From 5627a0cbdf94a053e55aa4749a5c83d8b18ad34c Mon Sep 17 00:00:00 2001
From: Xinguang Bian <mightbxg@hotmail.com>
Date: Wed, 7 Jul 2021 12:35:11 +0800
Subject: [PATCH] fix scale problem in DefaultViewPort::controlImagePosition()

---
 modules/highgui/src/window_QT.cpp | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/modules/highgui/src/window_QT.cpp b/modules/highgui/src/window_QT.cpp
index 68289eb876..8dff03117e 100644
--- a/modules/highgui/src/window_QT.cpp
+++ b/modules/highgui/src/window_QT.cpp
@@ -2883,18 +2883,19 @@ inline bool DefaultViewPort::isSameSize(IplImage* img1, IplImage* img2)
 void DefaultViewPort::controlImagePosition()
 {
     qreal left, top, right, bottom;
+    qreal factor = 1.0 / param_matrixWorld.m11();
 
     //after check top-left, bottom right corner to avoid getting "out" during zoom/panning
     param_matrixWorld.map(0,0,&left,&top);
 
     if (left > 0)
     {
-        param_matrixWorld.translate(-left,0);
+        param_matrixWorld.translate(-left * factor, 0);
         left = 0;
     }
     if (top > 0)
     {
-        param_matrixWorld.translate(0,-top);
+        param_matrixWorld.translate(0, -top * factor);
         top = 0;
     }
     //-------
@@ -2903,12 +2904,12 @@ void DefaultViewPort::controlImagePosition()
     param_matrixWorld.map(sizeImage.width(),sizeImage.height(),&right,&bottom);
     if (right < sizeImage.width())
     {
-        param_matrixWorld.translate(sizeImage.width()-right,0);
+        param_matrixWorld.translate((sizeImage.width() - right) * factor, 0);
         right = sizeImage.width();
     }
     if (bottom < sizeImage.height())
     {
-        param_matrixWorld.translate(0,sizeImage.height()-bottom);
+        param_matrixWorld.translate(0, (sizeImage.height() - bottom) * factor);
         bottom = sizeImage.height();
     }