// 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)
}
func CairoEndianDependedARGB32ToRGBA(data []byte, out []byte) {
C.gowk2_cairo_endian_depended_ARGB32_to_RGBA((*C.uchar)(unsafe.Pointer(&data[0])), (*C.uchar)(unsafe.Pointer(&out[0])), (C.uint)(len(data)))
}
