blend_pixel Subroutine

public subroutine blend_pixel(image_data, img_w, img_h, x, y, alpha, new_r, new_g, new_b)

Alpha blend a pixel with existing pixel data

Core pixel blending routine used by all drawing functions. Uses consistent coordinate rounding (nint) to ensure alignment between line endpoints and marker centers (fixes issue #333).

Arguments

Type	Intent	Optional	Attributes		Name
integer(kind=1),	intent(inout)			::	image_data(:)
integer,	intent(in)			::	img_w
integer,	intent(in)			::	img_h
real(kind=wp),	intent(in)			::	x
real(kind=wp),	intent(in)			::	y
real(kind=wp),	intent(in)			::	alpha	Blending factor [0.0, 1.0] (clamped internally)
real(kind=wp),	intent(in)			::	new_r	Blending factor [0.0, 1.0] (clamped internally)
real(kind=wp),	intent(in)			::	new_g	Blending factor [0.0, 1.0] (clamped internally)
real(kind=wp),	intent(in)			::	new_b	Blending factor [0.0, 1.0] (clamped internally)