ebiten/examples/paint/main.go
Hajime Hoshi 431cd33839 ebiten: Add AppendInputChars, AppendGamepadIDs, and AppendTouchIDs
These functions reduce unnecessary allocations of arrays.

Closes #1692
2021-07-10 03:03:24 +09:00

125 lines
2.8 KiB
Go

// Copyright 2014 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//go:build example
// +build example
package main
import (
"fmt"
"image"
"image/color"
"log"
"math"
"github.com/hajimehoshi/ebiten/v2"
"github.com/hajimehoshi/ebiten/v2/ebitenutil"
)
const (
screenWidth = 640
screenHeight = 480
)
var (
brushImage *ebiten.Image
canvasImage = ebiten.NewImage(screenWidth, screenHeight)
)
func init() {
const (
a0 = 0x40
a1 = 0xc0
a2 = 0xff
)
pixels := []uint8{
a0, a1, a1, a0,
a1, a2, a2, a1,
a1, a2, a2, a1,
a0, a1, a1, a0,
}
brushImage = ebiten.NewImageFromImage(&image.Alpha{
Pix: pixels,
Stride: 4,
Rect: image.Rect(0, 0, 4, 4),
})
canvasImage.Fill(color.White)
}
type Game struct {
touches []ebiten.TouchID
count int
}
func (g *Game) Update() error {
drawn := false
// Paint the brush by mouse dragging
mx, my := ebiten.CursorPosition()
if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
g.paint(canvasImage, mx, my)
drawn = true
}
// Paint the brush by touches
g.touches = ebiten.AppendTouchIDs(g.touches[:0])
for _, t := range g.touches {
x, y := ebiten.TouchPosition(t)
g.paint(canvasImage, x, y)
drawn = true
}
if drawn {
g.count++
}
return nil
}
// paint draws the brush on the given canvas image at the position (x, y).
func (g *Game) paint(canvas *ebiten.Image, x, y int) {
op := &ebiten.DrawImageOptions{}
op.GeoM.Translate(float64(x), float64(y))
// Scale the color and rotate the hue so that colors vary on each frame.
op.ColorM.Scale(1.0, 0.50, 0.125, 1.0)
tps := ebiten.MaxTPS()
theta := 2.0 * math.Pi * float64(g.count%tps) / float64(tps)
op.ColorM.RotateHue(theta)
canvas.DrawImage(brushImage, op)
}
func (g *Game) Draw(screen *ebiten.Image) {
screen.DrawImage(canvasImage, nil)
mx, my := ebiten.CursorPosition()
msg := fmt.Sprintf("(%d, %d)", mx, my)
for _, t := range g.touches {
x, y := ebiten.TouchPosition(t)
msg += fmt.Sprintf("\n(%d, %d) touch %d", x, y, t)
}
ebitenutil.DebugPrint(screen, msg)
}
func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
return screenWidth, screenHeight
}
func main() {
ebiten.SetWindowSize(screenWidth, screenHeight)
ebiten.SetWindowTitle("Paint (Ebiten Demo)")
if err := ebiten.RunGame(&Game{}); err != nil {
log.Fatal(err)
}
}