[EXPLORER] Large taskbar icon support (#5465)

- Use HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\TaskbarSmallIcons
  registry key to store the icon size setting for the taskbar.
- If the registry value is missing, small icons will be used by default.
- If the registry value is set to 1, it will also use small icons.
- Only if the value exists and is set to 0 it will use large icons. This allows us
  to use the same registry value as Windows 7 explorer, while also keeping
  the taskbar icons small in most cases, especially running the shell
  on unmodified Windows Server 2003.

CORE-11698

base/shell/explorer/precomp.h

@@ -210,6 +210,7 @@ struct TaskbarSettings
     BOOL bShowSeconds;
     BOOL bPreferDate;
     BOOL bHideInactiveIcons;
+    BOOL bSmallIcons;
     TW_STRUCKRECTS2 sr;
 
     BOOL Load();

base/shell/explorer/settings.cpp

@@ -31,6 +31,7 @@ BOOL TaskbarSettings::Save()
     BOOL bAllowSizeMove = !bLock;
     SHSetValueW(hkExplorer, L"Advanced", L"TaskbarSizeMove", REG_DWORD, &bAllowSizeMove, sizeof(bAllowSizeMove));
     sr.cbSize = sizeof(sr);
+    SHSetValueW(hkExplorer, L"Advanced", L"TaskbarSmallIcons", REG_DWORD, &bSmallIcons, sizeof(bSmallIcons));
     SHSetValueW(hkExplorer, L"StuckRects2", L"Settings", REG_BINARY, &sr, sizeof(sr));
 
     /* TODO: AutoHide writes something to HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Desktop\Components\0 figure out what and why */
@@ -57,6 +58,9 @@ BOOL TaskbarSettings::Load()
     dwRet = SHGetValueW(hkExplorer, NULL, L"EnableAutotray", NULL, &dwValue, &cbSize);
     bHideInactiveIcons = (dwRet == ERROR_SUCCESS) ? (dwValue != 0) : FALSE;
 
+    dwRet = SHGetValueW(hkExplorer, L"Advanced", L"TaskbarSmallIcons", NULL, &dwValue, &cbSize);
+    bSmallIcons = (dwRet == ERROR_SUCCESS) ? (dwValue != 0) : TRUE;
+
     cbSize = sizeof(sr);
     dwRet = SHGetValueW(hkExplorer, L"StuckRects2", L"Settings", NULL, &sr, &cbSize);
 

base/shell/explorer/taskswnd.cpp

@@ -494,7 +494,7 @@ class CTaskSwitchWnd :
 #define GET_ICON(type) \
     SendMessageTimeout(hwnd, WM_GETICON, (type), 0, SMTO_NOTIMEOUTIFNOTHUNG, 100, (PDWORD_PTR)&hIcon)
 
-        LRESULT bAlive = GET_ICON(ICON_SMALL2);
+        LRESULT bAlive = GET_ICON(g_TaskbarSettings.bSmallIcons ? ICON_SMALL2 : ICON_BIG);
         if (hIcon)
             return hIcon;
 
@@ -507,7 +507,7 @@ class CTaskSwitchWnd :
 
         if (bAlive)
         {
-            GET_ICON(ICON_BIG);
+            GET_ICON(g_TaskbarSettings.bSmallIcons ? ICON_BIG : ICON_SMALL2);
             if (hIcon)
                 return hIcon;
         }
@@ -1262,9 +1262,12 @@ class CTaskSwitchWnd :
         /* Update the size of the image list if needed */
         int cx, cy;
         ImageList_GetIconSize(m_ImageList, &cx, &cy);
-        if (cx != GetSystemMetrics(SM_CXSMICON) || cy != GetSystemMetrics(SM_CYSMICON))
+        if (cx != GetSystemMetrics(g_TaskbarSettings.bSmallIcons ? SM_CXSMICON : SM_CXICON) ||
+            cy != GetSystemMetrics(g_TaskbarSettings.bSmallIcons ? SM_CYSMICON : SM_CYICON))
         {
-            ImageList_SetIconSize(m_ImageList, GetSystemMetrics(SM_CXSMICON), GetSystemMetrics(SM_CYSMICON));
+            ImageList_SetIconSize(m_ImageList,
+                                  GetSystemMetrics(g_TaskbarSettings.bSmallIcons ? SM_CXSMICON : SM_CXICON),
+                                  GetSystemMetrics(g_TaskbarSettings.bSmallIcons ? SM_CYSMICON : SM_CYICON));
 
             /* SetIconSize removes all icons so we have to reinsert them */
             PTASK_ITEM TaskItem = m_TaskItems;
@@ -1430,7 +1433,9 @@ class CTaskSwitchWnd :
 
         SetWindowTheme(m_TaskBar.m_hWnd, L"TaskBand", NULL);
 
-        m_ImageList = ImageList_Create(GetSystemMetrics(SM_CXSMICON), GetSystemMetrics(SM_CYSMICON), ILC_COLOR32 | ILC_MASK, 0, 1000);
+        m_ImageList = ImageList_Create(GetSystemMetrics(g_TaskbarSettings.bSmallIcons ? SM_CXSMICON : SM_CXICON),
+                                       GetSystemMetrics(g_TaskbarSettings.bSmallIcons ? SM_CYSMICON : SM_CYICON),
+                                       ILC_COLOR32 | ILC_MASK, 0, 1000);
         m_TaskBar.SetImageList(m_ImageList);
 
         /* Set proper spacing between buttons */