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Elias Naur
b1af8aa75e
And use a constant 72 DPI for the default scale, to ensure consistent image sizes across display densities. Signed-off-by: Elias Naur <mail@eliasnaur.com>
50 lines
1.2 KiB
Go
50 lines
1.2 KiB
Go
// SPDX-License-Identifier: Unlicense OR MIT
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package widget
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import (
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"image"
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"gioui.org/ui"
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"gioui.org/ui/draw"
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"gioui.org/ui/f32"
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"gioui.org/ui/layout"
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)
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type Image struct {
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// Src is the image to display.
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Src image.Image
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// Rect is the source rectangle.
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Rect image.Rectangle
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// Scale is the ratio of image pixels to
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// device pixels. If zero, a scale that
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// makes the image appear at approximately
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// 72 DPI is used.
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Scale float32
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}
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func (im Image) Layout(c *ui.Config, ops *ui.Ops, cs layout.Constraints) layout.Dimens {
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size := im.Src.Bounds()
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scale := im.Scale
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if scale == 0 {
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const dpPrPx = 160 / 72
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scale = c.Val(ui.Dp(dpPrPx))
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}
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w, h := int(float32(size.Dx())*scale+.5), int(float32(size.Dy())*scale+.5)
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d := image.Point{X: cs.Width.Constrain(w), Y: cs.Height.Constrain(h)}
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aspect := float32(w) / float32(h)
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dw, dh := float32(d.X), float32(d.Y)
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dAspect := dw / dh
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if aspect < dAspect {
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d.X = int(dh*aspect + 0.5)
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} else {
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d.Y = int(dw/aspect + 0.5)
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}
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dr := f32.Rectangle{
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Max: f32.Point{X: float32(d.X), Y: float32(d.Y)},
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}
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draw.ImageOp{Img: im.Src, Rect: im.Rect}.Add(ops)
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draw.DrawOp{Rect: dr}.Add(ops)
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return layout.Dimens{Size: d, Baseline: d.Y}
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}
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