func cNewImageSurface(s *C.cairo_surface_t) (Surface, error) {
format := Format(C.cairo_image_surface_get_format(s))
width := int(C.cairo_image_surface_get_width(s))
height := int(C.cairo_image_surface_get_height(s))
stride := int(C.cairo_image_surface_get_stride(s))
return newImg(s, format, width, height, stride)
}
// pdf, ps, and svg surfaces use the current surface (page)
func (g *Graphic) Image() (image.Image, error) {
var surface *C.cairo_surface_t
switch g.format {
case "eps", "pdf", "ps", "svg":
// map vector surfaces to an image surface
surface = C.cairo_surface_map_to_image(g.surface, nil)
defer C.cairo_surface_unmap_image(g.surface, surface)
status := C.cairo_surface_status(surface)
err := statusToError(status)
if err != nil {
return nil, err
}
case "png", "jpeg":
// no conversion needed
surface = g.surface
}
width := int(C.cairo_image_surface_get_width(surface))
height := int(C.cairo_image_surface_get_height(surface))
stride := int(C.cairo_image_surface_get_stride(surface))
format := C.cairo_image_surface_get_format(surface)
dataPtr := C.cairo_image_surface_get_data(surface)
data := C.GoBytes(unsafe.Pointer(dataPtr), C.int(stride*height))
var img image.Image
switch format {
case C.CAIRO_FORMAT_ARGB32:
img = &extimage.ARGB{
Pix: data,
Stride: stride,
Rect: image.Rect(0, 0, width, height),
}
case C.CAIRO_FORMAT_RGB24:
img = &extimage.RGB{
Pix: data,
Stride: stride,
Rect: image.Rect(0, 0, width, height),
}
case C.CAIRO_FORMAT_A8:
img = &image.Alpha{
Pix: data,
Stride: stride,
Rect: image.Rect(0, 0, width, height),
}
default:
// known unsupported formats:
// CAIRO_FORMAT_INVALID = -1,
// CAIRO_FORMAT_A1 = 3,
// CAIRO_FORMAT_RGB16_565 = 4,
// CAIRO_FORMAT_RGB30 = 5
panic(fmt.Sprintf("unsupported cairo image surface format: %d", int(format)))
}
return img, nil
}
// GetData returns a copy of the surfaces raw pixel data.
// This method also calls Flush.
func (self *Surface) GetData() []byte {
self.Flush()
dataPtr := C.cairo_image_surface_get_data(self.surface)
if dataPtr == nil {
panic("cairo.Surface.GetData(): can't access surface pixel data")
}
stride := C.cairo_image_surface_get_stride(self.surface)
height := C.cairo_image_surface_get_height(self.surface)
return C.GoBytes(unsafe.Pointer(dataPtr), stride*height)
}
//CreateSimilarImage creates a new surface that is as compatible as possible
//for uploading to and using in conjunction with existing surface.
//However, this surface can still be used like any normal image surface.
//
//Initially the contents of the returned surface are all 0 (transparent if contents
//have transparency, black otherwise.)
//
//Originally cairo_surface_create_similar_image.
func (e *XtensionSurface) CreateSimilarImage(f Format, w, h int) (ImageSurface, error) {
s := C.cairo_surface_create_similar_image(e.s, f.c(), C.int(w), C.int(h))
stride := int(C.cairo_image_surface_get_stride(s))
o := ImageSurface{
XtensionSurface: NewXtensionSurface(s),
format: f,
width: w,
height: h,
stride: stride,
}
return o, o.Err()
}
func (v *Surface) GetData() []byte {
c_data := C.cairo_image_surface_get_data(v.native())
c_data_len := int(C.cairo_image_surface_get_stride(v.native()) *
C.cairo_image_surface_get_height(v.native()))
hdr := reflect.SliceHeader{
Data: uintptr(unsafe.Pointer(c_data)),
Len: c_data_len,
Cap: c_data_len,
}
goSlice := *(*[]byte)(unsafe.Pointer(&hdr))
return goSlice
}
// GetSnapshotCustom runs asynchronously, taking a snapshot of the WebView.
// Upon completion, resultCallback will be called with a copy of the underlying
// bitmap backing store for the frame, or with an error encountered during
// execution.
