Improve ImageCanvas - zoom, selection fixes, tool modes

- Add zoom support via prop (scales image around center)
- Fix selection interaction: clicking on selection transforms, clicking elsewhere creates new
- Use refs for state accessed in event handlers (fixes stale closure issue)
- Add smart select mode (clicks call onSmartSelect with image coordinates)
- Add color select mode placeholder
- Add pan mode with cursor feedback
- Add move mode for manipulating selections
- Use dashed blue selection style (more visible)
- forwardRef to expose canvas methods

frontend/src/components/ImageCanvas.jsx

@@ -1,26 +1,47 @@
-import React, { useEffect, useRef, useState, useCallback } from 'react';
+import React, { useEffect, useRef, useState, useCallback, forwardRef, useImperativeHandle } from 'react';
 import { fabric } from 'fabric';
 import './ImageCanvas.css';
 
-const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
+const ImageCanvas = forwardRef(({
+  imageUrl,
+  onSelectionChange,
+  selectionMode,
+  activeTool,
+  zoom = 100,
+  onSmartSelect,
+  isProcessing
+}, ref) => {
   const canvasRef = useRef(null);
   const fabricCanvasRef = useRef(null);
   const [currentSelection, setCurrentSelection] = useState(null);
-  const [isDrawing, setIsDrawing] = useState(false);
-  const [isTransformMode, setIsTransformMode] = useState(false);
+  const currentSelectionRef = useRef(null);
   const lassoPoints = useRef([]);
+  const isDrawingRef = useRef(false);
+  const imageRef = useRef(null);
+  const baseScaleRef = useRef(1);
 
+  // Expose methods to parent
+  useImperativeHandle(ref, () => ({
+    getCanvas: () => fabricCanvasRef.current,
+    clearSelection: () => clearSelection(),
+  }));
+
+  // Update selection ref when state changes
+  useEffect(() => {
+    currentSelectionRef.current = currentSelection;
+  }, [currentSelection]);
+
+  // Initialize canvas
   useEffect(() => {
     if (!canvasRef.current) return;
 
-    // Initialize Fabric.js canvas
     const canvas = new fabric.Canvas(canvasRef.current, {
       selection: false,
-      backgroundColor: '#2a2a2a',
+      backgroundColor: 'transparent',
+      preserveObjectStacking: true,
     });
     fabricCanvasRef.current = canvas;
 
-    // Handle window resize
     const handleResize = () => {
       const container = canvasRef.current?.parentElement;
       if (container) {
@@ -29,19 +50,9 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
         canvas.setWidth(width);
         canvas.setHeight(height);
 
-        // Re-center and rescale the image if it exists
-        const bgImage = canvas.backgroundImage;
-        if (bgImage) {
-          // Allow scaling up to fill the canvas
-          const scale = Math.min(
-            (width - 40) / bgImage.width,
-            (height - 40) / bgImage.height
-          );
-          bgImage.scale(scale);
-          bgImage.set({
-            left: (width - bgImage.width * scale) / 2,
-            top: (height - bgImage.height * scale) / 2,
-          });
+        // Re-center image if it exists
+        if (imageRef.current) {
+          centerImage(canvas, imageRef.current, zoom / 100);
         }
         canvas.renderAll();
       }
@@ -56,97 +67,211 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
     };
   }, []);
 
+  // Center and scale image
+  const centerImage = (canvas, img, zoomFactor) => {
+    if (!img) return;
+
+    const padding = 40;
+    const availableWidth = canvas.width - padding;
+    const availableHeight = canvas.height - padding;
+
+    // Calculate base scale to fit
+    const fitScale = Math.min(
+      availableWidth / img.width,
+      availableHeight / img.height
+    );
+
+    baseScaleRef.current = fitScale;
+    const scale = fitScale * zoomFactor;
+
+    img.scale(scale);
+    img.set({
+      left: (canvas.width - img.width * scale) / 2,
+      top: (canvas.height - img.height * scale) / 2,
+    });
+  };
+
+  // Apply zoom changes
+  useEffect(() => {
+    const canvas = fabricCanvasRef.current;
+    if (!canvas || !imageRef.current) return;
+
+    centerImage(canvas, imageRef.current, zoom / 100);
+    canvas.renderAll();
+  }, [zoom]);
+
   // Load image when URL changes
   useEffect(() => {
     if (!fabricCanvasRef.current || !imageUrl) return;
 
