fix DecodeConfig in dynamic mode too

.github/workflows/test.yml

@@ -4,7 +4,6 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.23.x]
         os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
     env:
@@ -15,6 +14,27 @@ jobs:
     - name: Install Go
       uses: actions/setup-go@v5
       with:
-        go-version: ${{ matrix.go-version }}
+        go-version-file: go.mod
+    - name: "[macos] install libheif"
+      if: runner.os == 'macOS'
+      run: brew install libheif
+    - name: "[linux] install libheif"
+      if: runner.os == 'Linux'
+      run: sudo apt-get update && sudo apt-get install -y libheif-dev libheif1
+    - name: "[windows] cache vcpkg artifacts"
+      if: runner.os == 'Windows'
+      uses: actions/cache@v4
+      id: vcpkg-cache
+      with:
+        path: C:\Users\runneradmin\AppData\Local\vcpkg\archives
+        key: vcpkg-libheif-v1
+    - name: "[windows] install libheif"
+      if: runner.os == 'Windows'
+      run: |
+        vcpkg install libheif:x64-windows
+        vcpkg integrate install
+        dir C:/vcpkg/installed/x64-windows/bin
+        Get-ChildItem -Path "C:\vcpkg\installed\x64-windows\bin\*.dll" | Copy-Item -Destination .
+        dir
     - name: Test
-      run: go test
+      run: go test -v -bench=. -benchtime=1x

decode_dynamic.go

@@ -19,8 +19,7 @@ func decodeDynamic(r io.Reader, configOnly bool) (image.Image, image.Config, err
 	var data []byte
 
 	if configOnly {
-		data = make([]byte, heifMaxHeaderSize)
-		_, err = r.Read(data)
+		data, err = io.ReadAll(io.LimitReader(r, heifMaxHeaderSize))
 		if err != nil {
 			return nil, cfg, fmt.Errorf("read: %w", err)
 		}
@@ -188,6 +187,12 @@ func decodeDynamic(r io.Reader, configOnly bool) (image.Image, image.Config, err
 }
 
 func init() {
+	if runtime.GOOS == "windows" {
+		dynamic = false
+		dynamicErr = fmt.Errorf("dynamic library loading not supported on windows yet; see https://github.com/gen2brain/heic/issues/11")
+		return
+	}
+
 	var err error
 	defer func() {
 		if r := recover(); r != nil {

decode_test.go

@@ -3,11 +3,12 @@ package heic
 import (
 	"bytes"
 	_ "embed"
-	"fmt"
 	"image"
 	"image/jpeg"
 	"io"
 	"os"
+	"runtime"
+	"strconv"
 	"sync"
 	"testing"
 )
@@ -96,11 +97,23 @@ func TestDecodeGray(t *testing.T) {
 	}
 }
 
-func TestDecodeDynamic(t *testing.T) {
+var inCI, _ = strconv.ParseBool(os.Getenv("CI"))
+
+func requireDynamic(t testing.TB) {
 	if err := Dynamic(); err != nil {
-		fmt.Println(err)
-		t.Skip()
+		if runtime.GOOS == "windows" {
+			t.Skip("skipping dynamic library test on Windows in CI; it doesn't work yet: https://github.com/gen2brain/heic/issues/11")
+		}
+		if inCI {
+			t.Fatalf("libheif should be available in CI on %s, but got: %v", runtime.GOOS, err)
+		}
+		t.Helper()
+		t.Skipf("skipping dynamic library test; libheif not available: %v", err)
 	}
+}
+
+func TestDecodeDynamic(t *testing.T) {
+	requireDynamic(t)
 
 	img, _, err := decodeDynamic(bytes.NewReader(testHeic), false)
 	if err != nil {
@@ -120,10 +133,7 @@ func TestDecodeDynamic(t *testing.T) {
 }
 
 func TestDecode8Dynamic(t *testing.T) {
-	if err := Dynamic(); err != nil {
-		fmt.Println(err)
-		t.Skip()
-	}
+	requireDynamic(t)
 
 	img, _, err := decodeDynamic(bytes.NewReader(testHeic8), false)
 	if err != nil {
@@ -143,10 +153,7 @@ func TestDecode8Dynamic(t *testing.T) {
 }
 
 func TestDecode12Dynamic(t *testing.T) {
-	if err := Dynamic(); err != nil {
-		fmt.Println(err)
-		t.Skip()
-	}
+	requireDynamic(t)
 
