Documentation
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Overview ¶
Package pagemap encodes a rendered page into the Gothic page-view payload: the page's own colour palette, one letter per grid cell, the DOM regions the cells land in, and the alerts the raster itself implies (palette coverage, edge bleed, overflow). Everything after the PNG is a pure function of the raster plus the DOM manifest, so the encoder is testable against fixture PNGs with no browser and no timing.
Index ¶
Constants ¶
const ( DefaultGridW = 48 DefaultGridH = 24 )
Locked defaults: the grid shape and the palette size.
const DefaultMaxColors = 10
DefaultMaxColors is the palette size the encoder quantizes to. A UI page has a couple dozen real colours plus an antialiasing tail; the top exact colours carry the layout, and every other pixel snaps to the nearest one.
Variables ¶
This section is empty.
Functions ¶
func Encode ¶
Encode turns a rendered page into the page-view payload a text-only model reads: grid = geometry and colour, legend = identity and content, alerts = the conclusions. img is the full-resolution screenshot; m the DOM manifest (nil is allowed and simply produces no regions and no manifest-derived alerts).
Types ¶
type Alert ¶
Alert is one derived warning: a headline plus indented bullets that carry the conclusion. Thresholds live as named constants so they read as policy.
type Color ¶
type Color struct{ R, G, B, A uint8 }
Color is one exact sRGB colour with alpha. It is the currency the whole encoder works in and doubles as a hash-map key for the exact-colour histogram.
type Element ¶
type Element struct {
Selector string `json:"sel"`
X float64 `json:"x"`
Y float64 `json:"y"`
W float64 `json:"w"`
H float64 `json:"h"`
BG string `json:"bg"` // computed background-color, "" or "transparent" when none
FG string `json:"fg"` // computed color
Overflows bool `json:"overflows"` // scrollWidth > clientWidth at capture time
}
Element is one visible element's rect and computed colours.
type Grid ¶
type Grid struct {
Cols, Rows int
Width int // source raster size in pixels
Height int
Cells []int // len = Rows*Cols, row-major palette index per cell
}
Grid is the raster downsampled to one palette class per cell. The cell stores a palette index — the class its pixels BELONG to, never an average: averaging a purple button into a dark background is exactly the blend that makes the widget unreadable, and the mode keeps it.
type Manifest ¶
type Manifest struct {
Scroll [2]float64 `json:"scroll"` // [scrollX, scrollY] at capture time
Rects []Element `json:"rects"`
}
Manifest is the DOM-side document the browser layer writes next to the screenshot: the scroll position plus, for every visible element, its viewport rect and the computed colours worth checking against the raster. The browser layer produces it with one page.Eval() — this package only consumes it.
func ParseManifest ¶
ParseManifest decodes the DOM manifest JSON.
type Options ¶
Options carries what the raster alone cannot tell the encoder. URL and Engine are capture metadata; ViewportW/H override the reported viewport (0 = use the raster size); GridW/H are the cell grid (0 = 48x24).
type Palette ¶
type Palette struct {
Entries []PaletteEntry
}
Palette is an extracted colour palette, sorted by pixel frequency with the dominant (background) colour first.
func (Palette) Dominant ¶
func (p Palette) Dominant() PaletteEntry
Dominant returns the most frequent colour — the page's background.
type PaletteEntry ¶
type PaletteEntry struct {
Color Color
Hex string
Exact int // pixels whose colour is exactly this one
}
PaletteEntry is one palette slot: an exact colour from the raster, how many pixels carried it verbatim, and its share of the image once the antialiasing tail snapped to the nearest palette entry.
type Region ¶
type Region struct {
Selector string
// RowFrom/RowTo and ColFrom/ColTo are INCLUSIVE cell spans.
RowFrom, RowTo int
ColFrom, ColTo int
X0, X1 int // the element's pixel span, clipped to the raster
DeclaredHex string // parsed BG as hex, "" when none/transparent
RenderedHex string // hex of the palette class dominating the region, "" when none
// contains filtered or unexported fields
}
Region is one element's footprint on the grid: the cell span its own pixels land in and the palette class dominating them.
Source Files