double buffering implementation for pre-Vista systems

label is now drawn double-buffered to reduce flicker

1 files changed, 16 insertions, 4 deletions

diff --git a/alf/alflabel.cpp b/alf/alflabel.cpp
index b3a87c4..0a47d58 100644
--- a/alf/alflabel.cpp
+++ b/alf/alflabel.cpp
@@ -222,16 +222,28 @@ ALF_Label_WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
         PAINTSTRUCT ps;
         HDC hdc = BeginPaint(hwnd, &ps);
 
-        ALF_Label_Paint(hwnd, priv, hdc, &ps.rcPaint);
+        RECT rcClient;
+        GetClientRect(hwnd, &rcClient);
+        RECT rcPaint = { 0, 0, rcClient.right - rcClient.left, rcClient.bottom - rcClient.top };
+
+        HDC hdcBuffer = NULL;
+        ALF_Compat_HPAINTBUFFER hpb = ALF_Compat_BeginBufferedPaint(hdc, &rcPaint, 0, NULL, &hdcBuffer);
+        if (hpb) {
+            ALF_Label_Paint(hwnd, priv, hdcBuffer, &ps.rcPaint);
+            ALF_Compat_EndBufferedPaint(hpb, TRUE);
+        } else {
+            ALF_Label_Paint(hwnd, priv, hdc, &ps.rcPaint);
+        }
 
         EndPaint(hwnd, &ps);
 
         return TRUE;
     } else if (uMsg == WM_PRINTCLIENT) {
-        RECT rc;
-        GetClientRect(hwnd, &rc);
+        RECT rcClient;
+        GetClientRect(hwnd, &rcClient);
+        RECT rcPaint = { 0, 0, rcClient.right - rcClient.left, rcClient.bottom - rcClient.top };
 
-        ALF_Label_Paint(hwnd, priv, (HDC)wParam, &rc);
+        ALF_Label_Paint(hwnd, priv, (HDC)wParam, &rcPaint);
     } else if (uMsg == WM_NCHITTEST) {
         return HTTRANSPARENT;
     } else if (uMsg == ALF_WM_QUERYSIZE) {