[backport 1.25] Fix Alt+click create reroute (2/2) (#4869)

Co-authored-by: Christian Byrne <cbyrne@comfy.org>
Co-authored-by: github-actions <github-actions@github.com>

browser_tests/tests/rerouteNode.spec.ts

@@ -48,7 +48,9 @@ test.describe('LiteGraph Native Reroute Node', () => {
     await expect(comfyPage.canvas).toHaveScreenshot('native_reroute.png')
   })
 
-  test('Can add reroute by alt clicking on link', async ({ comfyPage }) => {
+  test('@2x @0.5x Can add reroute by alt clicking on link', async ({
+    comfyPage
+  }) => {
     const loadCheckpointNode = (
       await comfyPage.getNodeRefsByTitle('Load Checkpoint')
     )[0]

playwright.config.ts

@@ -49,6 +49,13 @@ export default defineConfig({
       grep: /@2x/ // Run all tests tagged with @2x
     },
 
+    {
+      name: 'chromium-0.5x',
+      use: { ...devices['Desktop Chrome'], deviceScaleFactor: 0.5 },
+      timeout: 15000,
+      grep: /@0.5x/ // Run all tests tagged with @0.5x
+    },
+
     // {
     //   name: 'firefox',
     //   use: { ...devices['Desktop Firefox'] },

src/lib/litegraph/src/LGraphCanvas.ts

@@ -2384,6 +2384,7 @@ export class LGraphCanvas
       // Set the width of the line for isPointInStroke checks
       const { lineWidth } = this.ctx
       this.ctx.lineWidth = this.connections_width + 7
+      const dpi = Math.max(window?.devicePixelRatio ?? 1, 1)
 
       for (const linkSegment of this.renderedPaths) {
         const centre = linkSegment._pos
@@ -2393,7 +2394,7 @@ export class LGraphCanvas
         if (
           (e.shiftKey || e.altKey) &&
           linkSegment.path &&
-          this.ctx.isPointInStroke(linkSegment.path, x, y)
+          this.ctx.isPointInStroke(linkSegment.path, x * dpi, y * dpi)
         ) {
           this.ctx.lineWidth = lineWidth