Pad/internal/ui/unit.go
Greg Pomerantz b8c6878f46 Introduce distinct Dp/Px types to prevent coordinate mixing at compile time
- Add ui.Dp and ui.Px as distinct named types
- Logic layer works exclusively in Dp (positions, sizes, regions)
- Renderer converts Dp→Px at Gio interop boundaries
- Capture gtx.Constraints once at start of Draw() for consistent positioning
- main.go converts app.ConfigEvent pixels to Dp before passing to logic layer
- Update documentation with new coordinate system architecture
2026-05-09 18:40:47 -04:00

66 lines
1.8 KiB
Go

package ui
import "gioui.org/unit"
// Dp represents device-independent pixels. Use for all element positions,
// sizes, and spacing in the logic/layout layer.
type Dp unit.Dp
// Px represents physical device pixels. Use only when interfacing with
// Gio's layout.Context (gtx.Constraints, gtx.Dp(), etc.).
type Px int
// ToDp converts physical pixels to device-independent pixels using the
// given scale factor (pixels per DP). Typically from gtx.Metric.PxPerDp.
func ToDp(px Px, scale float32) Dp {
return Dp(float32(px) / scale)
}
// ToPx converts device-independent pixels to physical pixels using the
// given scale factor (pixels per DP).
func ToPx(dp Dp, scale float32) Px {
return Px(float32(dp) * scale)
}
// PxPerDp returns the scale factor: how many physical pixels per DP.
// Use this to convert between Dp and Px.
func PxPerDp(scale float32) float32 { return scale }
// --- Gio interop helpers ---
// DpToPx converts a gioui unit.Dp to our Px using the scale factor.
func DpToPx(d unit.Dp, scale float32) Px {
return Px(float32(d) * scale)
}
// PxToDp converts our Px to a gioui unit.Dp using the scale factor.
func PxToDp(p Px, scale float32) unit.Dp {
return unit.Dp(float32(p) / scale)
}
// RegionPx is a region in physical pixels. Used for Gio interop only.
type RegionPx struct {
X, Y Px
W, H Px
}
// ToDp converts a RegionPx to a Region (Dp) using the scale factor.
func (r RegionPx) ToDp(scale float32) Region {
return Region{
X: ToDp(r.X, scale),
Y: ToDp(r.Y, scale),
W: ToDp(r.W, scale),
H: ToDp(r.H, scale),
}
}
// FromDp converts a Region (Dp) to a RegionPx using the scale factor.
func FromDp(r Region, scale float32) RegionPx {
return RegionPx{
X: ToPx(r.X, scale),
Y: ToPx(r.Y, scale),
W: ToPx(r.W, scale),
H: ToPx(r.H, scale),
}
}