, mode: impl Into<ScrollToMode>) {
+    scroll_to_info_impl(target, mode.into(), None)
+}
+
+/// Like [`scroll_to_info`], but also adjusts the zoom scale.
+pub fn scroll_to_info_zoom(target: &crate::core::widget_info::WidgetInfo, mode: impl Into<ScrollToMode>, zoom: impl Into<Factor>) {
+    scroll_to_info_impl(target, mode.into(), Some(zoom.into()))
+}
+
+fn scroll_to_impl(target: WidgetId, mode: ScrollToMode, zoom: Option<Factor>) {
+    for w in crate::core::window::WINDOWS.widget_trees() {
+        if let Some(target) = w.get(target) {
+            scroll_to_info_impl(&target, mode, zoom);
+            break;
+        }
+    }
+}
+
+fn scroll_to_info_impl(target: &crate::core::widget_info::WidgetInfo, mode: ScrollToMode, zoom: Option<Factor>) {
     let mut t = target.id();
-    let mode = mode.into();
     for a in target.ancestors() {
         if a.is_scroll() {
             SCROLL_TO_CMD.scoped(a.id()).notify_param(ScrollToRequest {
                 widget_id: t,
                 mode: mode.clone(),
+                zoom,
             });
             t = a.id();
         }

zero-ui/src/widgets/scroll/scroll_properties.rs

@@ -209,6 +209,8 @@ pub fn define_viewport_unit(child: impl UiNode, enabled: impl IntoVar<bool>) ->
 }
 
 /// Smooth scrolling config.
+///
+/// Defines the easing animation applied to scroll offset and zoom value changes.
 #[property(CONTEXT, default(SMOOTH_SCROLLING_VAR), widget_impl(Scroll))]
 pub fn smooth_scrolling(child: impl UiNode, config: impl IntoVar<SmoothScrolling>) -> impl UiNode {
     with_context_var(child, SMOOTH_SCROLLING_VAR, config)

zero-ui/src/widgets/scroll/types.rs

@@ -54,13 +54,11 @@ impl_from_and_into_var! {
 context_var! {
     /// Vertical offset of the parent scroll.
     ///
-    /// The value is a percentage of `content.height - viewport.height`. This variable is usually read-write,
-    /// scrollable content can modify it to scroll the parent.
+    /// The value is a percentage of `content.height - viewport.height`.
     pub(super) static SCROLL_VERTICAL_OFFSET_VAR: Factor = 0.fct();
     /// Horizontal offset of the parent scroll.
     ///
-    /// The value is a percentage of `content.width - viewport.width`. This variable is usually read-write,
-    /// scrollable content can modify it to scroll the parent.
+    /// The value is a percentage of `content.width - viewport.width`.
     pub(super) static SCROLL_HORIZONTAL_OFFSET_VAR: Factor = 0.fct();
 
     /// Extra vertical offset requested that could not be fulfilled because [`SCROLL_VERTICAL_OFFSET_VAR`]
@@ -91,8 +89,13 @@ context_var! {
     pub(super) static SCROLL_VIEWPORT_SIZE_VAR: PxSize = PxSize::zero();
 
     /// Latest computed content size of the parent scroll.
+    ///
+    /// The size is scaled if zoom is set.
     pub(super) static SCROLL_CONTENT_SIZE_VAR: PxSize = PxSize::zero();
 
+    /// Zoom scaling of the parent scroll.
+    pub(super) static SCROLL_SCALE_VAR: Factor = 1.fct();
+
 }
 
 context_local! {
@@ -594,6 +597,7 @@ impl SCROLL {
         todo!()
     }
 
+    /// Returns `true` if the content can be scaled and the current scale is more than the min.
     pub fn can_zoom_out(&self) -> bool {
         todo!()
     }