ebiten/docs/examples/paint.html

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  <h2>Ebiten example - paint</h2>
  <iframe src="paint.content.html" width="640" height="480"></iframe>
  <pre><code class="language-go">// &#43;build example

package main

import (
        &#34;fmt&#34;
        &#34;image&#34;
        &#34;image/color&#34;
        &#34;log&#34;
        &#34;math&#34;

        &#34;github.com/hajimehoshi/ebiten&#34;
        &#34;github.com/hajimehoshi/ebiten/ebitenutil&#34;
)

const (
        screenWidth  = 320
        screenHeight = 240
)

var (
        count       int
        brushImage  *ebiten.Image
        canvasImage *ebiten.Image
)

func paint(screen *ebiten.Image, x, y int) error {
        op := &amp;ebiten.DrawImageOptions{}
        op.GeoM.Translate(float64(x), float64(y))
        op.ColorM.Scale(1.0, 0.50, 0.125, 1.0)
        theta := 2.0 * math.Pi * float64(count%60) / ebiten.FPS
        op.ColorM.RotateHue(theta)
        if err := canvasImage.DrawImage(brushImage, op); err != nil {
                return err
        }
        return nil
}

func update(screen *ebiten.Image) error {
        drawn := false
        mx, my := ebiten.CursorPosition()
        if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
                if err := paint(screen, mx, my); err != nil {
                        return err
                }
                drawn = true
        }
        for _, t := range ebiten.Touches() {
                x, y := t.Position()
                if err := paint(screen, x, y); err != nil {
                        return err
                }
                drawn = true
        }
        if drawn {
                count&#43;&#43;
        }

        if err := screen.DrawImage(canvasImage, nil); err != nil {
                return err
        }

        msg := fmt.Sprintf(&#34;(%d, %d)&#34;, mx, my)
        for _, t := range ebiten.Touches() {
                x, y := t.Position()
                msg &#43;= fmt.Sprintf(&#34;\n(%d, %d) touch %d&#34;, x, y, t.ID())
        }
        if err := ebitenutil.DebugPrint(screen, msg); err != nil {
                return err
        }
        return nil
}

func main() {
        var err error
        const a0, a1, a2 = 0x40, 0xc0, 0xff
        pixels := []uint8{
                a0, a1, a1, a0,
                a1, a2, a2, a1,
                a1, a2, a2, a1,
                a0, a1, a1, a0,
        }
        brushImage, err = ebiten.NewImageFromImage(&amp;image.Alpha{
                Pix:    pixels,
                Stride: 4,
                Rect:   image.Rect(0, 0, 4, 4),
        }, ebiten.FilterNearest)
        if err != nil {
                log.Fatal(err)
        }

        canvasImage, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
        if err != nil {
                log.Fatal(err)
        }
        if err := canvasImage.Fill(color.White); err != nil {
                log.Fatal(err)
        }

        if err := ebiten.Run(update, screenWidth, screenHeight, 2, &#34;Paint (Ebiten Demo)&#34;); err != nil {
                log.Fatal(err)
        }
}
</code></pre>

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  <p>© 2013 Hajime Hoshi</p>
  <p>Code is licensed under <a href="https://github.com/hajimehoshi/ebiten/blob/master/LICENSE">the Apache License 2.0</a>.</p>
  <p>The content of this page is licensed under <a href="https://creativecommons.org/licenses/by/4.0/">the Creative Commons Attribution 4.0 License</a>.</p>
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docs: Add example paint 2015-01-08 18:39:20 +01:00			`<!DOCTYPE html>`
doc: Force HTTPS 2016-08-27 17:58:27 +02:00			`<script src="../scripts/force-https.js"></script>`
Bug fix: Add favicon to example/*.html 2015-01-08 18:48:25 +01:00			`<link rel="shortcut icon" href="../favicon.png" type="image/png" >`
			`<link rel="icon" href="../favicon.png" type="image/png" >`
docs: Add <title> to examples 2015-01-08 19:29:59 +01:00			`<title>Ebiten example - paint</title>`
doc: Use relative path 2016-08-27 17:48:15 +02:00			`<link rel="stylesheet" href="../stylesheets/bootstrap.min.css">`
			`<link rel="stylesheet" href="../stylesheets/highlight-github.css">`
			`<link rel="stylesheet" href="../stylesheets/ebiten.css">`
doc: Bug fix: wrong path 2016-09-02 18:55:07 +02:00			`<script src="../scripts/googleanalytics.js"></script>`
doc: Apply bootstrap 2016-08-26 19:28:57 +02:00
			`<header class="navbar"><div class="container">`
			`<div class="navbar-header">`
doc: Use relative path 2016-08-27 17:48:15 +02:00			`<a class="navbar-brand" href="..">Ebiten</a>`
doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`</div>`
doc: Fix thumbnail size 2016-08-26 19:37:08 +02:00			`<nav class="collapse navbar-collapse">`
			`<ul class="nav navbar-nav navbar-right">`
			`<li><a href="https://github.com/hajimehoshi/ebiten">GitHub</a></li>`
doc: Force HTTPS 2016-08-27 17:58:27 +02:00			`<li><a href="https://godoc.org/github.com/hajimehoshi/ebiten">GoDoc</a></li>`
doc: Fix thumbnail size 2016-08-26 19:37:08 +02:00			`<li><a href="https://github.com/hajimehoshi/ebiten/wiki">Wiki</a>`
			`</ul>`
			`</nav>`
doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`</header>`
docs: Add example paint 2015-01-08 18:39:20 +01:00
doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`<main><div class="container">`