     const canvas = fabricCanvasRef.current;
-
-    // Add cache buster to force reload
-    const cacheBustedUrl = `${imageUrl}?t=${Date.now()}`;
+    const cacheBustedUrl = imageUrl.includes('?') ? `${imageUrl}&_t=${Date.now()}` : `${imageUrl}?t=${Date.now()}`;
 
     fabric.Image.fromURL(cacheBustedUrl, (img) => {
-      canvas.clear();
+      // Remove old image
+      if (imageRef.current) {
+        canvas.remove(imageRef.current);
+      }
 
-      // Scale image to fit canvas with padding
-      const padding = 40;
-      const availableWidth = canvas.width - padding;
-      const availableHeight = canvas.height - padding;
-      const scale = Math.min(
-        availableWidth / img.width,
-        availableHeight / img.height
-      );
+      // Clear selection
+      if (currentSelectionRef.current) {
+        canvas.remove(currentSelectionRef.current);
+        setCurrentSelection(null);
+        onSelectionChange(null);
+      }
 
-      img.scale(scale);
       img.set({
-        left: (canvas.width - img.width * scale) / 2,
-        top: (canvas.height - img.height * scale) / 2,
         selectable: false,
         evented: false,
+        hoverCursor: 'default',
       });
 
+      imageRef.current = img;
       canvas.add(img);
       canvas.sendToBack(img);
-      canvas.renderAll();
 
-      // Store image reference
-      canvas.backgroundImage = img;
+      centerImage(canvas, img, zoom / 100);
+      canvas.renderAll();
     }, { crossOrigin: 'anonymous' });
   }, [imageUrl]);
 
-  // Handle selection mode changes
+  // Handle tool/mode changes
   useEffect(() => {
     if (!fabricCanvasRef.current) return;
 
     const canvas = fabricCanvasRef.current;
 
-    // Clear previous selection when changing modes
-    if (currentSelection) {
-      canvas.remove(currentSelection);
-      setCurrentSelection(null);
-      onSelectionChange(null);
-    }
-
-    // Reset transform mode
-    setIsTransformMode(false);
-
-    // Set up event handlers based on mode
+    // Remove all event handlers
     canvas.off('mouse:down');
     canvas.off('mouse:move');
     canvas.off('mouse:up');
     canvas.off('object:modified');
+    canvas.off('object:moving');
+    canvas.off('object:scaling');
 
+    // Set up handlers based on selection mode
     if (selectionMode === 'rectangle') {
       setupRectangleMode(canvas);
     } else if (selectionMode === 'ellipse') {
       setupEllipseMode(canvas);
     } else if (selectionMode === 'lasso') {
       setupLassoMode(canvas);
+    } else if (selectionMode === 'smart') {
+      setupSmartSelectMode(canvas);
+    } else if (selectionMode === 'color') {
+      setupColorSelectMode(canvas);
+    } else if (activeTool === 'move') {
+      setupMoveMode(canvas);
+    } else if (activeTool === 'pan') {
+      setupPanMode(canvas);
     }
-  }, [selectionMode]);
+  }, [selectionMode, activeTool, onSmartSelect]);
 
-  const setupRectangleMode = (canvas) => {
-    let rect, isDown, startX, startY;
+  const setupMoveMode = (canvas) => {
+    // In move mode, allow selecting and moving selection objects
+    const sel = currentSelectionRef.current;
+    if (sel) {
+      sel.set({ selectable: true, evented: true });
+      canvas.setActiveObject(sel);
+    }
+
+    canvas.on('object:modified', (e) => {
+      if (e.target && e.target === currentSelectionRef.current) {
+        updateTransformedSelection(e.target);
+      }
+    });
+  };
+
+  const setupPanMode = (canvas) => {
+    let isPanning = false;
+    let lastPosX, lastPosY;
 
