Add support for clip on Path elements

This allows clipping the viewbox conveniently.

CHANGELOG.md

@@ -124,7 +124,7 @@ All notable changes to this project will be documented in this file.
  - Signals can have return a value
  - `has_hover` property in `TouchArea`
  - `font-weight` property on Text
- - `viewbox-x/y/width/height` properties for `Path`
+ - `viewbox-x/y/width/height` and `clip` properties for `Path`
 
 
 ## [0.0.2] - 2020-10-22

docs/builtin_elements.md

@@ -231,6 +231,9 @@ accordingly.
   defining the position and size of the viewport of the path in path coordinates. In the rendered output, the
   If the `viewbox-width` or `viewbox-height` is less or equal than zero, the viewbox properties are ignored
   and instead the bounding rectangle of all path elements are used to define the view port.
+* **`clip`** (*bool*): By default, when a path has a view box defined and the elements render outside of it, they are still
+    rendered. When this property is set to true, then rendering will be clipped at the boundaries of the view box.
+    This property must be a literal `true` or `false` (default: false)
 
 #### Path Using SVG commands
 

sixtyfps_compiler/builtins.60

@@ -323,6 +323,7 @@ export Path := _ {
     property <float> viewbox_y;
     property <float> viewbox_width;
     property <float> viewbox_height;
+    property <bool> clip;
 
     //-disallow_global_types_as_child_elements
     MoveTo {}

sixtyfps_compiler/passes/clip.rs

@@ -31,13 +31,22 @@ pub fn handle_clip(
         &mut |elem_rc: &ElementRc, _| {
             let mut elem = elem_rc.borrow_mut();
             if let Some(clip_prop) = elem.bindings.remove("clip") {
-                if !elem.builtin_type().map_or(false, |bt| bt.name == "Rectangle") {
-                    diag.push_error(
-                        "The 'clip' property can only be applied to a Rectangle for now".into(),
-                        &clip_prop.span,
-                    );
-                    return;
-                };
+                match elem.builtin_type().as_ref().map(|ty| ty.name.as_str()) {
+                    Some("Rectangle") => {}
+                    Some("Path") => {
+                        // it's an actual property, so keep the binding
+                        elem.bindings.insert("clip".into(), clip_prop);
+                        return;
+                    }
+                    _ => {
+                        diag.push_error(
+                            "The 'clip' property can only be applied to a Rectangle or a Path for now"
+                                .into(),
+                            &clip_prop.span,
+                        );
+                        return;
+                    }
+                }
                 // Was added by the meterialier_fake_properties pass
                 elem.property_declarations.remove("clip");
                 match &clip_prop.expression {

sixtyfps_compiler/tests/syntax/basic/clip.60

@@ -17,7 +17,7 @@ SubElements := Rectangle {
     }
     Image {
         clip: false;
-//           ^error{The 'clip' property can only be applied to a Rectangle for now}
+//           ^error{The 'clip' property can only be applied to a Rectangle or a Path for now}
     }
     for a in 12 : Rectangle {
         clip: true || true;

sixtyfps_runtime/corelib/items.rs

@@ -776,6 +776,7 @@ pub struct Path {
     pub viewbox_y: Property<f32>,
     pub viewbox_width: Property<f32>,
     pub viewbox_height: Property<f32>,
+    pub clip: Property<bool>,
     pub cached_rendering_data: CachedRenderingData,
 }
 
@@ -783,7 +784,7 @@ impl Item for Path {
     fn init(self: Pin<&Self>, _window: &ComponentWindow) {}
 
     fn geometry(self: Pin<&Self>) -> Rect {
-        euclid::rect(self.x(), self.y(), 0., 0.)
+        euclid::rect(self.x(), self.y(), self.width(), self.height())
     }
 
     fn layouting_info(self: Pin<&Self>, _window: &ComponentWindow) -> LayoutInfo {
@@ -815,7 +816,15 @@ impl Item for Path {
     fn focus_event(self: Pin<&Self>, _: &FocusEvent, _window: &ComponentWindow) {}
 
     fn render(self: Pin<&Self>, backend: &mut ItemRendererRef) {
-        (*backend).draw_path(self)
+        let clip = self.clip();
+        if clip {
+            (*backend).save_state();
+            (*backend).combine_clip(self.geometry(), 0., 0.)
+        }
+        (*backend).draw_path(self);
+        if clip {
+            (*backend).restore_state();
+        }
     }
 }
 

tests/cases/examples/path_viewbox.60

@@ -0,0 +1,98 @@
+/* LICENSE BEGIN
+    This file is part of the SixtyFPS Project -- https://sixtyfps.io
+    Copyright (c) 2020 Olivier Goffart <olivier.goffart@sixtyfps.io>
+    Copyright (c) 2020 Simon Hausmann <simon.hausmann@sixtyfps.io>
+
+    SPDX-License-Identifier: GPL-3.0-only
+    This file is also available under commercial licensing terms.
+    Please contact info@sixtyfps.io for more information.
+LICENSE END */
+
+RectPath := Path {
+    MoveTo {
+        x: 0;
+        y: 0;
+    }
+
+    LineTo {
+        x: 100;
+        y: 0;
+    }
+
+    LineTo {
+        x: 100;
+        y: 100;
+    }
+
+    LineTo {
+        x: 0;
+        y: 100;
+    }
+
+    Close {}
+}
+
+PathViewBox := Window {
+    preferred-width: 600px;
+    preferred-height: 600px;
+
+    // This is the reference path rectangle
+    RectPath {
+        x: 100px;
+        y: 100px;
+        width: 100px;
+        height: 100px;
+
+        stroke-width: 1px;
+        stroke: black;
+    }
+
+    // This path rectangle uses an unclipped viewbox and therefore
+    // draws outside the boundaries of the underlying green rectangle.
+    Rectangle {
+        background: #26e115da;
+        x: 300px;
+        y: 100px;
+        width: 100px;
+        height: 100px;
+
+        RectPath {
+            width: 100px;
+            height: 100px;
+
+            stroke-width: 1px;
+            stroke: black;
+
+            viewbox-x: 50;
+            viewbox-y: 0;
+            viewbox-width: 100;
+            viewbox-height: 100;
+        }
+    }
+
+    // This path rectangle uses an clipped viewbox and therefore
+    // draws only inside the boundaries of the underlying green rectangle.
+    Rectangle {
+        background: #26e115da;
+        x: 100px;
+        y: 300px;
+        width: 100px;
+        height: 100px;
+
+        RectPath {
+            width: 100px;
+            height: 100px;
+
+            stroke-width: 1px;
+            stroke: black;
+
+            clip: true;
+
+            viewbox-x: 50;
+            viewbox-y: 0;
+            viewbox-width: 100;
+            viewbox-height: 100;
+        }        
+    }
+}
+