fix: screenshot by render frame

QtScrcpy/device/decoder/videobuffer.cpp

@@ -105,6 +105,11 @@ const AVFrame *VideoBuffer::consumeRenderedFrame()
     return m_renderingframe;
 }
 
+const AVFrame *VideoBuffer::peekRenderedFrame()
+{
+    return m_renderingframe;
+}
+
 void VideoBuffer::interrupt()
 {
     if (m_renderExpiredFrames) {

QtScrcpy/device/decoder/videobuffer.h

@@ -32,6 +32,8 @@ public:
     // unlocking m_mutex
     const AVFrame* consumeRenderedFrame();
 
+    const AVFrame* peekRenderedFrame();
+
     // wake up and avoid any blocking call
     void interrupt();
 

QtScrcpy/device/device.cpp

@@ -105,7 +105,14 @@ void Device::updateScript(QString script)
 
 void Device::onScreenshot()
 {
-    m_screenshot = true;
+    if (!m_vb) {
+        return;
+    }
+
+    m_vb->lock();
+    // screenshot
+    saveFrame(m_vb->peekRenderedFrame());
+    m_vb->unLock();
 }
 
 void Device::initSignals()
@@ -201,12 +208,6 @@ void Device::initSignals()
             if (m_videoForm) {
                 m_videoForm->updateRender(frame);
             }
-
-            // screenshot
-            if (m_screenshot) {
-                saveFrame(frame);
-                m_screenshot = false;
-            }
             m_vb->unLock();
         },Qt::QueuedConnection);
     }

QtScrcpy/device/device.h

@@ -65,8 +65,6 @@ private:
 
     QTime m_startTimeCount;
     DeviceParams m_params;
-
-    bool m_screenshot = false;
 };
 
 #endif // DEVICE_H