ebiten/internal/ui/graphics.go

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// Copyright 2022 The Ebiten Authors
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//
// 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.
package ui
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import (
"fmt"
"os"
"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
)
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type graphicsDriverCreator interface {
newAuto() (graphicsdriver.Graphics, error)
newOpenGL() (graphicsdriver.Graphics, error)
newDirectX() (graphicsdriver.Graphics, error)
newMetal() (graphicsdriver.Graphics, error)
}
func newGraphicsDriver(creator graphicsDriverCreator) (graphicsdriver.Graphics, error) {
envName := "EBITENGINE_GRAPHICS_LIBRARY"
env := os.Getenv(envName)
if env == "" {
// For backward compatibility, read the EBITEN_ version.
envName = "EBITEN_GRAPHICS_LIBRARY"
env = os.Getenv(envName)
}
switch env {
case "", "auto":
g, err := creator.newAuto()
if err != nil {
return nil, err
}
if g == nil {
return nil, fmt.Errorf("ui: no graphics library is available")
}
return g, nil
case "opengl":
g, err := creator.newOpenGL()
if err != nil {
return nil, err
}
if g == nil {
return nil, fmt.Errorf("ui: %s=%s is specified but OpenGL is not available", envName, env)
}
return g, nil
case "directx":
g, err := creator.newDirectX()
if err != nil {
return nil, err
}
if g == nil {
return nil, fmt.Errorf("ui: %s=%s is specified but DirectX is not available.", envName, env)
}
return g, nil
case "metal":
g, err := creator.newMetal()
if err != nil {
return nil, err
}
if g == nil {
return nil, fmt.Errorf("ui: %s=%s is specified but Metal is not available", envName, env)
}
return g, nil
default:
return nil, fmt.Errorf("ui: an unsupported graphics library is specified: %s", env)
}
}
func GraphicsDriverForTesting() graphicsdriver.Graphics {
return theUI.graphicsDriver
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}