no-wrap option; pivoted exponential zoom

client/editor.go

@@ -2,6 +2,7 @@ package client
 
 import (
 	"image"
+	"math"
 	"sync"
 
 	"fyne.io/fyne/v2"
@@ -78,11 +79,89 @@ func (e *editor) updateSizes() {
 
 		e.wp.CameraZoom = e.world.CorrectCameraZoom(e.wp.CameraZoom, e.wp.ViewportWidthPx, e.wp.ViewportHeightPx)
 		e.world.IndexOnViewportChange(e.wp.ViewportWidthPx, e.wp.ViewportHeightPx, e.wp.CameraZoom)
-
+		e.world.ClampRenderParamsNoWrap(e.wp)
 		e.co.Request(*e.wp)
 	}
 }
 
+func (e *editor) onScrolled(s *fyne.ScrollEvent) {
+	vw := e.wp.ViewportWidthPx
+	vh := e.wp.ViewportHeightPx
+	if vw <= 0 || vh <= 0 {
+		return
+	}
+
+	// Cursor position in viewport pixels (Fyne units -> px by multiplying).
+	cxPx := int(float32(s.Position.X) * e.canvasScale)
+	cyPx := int(float32(s.Position.Y) * e.canvasScale)
+
+	if cxPx < 0 {
+		cxPx = 0
+	} else if cxPx > vw {
+		cxPx = vw
+	}
+	if cyPx < 0 {
+		cyPx = 0
+	} else if cyPx > vh {
+		cyPx = vh
+	}
+
+	oldZoom := e.wp.CameraZoom
+
+	// Exponential zoom:
+	// - Each "notch" multiplies zoom by a fixed factor.
+	// - Using DY directly as exponent gives smooth trackpad behavior too.
+	//
+	// Tune base:
+	//   base=1.10 => ~10% per wheel step (if DY≈1 per step)
+	//   base=1.05 => ~5% per step
+	//
+	// In user settings, better store on percents userZoomLevelPercent = (0,100]: base = 1 + (userZoomLevelPercent) / 10
+	const base = 1.005
+
+	// Negative DY => zoom out, positive DY => zoom in (depending on platform settings).
+	// If you want inverted direction, negate float64(s.Scrolled.DY).
+	delta := float64(s.Scrolled.DY)
+
+	newZoom := oldZoom * math.Pow(base, delta)
+
+	// Clamp/correct (min/max + prevent wrap if needed).
+	newZoom = e.world.CorrectCameraZoom(newZoom, vw, vh)
+	if newZoom == oldZoom {
+		return
+	}
+
+	oldZoomFp, err := world.CameraZoomToWorldFixed(oldZoom)
+	if err != nil {
+		return
+	}
+	newZoomFp, err := world.CameraZoomToWorldFixed(newZoom)
+	if err != nil {
+		return
+	}
+
+	newCamX, newCamY := world.PivotZoomCameraNoWrap(
+		e.wp.CameraXWorldFp, e.wp.CameraYWorldFp,
+		vw, vh,
+		cxPx, cyPx,
+		oldZoomFp, newZoomFp,
+	)
+
+	e.wp.CameraZoom = newZoom
+	e.wp.CameraXWorldFp = newCamX
+	e.wp.CameraYWorldFp = newCamY
+
+	e.world.IndexOnViewportChange(vw, vh, e.wp.CameraZoom)
+
+	// No-wrap clamp to avoid "detaching" from borders.
+	e.world.ClampRenderParamsNoWrap(e.wp)
+
+	// Zoom changes are best done as full redraw.
+	e.world.ForceFullRedrawNext()
+
+	e.co.Request(*e.wp)
+}
+
 func (e *editor) onDragged(ev *fyne.DragEvent) {
 	e.pan.Dragged(ev)
 }
@@ -120,6 +199,7 @@ func NewEditor() *editor {
 			CameraXWorldFp: 300 * world.SCALE,
 			CameraYWorldFp: 300 * world.SCALE,
 			// Viewport sizes and margins will be filled from draw(w,h).
+			Options: &world.RenderOptions{DisableWrapScroll: false},
 		},
 		canvasScale: 1.0,
 	}
@@ -132,7 +212,7 @@ func NewEditor() *editor {
 		return e.draw(wPx, hPx)
 	})
 
-	e.canvas = newInteractiveRaster(e, e.raster, e.onMapLayout, e.onDragged, e.onDradEnd)
+	e.canvas = newInteractiveRaster(e, e.raster, e.onMapLayout, e.onScrolled, e.onDragged, e.onDradEnd)
 	e.pan = NewPanController(e)
 
 	// Wire coalescer: it schedules raster.Refresh() on UI thread and renders once per draw call.