Golang C.CheckException类(方法)实例源码

// Negate inverts the colors in the image
func (im *MagickImage) Negate() (err error) {
	exception := C.AcquireExceptionInfo()
	defer C.DestroyExceptionInfo(exception)
	new_image := C.Negate(im.Image, exception)
	if failed := C.CheckException(exception); failed == C.MagickTrue {
		return ErrorFromExceptionInfo(exception)
	}
	im.ReplaceImage(new_image)
	return nil
}

// IntegralRotateImage rotates the image an integral of 90 degrees
func (im *MagickImage) IntegralRotateImage(rotations int) (err error) {
	exception := C.AcquireExceptionInfo()
	defer C.DestroyExceptionInfo(exception)

	new_image := C.IntegralRotateImage(im.Image, C.size_t(rotations), exception)
	if failed := C.CheckException(exception); failed == C.MagickTrue {
		return ErrorFromExceptionInfo(exception)
	}
	im.ReplaceImage(new_image)
	return nil
}

// ParseGeometryToRectangleInfo converts from a geometry string (WxH+X+Y) into a Magick
// RectangleInfo that contains the individual properties
func (im *MagickImage) ParseGeometryToRectangleInfo(geometry string) (info C.RectangleInfo, err error) {
	c_geometry := C.CString(geometry)
	defer C.free(unsafe.Pointer(c_geometry))
	exception := C.AcquireExceptionInfo()
	defer C.DestroyExceptionInfo(exception)
	C.ParseRegionGeometry(im.Image, c_geometry, &info, exception)
	if failed := C.CheckException(exception); failed == C.MagickTrue {
		err = ErrorFromExceptionInfo(exception)
	}
	return
}

// FillBackgroundColor fills transparent areas of an image with a solid color and stores the filled image in place.
// color can be any color format that image magick understands, see: http://www.imagemagick.org/ImageMagick-7.0.0/script/color.php#models
func (im *MagickImage) FillBackgroundColor(color string) (err error) {
	exception := C.AcquireExceptionInfo()
	defer C.DestroyExceptionInfo(exception)
	c_color := C.CString(color)
	defer C.free(unsafe.Pointer(c_color))
	new_image := C.FillBackgroundColor(im.Image, c_color, exception)
	if failed := C.CheckException(exception); failed == C.MagickTrue {
		return ErrorFromExceptionInfo(exception)
	}
	im.ReplaceImage(new_image)
	return nil
}

// Crop crops the image based on the geometry string passed and stores the cropped image in place
// For more info about Geometry see http://www.imagemagick.org/script/command-line-processing.php#geometry
func (im *MagickImage) Crop(geometry string) (err error) {
	exception := C.AcquireExceptionInfo()
	defer C.DestroyExceptionInfo(exception)
	rect, err := im.ParseGeometryToRectangleInfo(geometry)
	if err != nil {
		return err
	}
	new_image := C.CropImage(im.Image, &rect, exception)
	if failed := C.CheckException(exception); failed == C.MagickTrue {
		return ErrorFromExceptionInfo(exception)
	}
	im.ReplaceImage(new_image)
	return nil
}

// NewFromFile loads a file at filename into a MagickImage.
// Exceptions are returned as MagickErrors.
func NewFromFile(filename string) (im *MagickImage, err error) {
	exception := C.AcquireExceptionInfo()
	defer C.DestroyExceptionInfo(exception)
	info := C.AcquireImageInfo()
	c_filename := C.CString(filename)
	defer C.free(unsafe.Pointer(c_filename))
	C.SetImageInfoFilename(info, c_filename)
	image := C.ReadImage(info, exception)
	if failed := C.CheckException(exception); failed == C.MagickTrue {
		C.DestroyImageInfo(info)
		return nil, ErrorFromExceptionInfo(exception)
	}
	return &MagickImage{Image: image, ImageInfo: info}, nil
}

// ToFile writes the (transformed) MagickImage to the regular file at filename. Magick determines
// the encoding of the output file by the extension given to the filename (e.g. "image.jpg", "image.png")
func (im *MagickImage) ToFile(filename string) (err error) {
	exception := C.AcquireExceptionInfo()
	defer C.DestroyExceptionInfo(exception)
	c_outpath := C.CString(filename)
	defer C.free(unsafe.Pointer(c_outpath))
	C.SetImageInfoFilename(im.ImageInfo, c_outpath)
	success := C.WriteImages(im.ImageInfo, im.Image, c_outpath, exception)
	if failed := C.CheckException(exception); failed == C.MagickTrue {
		return ErrorFromExceptionInfo(exception)
	}
	if success != C.MagickTrue {
		return &MagickError{"fatal", "", "could not write to " + filename + " for unknown reason"}
	}
	return nil
}

// ToBlob takes a (transformed) MagickImage and returns a byte slice in the format you specify with extension.
// Magick uses the extension to transform the image in to the proper encoding (e.g. "jpg", "png")
func (im *MagickImage) ToBlob(extension string) (blob []byte, err error) {
	exception := C.AcquireExceptionInfo()
	defer C.DestroyExceptionInfo(exception)
	c_outpath := C.CString("image." + extension)
	defer C.free(unsafe.Pointer(c_outpath))
	C.SetImageInfoFilename(im.ImageInfo, c_outpath)
	var outlength (C.size_t)
	outblob := C.ImageToBlob(im.ImageInfo, im.Image, &outlength, exception)
	if failed := C.CheckException(exception); failed == C.MagickTrue {
		return nil, ErrorFromExceptionInfo(exception)
	}
	char_pointer := unsafe.Pointer(outblob)
	defer C.free(char_pointer)
	return C.GoBytes(char_pointer, (C.int)(outlength)), nil
}

// Shadow adds a dropshadow to the current (transparent) image and stores the shadowed image in place
// For more information about shadow options see: http://www.imagemagick.org/Usage/blur/#shadow
func (im *MagickImage) Shadow(color string, opacity, sigma float32, xoffset, yoffset int) (err error) {
	exception := C.AcquireExceptionInfo()
	defer C.DestroyExceptionInfo(exception)
	c_opacity := (C.double)(opacity)
	c_sigma := (C.double)(sigma)
	c_x := (C.ssize_t)(xoffset)
	c_y := (C.ssize_t)(yoffset)
	c_color := C.CString(color)
	defer C.free(unsafe.Pointer(c_color))
	new_image := C.AddShadowToImage(im.Image, c_color, c_opacity, c_sigma, c_x, c_y, exception)
	if failed := C.CheckException(exception); failed == C.MagickTrue {
		return ErrorFromExceptionInfo(exception)
	}
	im.ReplaceImage(new_image)
	return nil
}

// 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
}

// Resize resizes the image based on the geometry string passed and stores the resized image in place
// For more info about Geometry see http://www.imagemagick.org/script/command-line-processing.php#geometry
func (im *MagickImage) Resize(geometry string) (err error) {
	exception := C.AcquireExceptionInfo()
	defer C.DestroyExceptionInfo(exception)
	rect, err := im.ParseGeometryToRectangleInfo(geometry)
	if err != nil {
		return err
	}
	ratio := im.ResizeRatio(int(rect.width), int(rect.height))
	var new_image *C.Image
	if ratio > 0.4 {
		new_image = C.AdaptiveResizeImage(im.Image, rect.width, rect.height, exception)
	} else {
		new_image = C.ThumbnailImage(im.Image, rect.width, rect.height, exception)
	}
	if failed := C.CheckException(exception); failed == C.MagickTrue {
		return ErrorFromExceptionInfo(exception)
	}
	im.ReplaceImage(new_image)
	return nil
}