Support :transform-smoothing on images (MS-Windows) (bug#57166)

* src/dispextern.h (struct image): Add field 'smoothing' for
NTGUI.
* src/image.c (image_set_transform): Assign the 'smoothing'
field of the image struct.
* src/w32gdiplus.h: Add references to more GDI+ functions.
* src/w32image.c (gdiplus_init): Add references to more GDI+
functions.
* src/w32term.c (w32_draw_image_foreground): If the image is
marked for smoothing and GDI+ is available, draw it with GDI+
bilinear interpolation.
* etc/NEWS: New entry for this change.

1 files changed, 50 insertions, 10 deletions

diff --git a/src/w32term.c b/src/w32term.c
index 88622700386..e18f39dd2a8 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -24,6 +24,9 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include "blockinput.h"
 #include "w32term.h"
 #include "w32common.h"  /* for OS version info */
+#include <wtypes.h>
+#include <gdiplus.h>
+#include "w32gdiplus.h"
 
 #include <ctype.h>
 #include <errno.h>
@@ -2106,16 +2109,53 @@ w32_draw_image_foreground (struct glyph_string *s)
                     compat_hdc, s->slice.x, s->slice.y, SRCCOPY);
           else
             {
-              int pmode = 0;
-              /* Windows 9X doesn't support HALFTONE.  */
-              if (os_subtype == OS_SUBTYPE_NT
-                  && (pmode = SetStretchBltMode (s->hdc, HALFTONE)) != 0)
-                SetBrushOrgEx (s->hdc, 0, 0, NULL);
-              StretchBlt (s->hdc, x, y, s->slice.width, s->slice.height,
-                          compat_hdc, orig_slice_x, orig_slice_y,
-                          orig_slice_width, orig_slice_height, SRCCOPY);
-              if (pmode)
-                SetStretchBltMode (s->hdc, pmode);
+#ifdef HAVE_NATIVE_IMAGE_API
+              if (s->img->smoothing && w32_gdiplus_startup ())
+                {
+                  GpGraphics *graphics;
+                  if (GdipCreateFromHDC (s->hdc, &graphics) == Ok)
+                    {
+                      GpBitmap *gp_bitmap;
+                      /* Can't create a GpBitmap from a HBITMAP that was
+                         ever selected into a DC, so we need to copy.  */
+                      HBITMAP copy
+                        = CopyImage (GetCurrentObject (compat_hdc, OBJ_BITMAP),
+                                     IMAGE_BITMAP, 0, 0, 0);
+                      if (GdipCreateBitmapFromHBITMAP (copy, NULL,
+                                                       &gp_bitmap) == Ok)
+                        {
+                          GdipSetInterpolationMode (graphics,
+                                                    InterpolationModeHighQualityBilinear);
+                          GdipDrawImageRectRectI (graphics,
+                                                  gp_bitmap, x, y,
+                                                  s->slice.width,
+                                                  s->slice.height,
+                                                  orig_slice_x,
+                                                  orig_slice_y,
+                                                  orig_slice_width,
+                                                  orig_slice_height,
+                                                  UnitPixel,
+                                                  NULL, NULL, NULL);
+                          GdipDisposeImage (gp_bitmap);
+                        }
+                      DeleteObject (copy);
+                      GdipDeleteGraphics (graphics);
+                    }
+                }
+              else
+#endif
+                {
+                  int pmode = 0;
+                  /* Windows 9X doesn't support HALFTONE.  */
+                  if (os_subtype == OS_SUBTYPE_NT
+                      && (pmode = SetStretchBltMode (s->hdc, HALFTONE)) != 0)
+                    SetBrushOrgEx (s->hdc, 0, 0, NULL);
+                  StretchBlt (s->hdc, x, y, s->slice.width, s->slice.height,
+                              compat_hdc, orig_slice_x, orig_slice_y,
+                              orig_slice_width, orig_slice_height, SRCCOPY);
+                  if (pmode)
+                    SetStretchBltMode (s->hdc, pmode);
+                }
             }
 
           /* When the image has a mask, we can expect that at