764 lines
25 KiB
Go
764 lines
25 KiB
Go
package tview
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import (
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"image"
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"math"
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"github.com/gdamore/tcell/v2"
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)
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// Types of dithering applied to images.
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const (
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DitheringNone = iota // No dithering.
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DitheringFloydSteinberg // Floyd-Steinberg dithering (the default).
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)
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// The number of colors supported by true color terminals (R*G*B = 256*256*256).
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const TrueColor = 16777216
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// This map describes what each block element looks like. A 1 bit represents a
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// pixel that is drawn, a 0 bit represents a pixel that is not drawn. The least
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// significant bit is the top left pixel, the most significant bit is the bottom
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// right pixel, moving row by row from left to right, top to bottom.
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var blockElements = map[rune]uint64{
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BlockLowerOneEighthBlock: 0b1111111100000000000000000000000000000000000000000000000000000000,
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BlockLowerOneQuarterBlock: 0b1111111111111111000000000000000000000000000000000000000000000000,
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BlockLowerThreeEighthsBlock: 0b1111111111111111111111110000000000000000000000000000000000000000,
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BlockLowerHalfBlock: 0b1111111111111111111111111111111100000000000000000000000000000000,
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BlockLowerFiveEighthsBlock: 0b1111111111111111111111111111111111111111000000000000000000000000,
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BlockLowerThreeQuartersBlock: 0b1111111111111111111111111111111111111111111111110000000000000000,
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BlockLowerSevenEighthsBlock: 0b1111111111111111111111111111111111111111111111111111111100000000,
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BlockLeftSevenEighthsBlock: 0b0111111101111111011111110111111101111111011111110111111101111111,
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BlockLeftThreeQuartersBlock: 0b0011111100111111001111110011111100111111001111110011111100111111,
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BlockLeftFiveEighthsBlock: 0b0001111100011111000111110001111100011111000111110001111100011111,
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BlockLeftHalfBlock: 0b0000111100001111000011110000111100001111000011110000111100001111,
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BlockLeftThreeEighthsBlock: 0b0000011100000111000001110000011100000111000001110000011100000111,
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BlockLeftOneQuarterBlock: 0b0000001100000011000000110000001100000011000000110000001100000011,
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BlockLeftOneEighthBlock: 0b0000000100000001000000010000000100000001000000010000000100000001,
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BlockQuadrantLowerLeft: 0b0000111100001111000011110000111100000000000000000000000000000000,
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BlockQuadrantLowerRight: 0b1111000011110000111100001111000000000000000000000000000000000000,
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BlockQuadrantUpperLeft: 0b0000000000000000000000000000000000001111000011110000111100001111,
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BlockQuadrantUpperRight: 0b0000000000000000000000000000000011110000111100001111000011110000,
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BlockQuadrantUpperLeftAndLowerRight: 0b1111000011110000111100001111000000001111000011110000111100001111,
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}
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// pixel represents a character on screen used to draw part of an image.
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type pixel struct {
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style tcell.Style
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element rune // The block element.
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}
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// Image implements a widget that displays one image. The original image
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// (specified with [Image.SetImage]) is resized according to the specified size
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// (see [Image.SetSize]), using the specified number of colors (see
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// [Image.SetColors]), while applying dithering if necessary (see
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// [Image.SetDithering]).
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//
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// Images are approximated by graphical characters in the terminal. The
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// resolution is therefore limited by the number and type of characters that can
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// be drawn in the terminal and the colors available in the terminal. The
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// quality of the final image also depends on the terminal's font and spacing
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// settings, none of which are under the control of this package. Results may
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// vary.
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type Image struct {
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*Box
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// The image to be displayed. If nil, the widget will be empty.
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image image.Image
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// The size of the image. If a value is 0, the corresponding size is chosen
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// automatically based on the other size while preserving the image's aspect
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// ratio. If both are 0, the image uses as much space as possible. A
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// negative value represents a percentage, e.g. -50 means 50% of the
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// available space.
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width, height int
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// The number of colors to use. If 0, the number of colors is chosen based
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// on the terminal's capabilities.
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colors int
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// The dithering algorithm to use, one of the constants starting with
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// "ImageDithering".
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dithering int
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// The width of a terminal's cell divided by its height.
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aspectRatio float64
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// Horizontal and vertical alignment, one of the "Align" constants.
