96 lines
2.3 KiB
Go
96 lines
2.3 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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"github.com/p9c/p9/pkg/gel/gio/f32"
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"github.com/p9c/p9/pkg/gel/gio/layout"
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)
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// Fit scales a widget to fit and clip to the constraints.
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type Fit uint8
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const (
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// Unscaled does not alter the scale of a widget.
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Unscaled Fit = iota
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// Contain scales widget as large as possible without cropping
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// and it preserves aspect-ratio.
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Contain
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// Cover scales the widget to cover the constraint area and
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// preserves aspect-ratio.
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Cover
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// ScaleDown scales the widget smaller without cropping,
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// when it exceeds the constraint area.
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// It preserves aspect-ratio.
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ScaleDown
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// Fill stretches the widget to the constraints and does not
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// preserve aspect-ratio.
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Fill
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)
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// scale computes the new dimensions and transformation required to fit dims to cs, given the position.
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func (fit Fit) scale(cs layout.Constraints, pos layout.Direction, dims layout.Dimensions) (layout.Dimensions, f32.Affine2D) {
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widgetSize := dims.Size
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if fit == Unscaled || dims.Size.X == 0 || dims.Size.Y == 0 {
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dims.Size = cs.Constrain(dims.Size)
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offset := pos.Position(widgetSize, dims.Size)
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dims.Baseline += offset.Y
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return dims, f32.AffineId().Offset(layout.FPt(offset))
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}
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scale := f32.Point{
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X: float32(cs.Max.X) / float32(dims.Size.X),
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Y: float32(cs.Max.Y) / float32(dims.Size.Y),
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}
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switch fit {
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case Contain:
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if scale.Y < scale.X {
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scale.X = scale.Y
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} else {
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scale.Y = scale.X
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}
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case Cover:
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if scale.Y > scale.X {
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scale.X = scale.Y
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} else {
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scale.Y = scale.X
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}
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case ScaleDown:
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if scale.Y < scale.X {
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scale.X = scale.Y
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} else {
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scale.Y = scale.X
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}
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// The widget would need to be scaled up, no change needed.
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if scale.X >= 1 {
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dims.Size = cs.Constrain(dims.Size)
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offset := pos.Position(widgetSize, dims.Size)
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dims.Baseline += offset.Y
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return dims, f32.AffineId().Offset(layout.FPt(offset))
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}
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case Fill:
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}
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var scaledSize image.Point
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scaledSize.X = int(float32(widgetSize.X) * scale.X)
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scaledSize.Y = int(float32(widgetSize.Y) * scale.Y)
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dims.Size = cs.Constrain(scaledSize)
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dims.Baseline = int(float32(dims.Baseline) * scale.Y)
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offset := pos.Position(scaledSize, dims.Size)
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trans := f32.AffineId().
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Scale(f32.Point{}, scale).
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Offset(layout.FPt(offset))
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dims.Baseline += offset.Y
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return dims, trans
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}
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