//
// See also: webkit_web_view_get_snapshot at
// http://webkitgtk.org/reference/webkit2gtk/stable/WebKitWebView.html#webkit-web-view-get-snapshot
func (v *WebView) GetSnapshotCustom(region SnapshotRegion, options SnapshotOptions, resultCallback func(result *image.RGBA, err error)) {
var cCallback C.GAsyncReadyCallback
var userData C.gpointer
var err error
if resultCallback != nil {
callback := func(result *C.GAsyncResult) {
var snapErr *C.GError
snapResult := C.webkit_web_view_get_snapshot_finish(v.webView, result, &snapErr)
if snapResult == nil {
defer C.g_error_free(snapErr)
msg := C.GoString((*C.char)(snapErr.message))
resultCallback(nil, errors.New(msg))
return
}
defer C.cairo_surface_destroy(snapResult)
if C.cairo_surface_get_type(snapResult) != cairoSurfaceTypeImage ||
C.cairo_image_surface_get_format(snapResult) != cairoImageSurfaceFormatARGB32 {
panic("Snapshot in unexpected format")
}
w := int(C.cairo_image_surface_get_width(snapResult))
h := int(C.cairo_image_surface_get_height(snapResult))
stride := int(C.cairo_image_surface_get_stride(snapResult))
C.cairo_surface_flush(snapResult)
data := unsafe.Pointer(C.cairo_image_surface_get_data(snapResult))
//(miha) fix endianes depended byte order, and copy to go slice at the same time.
data_fixed := make([]byte, stride*h)
C.gowk2_cairo_endian_depended_ARGB32_to_RGBA((*C.uchar)(data), (*C.uchar)(&data_fixed[0]), C.uint(stride*h))
rgba := &image.RGBA{data_fixed, stride, image.Rect(0, 0, w, h)}
// slower but doesn't use Go pointers inside C. See https://github.com/golang/go/issues/8310 !!!!!!!
//C.gowk2_cairo_endian_depended_ARGB32_to_RGBA((*C.uchar)(data), C.uint(stride*h))
//rgba := &image.RGBA{C.GoBytes(data, C.int(stride*h)), stride, image.Rect(0, 0, w, h)}
resultCallback(rgba, nil)
}
cCallback, userData, err = newGAsyncReadyCallback(callback)
if err != nil {
panic(err)
}
}
C.webkit_web_view_get_snapshot(v.webView,
(C.WebKitSnapshotRegion)(region),
(C.WebKitSnapshotOptions)(options),
nil,
cCallback,
userData)
}
// SetData sets the surfaces raw pixel data.
// This method also calls Flush and MarkDirty.
func (self *Surface) SetData(data []byte) {
self.Flush()
dataPtr := unsafe.Pointer(C.cairo_image_surface_get_data(self.surface))
if dataPtr == nil {
panic("cairo.Surface.SetData(): can't access surface pixel data")
}
stride := C.cairo_image_surface_get_stride(self.surface)
height := C.cairo_image_surface_get_height(self.surface)
if len(data) != int(stride*height) {
panic("cairo.Surface.SetData(): invalid data size")
}
C.memcpy(dataPtr, unsafe.Pointer(&data[0]), C.size_t(stride*height))
self.MarkDirty()
}
// GetSnapshot runs asynchronously, taking a snapshot of the WebView.
// Upon completion, resultCallback will be called with a copy of the underlying
// bitmap backing store for the frame, or with an error encountered during
// execution.