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alignHorizontal, alignVertical int
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// The text to be displayed before the image.
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label string
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// The label style.
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labelStyle tcell.Style
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// The screen width of the label area. A value of 0 means use the width of
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// the label text.
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labelWidth int
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// The actual image size (in cells) when it was drawn the last time.
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lastWidth, lastHeight int
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// The actual image (in cells) when it was drawn the last time. The size of
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// this slice is lastWidth * lastHeight, indexed by y*lastWidth + x.
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pixels []pixel
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// A callback function set by the Form class and called when the user leaves
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// this form item.
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finished func(tcell.Key)
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}
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// NewImage returns a new image widget with an empty image (use [Image.SetImage]
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// to specify the image to be displayed). The image will use the widget's entire
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// available space. The dithering algorithm is set to Floyd-Steinberg dithering.
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// The terminal's cell aspect ratio defaults to 0.5.
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func NewImage() *Image {
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return &Image{
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Box: NewBox(),
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dithering: DitheringFloydSteinberg,
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aspectRatio: 0.5,
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alignHorizontal: AlignCenter,
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alignVertical: AlignCenter,
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}
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}
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// SetImage sets the image to be displayed. If nil, the widget will be empty.
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func (i *Image) SetImage(image image.Image) *Image {
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i.image = image
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i.lastWidth, i.lastHeight = 0, 0
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return i
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}
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// SetSize sets the size of the image. Positive values refer to cells in the
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// terminal. Negative values refer to a percentage of the available space (e.g.
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// -50 means 50%). A value of 0 means that the corresponding size is chosen
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// automatically based on the other size while preserving the image's aspect
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// ratio. If both are 0, the image uses as much space as possible while still
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// preserving the aspect ratio.
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func (i *Image) SetSize(rows, columns int) *Image {
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i.width = columns
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i.height = rows
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return i
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}
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// SetColors sets the number of colors to use. This should be the number of
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// colors supported by the terminal. If 0, the number of colors is chosen based
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// on the TERM environment variable (which may or may not be reliable).
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//
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// Only the values 0, 2, 8, 256, and 16777216 ([TrueColor]) are supported. Other
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// values will be rounded up to the next supported value, to a maximum of
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// 16777216.
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//
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// The effect of using more colors than supported by the terminal is undefined.
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func (i *Image) SetColors(colors int) *Image {
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i.colors = colors
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i.lastWidth, i.lastHeight = 0, 0
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return i
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}
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// GetColors returns the number of colors that will be used while drawing the
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// image. This is one of the values listed in [Image.SetColors], except 0 which
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// will be replaced by the actual number of colors used.
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func (i *Image) GetColors() int {
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switch {
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case i.colors == 0:
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return availableColors
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case i.colors <= 2:
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return 2
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case i.colors <= 8:
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return 8
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case i.colors <= 256:
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return 256
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}
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return TrueColor
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}
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// SetDithering sets the dithering algorithm to use, one of the constants
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// starting with "Dithering", for example [DitheringFloydSteinberg] (the
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// default). Dithering is not applied when rendering in true-color.
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func (i *Image) SetDithering(dithering int) *Image {
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i.dithering = dithering
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i.lastWidth, i.lastHeight = 0, 0
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return i
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}
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// SetAspectRatio sets the width of a terminal's cell divided by its height.
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// You may change the default of 0.5 if your terminal / font has a different
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// aspect ratio. This is used to calculate the size of the image if the
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// specified width or height is 0. The function will panic if the aspect ratio
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// is 0 or less.
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func (i *Image) SetAspectRatio(aspectRatio float64) *Image {
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if aspectRatio <= 0 {
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panic("aspect ratio must be greater than 0")
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}
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i.aspectRatio = aspectRatio
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i.lastWidth, i.lastHeight = 0, 0
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return i
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}
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// SetAlign sets the vertical and horizontal alignment of the image within the
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// widget's space. The possible values are [AlignTop], [AlignCenter], and
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// [AlignBottom] for vertical alignment and [AlignLeft], [AlignCenter], and
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// [AlignRight] for horizontal alignment. The default is [AlignCenter] for both
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// (or [AlignTop] and [AlignLeft] if the image is part of a [Form]).
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func (i *Image) SetAlign(vertical, horizontal int) *Image {
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i.alignHorizontal = horizontal
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i.alignVertical = vertical
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return i
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}
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// SetLabel sets the text to be displayed before the image.