 	img, _, err := decodeDynamic(bytes.NewReader(testHeic12), false)
 	if err != nil {
@@ -166,10 +173,7 @@ func TestDecode12Dynamic(t *testing.T) {
 }
 
 func TestDecodeGrayDynamic(t *testing.T) {
-	if err := Dynamic(); err != nil {
-		fmt.Println(err)
-		t.Skip()
-	}
+	requireDynamic(t)
 
 	img, _, err := decodeDynamic(bytes.NewReader(testGray), false)
 	if err != nil {
@@ -189,50 +193,34 @@ func TestDecodeGrayDynamic(t *testing.T) {
 }
 
 func TestImageDecode(t *testing.T) {
-	img, _, err := image.Decode(bytes.NewReader(testHeic8))
-	if err != nil {
-		t.Fatal(err)
-	}
+	testBothWays(t, func(t *testing.T) {
+		img, _, err := image.Decode(bytes.NewReader(testHeic8))
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	err = jpeg.Encode(io.Discard, img, nil)
-	if err != nil {
-		t.Error(err)
-	}
+		err = jpeg.Encode(io.Discard, img, nil)
+		if err != nil {
+			t.Error(err)
+		}
+	})
 }
 
 func TestDecodeConfig(t *testing.T) {
-	_, cfg, err := decode(bytes.NewReader(testHeic8), true)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if cfg.Width != 512 {
-		t.Errorf("width: got %d, want %d", cfg.Width, 512)
-	}
-
-	if cfg.Height != 512 {
-		t.Errorf("height: got %d, want %d", cfg.Height, 512)
-	}
-}
-
-func TestDecodeConfigDynamic(t *testing.T) {
-	if err := Dynamic(); err != nil {
-		fmt.Println(err)
-		t.Skip()
-	}
-
-	_, cfg, err := decodeDynamic(bytes.NewReader(testHeic8), true)
-	if err != nil {
-		t.Fatal(err)
-	}
+	testBothWays(t, func(t *testing.T) {
+		cfg, err := DecodeConfig(bytes.NewReader(testHeic8))
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	if cfg.Width != 512 {
-		t.Errorf("width: got %d, want %d", cfg.Width, 512)
-	}
+		if cfg.Width != 512 {
+			t.Errorf("width: got %d, want %d", cfg.Width, 512)
+		}
 
-	if cfg.Height != 512 {
-		t.Errorf("height: got %d, want %d", cfg.Height, 512)
-	}
+		if cfg.Height != 512 {
+			t.Errorf("height: got %d, want %d", cfg.Height, 512)
+		}
+	})
 }
 
 func TestDecodeSync(t *testing.T) {
@@ -257,10 +245,7 @@ func TestDecodeSync(t *testing.T) {
 }
 
 func TestDecodeSyncDynamic(t *testing.T) {
-	if err := Dynamic(); err != nil {
-		fmt.Println(err)
-		t.Skip()
-	}
+	requireDynamic(t)
 
 	wg := sync.WaitGroup{}
 	ch := make(chan bool, 2)
@@ -296,19 +281,35 @@ func (r smallChunkReader) Read(p []byte) (int, error) {
 }
 
 func TestDecodeConfigViaImagesPackage(t *testing.T) {
-	cfg, typ, err := image.DecodeConfig(smallChunkReader{bytes.NewReader(testHeic)})
-	if err != nil {
-		t.Fatal(err)
-	}
-	if g, w := cfg.Width, 1346; g != w {
-		t.Fatalf("invalid width: got %d, want %d", g, w)
-	}
-	if g, h := cfg.Height, 1346; g != h {
-		t.Fatalf("invalid height: got %d, want %d", g, h)
-	}
-	if typ != "heic" {
-		t.Fatalf("invalid type; got %q; want %q", typ, "heic")
-	}
+	testBothWays(t, func(t *testing.T) {
+		cfg, typ, err := image.DecodeConfig(smallChunkReader{bytes.NewReader(testHeic)})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if g, w := cfg.Width, 1346; g != w {
+			t.Fatalf("invalid width: got %d, want %d", g, w)
+		}
+		if g, h := cfg.Height, 1346; g != h {
+			t.Fatalf("invalid height: got %d, want %d", g, h)
+		}
+		if typ != "heic" {
+			t.Fatalf("invalid type; got %q; want %q", typ, "heic")
+		}
+	})
+}
+
+// testBothWays runs fn in both wasm mode and dynamic library mode, if possible.
+func testBothWays(t *testing.T, fn func(t *testing.T)) {
+	t.Run("wasm", func(t *testing.T) {
+		was := ForceWasmMode
+		ForceWasmMode = true
+		t.Cleanup(func() { ForceWasmMode = was })
+		fn(t)
+	})
+	t.Run("dynamic", func(t *testing.T) {
+		requireDynamic(t)
+		fn(t)
+	})
 }
 