//
// See also: webkit_web_view_get_snapshot at
// http://webkitgtk.org/reference/webkit2gtk/stable/WebKitWebView.html#webkit-web-view-get-snapshot
func (v *WebView) GetSnapshot(resultCallback func(result *image.RGBA, err error)) {
var cCallback C.GAsyncReadyCallback
var userData C.gpointer
var err error
if resultCallback != nil {
callback := func(result *C.GAsyncResult) {
var snapErr *C.GError
snapResult := C.webkit_web_view_get_snapshot_finish(v.webView, result, &snapErr)
if snapResult == nil {
defer C.g_error_free(snapErr)
msg := C.GoString((*C.char)(snapErr.message))
resultCallback(nil, errors.New(msg))
return
}
defer C.cairo_surface_destroy(snapResult)
if C.cairo_surface_get_type(snapResult) != cairoSurfaceTypeImage ||
C.cairo_image_surface_get_format(snapResult) != cairoImageSurfaceFormatARB32 {
panic("Snapshot in unexpected format")
}
w := int(C.cairo_image_surface_get_width(snapResult))
h := int(C.cairo_image_surface_get_height(snapResult))
stride := int(C.cairo_image_surface_get_stride(snapResult))
data := unsafe.Pointer(C.cairo_image_surface_get_data(snapResult))
rgba := &image.RGBA{C.GoBytes(data, C.int(stride*h)), stride, image.Rect(0, 0, w, h)}
resultCallback(rgba, nil)
}
cCallback, userData, err = newGAsyncReadyCallback(callback)
if err != nil {
panic(err)
}
}
C.webkit_web_view_get_snapshot(v.webView,
(C.WebKitSnapshotRegion)(1), // FullDocument is the only working region at this point
(C.WebKitSnapshotOptions)(0),
nil,
cCallback,
userData)
}
//export our_area_draw_callback
func our_area_draw_callback(widget *C.GtkWidget, cr *C.cairo_t, data C.gpointer) C.gboolean {
var x0, y0, x1, y1 C.double
var maxwid, maxht C.gint
s := (*sysData)(unsafe.Pointer(data))
// thanks to desrt in irc.gimp.net/#gtk+
// these are in user coordinates, which match what coordinates we want by default, even out of a draw event handler (thanks johncc3, mclasen, and Company in irc.gimp.net/#gtk+)
C.cairo_clip_extents(cr, &x0, &y0, &x1, &y1)
// we do not need to clear the cliprect; GtkDrawingArea did it for us beforehand
cliprect := image.Rect(int(x0), int(y0), int(x1), int(y1))
// the cliprect can actually fall outside the size of the Area; clip it by intersecting the two rectangles
C.gtk_widget_get_size_request(widget, &maxwid, &maxht)
cliprect = image.Rect(0, 0, int(maxwid), int(maxht)).Intersect(cliprect)
if cliprect.Empty() { // no intersection; nothing to paint
return C.FALSE // signals handled without stopping the event chain (thanks to desrt again)
}
i := s.handler.Paint(cliprect)
surface := C.cairo_image_surface_create(
C.CAIRO_FORMAT_ARGB32, // alpha-premultiplied; native byte order
C.int(i.Rect.Dx()),
C.int(i.Rect.Dy()))
if status := C.cairo_surface_status(surface); status != C.CAIRO_STATUS_SUCCESS {
panic(fmt.Errorf("cairo_create_image_surface() failed: %s\n",
C.GoString(C.cairo_status_to_string(status))))
}
// the flush and mark_dirty calls are required; see the cairo docs and https://git.gnome.org/browse/gtk+/tree/gdk/gdkcairo.c#n232 (thanks desrt in irc.gimp.net/#gtk+)
C.cairo_surface_flush(surface)
toARGB(i, uintptr(unsafe.Pointer(C.cairo_image_surface_get_data(surface))),
int(C.cairo_image_surface_get_stride(surface)))
C.cairo_surface_mark_dirty(surface)
C.cairo_set_source_surface(cr,
surface,
0, 0) // origin of the surface
// that just set the brush that cairo uses: we have to actually draw now
// (via https://developer.gnome.org/gtkmm-tutorial/stable/sec-draw-images.html.en)
C.cairo_rectangle(cr, x0, y0, x1, y1) // breaking the nrom here since we have the coordinates as a C double already
C.cairo_fill(cr)
C.cairo_surface_destroy(surface) // free surface
return C.FALSE // signals handled without stopping the event chain (thanks to desrt again)
}
func (i *imagelist) Append(img *image.RGBA) {
var width, height C.gint
surface := C.cairo_image_surface_create(C.CAIRO_FORMAT_ARGB32,
C.int(img.Rect.Dx()),
C.int(img.Rect.Dy()))
if status := C.cairo_surface_status(surface); status != C.CAIRO_STATUS_SUCCESS {
panic(fmt.Errorf("cairo_create_image_surface() failed in ImageList.Append(): %s\n",
C.GoString(C.cairo_status_to_string(status))))
}
C.cairo_surface_flush(surface)
toARGB(img, uintptr(unsafe.Pointer(C.cairo_image_surface_get_data(surface))),
int(C.cairo_image_surface_get_stride(surface)), false) // not NRGBA
C.cairo_surface_mark_dirty(surface)
basepixbuf := C.gdk_pixbuf_get_from_surface(surface, 0, 0, C.gint(img.Rect.Dx()), C.gint(img.Rect.Dy()))
if basepixbuf == nil {
panic(fmt.Errorf("gdk_pixbuf_get_from_surface() failed in ImageList.Append() (no reason available)"))
}
if C.gtk_icon_size_lookup(scaleTo, &width, &height) == C.FALSE {
panic(fmt.Errorf("gtk_icon_size_lookup() failed in ImageList.Append() (no reason available)"))
}
if int(width) == img.Rect.Dx() && int(height) == img.Rect.Dy() {
// just add the base pixbuf; we're good
i.list = append(i.list, basepixbuf)
C.cairo_surface_destroy(surface)
return
}
// else scale
pixbuf := C.gdk_pixbuf_scale_simple(basepixbuf, C.int(width), C.int(height), C.GDK_INTERP_NEAREST)
if pixbuf == nil {
panic(fmt.Errorf("gdk_pixbuf_scale_simple() failed in ImageList.Append() (no reason available)"))
}
i.list = append(i.list, pixbuf)
C.gdk_pixbuf_unref(basepixbuf)
C.cairo_surface_destroy(surface)
}
func (self *Surface) GetStride() int {
return int(C.cairo_image_surface_get_stride(self.surface))
}
// GetSnapshot runs asynchronously, taking a snapshot of the WebView.
