Yalantis/uCrop · error · CImgArgumentException

draw_spline(): Invalid specified texture (%u,%u,%u,%u,%p).

Error message

draw_spline(): Invalid specified texture (%u,%u,%u,%u,%p).

What it means

draw_spline() with a texture validates texture._depth<=1 and texture._spectrum>=instance._spectrum. Textures must be flat 2D images with enough channels; otherwise CImgArgumentException reports the texture dimensions.

Source

Thrown at ucrop/src/main/jni/CImg.h:50483

       \param tx0 X-coordinate of the starting texture point.
       \param ty0 Y-coordinate of the starting texture point.
       \param tx1 X-coordinate of the ending texture point.
       \param ty1 Y-coordinate of the ending texture point.
       \param precision Curve drawing precision.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the line pattern.
       \param init_hatch if \c true, reinit hatch motif.
    **/
    template<typename t>
    CImg<T>& draw_spline(const int x0, const int y0, const float u0, const float v0,
                         const int x1, const int y1, const float u1, const float v1,
                         const CImg<t>& texture,
                         const int tx0, const int ty0, const int tx1, const int ty1,
                         const float opacity=1,
                         const float precision=4, const unsigned int pattern=~0U,
                         const bool init_hatch=true) {
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_spline(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (is_empty()) return *this;
      if (is_overlapped(texture))
        return draw_spline(x0,y0,u0,v0,x1,y1,u1,v1,+texture,tx0,ty0,tx1,ty1,precision,opacity,pattern,init_hatch);
      if (x0==x1 && y0==y1)
        return draw_point(x0,y0,texture.get_vector_at(x0<=0?0:x0>=texture.width()?texture.width() - 1:x0,
                                                      y0<=0?0:y0>=texture.height()?texture.height() - 1:y0).data(),
                          opacity);
      bool ninit_hatch = init_hatch;
      const float
        ax = u0 + u1 + 2*(x0 - x1),
        bx = 3*(x1 - x0) - 2*u0 - u1,
        ay = v0 + v1 + 2*(y0 - y1),
        by = 3*(y1 - y0) - 2*v0 - v1,
        _precision = 1/(cimg::hypot((float)x0 - x1,(float)y0 - y1)*(precision>0?precision:1));
      int ox = x0, oy = y0, otx = tx0, oty = ty0;

View on GitHub (pinned to f788b534b4)

Solutions

  1. Flatten the texture to depth 1 and resize channels: tex.get_resize(tex.width(),tex.height(),1,img.spectrum()).
  2. Ensure the texture is 2D before passing.
  3. Match or exceed the image channel count in the texture.
  4. For overlap the library handles copies internally; only depth/spectrum need pre-checks.

Example fix

// before
CImg<float> grad(128,128,1,1); // 1 channel
img.draw_spline(x0,y0,u0,v0,x1,y1,u1,v1,grad,0,0,127,127,1.0f);
// after
CImg<float> grad3 = grad.get_resize(grad.width(),grad.height(),1,img.spectrum());
img.draw_spline(x0,y0,u0,v0,x1,y1,u1,v1,grad3,0,0,127,127,1.0f);
Defensive patterns

Strategy: validation

Validate before calling

if (texture.depth()>1 || texture.spectrum()<img.spectrum()) {
  texture = texture.get_resize(-100,-100,1,img.spectrum());
}
img.draw_spline(x0,y0,u0,v0,x1,y1,u1,v1, texture, tx0,ty0,tx1,ty1, opacity, precision);

Type guard

template<typename T, typename t>
bool isFlatSufficientTexture(const CImg<T>& img, const CImg<t>& tex) {
  return tex.depth()<=1 && tex.spectrum()>=img.spectrum();
}

Try / catch

try {
  img.draw_spline(x0,y0,u0,v0,x1,y1,u1,v1, texture, tx0,ty0,tx1,ty1);
} catch (const cimg_library::CImgArgumentException& e) {
  std::fprintf(stderr, "draw_spline texture: %s\n", e.what());
}

Prevention

When it happens

Trigger: Passing a 3D (depth>1) image or a texture with fewer spectrum channels than the drawing image as the texture parameter of the tangent-based draw_spline overload.

Common situations: Gradient/gradient-map textures stored as volumes; grayscale gradient map used on an RGB image; texture loaded with wrong channel count.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of Yalantis/uCrop@f788b534b4 (2026-09-08). Data as JSON: /api/errors/93f7373327b90c51. Report an issue: GitHub.