Method GetFrame

src/effects/Hue.cpp:47–94

This method is required for all derived classes of EffectBase, and returns a modified openshot::Frame object

// This method is required for all derived classes of EffectBase, and returns a
// modified openshot::Frame object
std::shared_ptr<openshot::Frame> Hue::GetFrame(std::shared_ptr<openshot::Frame> frame, int64_t frame_number)
{
	// Get the frame's image
	std::shared_ptr<QImage> frame_image = frame->GetImage();

	int pixel_count = frame_image->width() * frame_image->height();

	// Get the current hue percentage shift amount, and convert to degrees
	double degrees = 360.0 * hue.GetValue(frame_number);
	float cosA = cos(degrees*3.14159265f/180);
	float sinA = sin(degrees*3.14159265f/180);

	// Calculate a rotation matrix for the RGB colorspace (based on the current hue shift keyframe value)
	float matrix[3] = {
		cosA + (1.0f - cosA) / 3.0f,
		1.0f/3.0f * (1.0f - cosA) - sqrtf(1.0f/3.0f) * sinA,
		1.0f/3.0f * (1.0f - cosA) + sqrtf(1.0f/3.0f) * sinA
	};

	// Loop through pixels
	unsigned char *pixels = (unsigned char *) frame_image->bits();

	#pragma omp parallel for shared (pixels)
	for (int pixel = 0; pixel < pixel_count; ++pixel)
	{
		// Calculate alpha % (to be used for removing pre-multiplied alpha value)
		int A = pixels[pixel * 4 + 3];
		float alpha_percent = A / 255.0;

		// Get RGB values, and remove pre-multiplied alpha
		int R = pixels[pixel * 4 + 0] / alpha_percent;
		int G = pixels[pixel * 4 + 1] / alpha_percent;
		int B = pixels[pixel * 4 + 2] / alpha_percent;

		// Multiply each color by the hue rotation matrix
		pixels[pixel * 4] = constrain(R * matrix[0] + G * matrix[1] + B * matrix[2]);
		pixels[pixel * 4 + 1] = constrain(R * matrix[2] + G * matrix[0] + B * matrix[1]);
		pixels[pixel * 4 + 2] = constrain(R * matrix[1] + G * matrix[2] + B * matrix[0]);

		// Pre-multiply the alpha back into the color channels
		pixels[pixel * 4 + 0] *= alpha_percent;
		pixels[pixel * 4 + 1] *= alpha_percent;
		pixels[pixel * 4 + 2] *= alpha_percent;
	}

	// return the modified frame
	return frame;
}

bool Hue::UseCustomMaskBlend(int64_t frame_number) const {
	(void) frame_number;