// Upon completion, resultCallback will be called with a copy of the underlying
// bitmap backing store for the frame, or with an error encountered during
// execution.
//
// See also: webkit_web_view_get_snapshot at
// http://webkitgtk.org/reference/webkit2gtk/stable/WebKitWebView.html#webkit-web-view-get-snapshot
func (v *WebView) GetSnapshot(resultCallback func(result *image.RGBA, err error)) {
var cCallback C.GAsyncReadyCallback
var userData C.gpointer
var err error
if resultCallback != nil {
callback := func(result *C.GAsyncResult) {
var snapErr *C.GError
snapResult := C.webkit_web_view_get_snapshot_finish(v.webView, result, &snapErr)
if snapResult == nil {
defer C.g_error_free(snapErr)
msg := C.GoString((*C.char)(snapErr.message))
resultCallback(nil, errors.New(msg))
return
}
defer C.cairo_surface_destroy(snapResult)
if C.cairo_surface_get_type(snapResult) != cairoSurfaceTypeImage ||
C.cairo_image_surface_get_format(snapResult) != cairoImageSurfaceFormatARGB32 {
panic("Snapshot in unexpected format")
}
w := int(C.cairo_image_surface_get_width(snapResult))
h := int(C.cairo_image_surface_get_height(snapResult))
stride := int(C.cairo_image_surface_get_stride(snapResult))
data := unsafe.Pointer(C.cairo_image_surface_get_data(snapResult))
surfaceBytes := C.GoBytes(data, C.int(stride*h))
// convert from b,g,r,a or a,r,g,b(local endianness) to r,g,b,a
testint, _ := binary.ReadUvarint(bytes.NewBuffer([]byte{0x1, 0}))
if testint == 0x1 {
// Little: b,g,r,a -> r,g,b,a
for i := 0; i < w*h; i++ {
b := surfaceBytes[4*i+0]
r := surfaceBytes[4*i+2]
surfaceBytes[4*i+0] = r
surfaceBytes[4*i+2] = b
}
} else {
// Big: a,r,g,b -> r,g,b,a
for i := 0; i < w*h; i++ {
a := surfaceBytes[4*i+0]
r := surfaceBytes[4*i+1]
g := surfaceBytes[4*i+2]
b := surfaceBytes[4*i+3]
surfaceBytes[4*i+0] = r
surfaceBytes[4*i+1] = g
surfaceBytes[4*i+2] = b
surfaceBytes[4*i+3] = a
}
}
rgba := &image.RGBA{surfaceBytes, stride, image.Rect(0, 0, w, h)}
resultCallback(rgba, nil)
}
cCallback, userData, err = newGAsyncReadyCallback(callback)
if err != nil {
panic(err)
}
}
C.webkit_web_view_get_snapshot(v.webView,
(C.WebKitSnapshotRegion)(1), // FullDocument is the only working region at this point
(C.WebKitSnapshotOptions)(0),
nil,
cCallback,
userData)
}
//NewImageSurface creates an image surface of the given width, height,
//and format.
