feat(#1): initial implementation

vips.go

@@ -0,0 +1,100 @@
+package bimg
+
+/*
+#cgo pkg-config: vips
+#include "vips.h"
+*/
+import "C"
+
+import (
+	"errors"
+	"runtime"
+	"unsafe"
+)
+
+func init() {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	err := C.vips_init(C.CString("bimg"))
+	if err != 0 {
+		C.vips_shutdown()
+		panic("unable to start vips!")
+	}
+
+	C.vips_concurrency_set(1)                   // default
+	C.vips_cache_set_max_mem(100 * 1024 * 1024) // 100 MB
+	C.vips_cache_set_max(500)                   // 500 operations
+}
+
+type Vips struct {
+	buf []byte
+}
+
+func vipsRotate(image *C.struct__VipsImage, degrees int) (*C.struct__VipsImage, error) {
+	var out *C.struct__VipsImage
+
+	err := C.vips_rotate(image, &out, C.int(degrees))
+	C.g_object_unref(C.gpointer(image))
+	if err != 0 {
+		return nil, vipsError()
+	}
+	defer C.g_object_unref(C.gpointer(out))
+
+	return out, nil
+}
+
+func vipsRead(buf []byte) (*C.struct__VipsImage, error) {
+	var image *C.struct__VipsImage
+
+	// feed it
+	length := C.size_t(len(buf))
+	imageBuf := unsafe.Pointer(&buf[0])
+
+	err := C.vips_jpegload_buffer_seq(imageBuf, length, &image)
+	if err != 0 {
+		return nil, vipsError()
+	}
+
+	return image, nil
+}
+
+func vipsExtract(image *C.struct__VipsImage, left int, top int, width int, height int) (*C.struct__VipsImage, error) {
+	var buf *C.struct__VipsImage
+
+	err := C.vips_extract_area_0(image, &buf, C.int(left), C.int(top), C.int(width), C.int(height))
+	C.g_object_unref(C.gpointer(image))
+	if err != 0 {
+		return nil, vipsError()
+	}
+
+	return buf, nil
+}
+
+type vipsSaveOptions struct {
+	Quality int
+}
+
+func vipsSave(image *C.struct__VipsImage, o vipsSaveOptions) ([]byte, error) {
+	var ptr unsafe.Pointer
+	length := C.size_t(0)
+
+	err := C.vips_jpegsave_custom(image, &ptr, &length, 1, C.int(o.Quality), 0)
+	if err != 0 {
+		return nil, vipsError()
+	}
+	C.g_object_unref(C.gpointer(image))
+
+	buf := C.GoBytes(ptr, C.int(length))
+	// cleanup
+	C.g_free(C.gpointer(ptr))
+
+	return buf, nil
+}
+
+func vipsError() error {
+	s := C.GoString(C.vips_error_buffer())
+	C.vips_error_clear()
+	C.vips_thread_shutdown()
+	return errors.New(s)
+}