[PATCH 6/6] winex11: Use offscreen rendering to scale DPI-unaware GL windows.

[Rémi Bernon]

From: Rémi Bernon

---
 dlls/winex11.drv/opengl.c | 61 +++++++++++++++++++++++++++++++++++----
 1 file changed, 56 insertions(+), 5 deletions(-)

diff --git a/dlls/winex11.drv/opengl.c b/dlls/winex11.drv/opengl.c
index 5f40f28de3d..dac856e992e 100644
--- a/dlls/winex11.drv/opengl.c
+++ b/dlls/winex11.drv/opengl.c
@@ -1086,6 +1086,16 @@ static GLXContext create_glxcontext(Display *display, struct wgl_context *contex
     return ctx;
 }

+static BOOL needs_offscreen_rendering( HWND hwnd, BOOL known_child )
+{
+    if (NtUserGetDpiForWindow( hwnd ) != get_win_monitor_dpi( hwnd )) return TRUE;
+
+    if (!known_child && !NtUserGetWindowRelative( hwnd, GW_CHILD ) &&
+        NtUserGetAncestor( hwnd, GA_PARENT ) == NtUserGetDesktopWindow())
+        return FALSE;  /* childless top-level window */
+
+    return TRUE;
+}

/***********************************************************************
  *              create_gl_drawable
@@ -1114,8 +1124,7 @@ static struct gl_drawable *create_gl_drawable( HWND hwnd, const struct glx_pixel
     gl->hwnd = hwnd;
     gl->mutable_pf = mutable_pf;

-    if (!known_child && !NtUserGetWindowRelative( hwnd, GW_CHILD ) &&
-        NtUserGetAncestor( hwnd, GA_PARENT ) == NtUserGetDesktopWindow())  /* childless top-level window */
+    if (!needs_offscreen_rendering( hwnd, known_child ))
     {
         gl->type = DC_GL_WINDOW;
         gl->colormap = XCreateColormap( gdi_display, get_dummy_parent(), visual->visual,
@@ -1842,15 +1851,49 @@ static Drawable get_dc_drawable( HDC hdc, RECT *rect )
     return escape.drawable;
 }

+static HRGN get_dc_monitor_region( HWND hwnd, HDC hdc )
+{
+    RGNDATA *data;
+    UINT i, size;
+    HRGN region;
+    POINT pt;
+
+    if (!(region = NtGdiCreateRectRgn( 0, 0, 0, 0 ))) return 0;
+    if (NtGdiGetRandomRgn( hdc, region, SYSRGN ) <= 0) goto failed;
+    if (!(size = NtGdiGetRegionData( region, 0, NULL ))) goto failed;
+    if (!(data = malloc( size ))) goto failed;
+    NtGdiGetRegionData( region, size, data );
+    NtGdiDeleteObjectApp( region );
+
+    NtGdiGetDCPoint( hdc, NtGdiGetDCOrg, &pt );
+    NtUserLogicalToPerMonitorDPIPhysicalPoint( hwnd, &pt );
+    for (i = 0; i < data->rdh.nCount; i++)
+    {
+        RECT *rect = (RECT *)data->Buffer + i;
+        NtUserLogicalToPerMonitorDPIPhysicalPoint( hwnd, (POINT *)&rect->left );
+        NtUserLogicalToPerMonitorDPIPhysicalPoint( hwnd, (POINT *)&rect->right );
+        OffsetRect( rect, -pt.x, -pt.y );
+    }
+
+    region = NtGdiExtCreateRegion( NULL, size, data );
+    free( data );
+    return region;
+
+failed:
+    NtGdiDeleteObjectApp( region );
+    return 0;
+}
+
 static void present_gl_drawable( HWND hwnd, HDC hdc, struct gl_drawable *gl, BOOL flush )
 {
     static const WCHAR displayW[] = {'D','I','S','P','L','A','Y'};
-    static HDC hdc_src;
+    static HDC hdc_src, hdc_dst;

UNICODE_STRING device_str = RTL_CONSTANT_STRING(displayW);
     HWND toplevel = NtUserGetAncestor( hwnd, GA_ROOT );
     RECT rect_dst, rect_src, rect;
-    Drawable drawable;
+    Drawable window, drawable;
+    HRGN region;

if (!gl) return;
     switch (gl->type)
@@ -1860,6 +1903,8 @@ static void present_gl_drawable( HWND hwnd, HDC hdc, struct gl_drawable *gl, BOO
     default: drawable = 0; break;
     }
     if (!drawable) return;
+    window = get_dc_drawable( hdc, &rect );
+    region = get_dc_monitor_region( hwnd, hdc );

if (flush) XFlush( gdi_display );

@@ -1872,15 +1917,21 @@ static void present_gl_drawable( HWND hwnd, HDC hdc, struct gl_drawable *gl, BOO
     pthread_mutex_lock( &context_mutex );

if (!hdc_src && !(hdc_src = NtGdiOpenDCW( &device_str, NULL, NULL, 0, TRUE, NULL, NULL, NULL ))) goto done;
+    if (!hdc_dst && !(hdc_dst = NtGdiOpenDCW( &device_str, NULL, NULL, 0, TRUE, NULL, NULL, NULL ))) goto done;

if (get_dc_drawable( hdc_src, &rect ) != drawable || !EqualRect( &rect, &rect_src ))
         set_dc_drawable( hdc_src, drawable, &rect_src, IncludeInferiors );
+    if (get_dc_drawable( hdc_dst, &rect ) != window || !EqualRect( &rect, &rect_dst ))
+        set_dc_drawable( hdc_dst, window, &rect_dst, ClipByChildren );
+    if (region) NtGdiExtSelectClipRgn( hdc_dst, region, RGN_COPY );

-    NtGdiStretchBlt( hdc, 0, 0, rect_dst.right - rect_dst.left, rect_dst.bottom - rect_dst.top,
+    NtGdiStretchBlt( hdc_dst, 0, 0, rect_dst.right - rect_dst.left, rect_dst.bottom - rect_dst.top,
                      hdc_src, 0, 0, rect_src.right, rect_src.bottom, SRCCOPY, 0 );

done:
     pthread_mutex_unlock( &context_mutex );
+
+    if (region) NtGdiDeleteObjectApp( region );
 }

static void wglFinish(void)