     canvas.on('mouse:down', (e) => {
-      // If clicking on existing selection, enable transform mode
-      if (e.target && e.target === currentSelection) {
-        setIsTransformMode(true);
+      isPanning = true;
+      lastPosX = e.e.clientX;
+      lastPosY = e.e.clientY;
+      canvas.setCursor('grabbing');
+    });
+
+    canvas.on('mouse:move', (e) => {
+      if (!isPanning) return;
+
+      const deltaX = e.e.clientX - lastPosX;
+      const deltaY = e.e.clientY - lastPosY;
+
+      canvas.relativePan({ x: deltaX, y: deltaY });
+
+      lastPosX = e.e.clientX;
+      lastPosY = e.e.clientY;
+    });
+
+    canvas.on('mouse:up', () => {
+      isPanning = false;
+      canvas.setCursor('grab');
+    });
+
+    canvas.setCursor('grab');
+  };
+
+  const setupSmartSelectMode = (canvas) => {
+    canvas.on('mouse:down', (e) => {
+      if (isProcessing) return;
+
+      const pointer = canvas.getPointer(e.e);
+      const img = imageRef.current;
+
+      if (!img) return;
+
+      // Convert to image coordinates
+      const imgScale = img.scaleX;
+      const imgLeft = img.left;
+      const imgTop = img.top;
+
+      const x = Math.round((pointer.x - imgLeft) / imgScale);
+      const y = Math.round((pointer.y - imgTop) / imgScale);
+
+      // Check if click is within image bounds
+      if (x >= 0 && x < img.width && y >= 0 && y < img.height) {
+        onSmartSelect?.(x, y);
+      }
+    });
+
+    canvas.setCursor('crosshair');
+  };
+
+  const setupColorSelectMode = (canvas) => {
+    canvas.on('mouse:down', (e) => {
+      if (isProcessing) return;
+
+      // TODO: Get pixel color at click position
+      const pointer = canvas.getPointer(e.e);
+      console.log('Color select at:', pointer);
+    });
+
+    canvas.setCursor('crosshair');
+  };
+
+  const setupRectangleMode = (canvas) => {
+    let rect = null;
+    let isDown = false;
+    let startX, startY;
+
+    canvas.on('mouse:down', (e) => {
+      // Check if clicking on existing selection
+      const sel = currentSelectionRef.current;
+      if (e.target && e.target === sel) {
+        // Allow moving/transforming
         return;
       }
 
-      // If in transform mode and clicking elsewhere, exit transform mode
-      if (isTransformMode) {
-        setIsTransformMode(false);
-      }
-
-      // Clear previous selection if exists
-      if (currentSelection) {
-        canvas.remove(currentSelection);
+      // Clear previous selection
+      if (sel) {
+        canvas.remove(sel);
         setCurrentSelection(null);
       }
 
       isDown = true;
+      isDrawingRef.current = true;
       const pointer = canvas.getPointer(e.e);
       startX = pointer.x;
       startY = pointer.y;
@@ -156,26 +281,24 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
         top: startY,
         width: 0,
         height: 0,
-        fill: 'rgba(255, 255, 255, 0.3)',
-        stroke: '#00ff00',
+        fill: 'rgba(0, 136, 255, 0.2)',
+        stroke: '#0088ff',
         strokeWidth: 2,
+        strokeDashArray: [5, 5],
         selectable: true,
         hasControls: true,
         hasBorders: true,
-        lockRotation: false,
-        cornerColor: '#00ff00',
-        cornerSize: 10,
+        cornerColor: '#0088ff',
+        cornerSize: 8,
         transparentCorners: false,
-        borderColor: '#00ff00',
-        borderScaleFactor: 2,
+        borderColor: '#0088ff',
       });
 
       canvas.add(rect);
-      setCurrentSelection(rect);
     });
 
     canvas.on('mouse:move', (e) => {
-      if (!isDown || isTransformMode) return;
+      if (!isDown || !rect) return;
 
       const pointer = canvas.getPointer(e.e);
       const width = pointer.x - startX;
@@ -192,39 +315,40 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
     });
 
     canvas.on('mouse:up', () => {
-      if (isDown && !isTransformMode) {
+      if (isDown && rect && rect.width > 5 && rect.height > 5) {
         isDown = false;
+        isDrawingRef.current = false;
+        setCurrentSelection(rect);
         canvas.setActiveObject(rect);
         updateSelection(rect, 'rectangle');
+      } else if (isDown && rect) {
+        // Selection too small, remove it
+        canvas.remove(rect);
+        isDown = false;
+        isDrawingRef.current = false;
       }
     });
 