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func (i *Image) SetLabel(label string) *Image {
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i.label = label
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return i
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}
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// GetLabel returns the text to be displayed before the image.
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func (i *Image) GetLabel() string {
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return i.label
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}
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// SetLabelWidth sets the screen width of the label. A value of 0 will cause the
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// primitive to use the width of the label string.
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func (i *Image) SetLabelWidth(width int) *Image {
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i.labelWidth = width
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return i
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}
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// GetFieldWidth returns this primitive's field width. This is the image's width
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// or, if the width is 0 or less, the proportional width of the image based on
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// its height as returned by [Image.GetFieldHeight]. If there is no image, 0 is
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// returned.
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func (i *Image) GetFieldWidth() int {
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if i.width <= 0 {
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if i.image == nil {
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return 0
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}
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bounds := i.image.Bounds()
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height := i.GetFieldHeight()
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return bounds.Dx() * height / bounds.Dy()
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}
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return i.width
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}
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// GetFieldHeight returns this primitive's field height. This is the image's
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// height or 8 if the height is 0 or less.
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func (i *Image) GetFieldHeight() int {
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if i.height <= 0 {
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return 8
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}
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return i.height
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}
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// SetDisabled sets whether or not the item is disabled / read-only.
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func (i *Image) SetDisabled(disabled bool) FormItem {
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return i // Images are always read-only.
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}
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// SetFormAttributes sets attributes shared by all form items.
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func (i *Image) SetFormAttributes(labelWidth int, labelColor, bgColor, fieldTextColor, fieldBgColor tcell.Color) FormItem {
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i.labelWidth = labelWidth
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i.backgroundColor = bgColor
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i.SetLabelStyle(tcell.StyleDefault.Foreground(labelColor).Background(bgColor))
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i.lastWidth, i.lastHeight = 0, 0
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return i
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}
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// SetLabelStyle sets the style of the label.
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func (i *Image) SetLabelStyle(style tcell.Style) *Image {
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i.labelStyle = style
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return i
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}
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// GetLabelStyle returns the style of the label.
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func (i *Image) GetLabelStyle() tcell.Style {
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return i.labelStyle
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}
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// SetFinishedFunc sets a callback invoked when the user leaves this form item.
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func (i *Image) SetFinishedFunc(handler func(key tcell.Key)) FormItem {
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i.finished = handler
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return i
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}
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// Focus is called when this primitive receives focus.
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func (i *Image) Focus(delegate func(p Primitive)) {
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// If we're part of a form, there's nothing the user can do here so we're
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// finished.
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if i.finished != nil {
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i.finished(-1)
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return
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}
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i.Box.Focus(delegate)
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}
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// render re-populates the [Image.pixels] slice based on the current settings,
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// if [Image.lastWidth] and [Image.lastHeight] don't match the current image's
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// size. It also sets the new image size in these two variables.
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func (i *Image) render() {
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// If there is no image, there are no pixels.
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if i.image == nil {
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i.pixels = nil
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return
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}
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// Calculate the new (terminal-space) image size.
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bounds := i.image.Bounds()
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imageWidth, imageHeight := bounds.Dx(), bounds.Dy()
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if i.aspectRatio != 1.0 {
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imageWidth = int(float64(imageWidth) / i.aspectRatio)
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}
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width, height := i.width, i.height
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_, _, innerWidth, innerHeight := i.GetInnerRect()
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if i.labelWidth > 0 {
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innerWidth -= i.labelWidth
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} else {
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innerWidth -= TaggedStringWidth(i.label)
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}
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if innerWidth <= 0 {
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i.pixels = nil
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return
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}
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if width == 0 && height == 0 {
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// Use all available space.
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width, height = innerWidth, innerHeight
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if adjustedWidth := imageWidth * height / imageHeight; adjustedWidth < width {
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width = adjustedWidth
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} else {
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height = imageHeight * width / imageWidth
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}
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} else {
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// Turn percentages into absolute values.
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if width < 0 {
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width = innerWidth * -width / 100
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}
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if height < 0 {
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height = innerHeight * -height / 100
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}
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if width == 0 {
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// Adjust the width.
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width = imageWidth * height / imageHeight
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} else if height == 0 {
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// Adjust the height.
