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// +build !windows,!darwin,!plan9
// 14 march 2014
package ui
import (
"unsafe"
"image"
)
// #cgo pkg-config: gtk+-3.0
// /* GTK+ 3.8 deprecates gtk_scrolled_window_add_with_viewport(); we need 3.4 miniimum though
// setting MIN_REQUIRED ensures nothing older; setting MAX_ALLOWED disallows newer functions - thanks to desrt in irc.gimp.net/#gtk+
// TODO add this to the other files too */
// #define GDK_VERSION_MIN_REQUIRED GDK_VERSION_3_4
// #define GDK_VERSION_MAX_ALLOWED GDK_VERSION_3_4
// #include <gtk/gtk.h>
// extern gboolean our_draw_callback(GtkWidget *, cairo_t *, gpointer);
// /* HACK - see https://code.google.com/p/go/issues/detail?id=7548 */
// struct _cairo {};
import "C"
func gtkAreaNew() *gtkWidget {
drawingarea := C.gtk_drawing_area_new()
C.gtk_widget_set_size_request(drawingarea, 320, 240)
scrollarea := C.gtk_scrolled_window_new((*C.GtkAdjustment)(nil), (*C.GtkAdjustment)(nil))
// need a viewport because GtkDrawingArea isn't natively scrollable
C.gtk_scrolled_window_add_with_viewport((*C.GtkScrolledWindow)(unsafe.Pointer(scrollarea)), drawingarea)
return fromgtkwidget(scrollarea)
}
//export our_draw_callback
func our_draw_callback(widget *C.GtkWidget, cr *C.cairo_t, data C.gpointer) C.gboolean {
var x, y, w, h C.double
s := (*sysData)(unsafe.Pointer(data))
// thanks to desrt in irc.gimp.net/#gtk+
C.cairo_clip_extents(cr, &x, &y, &w, &h)
cliprect := image.Rect(int(x), int(y), int(w), int(h))
imgret := make(chan *image.NRGBA)
defer close(imgret)
s.paint <- PaintRequest{
Rect: cliprect,
Out: imgret,
}
i := <-imgret
// pixel order is [R G B A] (see Example 1 on https://developer.gnome.org/gdk-pixbuf/2.26/gdk-pixbuf-The-GdkPixbuf-Structure.html) so we don't have to convert anything
// gdk-pixbuf is not alpha-premultiplied (thanks to desrt in irc.gimp.net/#gtk+)
pixbuf := C.gdk_pixbuf_new_from_data(
(*C.guchar)(unsafe.Pointer(&i.Pix[0])),
C.GDK_COLORSPACE_RGB,
C.TRUE, // has alpha channel
8, // bits per sample
C.int(i.Rect.Dx()),
C.int(i.Rect.Dy()),
C.int(i.Stride),
nil, nil) // do not free data
C.gdk_cairo_set_source_pixbuf(cr,
pixbuf,
C.gdouble(cliprect.Min.X),
C.gdouble(cliprect.Min.Y))
C.g_object_unref((C.gpointer)(unsafe.Pointer(pixbuf))) // free pixbuf
return C.FALSE // signals handled without stopping the event chain (thanks to desrt again)
}
var draw_callback = C.GCallback(C.our_draw_callback)
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