-    // Update selection when object is modified (moved, scaled, rotated)
     canvas.on('object:modified', (e) => {
-      if (e.target && e.target === currentSelection) {
-        updateTransformedSelection(e.target, 'rectangle');
+      if (e.target === currentSelectionRef.current) {
+        updateTransformedSelection(e.target);
       }
     });
   };
 
   const setupEllipseMode = (canvas) => {
-    let ellipse, isDown, startX, startY;
+    let ellipse = null;
+    let isDown = false;
+    let startX, startY;
 
     canvas.on('mouse:down', (e) => {
-      // If clicking on existing selection, enable transform mode
-      if (e.target && e.target === currentSelection) {
-        setIsTransformMode(true);
+      const sel = currentSelectionRef.current;
+      if (e.target && e.target === sel) {
         return;
       }
 
-      // If in transform mode and clicking elsewhere, exit transform mode
-      if (isTransformMode) {
-        setIsTransformMode(false);
-      }
-
-      // Clear previous selection if exists
-      if (currentSelection) {
-        canvas.remove(currentSelection);
+      if (sel) {
+        canvas.remove(sel);
         setCurrentSelection(null);
       }
 
@@ -238,26 +362,24 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
         top: startY,
         rx: 0,
         ry: 0,
-        fill: 'rgba(255, 255, 255, 0.3)',
-        stroke: '#00ff00',
+        fill: 'rgba(0, 136, 255, 0.2)',
+        stroke: '#0088ff',
         strokeWidth: 2,
+        strokeDashArray: [5, 5],
         selectable: true,
         hasControls: true,
         hasBorders: true,
-        lockRotation: false,
-        cornerColor: '#00ff00',
-        cornerSize: 10,
+        cornerColor: '#0088ff',
+        cornerSize: 8,
         transparentCorners: false,
-        borderColor: '#00ff00',
-        borderScaleFactor: 2,
+        borderColor: '#0088ff',
       });
 
       canvas.add(ellipse);
-      setCurrentSelection(ellipse);
     });
 
     canvas.on('mouse:move', (e) => {
-      if (!isDown || isTransformMode) return;
+      if (!isDown || !ellipse) return;
 
       const pointer = canvas.getPointer(e.e);
       const rx = Math.abs(pointer.x - startX) / 2;
@@ -266,58 +388,55 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
       ellipse.set({
         rx: rx,
         ry: ry,
-        left: startX < pointer.x ? startX : pointer.x,
-        top: startY < pointer.y ? startY : pointer.y,
+        left: Math.min(startX, pointer.x),
+        top: Math.min(startY, pointer.y),
       });
 
       canvas.renderAll();
     });
 
     canvas.on('mouse:up', () => {
-      if (isDown && !isTransformMode) {
+      if (isDown && ellipse && ellipse.rx > 5 && ellipse.ry > 5) {
         isDown = false;
+        setCurrentSelection(ellipse);
         canvas.setActiveObject(ellipse);
         updateSelection(ellipse, 'ellipse');
+      } else if (isDown && ellipse) {
+        canvas.remove(ellipse);
+        isDown = false;
       }
     });
 
-    // Update selection when object is modified (moved, scaled, rotated)
     canvas.on('object:modified', (e) => {
-      if (e.target && e.target === currentSelection) {
-        updateTransformedSelection(e.target, 'ellipse');
+      if (e.target === currentSelectionRef.current) {
+        updateTransformedSelection(e.target);
       }
     });
   };
 
   const setupLassoMode = (canvas) => {
-    let polygon, points = [], drawingLine;
+    let points = [];
+    let drawingLine = null;
+    let polygon = null;
 
     canvas.on('mouse:down', (e) => {
-      // If clicking on existing selection, enable transform mode
-      if (e.target && e.target === currentSelection) {
-        setIsTransformMode(true);
+      const sel = currentSelectionRef.current;
+      if (e.target && e.target === sel) {
         return;
       }
 
