66 lines
1.4 KiB
Go
66 lines
1.4 KiB
Go
package application
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import (
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"image"
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"math"
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"github.com/hajimehoshi/ebiten/v2"
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)
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type canvas struct {
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x, y int
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w, h int
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vx, vy float64 // Viewport position
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img *ebiten.Image
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scale float64
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op *ebiten.DrawImageOptions
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}
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func NewCanvas(w, h int) *canvas {
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return &canvas{
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x: uiWidth,
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y: 0,
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w: w,
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h: h,
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img: ebiten.NewImage(w, h),
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scale: 1,
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op: &ebiten.DrawImageOptions{},
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}
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}
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func (c *canvas) pixelScreenRect(x, y int) image.Rectangle {
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rx, ry := (float64(x)-c.vx)*c.scale, (float64(y)-c.vy)*c.scale
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rx += float64(c.x)
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ry += float64(c.y)
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rxCorner, ryCorner := (float64(x+1)-c.vx)*c.scale, (float64(y+1)-c.vy)*c.scale
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rxCorner += float64(c.x)
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ryCorner += float64(c.y)
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return image.Rect(int(math.Floor(rx)), int(math.Floor(ry)), int(math.Ceil(rxCorner)), int(math.Ceil(ryCorner)))
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}
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func (c *canvas) screenToCanvas(x, y int) (int, int) {
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cx, cy := float64(x-c.x)/c.scale, float64(y-c.y)/c.scale
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cx, cy = cx+c.vx, cy+c.vy
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return int(cx), int(cy)
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}
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func (c *canvas) Draw(screen *ebiten.Image) {
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// Draw canvas.
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c.op.GeoM.Reset()
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c.op.GeoM.Scale(c.scale, c.scale)
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c.op.GeoM.Translate(float64(c.x), float64(c.y))
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c.op.GeoM.Translate(-c.vx*c.scale, -c.vy*c.scale)
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screen.DrawImage(c.img, c.op)
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// Draw hover outline.
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cx, cy := c.screenToCanvas(cursorX, cursorY)
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p := c.pixelScreenRect(cx, cy)
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c.op.GeoM.Reset()
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c.op.GeoM.Translate(float64(p.Min.X), float64(p.Min.Y))
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screen.DrawImage(hoverImg, c.op)
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}
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