workflow-comics / src /lib /cropImage.ts
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async function cropImage(inputImage: string): Promise<{ croppedImage: string; x: number; y: number; width: number; height: number }> {
return new Promise((resolve, reject) => {
const img = new Image();
img.src = inputImage;
img.onload = () => {
const canvas = document.createElement('canvas');
const context = canvas.getContext('2d');
if (!context) {
reject("Context is null");
return;
}
canvas.width = img.width;
canvas.height = img.height;
context.drawImage(img, 0, 0, img.width, img.height);
const imageData = context.getImageData(0, 0, img.width, img.height);
const data = imageData.data;
let minX = img.width, minY = img.height, maxX = 0, maxY = 0;
for (let y = 0; y < img.height; y++) {
for (let x = 0; x < img.width; x++) {
const i = (y * 4) * img.width + x * 4;
const avg = (data[i] + data[i + 1] + data[i + 2]) / 3;
if (avg < 255) {
minX = Math.min(minX, x);
minY = Math.min(minY, y);
maxX = Math.max(maxX, x);
maxY = Math.max(maxY, y);
}
}
}
const width = maxX - minX;
const height = maxY - minY;
const croppedCanvas = document.createElement('canvas');
croppedCanvas.width = width;
croppedCanvas.height = height;
const croppedCtx = croppedCanvas.getContext('2d');
if (!croppedCtx) {
reject("croppedCtx is null");
return;
}
croppedCtx.drawImage(canvas, minX, minY, width, height, 0, 0, width, height);
resolve({
croppedImage: croppedCanvas.toDataURL(),
x: minX,
y: minY,
width,
height
});
};
img.onerror = reject;
});
}