graphics: Refactoring: Remove duplication of checking image size

image.go

@@ -444,7 +444,6 @@ type DrawImageOptions struct {
 //
 // Error returned by NewImage is always nil as of 1.5.0-alpha.
 func NewImage(width, height int, filter Filter) (*Image, error) {
-	checkSize(width, height)
 	var i *Image
 	s := newSharedImagePart(width, height)
 	if s != nil {
@@ -466,7 +465,6 @@ func NewImage(width, height int, filter Filter) (*Image, error) {
 
 // newImageWithoutInit creates an empty image without initialization.
 func newImageWithoutInit(width, height int) *Image {
-	checkSize(width, height)
 	var i *Image
 	s := newSharedImagePart(width, height)
 	if s != nil {
@@ -501,7 +499,6 @@ func newImageWithoutInit(width, height int) *Image {
 //
 // Error returned by newVolatileImage is always nil as of 1.5.0-alpha.
 func newVolatileImage(width, height int, filter Filter) *Image {
-	checkSize(width, height)
 	r := restorable.NewImage(width, height, true)
 	i := &Image{
 		restorable: r,
@@ -522,7 +519,6 @@ func newVolatileImage(width, height int, filter Filter) *Image {
 // Error returned by NewImageFromImage is always nil as of 1.5.0-alpha.
 func NewImageFromImage(source image.Image, filter Filter) (*Image, error) {
 	size := source.Bounds().Size()
-	checkSize(size.X, size.Y)
 
 	width, height := size.X, size.Y
 
@@ -547,7 +543,6 @@ func NewImageFromImage(source image.Image, filter Filter) (*Image, error) {
 }
 
 func newImageWithScreenFramebuffer(width, height int) *Image {
-	checkSize(width, height)
 	r := restorable.NewScreenFramebufferImage(width, height)
 	i := &Image{
 		restorable: r,
@@ -559,18 +554,3 @@ func newImageWithScreenFramebuffer(width, height int) *Image {
 
 // MaxImageSize represents the maximum width/height of an image.
 const MaxImageSize = graphics.MaxImageSize
-
-func checkSize(width, height int) {
-	if width <= 0 {
-		panic("ebiten: width must be more than 0")
-	}
-	if height <= 0 {
-		panic("ebiten: height must be more than 0")
-	}
-	if width > MaxImageSize {
-		panic(fmt.Sprintf("ebiten: width (%d) must be less than or equal to %d", width, MaxImageSize))
-	}
-	if height > MaxImageSize {
-		panic(fmt.Sprintf("ebiten: height (%d) must be less than or equal to %d", height, MaxImageSize))
-	}
-}

internal/graphics/command.go

@@ -15,7 +15,6 @@
 package graphics
 
 import (
-	"errors"
 	"fmt"
 
 	"github.com/hajimehoshi/ebiten/internal/affine"
@@ -326,16 +325,26 @@ type newImageCommand struct {
 	height int
 }
 
+func checkSize(width, height int) {
+	if width < 1 {
+		panic(fmt.Sprintf("graphics: width (%d) must be equal or more than 1.", width))
+	}
+	if height < 1 {
+		panic(fmt.Sprintf("graphics: height (%d) must be equal or more than 1.", height))
+	}
+	if width > MaxImageSize {
+		panic(fmt.Sprintf("graphics: width (%d) must be less than or equal to %d", width, MaxImageSize))
+	}
+	if height > MaxImageSize {
+		panic(fmt.Sprintf("graphics: height (%d) must be less than or equal to %d", height, MaxImageSize))
+	}
+}
+
 // Exec executes a newImageCommand.
 func (c *newImageCommand) Exec(indexOffsetInBytes int) error {
 	w := emath.NextPowerOf2Int(c.width)
 	h := emath.NextPowerOf2Int(c.height)
-	if w < 1 {
+	checkSize(w, h)
-		return errors.New("graphics: width must be equal or more than 1.")
-	}
-	if h < 1 {
-		return errors.New("graphics: height must be equal or more than 1.")
-	}
 	native, err := opengl.GetContext().NewTexture(w, h)
 	if err != nil {
 		return err
@@ -359,12 +368,7 @@ type newScreenFramebufferImageCommand struct {
 
 // Exec executes a newScreenFramebufferImageCommand.
 func (c *newScreenFramebufferImageCommand) Exec(indexOffsetInBytes int) error {
-	if c.width < 1 {
+	checkSize(c.width, c.height)
-		return errors.New("graphics: width must be equal or more than 1.")
-	}
-	if c.height < 1 {
-		return errors.New("graphics: height must be equal or more than 1.")
-	}
 	// The (default) framebuffer size can't be converted to a power of 2.
 	// On browsers, c.width and c.height are used as viewport size and
 	// Edge can't treat a bigger viewport than the drawing area (#71).