ebiten: add ReadDebugInfo for getting debug info (only graphics libray so far) (#2222)

Closes #2177

graphics.go

@@ -16,6 +16,7 @@ package ebiten
 
 import (
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
+	"github.com/hajimehoshi/ebiten/v2/internal/ui"
 )
 
 // Filter represents the type of texture filter to be used when an image is maginified or minified.
@@ -82,3 +83,29 @@ const (
 	// c_out = c_src * c_dst
 	CompositeModeMultiply CompositeMode = CompositeMode(graphicsdriver.CompositeModeMultiply)
 )
+
+// GraphicsLibrary represets graphics libraries supported by the engine.
+type GraphicsLibrary = ui.GraphicsLibrary
+
+const (
+	// GraphicsLibraryUnknown represents the state at which graphics library cannot be determined,
+	// e.g. hasn't loaded yet or failed to initialize.
+	GraphicsLibraryUnknown = ui.GraphicsLibraryUnknown
+	// GraphicsLibraryOpenGL current graphics library used is OpenGL.
+	GraphicsLibraryOpenGL = ui.GraphicsLibraryOpenGL
+	// GraphicsLibraryDirectX current graphics library used is Microsoft DirectX.
+	GraphicsLibraryDirectX = ui.GraphicsLibraryDirectX
+	// GraphicsLibraryMetal current graphics library used is Apple's Metal.
+	GraphicsLibraryMetal = ui.GraphicsLibraryMetal
+)
+
+// DebugInfo is a struct to store debug info about the graphics.
+type DebugInfo struct {
+	// GraphicsLibrary represents the graphics library currently in use.
+	GraphicsLibrary GraphicsLibrary
+}
+
+// ReadDebugInfo writes debug info (e.g. current graphics library) into a provided struct.
+func ReadDebugInfo(d *DebugInfo) {
+	d.GraphicsLibrary = ui.GetGraphicsLibrary()
+}

internal/ui/context.go

@@ -294,6 +294,7 @@ type globalState struct {
 	fpsMode_                   int32
 	isScreenClearedEveryFrame_ int32
 	screenFilterEnabled_       int32
+	graphicsLibrary_           int32
 }
 
 func (g *globalState) error() error {
@@ -342,6 +343,14 @@ func (g *globalState) setScreenFilterEnabled(enabled bool) {
 	atomic.StoreInt32(&g.screenFilterEnabled_, v)
 }
 
+func (g *globalState) setGraphicsLibrary(library GraphicsLibrary) {
+	atomic.StoreInt32(&g.graphicsLibrary_, int32(library))
+}
+
+func (g *globalState) graphicsLibrary() GraphicsLibrary {
+	return GraphicsLibrary(atomic.LoadInt32(&g.graphicsLibrary_))
+}
+
 func FPSMode() FPSModeType {
 	return theGlobalState.fpsMode()
 }
@@ -366,3 +375,7 @@ func IsScreenFilterEnabled() bool {
 func SetScreenFilterEnabled(enabled bool) {
 	theGlobalState.setScreenFilterEnabled(enabled)
 }
+
+func GetGraphicsLibrary() GraphicsLibrary {
+	return theGlobalState.graphicsLibrary()
+}

internal/ui/graphics.go

@@ -22,7 +22,7 @@ import (
 )
 
 type graphicsDriverCreator interface {
-	newAuto() (graphicsdriver.Graphics, error)
+	newAuto() (graphicsdriver.Graphics, GraphicsLibrary, error)
 	newOpenGL() (graphicsdriver.Graphics, error)
 	newDirectX() (graphicsdriver.Graphics, error)
 	newMetal() (graphicsdriver.Graphics, error)
@@ -39,13 +39,14 @@ func newGraphicsDriver(creator graphicsDriverCreator) (graphicsdriver.Graphics,
 
 	switch env {
 	case "", "auto":
-		g, err := creator.newAuto()
+		g, lib, err := creator.newAuto()
 		if err != nil {
 			return nil, err
 		}
 		if g == nil {
 			return nil, fmt.Errorf("ui: no graphics library is available")
 		}
+		theGlobalState.setGraphicsLibrary(lib)
 		return g, nil
 	case "opengl":
 		g, err := creator.newOpenGL()
@@ -55,6 +56,7 @@ func newGraphicsDriver(creator graphicsDriverCreator) (graphicsdriver.Graphics,
 		if g == nil {
 			return nil, fmt.Errorf("ui: %s=%s is specified but OpenGL is not available", envName, env)
 		}
+		theGlobalState.setGraphicsLibrary(GraphicsLibraryOpenGL)
 		return g, nil
 	case "directx":
 		g, err := creator.newDirectX()
@@ -64,6 +66,7 @@ func newGraphicsDriver(creator graphicsDriverCreator) (graphicsdriver.Graphics,
 		if g == nil {
 			return nil, fmt.Errorf("ui: %s=%s is specified but DirectX is not available.", envName, env)
 		}
+		theGlobalState.setGraphicsLibrary(GraphicsLibraryDirectX)
 		return g, nil
 	case "metal":
 		g, err := creator.newMetal()
@@ -73,6 +76,7 @@ func newGraphicsDriver(creator graphicsDriverCreator) (graphicsdriver.Graphics,
 		if g == nil {
 			return nil, fmt.Errorf("ui: %s=%s is specified but Metal is not available", envName, env)
 		}
+		theGlobalState.setGraphicsLibrary(GraphicsLibraryMetal)
 		return g, nil
 	default:
 		return nil, fmt.Errorf("ui: an unsupported graphics library is specified: %s", env)

internal/ui/ui.go

@@ -71,6 +71,15 @@ const (
 	WindowResizingModeEnabled
 )
 
