func main() {
// Some GraphicsMagick boilerplate
C.InitializeMagick(nil)
defer C.DestroyMagick()
C.GetExceptionInfo(&exceptionInfo)
imageInfo = C.CloneImageInfo(nil)
defer C.DestroyExceptionInfo(&exceptionInfo)
defer C.DestroyImageInfo(imageInfo)
// main OMIT
Show("./cgo/armed_gopher.jpg")
img, err := Read("./cgo/armed_gopher.jpg")
if err != nil {
fmt.Println(err)
return
}
if img, err = Resize(img, 200, 800); err != nil {
fmt.Println("resize error:", err)
return
}
if err = Save(img, "./cgo/resized_gopher.jpg"); err != nil {
fmt.Println("save error:", err)
return
}
Show("./cgo/resized_gopher.jpg")
}
// NewInfo returns a newly allocated *Info structure. Do not
// create Info objects directly, since they need to allocate
// some internal structures while being created.
func NewInfo() *Info {
cinfo := C.CloneImageInfo(nil)
info := new(Info)
info.info = cinfo
runtime.SetFinalizer(info, func(i *Info) {
if i.info != nil {
C.DestroyImageInfo(i.info)
i.info = nil
}
})
return info
}
func decodeData(data []byte, try int) (*Image, error) {
if len(data) == 0 {
return nil, ErrNoData
}
info := C.CloneImageInfo(nil)
defer C.DestroyImageInfo(info)
var ex C.ExceptionInfo
C.GetExceptionInfo(&ex)
defer C.DestroyExceptionInfo(&ex)
im := C.BlobToImage(info, unsafe.Pointer(&data[0]), C.size_t(len(data)), &ex)
if im == nil && try < maxGifTries && ex.severity == C.CorruptImageError && looksLikeGif(data) {
return fixAndDecodeGif(data, try)
}
return checkImage(im, nil, &ex, "decoding")
}
// NewFromBlob takes a byte slice of image data and an extension that defines the
// image type (e.g. "png", "jpg", etc). It loads the image data and returns a MagickImage.
// The extension is required so that Magick knows what processor to use.
func NewFromBlob(blob []byte, extension string) (im *MagickImage, err error) {
if len(blob) < 1 {
return nil, &MagickError{"fatal", "", "zero length blob passed to NewFromBlob"}
}
if len(extension) < 1 {
return nil, &MagickError{"fatal", "", "zero length extension passed to NewFromBlob"}
}
exception := C.AcquireExceptionInfo()
defer C.DestroyExceptionInfo(exception)
info := C.AcquireImageInfo()
defer C.DestroyImageInfo(info)
c_filename := C.CString("image." + extension)
defer C.free(unsafe.Pointer(c_filename))
C.SetImageInfoFilename(info, c_filename)
var success (C.MagickBooleanType)
success = C.SetImageInfo(info, 1, exception)
if success != C.MagickTrue {
return nil, ErrorFromExceptionInfo(exception)
}
cloned_info := C.CloneImageInfo(info)
success = C.GetBlobSupport(info)
if success != C.MagickTrue {
// No blob support, lets try reading from a file
file, err := ioutil.TempFile("", "image."+extension)
if _, err = file.Write(blob); err != nil {
return nil, &MagickError{"fatal", "", "image format " + extension + " does not support blobs and could not write temp file"}
}
file.Close()
return NewFromFile(file.Name())
}
length := (C.size_t)(len(blob))
if length == 0 {
return nil, &MagickError{"fatal", "", "empty blob"}
}
blob_start := unsafe.Pointer(&blob[0])
image := C.ReadImageFromBlob(info, blob_start, length)
if image == nil {
return nil, &MagickError{"fatal", "", "corrupt image, not a " + extension}
}
if failed := C.CheckException(exception); failed == C.MagickTrue {
return nil, ErrorFromExceptionInfo(exception)
}
return &MagickImage{Image: image, ImageInfo: cloned_info}, nil
}
func (im *Image) AnnotateImage(x, y int, text string, fontSize int, color string) {
image_info := C.CloneImageInfo(nil)
defer C.DestroyImageInfo(image_info)
draw_info := C.CloneDrawInfo(image_info, nil)
defer C.DestroyDrawInfo(draw_info)
textBytes := []byte(text)
bytesPointer := unsafe.Pointer(&textBytes[0])
textArray := (*C.uchar)(bytesPointer)
colorArray := C.CString(color)
defer C.free(unsafe.Pointer(colorArray))
draw_context := C.DrawAllocateContext(draw_info, im.image)
defer C.DrawDestroyContext(draw_context)
C.DrawSetFontSize(draw_context, C.double(fontSize))
C.DrawSetStrokeColorString(draw_context, colorArray)
C.DrawSetFillColorString(draw_context, colorArray)
C.DrawAnnotation(draw_context, C.double(x), C.double(y), textArray)
C.DrawRender(draw_context)
}