gdi32: Reimplement RoundRect in paths to avoid calling imprecise arc helper functions.

dlls/gdi32/path.c

@@ -896,59 +896,6 @@ static BOOL pathdrv_LineTo( PHYSDEV dev, INT x, INT y )
 
 
 /*************************************************************
- *           pathdrv_RoundRect
- *
- * FIXME: it adds the same entries to the path as windows does, but there
- * is an error in the bezier drawing code so that there are small pixel-size
- * gaps when the resulting path is drawn by StrokePath()
- */
-static BOOL pathdrv_RoundRect( PHYSDEV dev, INT x1, INT y1, INT x2, INT y2, INT ell_width, INT ell_height )
-{
-    struct path_physdev *physdev = get_path_physdev( dev );
-    POINT corners[2], pointTemp;
-    FLOAT_POINT ellCorners[2];
-
-    PATH_CheckCorners(dev->hdc,corners,x1,y1,x2,y2);
-
-   /* Add points to the roundrect path */
-   ellCorners[0].x = corners[1].x-ell_width;
-   ellCorners[0].y = corners[0].y;
-   ellCorners[1].x = corners[1].x;
-   ellCorners[1].y = corners[0].y+ell_height;
-   if(!PATH_DoArcPart(physdev->path, ellCorners, 0, -M_PI_2, PT_MOVETO))
-      return FALSE;
-   pointTemp.x = corners[0].x+ell_width/2;
-   pointTemp.y = corners[0].y;
-   if(!PATH_AddEntry(physdev->path, &pointTemp, PT_LINETO))
-      return FALSE;
-   ellCorners[0].x = corners[0].x;
-   ellCorners[1].x = corners[0].x+ell_width;
-   if(!PATH_DoArcPart(physdev->path, ellCorners, -M_PI_2, -M_PI, 0))
-      return FALSE;
-   pointTemp.x = corners[0].x;
-   pointTemp.y = corners[1].y-ell_height/2;
-   if(!PATH_AddEntry(physdev->path, &pointTemp, PT_LINETO))
-      return FALSE;
-   ellCorners[0].y = corners[1].y-ell_height;
-   ellCorners[1].y = corners[1].y;
-   if(!PATH_DoArcPart(physdev->path, ellCorners, M_PI, M_PI_2, 0))
-      return FALSE;
-   pointTemp.x = corners[1].x-ell_width/2;
-   pointTemp.y = corners[1].y;
-   if(!PATH_AddEntry(physdev->path, &pointTemp, PT_LINETO))
-      return FALSE;
-   ellCorners[0].x = corners[1].x-ell_width;
-   ellCorners[1].x = corners[1].x;
-   if(!PATH_DoArcPart(physdev->path, ellCorners, M_PI_2, 0, 0))
-      return FALSE;
-
-   /* Close the roundrect figure */
-   close_figure( physdev->path );
-   return TRUE;
-}
-
-
-/*************************************************************
  *           pathdrv_Rectangle
  */
 static BOOL pathdrv_Rectangle( PHYSDEV dev, INT x1, INT y1, INT x2, INT y2 )
@@ -974,6 +921,80 @@ static BOOL pathdrv_Rectangle( PHYSDEV dev, INT x1, INT y1, INT x2, INT y2 )
 }
 
 
+/*************************************************************
+ *           pathdrv_RoundRect
+ */
+static BOOL pathdrv_RoundRect( PHYSDEV dev, INT x1, INT y1, INT x2, INT y2, INT ell_width, INT ell_height )
+{
+    const double factor = 0.55428475; /* 4 / 3 * (sqrt(2) - 1) */
+    struct path_physdev *physdev = get_path_physdev( dev );
+    POINT corners[2], ellipse[2], points[16];
+    BYTE *type;
+    double width, height;
+
+    if (!ell_width || !ell_height) return pathdrv_Rectangle( dev, x1, y1, x2, y2 );
+
+    if (!PATH_CheckCorners( dev->hdc, corners, x1, y1, x2, y2 )) return TRUE;
+
+    ellipse[0].x = ellipse[0].y = 0;
+    ellipse[1].x = ell_width;
+    ellipse[1].y = ell_height;
+    LPtoDP( dev->hdc, (POINT *)&ellipse, 2 );
+    ell_width  = min( abs( ellipse[1].x - ellipse[0].x ), corners[1].x - corners[0].x );
+    ell_height = min( abs( ellipse[1].y - ellipse[0].y ), corners[1].y - corners[0].y );
+    width  = ell_width / 2.0;
+    height = ell_height / 2.0;
+
+    /* starting point */
+    points[0].x  = corners[1].x;
+    points[0].y  = corners[0].y + GDI_ROUND( height );
+    /* first curve */
+    points[1].x  = corners[1].x;
+    points[1].y  = corners[0].y + GDI_ROUND( height * (1 - factor) );
+    points[2].x  = corners[1].x - GDI_ROUND( width * (1 - factor) );
+    points[2].y  = corners[0].y;
+    points[3].x  = corners[1].x - GDI_ROUND( width );
+    points[3].y  = corners[0].y;
+    /* horizontal line */
+    points[4].x  = corners[0].x + GDI_ROUND( width );
+    points[4].y  = corners[0].y;
+    /* second curve */
+    points[5].x  = corners[0].x + GDI_ROUND( width * (1 - factor) );
+    points[5].y  = corners[0].y;
+    points[6].x  = corners[0].x;
+    points[6].y  = corners[0].y + GDI_ROUND( height * (1 - factor) );
+    points[7].x  = corners[0].x;
+    points[7].y  = corners[0].y + GDI_ROUND( height );
+    /* vertical line */
+    points[8].x  = corners[0].x;
+    points[8].y  = corners[1].y - GDI_ROUND( height );
+    /* third curve */
+    points[9].x  = corners[0].x;
+    points[9].y  = corners[1].y - GDI_ROUND( height * (1 - factor) );
+    points[10].x = corners[0].x + GDI_ROUND( width * (1 - factor) );
+    points[10].y = corners[1].y;
+    points[11].x = corners[0].x + GDI_ROUND( width );
+    points[11].y = corners[1].y;
+    /* horizontal line */
+    points[12].x = corners[1].x - GDI_ROUND( width );
+    points[12].y = corners[1].y;
+    /* fourth curve */
+    points[13].x = corners[1].x - GDI_ROUND( width * (1 - factor) );
+    points[13].y = corners[1].y;
+    points[14].x = corners[1].x;
+    points[14].y = corners[1].y - GDI_ROUND( height * (1 - factor) );
+    points[15].x = corners[1].x;
+    points[15].y = corners[1].y - GDI_ROUND( height );
+
+    if (GetArcDirection( dev->hdc ) == AD_CLOCKWISE) reverse_points( points, 16 );
+    if (!(type = add_points( physdev->path, points, 16, PT_BEZIERTO ))) return FALSE;
+    type[0] = PT_MOVETO;
+    type[4] = type[8] = type[12] = PT_LINETO;
+    close_figure( physdev->path );
+    return TRUE;
+}
+
+
 /* PATH_Arc
  *
  * Should be called when a call to Arc is performed on a DC that has