(#17) Added checks for valid windows

Author: Simon Hofmann

src/linux/window_manager.cc

@@ -39,7 +39,7 @@ std::vector<WindowHandle> getWindows() {
 std::string getWindowTitle(const WindowHandle windowHandle) {
     Display* xServer = XGetMainDisplay();
     std::string windowName = "";
-    if (xServer != NULL) {
+    if (xServer != NULL && windowHandle >= 0) {
         /*
          * While there's also `XFetchName` to retrieve a window's `WM_NAME` property, in my tests `XFetchName` always failed and return 0
          * `XGetWMName` on the other hand just worked as expected.
@@ -57,7 +57,7 @@ std::string getWindowTitle(const WindowHandle windowHandle) {
 MMRect getWindowRect(const WindowHandle windowHandle) {
     Display* xServer = XGetMainDisplay();
     MMRect windowRect = MMRectMake(0, 0, 0, 0);
-    if (xServer != NULL) {
+    if (xServer != NULL && windowHandle >= 0) {
         Window rootWindow;
         int32_t x, y;
         uint32_t width, height, border_width, border_height;

src/macos/window_manager.mm

@@ -75,7 +75,7 @@ WindowHandle getActiveWindow() {
 
 MMRect getWindowRect(const WindowHandle windowHandle) {
   auto windowInfo = getWindowInfo(windowHandle);
-  if (windowInfo != nullptr) {
+  if (windowInfo != nullptr && windowHandle >= 0) {
     CGRect windowRect;
     if (CGRectMakeWithDictionaryRepresentation((CFDictionaryRef)windowInfo[(id)kCGWindowBounds], &windowRect)) {
       return MMRectMake(windowRect.origin.x, windowRect.origin.y, windowRect.size.width, windowRect.size.height);
@@ -86,7 +86,7 @@ MMRect getWindowRect(const WindowHandle windowHandle) {
 
 std::string getWindowTitle(const WindowHandle windowHandle) {
   auto windowInfo = getWindowInfo(windowHandle);
-  if (windowInfo != nullptr) {
+  if (windowInfo != nullptr && windowHandle >= 0) {
     NSString *windowName = windowInfo[(id)kCGWindowName];
     return [windowName UTF8String];
   }

src/win32/window_manager.cc

@@ -22,8 +22,7 @@ std::vector<WindowHandle> getWindows() {
 }
 
 WindowHandle getActiveWindow() {
-    HWND foregroundWindow = GetForegroundWindow();
-    if (foregroundWindow != NULL) {
+    if (IsWindow(GetForegroundWindow())) {
         return reinterpret_cast<WindowHandle>(foregroundWindow);
     }
     return -1;
@@ -32,19 +31,21 @@ WindowHandle getActiveWindow() {
 MMRect getWindowRect(const WindowHandle windowHandle) {
     HWND hWnd = reinterpret_cast<HWND>(windowHandle);
     RECT windowRect;
-    if (GetWindowRect(hWnd, &windowRect)) {
+    if (IsWindow(hWnd) && GetWindowRect(hWnd, &windowRect)) {
         return MMRectMake(windowRect.left, windowRect.top, windowRect.right - windowRect.left, windowRect.bottom - windowRect.top);
     }
     return MMRectMake(0, 0, 0, 0);
 }
 
 std::string getWindowTitle(const WindowHandle windowHandle) {
     HWND hWnd = reinterpret_cast<HWND>(windowHandle);
-    auto BUFFER_SIZE = GetWindowTextLength(hWnd) + 1;
-    if (BUFFER_SIZE) {
-        LPSTR windowTitle = new CHAR[BUFFER_SIZE];
-        if (GetWindowText(hWnd, windowTitle, BUFFER_SIZE)) {
-            return std::string(windowTitle);
+    if (IsWindow(hWnd)) {
+        auto BUFFER_SIZE = GetWindowTextLength(hWnd) + 1;
+        if (BUFFER_SIZE) {
+            LPSTR windowTitle = new CHAR[BUFFER_SIZE];
+            if (GetWindowText(hWnd, windowTitle, BUFFER_SIZE)) {
+                return std::string(windowTitle);
+            }
         }
     }
     return "";