[Piglit] [v8 09/13] tests/spec: EXT_image_dma_buf_import sample argb

[Chad Versace]

>>> +enum piglit_result
>>> +probe_rect_argb(unsigned w, unsigned h, const unsigned char *argb,
>>> +		bool force_alpha_to_one)
>>> +{
>>> +	const unsigned cpp = 4;
>>> +	unsigned i, j;
>>> +
>>> +	for (i = 0; i < h; ++i) {
>>> +		for (j = 0; j < w; ++j) {
>>> +			float expected[] = {
>>> +				argb[i * w * cpp + j * cpp + 2] / 255.0f,
>>> +				argb[i * w * cpp + j * cpp + 1] / 255.0f,
>>> +				argb[i * w * cpp + j * cpp + 0] / 255.0f,
>>> +				argb[i * w * cpp + j * cpp + 3] / 255.0f};
>>> +
>>> +			if (force_alpha_to_one)
>>> +				expected[3] = 1.0f;
>>> +
>>> +			if (!piglit_probe_pixel_rgba(j, i, expected))
>>> +				return PIGLIT_FAIL;
>>> +		}
>>> +	}
>>> +
>>> +	return PIGLIT_PASS;
>>> +}
>>
>> This function looks correct, but has unneeded overhead. The speed of Piglit runs
>> does matter, especially when doing multiple runs back-to-back or when doing runs
>> on simulated hardware. So, we do strive to keep Piglit running fast when it
>> doesn't require too much effort on our part.
>>
>> One of the slowest GL functions is glReadPixels, and this function calls glReadPixels
>> for each pixel in the image. Instead, the function should be refactored so that it
>> makes a single call to piglit_probe_rect_rgba, and hence a single call to glReadPixels.
>>
>
> The framework utility 'piglit_probe_rect_rgba()' works for rectangles where all
> pixels are of same color. Should I augment the framework to have another flavour
> allowing each pixel to have different value (as is the case currently here) or
> just simply switch to single color here in this test case also?

I'm sorry, you're right: piglit_probe_rect_rgba won't work here. The should use
a a variant of piglit_probe that allows each pixel to have a different value.
Two existing candidates are piglit_probe_image_color and piglit_compare_images_color.
To use either function, you must first, as you're already doing in probe_rect_argb,
convert the argb array to a float array, but I see no problem in doing that.