 func BenchmarkDecode(b *testing.B) {
@@ -321,10 +322,7 @@ func BenchmarkDecode(b *testing.B) {
 }
 
 func BenchmarkDecodeDynamic(b *testing.B) {
-	if err := Dynamic(); err != nil {
-		fmt.Println(err)
-		b.Skip()
-	}
+	requireDynamic(b)
 
 	for i := 0; i < b.N; i++ {
 		_, _, err := decodeDynamic(bytes.NewReader(testHeic8), false)
@@ -344,10 +342,7 @@ func BenchmarkDecodeConfig(b *testing.B) {
 }
 
 func BenchmarkDecodeConfigDynamic(b *testing.B) {
-	if err := Dynamic(); err != nil {
-		fmt.Println(err)
-		b.Skip()
-	}
+	requireDynamic(b)
 
 	for i := 0; i < b.N; i++ {
 		_, _, err := decodeDynamic(bytes.NewReader(testHeic8), true)

go.mod

@@ -3,6 +3,6 @@ module github.com/gen2brain/heic
 go 1.23
 
 require (
-	github.com/ebitengine/purego v0.8.3
+	github.com/ebitengine/purego v0.9.1
 	github.com/tetratelabs/wazero v1.9.0
 )

go.sum

@@ -1,4 +1,4 @@
-github.com/ebitengine/purego v0.8.3 h1:K+0AjQp63JEZTEMZiwsI9g0+hAMNohwUOtY0RPGexmc=
-github.com/ebitengine/purego v0.8.3/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=
+github.com/ebitengine/purego v0.9.1 h1:a/k2f2HQU3Pi399RPW1MOaZyhKJL9w/xFpKAg4q1s0A=
+github.com/ebitengine/purego v0.9.1/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=
 github.com/tetratelabs/wazero v1.9.0 h1:IcZ56OuxrtaEz8UYNRHBrUa9bYeX9oVY93KspZZBf/I=
 github.com/tetratelabs/wazero v1.9.0/go.mod h1:TSbcXCfFP0L2FGkRPxHphadXPjo1T6W+CseNNY7EkjM=

heic.go

@@ -19,7 +19,7 @@ func Decode(r io.Reader) (image.Image, error) {
 	var err error
 	var img image.Image
 
-	if dynamic {
+	if dynamic && !ForceWasmMode {
 		img, _, err = decodeDynamic(r, false)
 		if err != nil {
 			return nil, err
@@ -39,7 +39,7 @@ func DecodeConfig(r io.Reader) (image.Config, error) {
 	var err error
 	var cfg image.Config
 
-	if dynamic {
+	if dynamic && !ForceWasmMode {
 		_, cfg, err = decodeDynamic(r, true)
 		if err != nil {
 			return image.Config{}, err
@@ -54,6 +54,15 @@ func DecodeConfig(r io.Reader) (image.Config, error) {
 	return cfg, nil
 }
 
+// ForceWasmMode, if true, forces using the WASM-based decoder even if a
+// dynamic/shared library is available.
+//
+// This exists mainly for testing purposes.
+//
+// It is not safe to change this concurrently with any other use of this
+// package.
+var ForceWasmMode bool
+
 // Dynamic returns error (if there was any) during opening dynamic/shared library.
 func Dynamic() error {
 	return dynamicErr

purego_darwin.go

@@ -3,20 +3,22 @@
 package heic
 
 import (
-	"fmt"
-
 	"github.com/ebitengine/purego"
 )
 
 const (
 	libname = "libheif.dylib"
 )
 
-func loadLibrary() (uintptr, error) {
-	handle, err := purego.Dlopen(libname, purego.RTLD_NOW|purego.RTLD_GLOBAL)
-	if err != nil {
-		return 0, fmt.Errorf("cannot load library: %w", err)
+func loadLibrary() (handle uintptr, err error) {
+	for _, path := range []string{
+		libname,
+		"/opt/homebrew/lib/libheif.dylib",
+	} {
+		handle, err = purego.Dlopen(path, purego.RTLD_NOW|purego.RTLD_GLOBAL)
+		if err == nil {
+			return handle, nil
+		}
 	}
-
-	return uintptr(handle), nil
+	return 0, err
 }