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height = imageHeight * width / imageWidth
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}
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}
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if width <= 0 || height <= 0 {
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i.pixels = nil
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return
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}
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// If nothing has changed, we're done.
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if i.lastWidth == width && i.lastHeight == height {
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return
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}
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i.lastWidth, i.lastHeight = width, height // This could still be larger than the available space but that's ok for now.
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// Generate the initial pixels by resizing the image (8x8 per cell).
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pixels := i.resize()
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// Turn them into block elements with background/foreground colors.
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i.stamp(pixels)
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}
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// resize resizes the image to the current size and returns the result as a
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// slice of pixels. It is assumed that [Image.lastWidth] (w) and
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// [Image.lastHeight] (h) are positive, non-zero values, and the slice has a
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// size of 64*w*h, with each pixel being represented by 3 float64 values in the
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// range of 0-1. The factor of 64 is due to the fact that we calculate 8x8
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// pixels per cell.
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func (i *Image) resize() [][3]float64 {
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// Because most of the time, we will be downsizing the image, we don't even
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// attempt to do any fancy interpolation. For each target pixel, we
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// calculate a weighted average of the source pixels using their coverage
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// area.
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bounds := i.image.Bounds()
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srcWidth, srcHeight := bounds.Dx(), bounds.Dy()
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tgtWidth, tgtHeight := i.lastWidth*8, i.lastHeight*8
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coverageWidth, coverageHeight := float64(tgtWidth)/float64(srcWidth), float64(tgtHeight)/float64(srcHeight)
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pixels := make([][3]float64, tgtWidth*tgtHeight)
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weights := make([]float64, tgtWidth*tgtHeight)
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for srcY := bounds.Min.Y; srcY < bounds.Max.Y; srcY++ {
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for srcX := bounds.Min.X; srcX < bounds.Max.X; srcX++ {
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r32, g32, b32, _ := i.image.At(srcX, srcY).RGBA()
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r, g, b := float64(r32)/0xffff, float64(g32)/0xffff, float64(b32)/0xffff
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// Iterate over all target pixels. Outer loop is Y.
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startY := float64(srcY-bounds.Min.Y) * coverageHeight
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endY := startY + coverageHeight
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fromY, toY := int(startY), int(endY)
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for tgtY := fromY; tgtY <= toY && tgtY < tgtHeight; tgtY++ {
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coverageY := 1.0
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if tgtY == fromY {
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coverageY -= math.Mod(startY, 1.0)
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}
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if tgtY == toY {
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coverageY -= 1.0 - math.Mod(endY, 1.0)
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}
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// Inner loop is X.
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startX := float64(srcX-bounds.Min.X) * coverageWidth
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endX := startX + coverageWidth
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fromX, toX := int(startX), int(endX)
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for tgtX := fromX; tgtX <= toX && tgtX < tgtWidth; tgtX++ {
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coverageX := 1.0
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if tgtX == fromX {
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coverageX -= math.Mod(startX, 1.0)
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}
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if tgtX == toX {
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coverageX -= 1.0 - math.Mod(endX, 1.0)
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}
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|
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// Add a weighted contribution to the target pixel.
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index := tgtY*tgtWidth + tgtX
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coverage := coverageX * coverageY
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pixels[index][0] += r * coverage
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pixels[index][1] += g * coverage
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pixels[index][2] += b * coverage
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weights[index] += coverage
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}
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}
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}
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}
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|
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// Normalize the pixels.
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for index, weight := range weights {
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if weight > 0 {
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pixels[index][0] /= weight
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pixels[index][1] /= weight
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pixels[index][2] /= weight
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}
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}
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return pixels
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}
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|
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// stamp takes the pixels generated by [Image.resize] and populates the
|
|
// [Image.pixels] slice accordingly.
|
|
func (i *Image) stamp(resized [][3]float64) {
|
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// For each 8x8 pixel block, we find the best block element to represent it,
|
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// given the available colors.
|
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i.pixels = make([]pixel, i.lastWidth*i.lastHeight)
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colors := i.GetColors()
|
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for row := 0; row < i.lastHeight; row++ {
|
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for col := 0; col < i.lastWidth; col++ {
|
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// Calculate an error for each potential block element + color. Keep
|
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// the one with the lowest error.
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|
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// Note that the values in "resize" may lie outside [0, 1] due to
|
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// the error distribution during dithering.