//
//Originally cairo_image_surface_create.
func NewImageSurface(format Format, width, height int) (ImageSurface, error) {
is := C.cairo_image_surface_create(format.c(), C.int(width), C.int(height))
stride := int(C.cairo_image_surface_get_stride(is))
return newImg(is, format, width, height, stride)
}
// Fill the image evaluating the function over each pixel
// You can specify one function per channel, or one function for all the channels
// The values will be normalized
// BUG(akiross) this should return an error
func (img *Image) FillMath(chanFuncs ...PixelFunc) {
nch := len(chanFuncs)
// BUG(akiross) this code introduces checks which may be unnecessary
// in production, would be nice to disable this checking
switch img.ColorSpace {
case MODE_A8:
if nch != 1 {
fmt.Println("ERROR! For A8 images is mandatory to use a single chanFunc")
return
}
case MODE_G8:
if nch != 1 {
fmt.Println("ERROR! For G8 images is mandatory to use a single chanFunc")
return
}
case MODE_RGB:
if nch < 1 || nch > 3 {
fmt.Println("ERROR! For mode RGB you need 1, 2 or 3 chanFuncs")
return
}
default:
fmt.Println("RGBA not implemented yet! Alpha must evaluate to 1, or value is always transparent!")
return
/*
if nch < 1 || nch > 4 {
fmt.Println("ERROR! For mode RGBA you need from 1 to 4 chanFuncs")
return
}
if nch == 4 {
// If 4 parameters are specified, the alpha gets moved in front
chanFuncs[0], chanFuncs[1], chanFuncs[2], chanFuncs[3] = chanFuncs[3], chanFuncs[0], chanFuncs[1], chanFuncs[2]
} else {
// Else, first parameter is alpha (nil), other parameters follow
chanFuncs2 := []PixelFunc{nil}
chanFuncs = append(chanFuncs2, chanFuncs...)
}
Problem: if alpha returns a constant value, or if it is nil, image is always transparent (normalized -> 0)
*/
}
// Evaluate the channel functions in every point
realData := make([][][]float64, nch)
//realData := make([]float64, img.H*img.W*nch)
max := make([]float64, nch) // Hold max value per each channel
min := make([]float64, nch) // Hold min value per each channel
for k := 0; k < nch; k++ {
realData[k] = make([][]float64, img.H)
// If the channel function is defined, use it on every pixel
// othersize, the data, min and max are already set to 0
if chanFuncs[k] != nil {
for i := 0; i < img.H; i++ {
realData[k][i] = make([]float64, img.W)
for j := 0; j < img.W; j++ {
realData[k][i][j] = chanFuncs[k](j, i)
max[k] = math.Max(max[k], realData[k][i][j])
min[k] = math.Min(min[k], realData[k][i][j])
}
}
}
}
// Copy the data onto the image
stride := int(C.cairo_image_surface_get_stride(img.Surf)) // Stride in bytes
rawData := unsafe.Pointer(C.cairo_image_surface_get_data(img.Surf))
// Prepare byte data, normalizing if necessary (we cannot write directly to unsafe.Pointer)
byteData := make([]byte, stride*img.H)
// Depending on format, we copy the data in different ways
switch img.ColorSpace {
case MODE_A8:
fmt.Println("Copying data for mode A8")
const k = 0
if max[k] != min[k] {
for i := 0; i < img.H; i++ {
for j := 0; j < img.W; j++ {
byteData[i*stride+j] = byte(0xff * (realData[k][i][j] - min[k]) / (max[k] - min[k]))
}
}
}
case MODE_G8:
fmt.Println("Copying data for mode G8")
const k = 0
if max[k] != min[k] {
for i := 0; i < img.H; i++ {
for j := 0; j < img.W; j++ {
p := i*stride + j*4
v := byte(0xff * (realData[k][i][j] - min[k]) / (max[k] - min[k]))
byteData[p], byteData[p+1], byteData[p+2] = v, v, v
}
}
}
case MODE_RGB:
fmt.Println("Copying data mode RGB")
for k := 0; k < nch; k++ {
if max[k] != min[k] {
for i := 0; i < img.H; i++ {
for j := 0; j < img.W; j++ {
p := i*stride + j*4 + 1
byteData[p+k] = byte(0xff * (realData[k][i][j] - min[k]) / (max[k] - min[k]))
