andlabs-ui/image_unix.go

57 lines
1.9 KiB
Go

// +build !windows,!darwin
// 16 august 2014
package ui
import (
"fmt"
"image"
"unsafe"
)
// #include "gtk_unix.h"
import "C"
// this is what GtkFileChooserWidget uses
// technically it uses max(width from that, height from that) if the call below fails and 16x16 otherwise, but we won't worry about that here (yet?)
const scaleTo = C.GTK_ICON_SIZE_MENU
func toIconSizedGdkPixbuf(img *image.RGBA) *C.GdkPixbuf {
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 return the base pixbuf; we're good
C.cairo_surface_destroy(surface)
return basepixbuf
}
// 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)"))
}
C.g_object_unref(C.gpointer(unsafe.Pointer(basepixbuf)))
C.cairo_surface_destroy(surface)
return pixbuf
}