graphics: Calculate vertices ahead of locking

image.go

@@ -88,15 +88,8 @@ func (i *Image) fill(clr color.Color) (err error) {
 // Be careful that this method is potentially slow.
 // It would be better if you could call this method fewer times.
 func (i *Image) DrawImage(image *Image, options *DrawImageOptions) (err error) {
-	imageM.Lock()
-	defer imageM.Unlock()
-	if i.isDisposed() {
-		return errors.New("ebiten: image is already disposed")
-	}
-	if i == image {
-		return errors.New("ebiten: Image.DrawImage: image should be different from the receiver")
-	}
-	i.pixels = nil
+	// Calculate vertices before locking because the user can do anything in
+	// options.ImageParts interface without deadlock (e.g. Call Image functions).
 	if options == nil {
 		options = &DrawImageOptions{}
 	}
@@ -111,8 +104,24 @@ func (i *Image) DrawImage(image *Image, options *DrawImageOptions) (err error) {
 		}
 	}
 	quads := &textureQuads{parts: parts, width: image.width, height: image.height}
+	// TODO: Reuse one vertices instead of making here, but this would need locking.
+	vertices := make([]int16, 16*graphics.MaxQuads)
+	n := quads.vertices(vertices)
+	if n == 0 {
+		return nil
+	}
+
+	imageM.Lock()
+	defer imageM.Unlock()
+	if i.isDisposed() {
+		return errors.New("ebiten: image is already disposed")
+	}
+	if i == image {
+		return errors.New("ebiten: Image.DrawImage: image should be different from the receiver")
+	}
+	i.pixels = nil
 	m := opengl.CompositeMode(options.CompositeMode)
-	return i.framebuffer.DrawTexture(glContext, image.texture, quads, &options.GeoM, &options.ColorM, m)
+	return i.framebuffer.DrawTexture(glContext, image.texture, vertices[:16*n], &options.GeoM, &options.ColorM, m)
 }
 
 // Bounds returns the bounds of the image.

imageparts.go

@@ -88,12 +88,8 @@ type textureQuads struct {
 	height int
 }
 
-func (t *textureQuads) Len() int {
-	return t.parts.Len()
-}
-
-func (t *textureQuads) SetVertices(vertices []int16) int {
-	l := t.Len()
+func (t *textureQuads) vertices(vertices []int16) int {
+	l := t.parts.Len()
 	if len(vertices) < l*16 {
 		panic(fmt.Sprintf("graphics: vertices size must be greater than %d but %d", l*16, len(vertices)))
 	}

internal/graphics/draw.go

@@ -33,11 +33,9 @@ type Matrix interface {
 	Element(i, j int) float64
 }
 
-var vertices = make([]int16, 16*quadsMaxNum)
-
 var shadersInitialized = false
 
-func drawTexture(c *opengl.Context, texture opengl.Texture, projectionMatrix *[4][4]float64, quads TextureQuads, geo Matrix, color Matrix, mode opengl.CompositeMode) error {
+func drawTexture(c *opengl.Context, texture opengl.Texture, projectionMatrix *[4][4]float64, vertices []int16, geo Matrix, color Matrix, mode opengl.CompositeMode) error {
 	c.BlendFunc(mode)
 
 	// NOTE: WebGL doesn't seem to have Check gl.MAX_ELEMENTS_VERTICES or gl.MAX_ELEMENTS_INDICES so far.
@@ -50,12 +48,12 @@ func drawTexture(c *opengl.Context, texture opengl.Texture, projectionMatrix *[4
 		shadersInitialized = true
 	}
 
-	l := quads.Len()
-	if l == 0 {
+	n := len(vertices) / 16
+	if n == 0 {
 		return nil
 	}
-	if quadsMaxNum < l {
-		return errors.New(fmt.Sprintf("len(quads) must be equal to or less than %d", quadsMaxNum))
+	if MaxQuads < n/16 {
+		return errors.New(fmt.Sprintf("len(quads) must be equal to or less than %d", MaxQuads))
 	}
 
 	p := programContext{
@@ -66,10 +64,6 @@ func drawTexture(c *opengl.Context, texture opengl.Texture, projectionMatrix *[4
 		geoM:             geo,
 		colorM:           color,
 	}
-	n := quads.SetVertices(vertices)
-	if n == 0 {
-		return nil
-	}
 	p.begin()
 	defer p.end()
 	c.BufferSubData(c.ArrayBuffer, vertices[:16*n])

internal/graphics/framebuffer.go

@@ -21,11 +21,6 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/graphics/opengl"
 )
 
-type TextureQuads interface {
-	Len() int
-	SetVertices(vertices []int16) int
-}
-
 func orthoProjectionMatrix(left, right, bottom, top int) *[4][4]float64 {
 	e11 := float64(2) / float64(right-left)
 	e22 := float64(2) / float64(top-bottom)
@@ -116,12 +111,12 @@ func (f *Framebuffer) Fill(c *opengl.Context, clr color.Color) error {
 	return c.FillFramebuffer(r, g, b, a)
 }
 
-func (f *Framebuffer) DrawTexture(c *opengl.Context, t *Texture, quads TextureQuads, geo, clr Matrix, mode opengl.CompositeMode) error {
+func (f *Framebuffer) DrawTexture(c *opengl.Context, t *Texture, vertices []int16, geo, clr Matrix, mode opengl.CompositeMode) error {
 	if err := f.setAsViewport(c); err != nil {
 		return err
 	}
 	p := f.projectionMatrix()
-	return drawTexture(c, t.native, p, quads, geo, clr, mode)
+	return drawTexture(c, t.native, p, vertices, geo, clr, mode)
 }
 
 func (f *Framebuffer) Pixels(c *opengl.Context) ([]uint8, error) {

internal/graphics/program.go

@@ -16,7 +16,6 @@ package graphics
 
 import (
 	"github.com/hajimehoshi/ebiten/internal/graphics/opengl"
-	"math"
 )
 
 var (
@@ -28,8 +27,8 @@ var (
 	programTexture opengl.Program
 )
 
-const indicesNum = math.MaxUint16 + 1
-const quadsMaxNum = indicesNum / 6
+const indicesNum = 1 << 16
+const MaxQuads = indicesNum / 6
 
 // unsafe.SizeOf can't be used because unsafe doesn't work with GopherJS.
 const int16Size = 2
@@ -56,12 +55,12 @@ func initialize(c *opengl.Context) error {
 		return err
 	}
 
-	// 16 [bytse] is an arbitrary number which seems enough to draw anything. Fix this if necessary.
+	// 16 [bytes] is an arbitrary number which seems enough to draw anything. Fix this if necessary.
 	const stride = 16
-	c.NewBuffer(c.ArrayBuffer, 4*stride*quadsMaxNum, c.DynamicDraw)
+	c.NewBuffer(c.ArrayBuffer, 4*stride*MaxQuads, c.DynamicDraw)
 
-	indices := make([]uint16, 6*quadsMaxNum)
-	for i := uint16(0); i < quadsMaxNum; i++ {
+	indices := make([]uint16, 6*MaxQuads)
+	for i := uint16(0); i < MaxQuads; i++ {
 		indices[6*i+0] = 4*i + 0
 		indices[6*i+1] = 4*i + 1
 		indices[6*i+2] = 4*i + 2