[PATCH yew-widget-toolkit 1/3] js-helper: add client-to-svg-coordinate conversion helper

[Dominik Csapak <d.csapak@proxmox.com>]

Doing this in rust would mean we have to expose additional web-sys
features or doing the binding ourselves. Also since error handling for
the necessary code would be longer than the actual two line javascript
code, just have a short helper here.

This will be used in the upcoming Map widget to convert from pointer
position to svg coordinates.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
 js-helper-module.js | 7 +++++++
 src/lib.rs          | 5 +++++
 2 files changed, 12 insertions(+)

diff --git a/js-helper-module.js b/js-helper-module.js
index 838c987..53291f3 100644
--- a/js-helper-module.js
+++ b/js-helper-module.js
@@ -31,6 +31,12 @@ function toggle_popover(popover) {
     popover.togglePopover();
 }
 
+function client_to_svg_coords(svg, x, y) {
+    const pt = new DOMPoint(x, y);
+    const svgPt = pt.matrixTransform(svg.getScreenCTM().inverse());
+    return [svgPt.x, svgPt.y];
+}
+
 export {
     test_alert,
     show_dialog,
@@ -39,4 +45,5 @@ export {
     hide_popover,
     show_popover,
     toggle_popover,
+    client_to_svg_coords,
 };
diff --git a/src/lib.rs b/src/lib.rs
index d3ac6ea..bd51b0d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -297,6 +297,7 @@ extern "C" {
     pub fn show_popover(popover: web_sys::Node);
     pub fn hide_popover(popover: web_sys::Node);
     pub fn toggle_popover(popover: web_sys::Node);
+    pub fn client_to_svg_coords(svg: &web_sys::Node, x: f64, y: f64) -> Vec<f64>;
 }
 
 // Create wrapper which panics if called from target_arch!=wasm32
@@ -329,6 +330,10 @@ mod panic_wrapper {
     pub fn toggle_popover(_popover: web_sys::Node) {
         unreachable!()
     }
+    /// Calculate the svg coordinates from viewport ones
+    pub fn client_to_svg_coords(_svg: &web_sys::Node, _x: f64, _y: f64) -> Vec<f64> {
+        unreachable!()
+    }
 }
 
 // some helpers
-- 
2.47.3