UXImage

UXImage is a width × height grid of packed 0xAARRGGBB pixels. It is the model behind the image well, canvas layers and thumbnails. A backend uploads and draws these images. The pixel arithmetic (compositing a sub-image in, clearing a region, cropping one out) lives here and can be tested without a backend. Colours pack and unpack through UXColor.

#use <UXKit>

Overview

UXImage* im = UXImage.make(64, 64);
im.fill(UXColor.rgba(255, 255, 255, 255));
im.fillRect(8, 8, 48, 48, UXColor.rgba(30, 90, 200, 255));
UXImage* thumb = im.subImage(0, 0, 32, 32);

Every mutation is clipped to the bounds. Writing off the edge writes nothing, and reading off the edge reads zero, so a blit near a corner needs no arithmetic from the caller.

Topics

Making · make · width / height Pixels · setPixel · pixelAt · setPixelRaw / pixelRaw · inBounds Regions · fill · fillRect · blit · subImage Drawing · drawIn Packing · pack / unpack

drawIn

void drawIn(UXGraphics* g, UXRect src, UXRect dst, i32 alpha)

Draws the region src of this image into a view’s drawRect at dst, scaled, with an overall alpha. It goes through UXGraphics.drawPixels, which may cache by this image’s pixel buffer, so change the pixels and the old ones may be drawn.

make

static UXImage* make(i32 width, i32 height)

A new image, zero-filled (transparent black). Degenerate sizes become 1×1.

width / height

i32 width(void)
i32 height(void)

The dimensions.

setPixel

void setPixel(i32 x, i32 y, UXColor* c)

Writes one pixel; out of bounds writes nothing.

pixelAt

UXColor* pixelAt(i32 x, i32 y)

Reads one pixel as a colour; out of bounds reads transparent black.

setPixelRaw / pixelRaw

void setPixelRaw(i32 x, i32 y, u32 v)
u32  pixelRaw(i32 x, i32 y)

The packed-word forms, for tight loops.

inBounds

bool inBounds(i32 x, i32 y)

The clip test every mutation uses.

fill

void fill(UXColor* c)

Sets every pixel to one colour.

fillRect

void fillRect(i32 rx, i32 ry, i32 rw, i32 rh, UXColor* c)

A rectangle, clipped to bounds.

blit

void blit(UXImage* src, i32 dx, i32 dy)

Copies src in with its top-left at (dx, dy), clipped. It overwrites pixels with no alpha blending; compositing belongs to the graphics seam.

subImage

UXImage* subImage(i32 rx, i32 ry, i32 rw, i32 rh)

A new image cropped out of this one. Out-of-bounds source pixels come back as transparent black.

pack / unpack

static u32      pack(UXColor* c)
static UXColor* unpack(u32 v)

Conversion between the 0xAARRGGBB word and UXColor. It is public so pixel loops and tests can use both forms.