-      // If in transform mode and clicking elsewhere, exit transform mode
-      if (isTransformMode) {
-        setIsTransformMode(false);
-      }
-
-      // Clear previous selection if exists
-      if (currentSelection) {
-        canvas.remove(currentSelection);
+      if (sel) {
+        canvas.remove(sel);
         setCurrentSelection(null);
       }
 
-      setIsDrawing(true);
+      isDrawingRef.current = true;
       const pointer = canvas.getPointer(e.e);
       points = [{ x: pointer.x, y: pointer.y }];
 
-      // Create a temporary line for visual feedback while drawing
       drawingLine = new fabric.Polyline(points, {
         fill: 'transparent',
-        stroke: '#00ff00',
+        stroke: '#0088ff',
         strokeWidth: 2,
         selectable: false,
         evented: false,
@@ -327,16 +446,15 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
     });
 
     canvas.on('mouse:move', (e) => {
-      if (!isDrawing || isTransformMode) return;
+      if (!isDrawingRef.current) return;
 
       const pointer = canvas.getPointer(e.e);
       points.push({ x: pointer.x, y: pointer.y });
 
-      // Remove old line and create new one with updated points
       canvas.remove(drawingLine);
       drawingLine = new fabric.Polyline([...points], {
         fill: 'transparent',
-        stroke: '#00ff00',
+        stroke: '#0088ff',
         strokeWidth: 2,
         selectable: false,
         evented: false,
@@ -346,59 +464,50 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
     });
 
     canvas.on('mouse:up', () => {
-      if (isDrawing && !isTransformMode && points.length > 2) {
-        setIsDrawing(false);
+      if (isDrawingRef.current && points.length > 5) {
+        isDrawingRef.current = false;
         lassoPoints.current = [...points];
 
-        // Remove drawing line
         canvas.remove(drawingLine);
 
-        // Create final polygon with fill
         polygon = new fabric.Polygon(points, {
-          fill: 'rgba(255, 255, 255, 0.3)',
-          stroke: '#00ff00',
+          fill: 'rgba(0, 136, 255, 0.2)',
+          stroke: '#0088ff',
           strokeWidth: 2,
+          strokeDashArray: [5, 5],
           selectable: true,
           hasControls: true,
           hasBorders: true,
-          lockRotation: false,
-          cornerColor: '#00ff00',
-          cornerSize: 10,
+          cornerColor: '#0088ff',
+          cornerSize: 8,
           transparentCorners: false,
-          borderColor: '#00ff00',
-          borderScaleFactor: 2,
+          borderColor: '#0088ff',
         });
 
         canvas.add(polygon);
         canvas.setActiveObject(polygon);
         setCurrentSelection(polygon);
         updateSelection(polygon, 'lasso');
-      } else if (isDrawing) {
-        setIsDrawing(false);
+      } else if (isDrawingRef.current) {
+        isDrawingRef.current = false;
         canvas.remove(drawingLine);
       }
     });
 
-    // Update selection when object is modified (moved, scaled, rotated)
     canvas.on('object:modified', (e) => {
-      if (e.target && e.target === currentSelection) {
-        updateTransformedSelection(e.target, 'lasso');
+      if (e.target === currentSelectionRef.current) {
+        updateTransformedSelection(e.target);
       }
     });
   };
 
   const updateSelection = (selection, type) => {
-    if (!selection || !fabricCanvasRef.current) return;
+    if (!selection || !imageRef.current) return;
 
-    const canvas = fabricCanvasRef.current;
-    const bgImage = canvas.backgroundImage;
-
-    if (!bgImage) return;
-
-    // Calculate bounding box in original image coordinates
-    const imgScale = bgImage.scaleX;
-    const imgLeft = bgImage.left;
-    const imgTop = bgImage.top;
+    const img = imageRef.current;
+    const imgScale = img.scaleX;
+    const imgLeft = img.left;
+    const imgTop = img.top;
 
     let bbox, selectionData = null;
 
