One axis of the viewport resolved against the image: coverage + source span. More...

#include <zoom_internal.h>

Data Fields
int32_t	d0
	First covered destination offset inside the viewport.
int32_t	d1
	One past the last covered destination offset.
uint32_t	s0
	First source index feeding the covered span.
uint32_t	count
	Source indices feeding the covered span (0 if none).

Detailed Description

One axis of the viewport resolved against the image: coverage + source span.

All four members describe the same axis at once, because they are derived together and are only consistent together. d0 / d1 are offsets within the viewport (not framebuffer coordinates), half-open, and the region outside them is letterbox. s0 / count name the source indices that feed [d0, d1), which is exactly the residency footprint of one frame on this axis.

Invariant: 0 <= d0 <= d1 <= extent.; count == 0 exactly when d0 == d1 (the image misses the viewport).; When count > 0, s0 + count <= src_dim.

Example:: zoom_axis_t ax = {};

priv_zoom_axis(v->anchor_x, v->dst.w, (int32_t)v->scale, (int32_t)v->src.width, &ax);

zoom_axis_t
One axis of the viewport resolved against the image: coverage + source span.
Definition zoom_internal.h:51

priv_zoom_axis
void priv_zoom_axis(int32_t anchor, int32_t extent, int32_t scale, int32_t src_dim, zoom_axis_t *out)
Resolve one viewport axis against the image at the current magnification.
Definition zoom.c:60