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feat: implement eraser tool functionality in canvas drawing #54

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Merged
merged 1 commit into from
Oct 31, 2025
Merged

feat: implement eraser tool functionality in canvas drawing #54

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53 changes: 53 additions & 0 deletions client/src/components/Canvas.jsx
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ const SHAPE_TYPE = {
LINE: "line",
PEN: "pen",
CIRCLE: "circle",
ERASER: "eraser",
};

export const Canvas = () => {
Expand Down Expand Up @@ -194,6 +195,22 @@ export const Canvas = () => {
ctx.stroke();
}
break;
case SHAPE_TYPE.ERASER:
if (shape.path && shape.path.length > 1) {
ctx.save();
ctx.globalCompositeOperation = "destination-out";
ctx.lineWidth = shape.width;
ctx.lineCap = "round";
ctx.lineJoin = "round";
ctx.strokeStyle = "rgba(0,0,0,1)";
ctx.beginPath();
ctx.moveTo(shape.path[0].x, shape.path[0].y);
shape.path.forEach(p => ctx.lineTo(p.x, p.y));
ctx.stroke();
ctx.restore();
}
break;

default:
break;
}
Expand Down Expand Up @@ -603,6 +620,22 @@ export const Canvas = () => {
manipulationMode.current = { mode: "area" };
return;
}
if (activeTool === SHAPE_TYPE.ERASER) {
setIsDrawing(true);
manipulationMode.current = { mode: "erase" };
const ctx = canvasRef.current.getContext("2d");
ctx.save();
ctx.globalCompositeOperation = "destination-out";
ctx.lineWidth = strokeWidth * 2;
ctx.lineCap = "round";
ctx.lineJoin = "round";
ctx.beginPath();
const { x, y } = getWorldPoint(e);
ctx.moveTo(x, y);
ctx.restore();
return;
}


// creation tools
if (Object.values(SHAPE_TYPE).includes(activeTool) || activeTool.startsWith('brush-')) {
Expand Down Expand Up @@ -765,6 +798,21 @@ export const Canvas = () => {

// AREA select skipping here
if (activeTool === 'area-select') return;
if (manipulationMode.current?.mode === "erase") {
const ctx = canvasRef.current.getContext("2d");
ctx.save();
ctx.globalCompositeOperation = "destination-out";
ctx.lineWidth = strokeWidth * 2;
ctx.lineCap = "round";
ctx.lineJoin = "round";
const { x, y } = getWorldPoint(e);
ctx.lineTo(x, y);
ctx.stroke();
ctx.restore();
return;
}



// CREATE
if (newShapeId.current && manipulationMode.current && manipulationMode.current.mode === 'create') {
Expand Down Expand Up @@ -800,6 +848,11 @@ export const Canvas = () => {
setIsDrawing(false);
newShapeId.current = null;
manipulationMode.current = null;
if (manipulationMode.current?.mode === "erase") {
const ctx = canvasRef.current.getContext("2d");
ctx.globalCompositeOperation = "source-over";
}

};

// delete
Expand Down
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