[MSPAINT] Reset scroll position in some situations (#5789)

In some situations, the scroll position should be reset.
- Add CCanvasWindow::resetScrollPos method.
- Reset the scroll position on loading a file.
- Reset the scroll position on mirroring/rotating
  the image.
CORE-19094

base/applications/mspaint/canvas.cpp

@@ -199,6 +199,12 @@ VOID CCanvasWindow::updateScrollInfo()
     SetScrollInfo(SB_VERT, &si);
 }
 
+VOID CCanvasWindow::resetScrollPos()
+{
+    SetScrollPos(SB_HORZ, 0);
+    SetScrollPos(SB_VERT, 0);
+}
+
 LRESULT CCanvasWindow::OnSize(UINT nMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)
 {
     if (m_hWnd)

base/applications/mspaint/canvas.h

@@ -43,6 +43,7 @@ public:
     VOID cancelDrawing();
     VOID finishDrawing();
     VOID updateScrollInfo();
+    VOID resetScrollPos();
 
     VOID ImageToCanvas(POINT& pt);
     VOID ImageToCanvas(RECT& rc);

base/applications/mspaint/dib.cpp

@@ -241,6 +241,7 @@ HBITMAP InitializeImage(LPCWSTR name, LPWIN32_FIND_DATAW pFound, BOOL isFile)
 HBITMAP SetBitmapAndInfo(HBITMAP hBitmap, LPCWSTR name, LPWIN32_FIND_DATAW pFound, BOOL isFile)
 {
     // update image
+    canvasWindow.resetScrollPos();
     imageModel.PushImageForUndo(hBitmap);
     imageModel.ClearHistory();
 

base/applications/mspaint/winproc.cpp

@@ -921,6 +921,7 @@ LRESULT CMainWindow::OnCommand(UINT nMsg, WPARAM wParam, LPARAM lParam, BOOL& bH
         case IDM_IMAGEROTATEMIRROR:
             {
                 CWaitCursor waitCursor;
+                canvasWindow.resetScrollPos();
                 switch (mirrorRotateDialog.DoModal(mainWindow.m_hWnd))
                 {
                     case 1: /* flip horizontally */