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|
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minMSE := math.MaxFloat64 // Mean squared error.
|
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var final [64][3]float64 // The final pixel values.
|
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for element, bits := range blockElements {
|
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// Calculate the average color for the pixels covered by the set
|
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// bits and unset bits.
|
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var (
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bg, fg [3]float64
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setBits float64
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bit uint64 = 1
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)
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for y := 0; y < 8; y++ {
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for x := 0; x < 8; x++ {
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index := (row*8+y)*i.lastWidth*8 + (col*8 + x)
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if bits&bit != 0 {
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fg[0] += resized[index][0]
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fg[1] += resized[index][1]
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fg[2] += resized[index][2]
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setBits++
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} else {
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bg[0] += resized[index][0]
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bg[1] += resized[index][1]
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bg[2] += resized[index][2]
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}
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bit <<= 1
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}
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}
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for ch := 0; ch < 3; ch++ {
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fg[ch] /= setBits
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if fg[ch] < 0 {
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fg[ch] = 0
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} else if fg[ch] > 1 {
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fg[ch] = 1
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}
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bg[ch] /= 64 - setBits
|
|
if bg[ch] < 0 {
|
|
bg[ch] = 0
|
|
}
|
|
if bg[ch] > 1 {
|
|
bg[ch] = 1
|
|
}
|
|
}
|
|
|
|
// Quantize to the nearest acceptable color.
|
|
for _, color := range []*[3]float64{&fg, &bg} {
|
|
if colors == 2 {
|
|
// Monochrome. The following weights correspond better
|
|
// to human perception than the arithmetic mean.
|
|
gray := 0.299*color[0] + 0.587*color[1] + 0.114*color[2]
|
|
if gray < 0.5 {
|
|
*color = [3]float64{0, 0, 0}
|
|
} else {
|
|
*color = [3]float64{1, 1, 1}
|
|
}
|
|
} else {
|
|
for index, ch := range color {
|
|
switch {
|
|
case colors == 8:
|
|
// Colors vary wildly for each terminal. Expect
|
|
// suboptimal results.
|
|
if ch < 0.5 {
|
|
color[index] = 0
|
|
} else {
|
|
color[index] = 1
|
|
}
|
|
case colors == 256:
|
|
color[index] = math.Round(ch*6) / 6
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Calculate the error (and the final pixel values).
|
|
var (
|
|
mse float64
|
|
values [64][3]float64
|
|
valuesIndex int
|
|
)
|
|
bit = 1
|
|
for y := 0; y < 8; y++ {
|
|
for x := 0; x < 8; x++ {
|
|
if bits&bit != 0 {
|
|
values[valuesIndex] = fg
|
|
} else {
|
|
values[valuesIndex] = bg
|
|
}
|
|
index := (row*8+y)*i.lastWidth*8 + (col*8 + x)
|
|
for ch := 0; ch < 3; ch++ {
|
|
err := resized[index][ch] - values[valuesIndex][ch]
|
|
mse += err * err
|
|
}
|
|
bit <<= 1
|
|
valuesIndex++
|
|
}
|
|
}
|
|
|
|
// Do we have a better match?
|
|
if mse < minMSE {
|
|
// Yes. Save it.
|
|
minMSE = mse
|
|
final = values
|
|
index := row*i.lastWidth + col
|
|
i.pixels[index].element = element
|
|
i.pixels[index].style = tcell.StyleDefault.
|
|
Foreground(tcell.NewRGBColor(int32(math.Min(255, fg[0]*255)), int32(math.Min(255, fg[1]*255)), int32(math.Min(255, fg[2]*255)))).
|
|
Background(tcell.NewRGBColor(int32(math.Min(255, bg[0]*255)), int32(math.Min(255, bg[1]*255)), int32(math.Min(255, bg[2]*255))))
|
|
}
|
|
}
|
|
|
|
// Check if there is a shade block which results in a smaller error.
|
|
|
|
// What's the overall average color?
|
|
var avg [3]float64
|
|
for y := 0; y < 8; y++ {
|
|
for x := 0; x < 8; x++ {
|
|
index := (row*8+y)*i.lastWidth*8 + (col*8 + x)
|
|
for ch := 0; ch < 3; ch++ {
|
|
avg[ch] += resized[index][ch] / 64
|
|
}
|
|
}
|
|
}
|
|
for ch := 0; ch < 3; ch++ {
|
|
if avg[ch] < 0 {
|
|
avg[ch] = 0
|
|
} else if avg[ch] > 1 {
|
|
avg[ch] = 1
|
|
}
|
|
}
|
|
|
|
// Quantize and choose shade element.
