From b678b2e226face9af9ba7fad543d809d0144afa2 Mon Sep 17 00:00:00 2001
From: Maxim Dolgolyov <maxim.dolgolyov@gmail.com>
Date: Wed, 3 Jun 2026 20:16:43 +0300
Subject: [PATCH] =?UTF-8?q?fix(svg-draw):=20=D1=80=D0=B8=D1=81=D0=BE=D0=B2?=
 =?UTF-8?q?=D0=B0=D0=BD=D0=B8=D0=B5=20=D0=B2=D0=BC=D0=B5=D1=81=D1=82=D0=BE?=
 =?UTF-8?q?=20=D0=BF=D0=B5=D1=80=D0=B5=D1=82=D0=B0=D1=81=D0=BA=D0=B8=D0=B2?=
 =?UTF-8?q?=D0=B0=D0=BD=D0=B8=D1=8F=20=D0=B1=D0=BB=D0=BE=D0=BA=D0=B0?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Блок-карточка урока draggable=true перехватывала зажатие мыши на холсте → тащился весь
блок, а не рисовалась линия. Теперь dragstart внутри .svgdraw-host отменяется, на холсте
заглушены нативный drag и выделение (user-select/-webkit-user-drag:none).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 frontend/js/svg-draw.js     | 5 ++++-
 frontend/lesson-editor.html | 2 ++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/frontend/js/svg-draw.js b/frontend/js/svg-draw.js
index d3fd6fb..a79c810 100644
--- a/frontend/js/svg-draw.js
+++ b/frontend/js/svg-draw.js
@@ -46,7 +46,7 @@
         linear-gradient(45deg,#f8fafc 25%,transparent 25%),linear-gradient(-45deg,#f8fafc 25%,transparent 25%),
         linear-gradient(45deg,transparent 75%,#f8fafc 75%),linear-gradient(-45deg,transparent 75%,#f8fafc 75%);
         background-size:18px 18px; background-position:0 0,0 9px,9px -9px,-9px 0; }
-      .svgd-canvas { display:block; width:100%; height:auto; touch-action:none; cursor:crosshair; }
+      .svgd-canvas { display:block; width:100%; height:auto; touch-action:none; cursor:crosshair; user-select:none; -webkit-user-select:none; -webkit-user-drag:none; }
       .svgd-canvas.tool-select { cursor:default; }
       .svgd-sel { outline:none; }
       .svgd-selbox { fill:none; stroke:#8b5cf6; stroke-width:1.5; stroke-dasharray:5 4; vector-effect:non-scaling-stroke; pointer-events:none; }
@@ -294,6 +294,9 @@
     }
     svg.addEventListener('pointerup', endDraw);
     svg.addEventListener('pointercancel', endDraw);
+    // Block native HTML5 drag (the lesson block-card is draggable=true; without
+    // this, pressing on the canvas drags the whole block instead of drawing).
+    svg.addEventListener('dragstart', function (e) { e.preventDefault(); });
 
     function isTiny(el) {
       const b = el.getBBox();
diff --git a/frontend/lesson-editor.html b/frontend/lesson-editor.html
index 41ccdf7..2976211 100644
--- a/frontend/lesson-editor.html
+++ b/frontend/lesson-editor.html
@@ -1320,6 +1320,8 @@
       // drag and drop
       card.setAttribute('draggable', 'true');
       card.addEventListener('dragstart', e => {
+        // не перехватывать холст SVG-рисовалки — там пользователь рисует
+        if (e.target.closest && e.target.closest('.svgdraw-host')) { e.preventDefault(); return; }
         e.dataTransfer.setData('text/plain', bid);
         card.classList.add('dragging');
       });