Use WM_CLIPBOARDUPDATE clipboard API

Windows Vista and later have a saner clipboard API where the clipboard viewer
linked list is no longer maintained by applications.  Use it when available.

Signed-off-by: Jon Turney <jon.turney@dronecode.org.uk>

3 files changed, 86 insertions, 39 deletions

diff --git a/hw/xwin/winclipboard/internal.h b/hw/xwin/winclipboard/internal.h
index 6c26caf2e..d0d8fbda1 100644
--- a/hw/xwin/winclipboard/internal.h
+++ b/hw/xwin/winclipboard/internal.h
@@ -77,6 +77,14 @@ typedef struct
     Atom atomTargets;
 } ClipboardAtoms;
 
+/* Modern clipboard API functions */
+typedef wBOOL WINAPI (*ADDCLIPBOARDFORMATLISTENERPROC)(HWND hwnd);
+typedef wBOOL WINAPI (*REMOVECLIPBOARDFORMATLISTENERPROC)(HWND hwnd);
+
+extern Bool g_fHasModernClipboardApi;
+extern ADDCLIPBOARDFORMATLISTENERPROC g_fpAddClipboardFormatListener;
+extern REMOVECLIPBOARDFORMATLISTENERPROC g_fpRemoveClipboardFormatListener;
+
 /*
  * winclipboardwndproc.c
  */
diff --git a/hw/xwin/winclipboard/thread.c b/hw/xwin/winclipboard/thread.c
index 456e7973a..58b3bf74d 100644
--- a/hw/xwin/winclipboard/thread.c
+++ b/hw/xwin/winclipboard/thread.c
@@ -84,6 +84,10 @@ static pthread_t g_winClipboardProcThread;
 int xfixes_event_base;
 int xfixes_error_base;
 
+Bool g_fHasModernClipboardApi = FALSE;
+ADDCLIPBOARDFORMATLISTENERPROC g_fpAddClipboardFormatListener;
+REMOVECLIPBOARDFORMATLISTENERPROC g_fpRemoveClipboardFormatListener;
+
 /*
  * Local function prototypes
  */
@@ -127,6 +131,10 @@ winClipboardProc(Bool fUseUnicode, char *szDisplay)
 
     winDebug("winClipboardProc - Hello\n");
 
+    g_fpAddClipboardFormatListener = (ADDCLIPBOARDFORMATLISTENERPROC)GetProcAddress(GetModuleHandle("user32"),"AddClipboardFormatListener");
+    g_fpRemoveClipboardFormatListener = (REMOVECLIPBOARDFORMATLISTENERPROC)GetProcAddress(GetModuleHandle("user32"),"RemoveClipboardFormatListener");
+    g_fHasModernClipboardApi = g_fpAddClipboardFormatListener && g_fpRemoveClipboardFormatListener;
+    ErrorF("OS maintains clipboard viewer chain: %s\n", g_fHasModernClipboardApi ? "yes" : "no");
 
     g_winClipboardProcThread = pthread_self();
 
diff --git a/hw/xwin/winclipboard/wndproc.c b/hw/xwin/winclipboard/wndproc.c
index 682f2280e..91f874f61 100644
--- a/hw/xwin/winclipboard/wndproc.c
+++ b/hw/xwin/winclipboard/wndproc.c
@@ -58,6 +58,9 @@
 
 #define WIN_POLL_TIMEOUT	1
 
+#ifndef WM_CLIPBOARDUPDATE
+#define WM_CLIPBOARDUPDATE 0x031D
+#endif
 
 /*
  * Process X events up to specified timeout
@@ -151,8 +154,16 @@ winClipboardWindowProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
     {
         winDebug("winClipboardWindowProc - WM_DESTROY\n");
 
-        /* Remove ourselves from the clipboard chain */
-        ChangeClipboardChain(hwnd, s_hwndNextViewer);
+        if (g_fHasModernClipboardApi)
+            {
+                /* Remove clipboard listener */
+                g_fpRemoveClipboardFormatListener(hwnd);
+            }
+        else
+            {
+                /* Remove ourselves from the clipboard chain */
+                ChangeClipboardChain(hwnd, s_hwndNextViewer);
+            }
 
         s_hwndNextViewer = NULL;
     }
@@ -168,8 +179,6 @@ winClipboardWindowProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 
     case WM_CREATE:
     {
-        HWND first, next;
-        DWORD error_code = 0;
         ClipboardWindowCreationParams *cwcp = (ClipboardWindowCreationParams *)((CREATESTRUCT *)lParam)->lpCreateParams;
 
         winDebug("winClipboardWindowProc - WM_CREATE\n");
@@ -179,16 +188,26 @@ winClipboardWindowProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
         atoms = cwcp->atoms;
         fRunning = TRUE;
 
