197 lines
5.0 KiB
Go
197 lines
5.0 KiB
Go
package canvas
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import (
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"image"
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"image/color"
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"image/draw"
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"fyne.io/fyne/v2"
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)
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// Declare conformity with CanvasObject interface
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var _ fyne.CanvasObject = (*Raster)(nil)
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// Raster describes a raster image area that can render in a Fyne canvas
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type Raster struct {
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baseObject
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// Render the raster image from code
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Generator func(w, h int) image.Image
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// Set a translucency value > 0.0 to fade the raster
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Translucency float64
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// Specify the type of scaling interpolation applied to the raster if it is not full-size
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// Since: 1.4.1
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ScaleMode ImageScale
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}
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// Alpha is a convenience function that returns the alpha value for a raster
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// based on its Translucency value. The result is 1.0 - Translucency.
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func (r *Raster) Alpha() float64 {
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return 1.0 - r.Translucency
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}
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// Hide will set this raster to not be visible
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func (r *Raster) Hide() {
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r.baseObject.Hide()
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repaint(r)
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}
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// Move the raster to a new position, relative to its parent / canvas
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func (r *Raster) Move(pos fyne.Position) {
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r.baseObject.Move(pos)
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repaint(r)
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}
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// Resize on a raster image causes the new size to be set and then calls Refresh.
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// This causes the underlying data to be recalculated and a new output to be drawn.
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func (r *Raster) Resize(s fyne.Size) {
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if s == r.Size() {
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return
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}
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r.baseObject.Resize(s)
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Refresh(r)
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}
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// Refresh causes this raster to be redrawn with its configured state.
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func (r *Raster) Refresh() {
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Refresh(r)
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}
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// NewRaster returns a new Image instance that is rendered dynamically using
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// the specified generate function.
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// Images returned from this method should draw dynamically to fill the width
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// and height parameters passed to pixelColor.
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func NewRaster(generate func(w, h int) image.Image) *Raster {
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return &Raster{Generator: generate}
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}
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type pixelRaster struct {
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r *Raster
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img draw.Image
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}
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// NewRasterWithPixels returns a new Image instance that is rendered dynamically
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// by iterating over the specified pixelColor function for each x, y pixel.
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// Images returned from this method should draw dynamically to fill the width
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// and height parameters passed to pixelColor.
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func NewRasterWithPixels(pixelColor func(x, y, w, h int) color.Color) *Raster {
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pix := &pixelRaster{}
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pix.r = &Raster{
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Generator: func(w, h int) image.Image {
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if pix.img == nil || pix.img.Bounds().Size().X != w || pix.img.Bounds().Size().Y != h {
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// raster first pixel, figure out color type
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var dst draw.Image
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rect := image.Rect(0, 0, w, h)
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switch pixelColor(0, 0, w, h).(type) {
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case color.Alpha:
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dst = image.NewAlpha(rect)
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case color.Alpha16:
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dst = image.NewAlpha16(rect)
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case color.CMYK:
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dst = image.NewCMYK(rect)
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case color.Gray:
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dst = image.NewGray(rect)
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case color.Gray16:
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dst = image.NewGray16(rect)
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case color.NRGBA:
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dst = image.NewNRGBA(rect)
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case color.NRGBA64:
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dst = image.NewNRGBA64(rect)
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case color.RGBA:
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dst = image.NewRGBA(rect)
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case color.RGBA64:
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dst = image.NewRGBA64(rect)
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default:
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dst = image.NewRGBA(rect)
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}
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pix.img = dst
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}
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for y := 0; y < h; y++ {
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for x := 0; x < w; x++ {
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pix.img.Set(x, y, pixelColor(x, y, w, h))
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}
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}
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return pix.img
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},
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}
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return pix.r
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}
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type subImg interface {
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SubImage(r image.Rectangle) image.Image
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}
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// NewRasterFromImage returns a new Raster instance that is rendered from the Go
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// image.Image passed in.
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// Rasters returned from this method will map pixel for pixel to the screen
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// starting img.Bounds().Min pixels from the top left of the canvas object.
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// Truncates rather than scales the image.
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// If smaller than the target space, the image will be padded with zero-pixels to the target size.
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func NewRasterFromImage(img image.Image) *Raster {
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return &Raster{
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Generator: func(w int, h int) image.Image {
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bounds := img.Bounds()
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rect := image.Rect(0, 0, w, h)
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switch {
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case w == bounds.Max.X && h == bounds.Max.Y:
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return img
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case w >= bounds.Max.X && h >= bounds.Max.Y:
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// try quickly truncating
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if sub, ok := img.(subImg); ok {
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return sub.SubImage(image.Rectangle{
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Min: bounds.Min,
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Max: image.Point{
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X: bounds.Min.X + w,
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Y: bounds.Min.Y + h,
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},
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})
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}
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default:
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if !rect.Overlaps(bounds) {
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return image.NewUniform(color.RGBA{})
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}
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bounds = bounds.Intersect(rect)
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}
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// respect the user's pixel format (if possible)
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var dst draw.Image
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switch i := img.(type) {
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case *image.Alpha:
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dst = image.NewAlpha(rect)
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case *image.Alpha16:
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dst = image.NewAlpha16(rect)
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case *image.CMYK:
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dst = image.NewCMYK(rect)
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case *image.Gray:
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dst = image.NewGray(rect)
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case *image.Gray16:
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dst = image.NewGray16(rect)
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case *image.NRGBA:
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dst = image.NewNRGBA(rect)
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case *image.NRGBA64:
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dst = image.NewNRGBA64(rect)
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case *image.Paletted:
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dst = image.NewPaletted(rect, i.Palette)
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case *image.RGBA:
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dst = image.NewRGBA(rect)
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case *image.RGBA64:
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dst = image.NewRGBA64(rect)
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default:
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dst = image.NewRGBA(rect)
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}
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draw.Draw(dst, bounds, img, bounds.Min, draw.Over)
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return dst
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},
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}
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}
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