gtk.ImageNewFromPixbuf and gdk gdk.PixbufNew binding

Fix provided by jrick: gdk.Pixbuf.GetPixels() now uses the reflect
package to return a non-copied slice of Pixbuf data

Implemented gtk.GetPixbuf binding for GtkImage objects

Added reference and runtime finalizer to Pixbuf in
gdk.Pixbuf.GetPixels() to avoid having the returned byte slice point
to freed memory.

Author: vvanpo

gdk/gdk.go

@@ -24,6 +24,7 @@ import "C"
 import (
 	"errors"
 	"github.com/conformal/gotk3/glib"
+	"reflect"
 	"runtime"
 	"unsafe"
 )
@@ -550,10 +551,19 @@ func (v *Pixbuf) GetBitsPerSample() int {
 // GetPixels is a wrapper around gdk_pixbuf_get_pixels_with_length().
 // A Go slice is used to represent the underlying Pixbuf data array, one
 // byte per channel.
-func (v *Pixbuf) GetPixels() []byte {
+func (v *Pixbuf) GetPixels() (channels []byte) {
 	var length C.guint
 	c := C.gdk_pixbuf_get_pixels_with_length(v.native(), &length)
-	return C.GoBytes(unsafe.Pointer(c), (C.int)(length))
+	sliceHeader := (*reflect.SliceHeader)(unsafe.Pointer(&channels))
+	sliceHeader.Data = uintptr(unsafe.Pointer(c))
+	sliceHeader.Len = int(length)
+	sliceHeader.Cap = int(length)
+	// To make sure the slice doesn't outlive the Pixbuf, add a reference
+	v.Ref()
+	runtime.SetFinalizer(&channels, func(_ *[]byte) {
+		v.Unref()
+	})
+	return
 }
 
 // GetWidth is a wrapper around gdk_pixbuf_get_width().
@@ -592,6 +602,20 @@ func (v *Pixbuf) GetOption(key string) (value string, ok bool) {
 	return C.GoString((*C.char)(c)), true
 }
 
+// PixbufNew is a wrapper around gdk_pixbuf_new().
+func PixbufNew(colorspace Colorspace, hasAlpha bool, bitsPerSample, width, height int) (*Pixbuf, error) {
+	c := C.gdk_pixbuf_new(C.GdkColorspace(colorspace), gbool(hasAlpha),
+		C.int(bitsPerSample), C.int(width), C.int(height))
+	if c == nil {
+		return nil, nilPtrErr
+	}
+	obj := &glib.Object{glib.ToGObject(unsafe.Pointer(c))}
+	p := &Pixbuf{obj}
+	obj.Ref()
+	runtime.SetFinalizer(obj, (*glib.Object).Unref)
+	return p, nil
+}
+
 /*
  * GdkScreen
  */

gtk/gtk.go

@@ -3942,11 +3942,19 @@ func ImageNewFromResource(resourcePath string) (*Image, error) {
 	return i, nil
 }
 
-// TODO(jrick) GdkPixbuf
-/*
-func ImageNewFromPixbuf() {
+// ImageNewFromPixbuf is a wrapper around gtk_image_new_from_pixbuf().
+func ImageNewFromPixbuf(pixbuf *gdk.Pixbuf) (*Image, error) {
+	ptr := (*C.GdkPixbuf)(unsafe.Pointer(pixbuf.Native()))
+	c := C.gtk_image_new_from_pixbuf(ptr)
+	if c == nil {
+		return nil, nilPtrErr
+	}
+	obj := &glib.Object{glib.ToGObject(unsafe.Pointer(c))}
+	i := wrapImage(obj)
+	obj.RefSink()
+	runtime.SetFinalizer(obj, (*glib.Object).Unref)
+	return i, nil
 }
-*/
 
 // TODO(jrick) GtkIconSet
 /*
@@ -4044,11 +4052,18 @@ func (v *Image) GetStorageType() ImageType {
 	return ImageType(c)
 }
 
-// TODO(jrick) GdkPixbuf
-/*
-func (v *Image) GetPixbuf() {
+// GetPixbuf() is a wrapper around gtk_image_get_pixbuf().
+func (v *Image) GetPixbuf() *gdk.Pixbuf {
+	c := C.gtk_image_get_pixbuf(v.native())
+	if c == nil {
+		return nil
+	}
+	obj := &glib.Object{glib.ToGObject(unsafe.Pointer(c))}
+	pb := &gdk.Pixbuf{obj}
+	obj.Ref()
+	runtime.SetFinalizer(obj, (*glib.Object).Unref)
+	return pb
 }
-*/
 
 // TODO(jrick) GtkIconSet
 /*