[WIN32SS][NTGDI] Fix wrong IN/OUT (#1539)

[reactos.git] / win32ss / gdi / ntgdi / xformobj.c

diff --git a/win32ss/gdi/ntgdi/xformobj.c b/win32ss/gdi/ntgdi/xformobj.c
index adf0972..e1d2241 100644 (file)
--- a/win32ss/gdi/ntgdi/xformobj.c
+++ b/win32ss/gdi/ntgdi/xformobj.c
@@ -105,7 +105,7 @@ HintFromAccel(ULONG flAccel)
 ULONG
 NTAPI
 XFORMOBJ_UpdateAccel(
-    IN XFORMOBJ *pxo)
+    IN OUT XFORMOBJ *pxo)
 {
     PMATRIX pmx = XFORMOBJ_pmx(pxo);
 
@@ -146,16 +146,25 @@ XFORMOBJ_UpdateAccel(
 ULONG
 NTAPI
 XFORMOBJ_iSetXform(
-    OUT XFORMOBJ *pxo,
+    IN OUT XFORMOBJ *pxo,
     IN const XFORML *pxform)
 {
     PMATRIX pmx = XFORMOBJ_pmx(pxo);
+    FLOATOBJ ef1, ef2, efTemp;
 
     /* Check parameters */
     if (!pxo || !pxform) return DDI_ERROR;
 
     /* Check if the xform is valid */
-    if ((pxform->eM11 == 0) || (pxform->eM22 == 0)) return DDI_ERROR;
+    /* M11 * M22 - M12 * M21 != 0 */
+    FLOATOBJ_SetFloat(&ef1, pxform->eM11);
+    FLOATOBJ_SetFloat(&efTemp, pxform->eM22);
+    FLOATOBJ_Mul(&ef1, &efTemp);
+    FLOATOBJ_SetFloat(&ef2, pxform->eM12);
+    FLOATOBJ_SetFloat(&efTemp, pxform->eM21);
+    FLOATOBJ_Mul(&ef2, &efTemp);
+    if (FLOATOBJ_Equal(&ef1, &ef2))
+        return DDI_ERROR;
 
     /* Copy members */
     FLOATOBJ_SetFloat(&pmx->efM11, pxform->eM11);
@@ -180,7 +189,7 @@ XFORMOBJ_iSetXform(
 ULONG
 NTAPI
 XFORMOBJ_iCombine(
-    IN XFORMOBJ *pxo,
+    IN OUT XFORMOBJ *pxo,
     IN XFORMOBJ *pxo1,
     IN XFORMOBJ *pxo2)
 {
@@ -213,7 +222,7 @@ XFORMOBJ_iCombine(
 ULONG
 NTAPI
 XFORMOBJ_iCombineXform(
-    IN XFORMOBJ *pxo,
+    IN OUT XFORMOBJ *pxo,
     IN XFORMOBJ *pxo1,
     IN XFORML *pxform,
     IN BOOL bLeftMultiply)