+type GraphicsLibrary int
+
+const (
+	GraphicsLibraryUnknown GraphicsLibrary = iota
+	GraphicsLibraryOpenGL
+	GraphicsLibraryDirectX
+	GraphicsLibraryMetal
+)
+
 type UserInterface struct {
 	userInterfaceImpl
 }

internal/ui/ui_android.go

@@ -23,8 +23,9 @@ type graphicsDriverCreatorImpl struct {
 	gomobileBuild bool
 }
 
-func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, error) {
-	return g.newOpenGL()
+func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, GraphicsLibrary, error) {
+	graphics, err := g.newOpenGL()
+	return graphics, GraphicsLibraryOpenGL, err
 }
 
 func (*graphicsDriverCreatorImpl) newOpenGL() (graphicsdriver.Graphics, error) {

internal/ui/ui_cbackend.go

@@ -27,8 +27,9 @@ import (
 
 type graphicsDriverCreatorImpl struct{}
 
-func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, error) {
-	return g.newOpenGL()
+func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, GraphicsLibrary, error) {
+	graphics, err := g.newOpenGL()
+	return graphics, GraphicsLibraryOpenGL, err
 }
 
 func (*graphicsDriverCreatorImpl) newOpenGL() (graphicsdriver.Graphics, error) {

internal/ui/ui_glfw_darwin.go

@@ -260,16 +260,16 @@ type graphicsDriverCreatorImpl struct {
 	transparent bool
 }
 
-func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, error) {
+func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, GraphicsLibrary, error) {
 	m, err1 := g.newMetal()
 	if err1 == nil {
-		return m, nil
+		return m, GraphicsLibraryMetal, nil
 	}
 	o, err2 := g.newOpenGL()
 	if err2 == nil {
-		return o, nil
+		return o, GraphicsLibraryOpenGL, nil
 	}
-	return nil, fmt.Errorf("ui: failed to choose graphics drivers: Metal: %v, OpenGL: %v", err1, err2)
+	return nil, GraphicsLibraryUnknown, fmt.Errorf("ui: failed to choose graphics drivers: Metal: %v, OpenGL: %v", err1, err2)
 }
 
 func (*graphicsDriverCreatorImpl) newOpenGL() (graphicsdriver.Graphics, error) {

internal/ui/ui_glfw_unix.go

@@ -35,8 +35,9 @@ type graphicsDriverCreatorImpl struct {
 	transparent bool
 }
 
-func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, error) {
-	return g.newOpenGL()
+func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, GraphicsLibrary, error) {
+	graphics, err := g.newOpenGL()
+	return graphics, GraphicsLibraryOpenGL, err
 }
 
 func (*graphicsDriverCreatorImpl) newOpenGL() (graphicsdriver.Graphics, error) {

internal/ui/ui_glfw_windows.go

@@ -36,16 +36,16 @@ type graphicsDriverCreatorImpl struct {
 	transparent bool
 }
 
-func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, error) {
+func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, GraphicsLibrary, error) {
 	d, err1 := g.newDirectX()
 	if err1 == nil {
-		return d, nil
+		return d, GraphicsLibraryDirectX, nil
 	}
 	o, err2 := g.newOpenGL()
 	if err2 == nil {
-		return o, nil
+		return o, GraphicsLibraryOpenGL, nil
 	}
-	return nil, fmt.Errorf("ui: failed to choose graphics drivers: DirectX: %v, OpenGL: %v", err1, err2)
+	return nil, GraphicsLibraryUnknown, fmt.Errorf("ui: failed to choose graphics drivers: DirectX: %v, OpenGL: %v", err1, err2)
 }
 
 func (*graphicsDriverCreatorImpl) newOpenGL() (graphicsdriver.Graphics, error) {

internal/ui/ui_ios.go

@@ -29,16 +29,16 @@ type graphicsDriverCreatorImpl struct {
 	gomobileBuild bool
 }
 
-func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, error) {
+func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, GraphicsLibrary, error) {
 	m, err1 := g.newMetal()
 	if err1 == nil {
-		return m, nil
+		return m, GraphicsLibraryMetal, nil
 	}
 	o, err2 := g.newOpenGL()
 	if err2 == nil {
-		return o, nil
+		return o, GraphicsLibraryMetal, nil
 	}
-	return nil, fmt.Errorf("ui: failed to choose graphics drivers: Metal: %v, OpenGL: %v", err1, err2)
+	return nil, GraphicsLibraryUnknown, fmt.Errorf("ui: failed to choose graphics drivers: Metal: %v, OpenGL: %v", err1, err2)
 }
 
 func (*graphicsDriverCreatorImpl) newOpenGL() (graphicsdriver.Graphics, error) {

internal/ui/ui_js.go

@@ -27,8 +27,9 @@ import (
 
 type graphicsDriverCreatorImpl struct{}
 
-func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, error) {
-	return g.newOpenGL()
+func (g *graphicsDriverCreatorImpl) newAuto() (graphicsdriver.Graphics, GraphicsLibrary, error) {
+	graphics, err := g.newOpenGL()
+	return graphics, GraphicsLibraryOpenGL, err
 }
 
 func (*graphicsDriverCreatorImpl) newOpenGL() (graphicsdriver.Graphics, error) {