-        first = GetClipboardViewer();   /* Get handle to first viewer in chain. */
-        if (first == hwnd)
-            return 0;           /* Make sure it's not us! */
-        /* Add ourselves to the clipboard viewer chain */
-        next = SetClipboardViewer(hwnd);
-        error_code = GetLastError();
-        if (SUCCEEDED(error_code) && (next == first))   /* SetClipboardViewer must have succeeded, and the handle */
-            s_hwndNextViewer = next;    /* it returned must have been the first window in the chain */
+        if (g_fHasModernClipboardApi)
+            {
+                g_fpAddClipboardFormatListener(hwnd);
+            }
         else
-            s_fCBCInitialized = FALSE;
+            {
+                HWND first, next;
+                DWORD error_code = 0;
+
+                first = GetClipboardViewer();   /* Get handle to first viewer in chain. */
+                if (first == hwnd)
+                    return 0;           /* Make sure it's not us! */
+                /* Add ourselves to the clipboard viewer chain */
+                next = SetClipboardViewer(hwnd);
+                error_code = GetLastError();
+                if (SUCCEEDED(error_code) && (next == first))   /* SetClipboardViewer must have succeeded, and the handle */
+                    s_hwndNextViewer = next;    /* it returned must have been the first window in the chain */
+                else
+                    s_fCBCInitialized = FALSE;
+            }
     }
         return 0;
 
@@ -233,6 +252,11 @@ winClipboardWindowProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 
         winDebug("winClipboardWindowProc - WM_WM_REINIT: Enter\n");
 
+        if (g_fHasModernClipboardApi)
+            {
+                return 0;
+            }
+
         first = GetClipboardViewer();   /* Get handle to first viewer in chain. */
         if (first == hwnd)
             return 0;           /* Make sure it's not us! */
@@ -257,38 +281,45 @@ winClipboardWindowProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
         return 0;
 
     case WM_DRAWCLIPBOARD:
+    case WM_CLIPBOARDUPDATE:
     {
         static Bool s_fProcessingDrawClipboard = FALSE;
         int iReturn;
 
-        winDebug("winClipboardWindowProc - WM_DRAWCLIPBOARD: Enter\n");
+        if (message == WM_DRAWCLIPBOARD)
+            winDebug("winClipboardWindowProc - WM_DRAWCLIPBOARD: Enter\n");
+        else
+            winDebug("winClipboardWindowProc -  WM_CLIPBOARDUPDATE: Enter\n");
 
-        /*
-         * We've occasionally seen a loop in the clipboard chain.
-         * Try and fix it on the first hint of recursion.
-         */
-        if (!s_fProcessingDrawClipboard) {
-            s_fProcessingDrawClipboard = TRUE;
-        }
-        else {
-            /* Attempt to break the nesting by getting out of the chain, twice?, and then fix and bail */
-            s_fCBCInitialized = FALSE;
-            ChangeClipboardChain(hwnd, s_hwndNextViewer);
-            winFixClipboardChain();
-            ErrorF("winClipboardWindowProc - WM_DRAWCLIPBOARD - "
-                   "Nested calls detected.  Re-initing.\n");
-            winDebug("winClipboardWindowProc - WM_DRAWCLIPBOARD: Exit\n");
-            s_fProcessingDrawClipboard = FALSE;
-            return 0;
-        }
+        if (!g_fHasModernClipboardApi)
+            {
+                /*
+                 * We've occasionally seen a loop in the clipboard chain.
+                 * Try and fix it on the first hint of recursion.
+                 */
+                if (!s_fProcessingDrawClipboard) {
+                    s_fProcessingDrawClipboard = TRUE;
+                }
+                else {
+                    /* Attempt to break the nesting by getting out of the chain, twice?, and then fix and bail */
+                    s_fCBCInitialized = FALSE;
+                    ChangeClipboardChain(hwnd, s_hwndNextViewer);
+                    winFixClipboardChain();
+                    ErrorF("winClipboardWindowProc - WM_DRAWCLIPBOARD - "
+                           "Nested calls detected.  Re-initing.\n");
+                    winDebug("winClipboardWindowProc - WM_DRAWCLIPBOARD: Exit\n");
+                    s_fProcessingDrawClipboard = FALSE;
+                    return 0;
+                }
 
-        /* Bail on first message */
-        if (!s_fCBCInitialized) {
-            s_fCBCInitialized = TRUE;
-            s_fProcessingDrawClipboard = FALSE;
-            winDebug("winClipboardWindowProc - WM_DRAWCLIPBOARD: Exit\n");
-            return 0;
-        }
+                /* Bail on first message */
+                if (!s_fCBCInitialized) {
+                    s_fCBCInitialized = TRUE;
+                    s_fProcessingDrawClipboard = FALSE;
+                    winDebug("winClipboardWindowProc - WM_DRAWCLIPBOARD: Exit\n");
+                    return 0;
+                }
+            }
 
         /*
          * NOTE: We cannot bail out when NULL == GetClipboardOwner ()