@@ -425,39 +534,32 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
         height: Math.round(bounds.height / imgScale),
       };
 
-      // Convert lasso points to relative coordinates within bbox
       const relativePoints = lassoPoints.current.map(p => [
-        Math.round((p.x - bounds.left) / imgScale),
-        Math.round((p.y - bounds.top) / imgScale),
+        Math.round((p.x - imgLeft) / imgScale) - bbox.x,
+        Math.round((p.y - imgTop) / imgScale) - bbox.y,
       ]);
 
       selectionData = { points: relativePoints };
     }
 
-    onSelectionChange({
+    onSelectionChange?.({
       type,
       bbox,
       selectionData,
     });
   };
 
-  // Update selection after transformation (move, scale, rotate)
-  const updateTransformedSelection = (selection, type) => {
-    if (!selection || !fabricCanvasRef.current) return;
+  const updateTransformedSelection = (selection) => {
+    if (!selection || !imageRef.current) return;
 
-    const canvas = fabricCanvasRef.current;
-    const bgImage = canvas.backgroundImage;
+    const img = imageRef.current;
+    const imgScale = img.scaleX;
+    const imgLeft = img.left;
+    const imgTop = img.top;
 
-    if (!bgImage) return;
-
-    const imgScale = bgImage.scaleX;
-    const imgLeft = bgImage.left;
-    const imgTop = bgImage.top;
-
-    // Get the transformed bounding rect (accounts for scale and rotation)
     const bounds = selection.getBoundingRect(true);
 
-    let bbox = {
+    const bbox = {
       x: Math.round((bounds.left - imgLeft) / imgScale),
       y: Math.round((bounds.top - imgTop) / imgScale),
       width: Math.round(bounds.width / imgScale),
@@ -465,8 +567,8 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
     };
 
     let selectionData = null;
+    const type = selection.type === 'polygon' ? 'lasso' : (selection.type === 'ellipse' ? 'ellipse' : 'rectangle');
 
-    // For lasso, we need to transform the points based on the object's transformation
     if (type === 'lasso' && lassoPoints.current.length > 0) {
       const matrix = selection.calcTransformMatrix();
       const transformedPoints = lassoPoints.current.map(p => {
@@ -475,14 +577,14 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
           matrix
         );
         return [
-          Math.round((transformed.x - bounds.left) / imgScale),
-          Math.round((transformed.y - bounds.top) / imgScale),
+          Math.round((transformed.x - imgLeft) / imgScale) - bbox.x,
+          Math.round((transformed.y - imgTop) / imgScale) - bbox.y,
         ];
       });
       selectionData = { points: transformedPoints };
     }
 
-    onSelectionChange({
+    onSelectionChange?.({
       type,
       bbox,
       selectionData,
@@ -490,10 +592,12 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
   };
 
   const clearSelection = () => {
-    if (currentSelection && fabricCanvasRef.current) {
-      fabricCanvasRef.current.remove(currentSelection);
+    const canvas = fabricCanvasRef.current;
+    const sel = currentSelectionRef.current;
+    if (sel && canvas) {
+      canvas.remove(sel);
       setCurrentSelection(null);
-      onSelectionChange(null);
+      onSelectionChange?.(null);
     }
   };
 
@@ -501,17 +605,14 @@ const ImageCanvas = ({ imageUrl, onSelectionChange, selectionMode }) => {
     <div className="canvas-container">
       <canvas ref={canvasRef} />
       {currentSelection && (
-        <>
-          <div className="selection-hint">
-            Click selection to move/resize/rotate
-          </div>
-          <button className="clear-selection-btn" onClick={clearSelection}>
-            Clear Selection
-          </button>
-        </>
+        <button className="clear-selection-btn" onClick={clearSelection}>
+          Clear
+        </button>
       )}
     </div>
   );
-};
+});
+
+ImageCanvas.displayName = 'ImageCanvas';
 
 export default ImageCanvas;