Fix: clear residual image outside remote frame in non-adaptive scroll mode

server/2015Remote/ScreenSpyDlg.cpp

@@ -1714,7 +1714,20 @@ void CScreenSpyDlg::OnPaint()
             StretchBlt(m_hFullDC, 0, 0, dstW, dstH, m_hFullMemDC, 0, 0, srcW, srcH, SRCCOPY);
         }
     } else {
-        BitBlt(m_hFullDC, 0, 0, srcW, srcH, m_hFullMemDC, m_ulHScrollPos, m_ulVScrollPos, SRCCOPY);
+        // 实际可见的位图像素数 = 位图剩余宽高（去掉滚动偏移后）与窗口的较小值
+        int visW = max(0, min(srcW - (int)m_ulHScrollPos, dstW));
+        int visH = max(0, min(srcH - (int)m_ulVScrollPos, dstH));
+        if (visW > 0 && visH > 0)
+            BitBlt(m_hFullDC, 0, 0, visW, visH, m_hFullMemDC, m_ulHScrollPos, m_ulVScrollPos, SRCCOPY);
+        // 位图未覆盖的区域（远程分辨率小于窗口 / 滚动到边缘）填黑，防止残影
+        if (visW < dstW) {
+            RECT rc = { visW, 0, dstW, dstH };
+            FillRect(m_hFullDC, &rc, (HBRUSH)GetStockObject(BLACK_BRUSH));
+        }
+        if (visH < dstH) {
+            RECT rc = { 0, visH, dstW, dstH };
+            FillRect(m_hFullDC, &rc, (HBRUSH)GetStockObject(BLACK_BRUSH));
+        }
     }
 
     // 绘制框选矩形（左键放大用红色，右键截图用绿色，二者颜色错开避免误操作）
@@ -2177,6 +2190,7 @@ void CScreenSpyDlg::OnSysCommand(UINT nID, LPARAM lParam)
         }
         ShowScrollBar(SB_BOTH, !m_bAdaptiveSize);
         SysMenu->CheckMenuItem(IDM_ADAPTIVE_SIZE, m_bAdaptiveSize ? MF_CHECKED : MF_UNCHECKED);
+        Invalidate(FALSE);  // 立即重绘，清除旧模式的残留画面
         break;
     }
     case IDM_AUDIO_TOGGLE: {