forked from joejulian/gio
Walter Werner SCHNEIDER
d76b4272aa
Reduces ambiguity by introducing AffineId() for representing identity transformation matrices. References: https://todo.sr.ht/~eliasnaur/gio/655 Signed-off-by: Walter Werner SCHNEIDER <contact@schnwalter.eu>
55 lines
1.4 KiB
Go
55 lines
1.4 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/f32"
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"gioui.org/layout"
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"gioui.org/op"
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"gioui.org/op/clip"
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"gioui.org/op/paint"
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"gioui.org/unit"
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)
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// Image is a widget that displays an image.
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type Image struct {
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// Src is the image to display.
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Src paint.ImageOp
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// Fit specifies how to scale the image to the constraints.
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// By default it does not do any scaling.
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Fit Fit
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// Position specifies where to position the image within
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// the constraints.
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Position layout.Direction
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// Scale is the factor used for converting image pixels to dp.
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// If Scale is zero it defaults to 1.
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//
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// To map one image pixel to one output pixel, set Scale to 1.0 / gtx.Metric.PxPerDp.
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Scale float32
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}
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func (im Image) Layout(gtx layout.Context) layout.Dimensions {
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scale := im.Scale
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if scale == 0 {
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scale = 1
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}
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size := im.Src.Size()
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wf, hf := float32(size.X), float32(size.Y)
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w, h := gtx.Dp(unit.Dp(wf*scale)), gtx.Dp(unit.Dp(hf*scale))
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dims, trans := im.Fit.scale(gtx.Constraints, im.Position, layout.Dimensions{Size: image.Pt(w, h)})
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defer clip.Rect{Max: dims.Size}.Push(gtx.Ops).Pop()
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pixelScale := scale * gtx.Metric.PxPerDp
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trans = trans.Mul(f32.AffineId().Scale(f32.Point{}, f32.Pt(pixelScale, pixelScale)))
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defer op.Affine(trans).Push(gtx.Ops).Pop()
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im.Src.Add(gtx.Ops)
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paint.PaintOp{}.Add(gtx.Ops)
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return dims
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}
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