parallax/jsPDF · error · Error

x/y invalid.

Error message

x/y invalid.

What it means

Thrown by GifWriter.addFrame when the frame's top-left coordinates x or y are negative or exceed 65535. Frame position is stored as unsigned 16-bit fields in the Image Descriptor, so any value outside 0..65535 is rejected. (Note: bounds against the canvas width/height are explicitly a TODO and NOT checked.)

Source

Thrown at src/libs/omggif.js:145

    buf[p++] = loop_count & 0xff;
    buf[p++] = (loop_count >> 8) & 0xff;
    buf[p++] = 0x00; // Terminator.
  }

  var ended = false;

  this.addFrame = function(x, y, w, h, indexed_pixels, opts) {
    if (ended === true) {
      --p;
      ended = false;
    } // Un-end.

    opts = opts === undefined ? {} : opts;

    // TODO(deanm): Bounds check x, y.  Do they need to be within the virtual
    // canvas width/height, I imagine?
    if (x < 0 || y < 0 || x > 65535 || y > 65535)
      throw new Error("x/y invalid.");

    if (w <= 0 || h <= 0 || w > 65535 || h > 65535)
      throw new Error("Width/Height invalid.");

    if (indexed_pixels.length < w * h)
      throw new Error("Not enough pixels for the frame size.");

    var using_local_palette = true;
    var palette = opts.palette;
    if (palette === undefined || palette === null) {
      using_local_palette = false;
      palette = global_palette;
    }

    if (palette === undefined || palette === null)
      throw new Error("Must supply either a local or global palette.");

    var num_colors = check_palette_and_num_colors(palette);

View on GitHub (pinned to a3930ce03a)

Solutions

1. Clamp x and y to 0..65535 (typically 0 and within canvas bounds).
2. If you need off-canvas content, crop the pixels instead of using negative offsets.
3. Validate coordinates are non-negative integers before addFrame.

Example fix

// before
gw.addFrame(offsetX, offsetY, w, h, pixels);
// after
var x = Math.max(0, Math.min(65535, Math.floor(offsetX)));
var y = Math.max(0, Math.min(65535, Math.floor(offsetY)));
gw.addFrame(x, y, w, h, pixels);

function clampCoord(c){ c = Math.floor(c); return c < 0 ? 0 : c > 65535 ? 65535 : c; }
gw.addFrame(clampCoord(x), clampCoord(y), w, h, pixels);

function isValidFrameCoord(v){ return Number.isInteger(v) && v >= 0 && v <= 65535; }

try { gw.addFrame(x, y, w, h, pixels); } catch (e) { if (/x\/y invalid/.test(e.message)) { /* clamp coords */ } else throw e; }

When it happens

Trigger: Calling addFrame(-5, 0, ...) for an off-canvas frame; passing x/y derived from a centering calc that goes negative; values > 65535 from large-canvas code.

Common situations: Sprite/packing algorithms that allow negative offsets; animation frames positioned relative to a moving origin; unit confusion producing huge coordinates.

Related errors

• Loop count invalid.
• Not enough pixels for the frame size.
• Must supply either a local or global palette.
• Disposal out of range.
• Transparent color index.

AI-assisted analysis of parallax/jsPDF@a3930ce03a (2026-08-13). Data as JSON: /api/errors/70380e0fa501cbe9. Report an issue: GitHub.