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examples/scroll: support a mouse wheel

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This commit is contained in:
Hajime Hoshi 2024-03-31 19:37:50 +09:00
parent 7ad9973d70
commit 4ae0712dc5
1 changed files with 9 additions and 1 deletions
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10
examples/scroll/main.go
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@ -91,6 +91,8 @@ func (g *Game) Update() error {
g.prevY = y
}()
hovering := image.Pt(x, y).In(g.contentArea)
// If a pointing device is just released, start scrolling.
if g.isPointingDeviceJustReleased() && g.dragging {
g.dragging = false
@ -98,9 +100,15 @@ func (g *Game) Update() error {
return nil
}
// Process a mouse wheel.
if _, wheelY := ebiten.Wheel(); wheelY != 0 && !g.dragging && hovering {
g.velocityY = int(wheelY)
}
// If a pointing device is NOT pressed, scroll by the inertia.
if !g.isPointingDevicePressed() {
g.dragging = false
g.setOffsetY(g.offsetY + g.velocityY)
if g.velocityY != 0 {
g.velocityY = int(float64(g.velocityY) * 15.0 / 16.0)
@ -111,7 +119,7 @@ func (g *Game) Update() error {
// As a pointing device is pressed, stop the inertia.
g.velocityY = 0
if !g.dragging && image.Pt(x, y).In(g.contentArea) {
if !g.dragging && hovering {
g.dragging = true
g.offsetStartY = g.offsetY
g.startY = y