}
}
}
}
/*
case MODE_RGBA:
fmt.Println("Copying data mode RGBA")
for k := 0; k < nch; k++ {
if max[k] != min[k] {
for i := 0; i < img.H; i++ {
for j := 0; j < img.W; j++ {
p := i*stride + j*4 + 1
byteData[p+k] = byte(0xff * (realData[k][i][j] - min[k]) / (max[k] - min[k]))
}
}
}
}
*/
default:
fmt.Println("ERROR! Not implemented yet")
}
// Copy the data on the C-side
C.memcpy(rawData, unsafe.Pointer(&byteData[0]), C.size_t(stride*img.H))
}
//export go_genericGAsyncCallback
func go_genericGAsyncCallback(source *C.GObject, result *C.GAsyncResult, callbackId *C.char) {
key := C.GoString(callbackId)
if obj, ok := cgoget(key); ok {
switch obj.(type) {
case *RunJavaScriptResponse:
var jserr *C.GError
response := obj.(*RunJavaScriptResponse)
if response.Autoremove {
defer cgounregister(key)
}
if jsResult := C.webkit_web_view_run_javascript_finish(response.CWebView, result, &jserr); jsResult == nil {
defer C.g_error_free(jserr)
msg := C.GoString((*C.char)(jserr.message))
response.Reply(nil, errors.New(msg))
} else {
ctxRaw := gojs.RawGlobalContext(unsafe.Pointer(C.webkit_javascript_result_get_global_context(jsResult)))
jsValRaw := gojs.RawValue(unsafe.Pointer(C.webkit_javascript_result_get_value(jsResult)))
ctx := (*gojs.Context)(gojs.NewGlobalContextFrom(ctxRaw))
jsVal := ctx.NewValueFrom(jsValRaw)
response.Reply(jsVal, nil)
}
case *GetSnapshotAsImageResponse:
var snapErr *C.GError
response := obj.(*GetSnapshotAsImageResponse)
if response.Autoremove {
defer cgounregister(key)
}
if snapResult := C.webkit_web_view_get_snapshot_finish(response.CWebView, result, &snapErr); snapResult == nil {
defer C.g_error_free(snapErr)
msg := C.GoString((*C.char)(snapErr.message))
response.Reply(nil, errors.New(msg))
} else {
defer C.cairo_surface_destroy(snapResult)
if C.cairo_surface_get_type(snapResult) != cairoSurfaceTypeImage ||
C.cairo_image_surface_get_format(snapResult) != cairoImageSurfaceFormatARGB32 {
response.Reply(nil, errors.New("Snapshot in unexpected format"))
return
}
w := int(C.cairo_image_surface_get_width(snapResult))
h := int(C.cairo_image_surface_get_height(snapResult))
stride := int(C.cairo_image_surface_get_stride(snapResult))
data := unsafe.Pointer(C.cairo_image_surface_get_data(snapResult))
surfaceBytes := C.GoBytes(data, C.int(stride*h))
// convert from b,g,r,a or a,r,g,b(local endianness) to r,g,b,a
testint, _ := binary.ReadUvarint(bytes.NewBuffer([]byte{0x1, 0}))
if testint == 0x1 {
// Little: b,g,r,a -> r,g,b,a
for i := 0; i < w*h; i++ {
b := surfaceBytes[4*i+0]
r := surfaceBytes[4*i+2]
surfaceBytes[4*i+0] = r
surfaceBytes[4*i+2] = b
}
} else {
// Big: a,r,g,b -> r,g,b,a
for i := 0; i < w*h; i++ {
a := surfaceBytes[4*i+0]
r := surfaceBytes[4*i+1]
g := surfaceBytes[4*i+2]
b := surfaceBytes[4*i+3]
surfaceBytes[4*i+0] = r
surfaceBytes[4*i+1] = g
surfaceBytes[4*i+2] = b
surfaceBytes[4*i+3] = a
}
}
rgba := &image.RGBA{
Pix: surfaceBytes,
Stride: stride,
Rect: image.Rect(0, 0, w, h),
}
response.Reply(rgba, nil)
}
case *GetSnapshotAsCairoSurfaceResponse:
var snapErr *C.GError
response := obj.(*GetSnapshotAsCairoSurfaceResponse)
snapResult := C.webkit_web_view_get_snapshot_finish(response.CWebView, result, &snapErr)
if snapResult == nil {
defer C.g_error_free(snapErr)
msg := C.GoString((*C.char)(snapErr.message))
response.Reply(nil, errors.New(msg))
} else {
surface := cairo.NewSurface(uintptr(unsafe.Pointer(snapResult)), false)
if status := surface.Status(); status == cairo.STATUS_SUCCESS {
response.Reply(surface, nil)
} else {
response.Reply(nil, fmt.Errorf("Cairo surface error %d", status))
}
}
}
}
}