|
|
element := BlockFullBlock
|
|
var fg, bg tcell.Color
|
|
shades := []rune{' ', BlockLightShade, BlockMediumShade, BlockDarkShade, BlockFullBlock}
|
|
if colors == 2 {
|
|
// Monochrome.
|
|
gray := 0.299*avg[0] + 0.587*avg[1] + 0.114*avg[2] // See above for details.
|
|
shade := int(math.Round(gray * 4))
|
|
element = shades[shade]
|
|
for ch := 0; ch < 3; ch++ {
|
|
avg[ch] = float64(shade) / 4
|
|
}
|
|
bg = tcell.ColorBlack
|
|
fg = tcell.ColorWhite
|
|
} else if colors == TrueColor {
|
|
// True color.
|
|
fg = tcell.NewRGBColor(int32(math.Min(255, avg[0]*255)), int32(math.Min(255, avg[1]*255)), int32(math.Min(255, avg[2]*255)))
|
|
bg = fg
|
|
} else {
|
|
// 8 or 256 colors.
|
|
steps := 1.0
|
|
if colors == 256 {
|
|
steps = 6.0
|
|
}
|
|
var (
|
|
lo, hi, pos [3]float64
|
|
shade float64
|
|
)
|
|
for ch := 0; ch < 3; ch++ {
|
|
lo[ch] = math.Floor(avg[ch]*steps) / steps
|
|
hi[ch] = math.Ceil(avg[ch]*steps) / steps
|
|
if r := hi[ch] - lo[ch]; r > 0 {
|
|
pos[ch] = (avg[ch] - lo[ch]) / r
|
|
if math.Abs(pos[ch]-0.5) < math.Abs(shade-0.5) {
|
|
shade = pos[ch]
|
|
}
|
|
}
|
|
}
|
|
shade = math.Round(shade * 4)
|
|
element = shades[int(shade)]
|
|
shade /= 4
|
|
for ch := 0; ch < 3; ch++ { // Find the closest channel value.
|
|
best := math.Abs(avg[ch] - (lo[ch] + (hi[ch]-lo[ch])*shade)) // Start shade from lo to hi.
|
|
if value := math.Abs(avg[ch] - (hi[ch] - (hi[ch]-lo[ch])*shade)); value < best {
|
|
best = value // Swap lo and hi.
|
|
lo[ch], hi[ch] = hi[ch], lo[ch]
|
|
}
|
|
if value := math.Abs(avg[ch] - lo[ch]); value < best {
|
|
best = value // Use lo.
|
|
hi[ch] = lo[ch]
|
|
}
|
|
if value := math.Abs(avg[ch] - hi[ch]); value < best {
|
|
lo[ch] = hi[ch] // Use hi.
|
|
}
|
|
avg[ch] = lo[ch] + (hi[ch]-lo[ch])*shade // Quantize.
|
|
}
|
|
bg = tcell.NewRGBColor(int32(math.Min(255, lo[0]*255)), int32(math.Min(255, lo[1]*255)), int32(math.Min(255, lo[2]*255)))
|
|
fg = tcell.NewRGBColor(int32(math.Min(255, hi[0]*255)), int32(math.Min(255, hi[1]*255)), int32(math.Min(255, hi[2]*255)))
|
|
}
|
|
|
|
// Calculate the error (and the final pixel values).
|
|
var (
|
|
mse float64
|
|
values [64][3]float64
|
|
valuesIndex int
|
|
)
|
|
for y := 0; y < 8; y++ {
|
|
for x := 0; x < 8; x++ {
|
|
index := (row*8+y)*i.lastWidth*8 + (col*8 + x)
|
|
for ch := 0; ch < 3; ch++ {
|
|
err := resized[index][ch] - avg[ch]
|
|
mse += err * err
|
|
}
|
|
values[valuesIndex] = avg
|
|
valuesIndex++
|
|
}
|
|
}
|
|
|
|
// Is this shade element better than the block element?
|
|
if mse < minMSE {
|
|
// Yes. Save it.
