avtopost.kultmost.ru/static/script/share.js

async function imageWithTextBlob(imageUrl, text, options = {}) {
  const response = await fetch(imageUrl, {
    mode: 'cors',
    credentials: 'same-origin',
  });
  if (!response.ok) throw new Error(`HTTP ${response.status}`);
  const imageBlob = await response.blob();
  const imageBitmap = await createImageBitmap(imageBlob);

  // OffscreenCanvas (works in modern browsers; fallback to normal canvas if needed)
  const canvas = typeof OffscreenCanvas !== 'undefined'
    ? new OffscreenCanvas(
        options.width ?? imageBitmap.width,
        options.height ?? imageBitmap.height
      )
    : document.createElement('canvas');

  const width = canvas.width ?? (options.width ?? imageBitmap.width);
  const height = canvas.height ?? (options.height ?? imageBitmap.height);

  if (!(canvas instanceof OffscreenCanvas)) {
    canvas.width = width;
    canvas.height = height;
  }

  const ctx = canvas.getContext('2d', { alpha: true });

  // Draw image
  ctx.drawImage(imageBitmap, 0, 0, width, height);

  // No text: return original bitmap as blob
  if (!text?.trim()) {
    if (canvas.convertToBlob) {
      return canvas.convertToBlob({
        type: options.type ?? 'image/png',
        quality: options.quality ?? 0.92,
      });
    }
    return await new Promise((resolve) =>
      canvas.toBlob((b) => resolve(b), options.type ?? 'image/png', options.quality ?? 0.92)
    );
  }

  // === Text rendering ===
  const basePadding = options.basePadding ?? 8;                 // internal left/right/top padding
  const fontSize = options.fontSize ?? Math.round(width * 0.05);
  ctx.font = `${fontSize}px ${options.fontFamily ?? 'sans-serif'}`;
  ctx.textBaseline = 'bottom';
  ctx.textAlign = 'center';

  const textColor = options.textColor ?? '#5F1798';
  const bgColor = options.bgColor ?? '#fff';
  const strokeColor = options.strokeColor ?? 'rgba(0,0,0,0.35)';
  const shadowBlur = options.shadowBlur ?? 6;
  const maxWidth = width - basePadding * 2 - (options.extraPadding ?? 0);

  // Wrap text into lines
  const words = text.split(' ');
  let line = '';
  const lines = [];
  for (const word of words) {
    const testLine = line ? line + ' ' + word : word;
    if (ctx.measureText(testLine).width > maxWidth && line) {
      lines.push(line);
      line = word;
    } else {
      line = testLine;
    }
  }
  if (line) lines.push(line);

  const lineHeight = fontSize + (options.lineGap ?? 6);

  // Extra internal bottom padding inside the rounded box
  const internalBottomPadding = options.internalBottomPadding ?? Math.round(fontSize * 0.35);
  const boxHeight = lines.length * lineHeight + basePadding + internalBottomPadding;

  const maxLineWidth = Math.max(...lines.map((l) => ctx.measureText(l).width));
  const boxWidth = maxLineWidth + basePadding * 2;

  // Distance from the very bottom of the image to the bottom of the text box
  const bottomPadding = options.bottomPadding ?? Math.round(fontSize * 0.9);

  const boxX = (width - boxWidth) / 2;
  const boxY = height - bottomPadding - boxHeight;
  const radius = options.radius ?? 8;

  // Background rounded rect
  ctx.save();
  ctx.fillStyle = bgColor;
  ctx.shadowColor = strokeColor;
  ctx.shadowBlur = shadowBlur;
  roundRect(ctx, boxX, boxY, boxWidth, boxHeight, radius, true, false);
  ctx.restore();

  // Text
  ctx.fillStyle = textColor;
  ctx.shadowColor = 'transparent';

  for (let i = 0; i < lines.length; i++) {
    const lineY = boxY + basePadding + (i + 1) * lineHeight - (lineHeight - fontSize) / 2;
    const lineX = width / 2;

    if (options.outline) {
      ctx.lineWidth = options.outlineWidth ?? 2;
      ctx.strokeStyle = options.outlineColor ?? 'rgba(255,255,255,0.8)';
      ctx.strokeText(lines[i], lineX, lineY);
    }
    ctx.fillText(lines[i], lineX, lineY);
  }

  // Convert to blob
  if (canvas.convertToBlob) {
    return await canvas.convertToBlob({
      type: options.type ?? 'image/png',
      quality: options.quality ?? 0.92,
    });
  }
  return await new Promise((resolve) =>
    canvas.toBlob((b) => resolve(b), options.type ?? 'image/png', options.quality ?? 0.92)
  );
}
function roundRect(ctx, x, y, w, h, r, fill, stroke) {
  if (typeof r === 'number') r = { tl: r, tr: r, br: r, bl: r };
  ctx.beginPath();
  ctx.moveTo(x + r.tl, y);
  ctx.lineTo(x + w - r.tr, y);
  ctx.quadraticCurveTo(x + w, y, x + w, y + r.tr);
  ctx.lineTo(x + w, y + h - r.br);
  ctx.quadraticCurveTo(x + w, y + h, x + w - r.br, y + h);
  ctx.lineTo(x + r.bl, y + h);
  ctx.quadraticCurveTo(x, y + h, x, y + h - r.bl);
  ctx.lineTo(x, y + r.tl);
  ctx.quadraticCurveTo(x, y, x + r.tl, y);
  ctx.closePath();
  if (fill) ctx.fill();
  if (stroke) ctx.stroke();
}