[vlc-devel] [PATCH] vout: wingdi: request filterchain resetting converter for expected display size.

[Xie Zhigang]

When using wingdi as video output module, if picture size is not
matching the display size, it have to use StretchBlt to perform video
scaling in poor quality.

If it requests video filter chain resetting the video converter in new
target picture size which matches display size, wingdi can get better
scaled picture ready for display in quality.
---
 modules/video_output/win32/wingdi.c | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/modules/video_output/win32/wingdi.c b/modules/video_output/win32/wingdi.c
index 2bead11..e61e2b4 100644
--- a/modules/video_output/win32/wingdi.c
+++ b/modules/video_output/win32/wingdi.c
@@ -75,6 +75,8 @@ struct vout_display_sys_t
         RGBQUAD    green;
         RGBQUAD    blue;
     };
+
+    int prev_size_diff;
 };
 
 static picture_pool_t *Pool  (vout_display_t *, unsigned);
@@ -144,22 +146,35 @@ static void Display(vout_display_t *vd, picture_t *picture)
 #define rect_src_clipped vd->sys->sys.rect_src_clipped
 #define rect_dest vd->sys->sys.rect_dest
 #define rect_dest_clipped vd->sys->sys.rect_dest_clipped
+
+    int size_diff = 0;
+    size_diff = (rect_dest_clipped.right - rect_dest_clipped.left) *
+                (rect_dest_clipped.bottom - rect_dest_clipped.top)
+              - (rect_src_clipped.right - rect_src_clipped.left) *
+                (rect_src_clipped.bottom - rect_src_clipped.top);
+
     RECT rect_dst = rect_dest_clipped;
     HDC hdc = GetDC(sys->sys.hvideownd);
 
     OffsetRect(&rect_dst, -rect_dest.left, -rect_dest.top);
     SelectObject(sys->off_dc, sys->off_bitmap);
 
-    if (rect_dest_clipped.right - rect_dest_clipped.left !=
-        rect_src_clipped.right - rect_src_clipped.left ||
-        rect_dest_clipped.bottom - rect_dest_clipped.top !=
-        rect_src_clipped.bottom - rect_src_clipped.top) {
-        StretchBlt(hdc, rect_dst.left, rect_dst.top,
-                   rect_dst.right, rect_dst.bottom,
-                   sys->off_dc,
-                   rect_src_clipped.left,  rect_src_clipped.top,
-                   rect_src_clipped.right, rect_src_clipped.bottom,
-                   SRCCOPY);
+    if (size_diff != sys->prev_size_diff)
+    {
+        sys->prev_size_diff = size_diff;
+        /* request new vout picture size should be scaled to */
+        vd->fmt.i_visible_width  = rect_dest_clipped.right  - rect_dest_clipped.left;
+        vd->fmt.i_visible_height = rect_dest_clipped.bottom - rect_dest_clipped.top;
+        /* align to 64 is expected to faster access. */
+        vd->fmt.i_width = (rect_dest_clipped.right  - rect_dest_clipped.left + 63) & (~63);
+        vd->fmt.i_height = (rect_dest_clipped.bottom - rect_dest_clipped.top + 63) & (~63);
+
+        video_format_t fmt = vd->fmt;
+
+        Clean(vd);
+        Init(vd, &fmt, fmt.i_width, fmt.i_height);
+
+        vout_display_SendEventPicturesInvalid(vd);
     } else {
         BitBlt(hdc, rect_dst.left, rect_dst.top,
                rect_dst.right, rect_dst.bottom,
-- 
2.7.4