|
|
final = values
|
|
index := row*i.lastWidth + col
|
|
i.pixels[index].element = element
|
|
i.pixels[index].style = tcell.StyleDefault.Foreground(fg).Background(bg)
|
|
}
|
|
|
|
// Apply dithering.
|
|
if colors < TrueColor && i.dithering == DitheringFloydSteinberg {
|
|
// The dithering mask determines how the error is distributed.
|
|
// Each element has three values: dx, dy, and weight (in 16th).
|
|
var mask = [4][3]int{
|
|
{1, 0, 7},
|
|
{-1, 1, 3},
|
|
{0, 1, 5},
|
|
{1, 1, 1},
|
|
}
|
|
|
|
// We dither the 8x8 block as a 2x2 block, transferring errors
|
|
// to its 2x2 neighbors.
|
|
for ch := 0; ch < 3; ch++ {
|
|
for y := 0; y < 2; y++ {
|
|
for x := 0; x < 2; x++ {
|
|
// What's the error for this 4x4 block?
|
|
var err float64
|
|
for dy := 0; dy < 4; dy++ {
|
|
for dx := 0; dx < 4; dx++ {
|
|
err += (final[(y*4+dy)*8+(x*4+dx)][ch] - resized[(row*8+(y*4+dy))*i.lastWidth*8+(col*8+(x*4+dx))][ch]) / 16
|
|
}
|
|
}
|
|
|
|
// Distribute it to the 2x2 neighbors.
|
|
for _, dist := range mask {
|
|
for dy := 0; dy < 4; dy++ {
|
|
for dx := 0; dx < 4; dx++ {
|
|
targetX, targetY := (x+dist[0])*4+dx, (y+dist[1])*4+dy
|
|
if targetX < 0 || col*8+targetX >= i.lastWidth*8 || targetY < 0 || row*8+targetY >= i.lastHeight*8 {
|
|
continue
|
|
}
|
|
resized[(row*8+targetY)*i.lastWidth*8+(col*8+targetX)][ch] -= err * float64(dist[2]) / 16
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Draw draws this primitive onto the screen.
|
|
func (i *Image) Draw(screen tcell.Screen) {
|
|
i.DrawForSubclass(screen, i)
|
|
|
|
// Regenerate image if necessary.
|
|
i.render()
|
|
|
|
// Draw label.
|
|
viewX, viewY, viewWidth, viewHeight := i.GetInnerRect()
|
|
_, labelBg, _ := i.labelStyle.Decompose()
|
|
if i.labelWidth > 0 {
|
|
labelWidth := i.labelWidth
|
|
if labelWidth > viewWidth {
|
|
labelWidth = viewWidth
|
|
}
|
|
printWithStyle(screen, i.label, viewX, viewY, 0, labelWidth, AlignLeft, i.labelStyle, labelBg == tcell.ColorDefault)
|
|
viewX += labelWidth
|
|
viewWidth -= labelWidth
|
|
} else {
|
|
_, _, drawnWidth := printWithStyle(screen, i.label, viewX, viewY, 0, viewWidth, AlignLeft, i.labelStyle, labelBg == tcell.ColorDefault)
|
|
viewX += drawnWidth
|
|
viewWidth -= drawnWidth
|
|
}
|
|
|
|
// Determine image placement.
|
|
x, y, width, height := viewX, viewY, i.lastWidth, i.lastHeight
|
|
if i.alignHorizontal == AlignCenter {
|
|
x += (viewWidth - width) / 2
|
|
} else if i.alignHorizontal == AlignRight {
|
|
x += viewWidth - width
|
|
}
|
|
if i.alignVertical == AlignCenter {
|
|
y += (viewHeight - height) / 2
|
|
} else if i.alignVertical == AlignBottom {
|
|
y += viewHeight - height
|
|
}
|
|
|
|
// Draw the image.
|
|
for row := 0; row < height; row++ {
|
|
if y+row < viewY || y+row >= viewY+viewHeight {
|
|
continue
|
|
}
|
|
for col := 0; col < width; col++ {
|
|
if x+col < viewX || x+col >= viewX+viewWidth {
|
|
continue
|
|
}
|
|
|
|
index := row*width + col
|
|
screen.SetContent(x+col, y+row, i.pixels[index].element, nil, i.pixels[index].style)
|
|
}
|
|
}
|
|
}
|