doc: Adjust fonts 2016-08-26 20:18:16 +02:00			`<h2>Ebiten example - paint</h2>`
doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`<iframe src="paint.content.html" width="640" height="480"></iframe>`
doc: Highlight code 2016-08-27 07:00:06 +02:00			`<pre><code class="language-go">// +build example`
doc: go generate; Add style.css 2016-08-26 16:33:36 +02:00
			`package main`
docs: Add example paint 2015-01-08 18:39:20 +01:00
			`import (`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`"fmt"`
			`"image"`
			`"image/color"`
			`"log"`
			`"math"`

			`"github.com/hajimehoshi/ebiten"`
			`"github.com/hajimehoshi/ebiten/ebitenutil"`
docs: Add example paint 2015-01-08 18:39:20 +01:00			`)`

			`const (`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`screenWidth = 320`
			`screenHeight = 240`
docs: Add example paint 2015-01-08 18:39:20 +01:00			`)`

			`var (`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`count int`
			`brushImage *ebiten.Image`
			`canvasImage *ebiten.Image`
docs: Add example paint 2015-01-08 18:39:20 +01:00			`)`

go generate _docs 2016-06-23 05:16:27 +02:00			`func paint(screen *ebiten.Image, x, y int) error {`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`op := &ebiten.DrawImageOptions{}`
			`op.GeoM.Translate(float64(x), float64(y))`
			`op.ColorM.Scale(1.0, 0.50, 0.125, 1.0)`
			`theta := 2.0 * math.Pi * float64(count%60) / ebiten.FPS`
			`op.ColorM.RotateHue(theta)`
			`if err := canvasImage.DrawImage(brushImage, op); err != nil {`
			`return err`
			`}`
			`return nil`
go generate _docs 2016-06-23 05:16:27 +02:00			`}`
docs: Add example paint 2015-01-08 18:39:20 +01:00
go generate _docs 2016-06-23 05:16:27 +02:00			`func update(screen *ebiten.Image) error {`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`drawn := false`
			`mx, my := ebiten.CursorPosition()`
			`if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {`
			`if err := paint(screen, mx, my); err != nil {`
			`return err`
			`}`
			`drawn = true`
			`}`
			`for _, t := range ebiten.Touches() {`
			`x, y := t.Position()`
			`if err := paint(screen, x, y); err != nil {`
			`return err`
			`}`
			`drawn = true`
			`}`
			`if drawn {`
			`count++`
			`}`

			`if err := screen.DrawImage(canvasImage, nil); err != nil {`
			`return err`
			`}`

			`msg := fmt.Sprintf("(%d, %d)", mx, my)`
			`for _, t := range ebiten.Touches() {`
			`x, y := t.Position()`
			`msg += fmt.Sprintf("\n(%d, %d) touch %d", x, y, t.ID())`
go generate _docs 2016-06-23 05:16:27 +02:00			`}`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`if err := ebitenutil.DebugPrint(screen, msg); err != nil {`
			`return err`
docs: Add example paint 2015-01-08 18:39:20 +01:00			`}`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`return nil`
docs: Add example paint 2015-01-08 18:39:20 +01:00			`}`

			`func main() {`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`var err error`
			`const a0, a1, a2 = 0x40, 0xc0, 0xff`
			`pixels := []uint8{`
			`a0, a1, a1, a0,`
			`a1, a2, a2, a1,`
			`a1, a2, a2, a1,`
			`a0, a1, a1, a0,`
			`}`
			`brushImage, err = ebiten.NewImageFromImage(&image.Alpha{`
			`Pix: pixels,`
			`Stride: 4,`
			`Rect: image.Rect(0, 0, 4, 4),`
			`}, ebiten.FilterNearest)`
			`if err != nil {`
			`log.Fatal(err)`
			`}`

			`canvasImage, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)`
			`if err != nil {`
			`log.Fatal(err)`
			`}`
			`if err := canvasImage.Fill(color.White); err != nil {`
			`log.Fatal(err)`
			`}`

			`if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Paint (Ebiten Demo)"); err != nil {`
			`log.Fatal(err)`
			`}`
docs: Add example paint 2015-01-08 18:39:20 +01:00			`}`
			`</code></pre>`

doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`</div></main>`

			`<footer><div class="container">`
			`<p>© 2013 Hajime Hoshi</p>`
doc: Add 'the' 2016-08-28 00:10:41 +02:00			`<p>Code is licensed under <a href="https://github.com/hajimehoshi/ebiten/blob/master/LICENSE">the Apache License 2.0</a>.</p>`
doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`<p>The content of this page is licensed under <a href="https://creativecommons.org/licenses/by/4.0/">the Creative Commons Attribution 4.0 License</a>.</p>`
			`</div></footer>`
docs: Add example paint 2015-01-08 18:39:20 +01:00
doc: Use relative path 2016-08-27 17:48:15 +02:00			`<script src="../scripts/highlight.pack.js"></script>`
doc: Highlight code 2016-08-27 07:00:06 +02:00			`<script>hljs.initHighlightingOnLoad();</script>`