Function downscaleImageForAgent

src/app/chartCache.ts:74–96

(
    dataUrl: string,
    maxDim: number = 200,
    quality: number = 0.75,
)

 * while preserving the original chart layout.
 */
export async function downscaleImageForAgent(
    dataUrl: string,
    maxDim: number = 200,
    quality: number = 0.75,
): Promise<string> {
    const img = new Image();
    await new Promise<void>((resolve, reject) => {
        img.onload = () => resolve();
        img.onerror = reject;
        img.src = dataUrl;
    });
    const scale = Math.min(maxDim / img.width, maxDim / img.height, 1);
    const w = Math.round(img.width * scale);
    const h = Math.round(img.height * scale);
    const canvas = document.createElement('canvas');
    canvas.width = w;
    canvas.height = h;
    const ctx = canvas.getContext('2d')!;
    ctx.fillStyle = 'white';
    ctx.fillRect(0, 0, w, h);
    ctx.drawImage(img, 0, 0, w, h);
    return canvas.toDataURL('image/jpeg', quality);
}

/**
 * Compute a deterministic cache key from chart rendering inputs.