FPDI: Achieving Accurate Positioning of Text and Image Elements Using Pixel Coordinates

Question

I'm currently working on a project that involves embedding text and image elements onto a PDF using FPDI. However, I'm encountering difficulties in positioning these elements accurately.

I've been referencing pixel coordinates from a demo PDF and attempting to translate these coordinates into FPDI's unit measurements for precise element placement. Despite converting pixel values to points (using a ratio of 72/96), the resulting elements do not align perfectly with the original coordinates obtained from the demo PDF.

The specific issue lies in understanding the unit measurement utilized by FPDI and ensuring that the translated pixel coordinates accurately reflect the positions of the embedded elements.

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What unit of measurement does FPDI utilize, and how can I accurately translate pixel coordinates to this unit for precise element placement? I aim to ensure that pixel coordinates align perfectly with FPDI-embedded elements, replicating the original positions from the demo PDF. Any insights or approaches would be greatly appreciated.

Here's a snippet of the code I'm using for text and image embedding:

public function addTextElement($pdf, $element): void {
    // Conversion of pixel coordinates to points
    $x = $element['response_meta_json']['cord']['x'] * (72 / 96);
    $y = $element['response_meta_json']['cord']['y'] * (72 / 96);

    // Set font and position
    $pdf->SetFont($element['response_meta_json']['font-family'] ?? 'Arial', '', $element['response_meta_json']['font-size'] ?? 12);
    $pdf->SetXY($x, $y);
    $pdf->MultiCell(
      $element['response_meta_json']['area']['width'],
      $element['response_meta_json']['area']['height'],
      $element['response_meta_json']['value']
    );
}

public function addImageElement($pdf, $element): void {
    // Conversion of pixel coordinates to points
    $x = $element['response_meta_json']['cord']['x'] * (72 / 96);
    $y = $element['response_meta_json']['cord']['y'] * (72 / 96);

    // Manual positioning for testing purposes
    $x = 132.29166667;
    $y = 200.81875;

    $imageSrc = $element['response_meta_json']['img_src'];

    // Image embedding with coordinates
    $pdf->Image(
      $imageSrc,
      $x,
      $y,
      $element['response_meta_json']['area']['width'],
      $element['response_meta_json']['area']['height']
    );
}