doodle/pkg/uix/canvas_cursor.go

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package uix
import (
"git.kirsle.net/apps/doodle/pkg/shmem"
"git.kirsle.net/go/render"
"git.kirsle.net/go/ui"
)
// IsCursorOver returns true if the mouse cursor is physically over top
// of the canvas's widget space.
func (w *Canvas) IsCursorOver() bool {
var (
P = ui.AbsolutePosition(w)
S = w.Size()
)
return shmem.Cursor.Inside(render.Rect{
X: P.X,
Y: P.Y,
W: S.W,
H: S.H,
})
}
// presentCursor draws something at the mouse cursor on the Canvas.
//
// This is currently used in Edit Mode when you're drawing a shape with a thick
// brush size, and draws a "preview rect" under the cursor of how big a click
// will be at that size.
func (w *Canvas) presentCursor(e render.Engine) {
if !w.IsCursorOver() {
return
}
// Are we editing with a thick brush?
if w.BrushSize > 0 {
var r = w.BrushSize
rect := render.Rect{
X: shmem.Cursor.X - r,
Y: shmem.Cursor.Y - r,
W: r * 2,
H: r * 2,
}
e.DrawRect(render.Black, rect)
rect.X++
rect.Y++
rect.W -= 2
rect.H -= 2
e.DrawRect(render.RGBA(153, 153, 153, 153), rect)
}
}