cv/video-widget: fixes

- don't copy pointlessly on ARGB32 input.
- add stride argument to QImage.
- don't do pointless stuff during painting on the main thread.

1 files changed, 27 insertions, 15 deletions

diff --git a/cv/video-widget.cpp b/cv/video-widget.cpp
index da9972f5..f2da8da7 100644
--- a/cv/video-widget.cpp
+++ b/cv/video-widget.cpp
@@ -6,10 +6,13 @@
  * copyright notice and this permission notice appear in all copies.
  */
 
+// XXX TODO remove hard opencv dependency -sh 20190210
+
 #include "video-widget.hpp"
 #include "compat/check-visible.hpp"
 #include "compat/math.hpp"
 
+#include <cstddef>
 #include <cstring>
 #include <opencv2/imgproc.hpp>
 
@@ -27,6 +30,12 @@ void cv_video_widget::update_image(const cv::Mat& frame)
 {
     QMutexLocker l(&mtx);
 
+    if (texture.width() != W || texture.height() != H)
+    {
+        frame2 = cv::Mat();
+        frame3 = cv::Mat();
+    }
+
     if (!freshp)
     {
         if (W < 1 || H < 1 || frame.rows < 1 || frame.cols < 1)
@@ -40,6 +49,8 @@ void cv_video_widget::update_image(const cv::Mat& frame)
         if (frame3.cols != W || frame3.rows != H)
             frame3 = cv::Mat(H, W, CV_8UC4);
 
+        const cv::Mat* argb = &frame2;
+
         switch (frame.channels())
         {
         case 1:
@@ -49,28 +60,32 @@ void cv_video_widget::update_image(const cv::Mat& frame)
             cv::cvtColor(frame, frame2, cv::COLOR_BGR2BGRA);
             break;
         case 4:
-            frame2.setTo(frame);
+            argb = &frame;
             break;
         default:
-            *(volatile int*)nullptr = 0; // NOLINT(clang-analyzer-core.NullDereference)
             unreachable();
         }
 
         const cv::Mat* img;
 
-        if (frame2.cols != W || frame2.rows != H)
+        if (argb->cols != W || argb->rows != H)
         {
-            cv::resize(frame2, frame3, cv::Size(W, H), 0, 0, cv::INTER_NEAREST);
+            cv::resize(*argb, frame3, cv::Size(W, H), 0, 0, cv::INTER_NEAREST);
             img = &frame3;
         }
         else
-            img = &frame2;
+            img = argb;
+
+        int stride = (int)img->step.p[0];
 
-        const unsigned nbytes = unsigned(4 * img->rows * img->cols);
-        vec.resize(nbytes);
+        if (stride < img->cols)
+            std::abort();
+
+        unsigned nbytes = (unsigned)(4 * img->rows * stride);
+        vec.resize(nbytes); vec.shrink_to_fit();
         std::memcpy(vec.data(), img->data, nbytes);
 
-        texture = QImage((const unsigned char*) vec.data(), W, H, QImage::Format_ARGB32);
+        texture = QImage((const unsigned char*) vec.data(), W, H, stride, QImage::Format_ARGB32);
         texture.setDevicePixelRatio(devicePixelRatioF());
     }
 }
@@ -83,18 +98,17 @@ void cv_video_widget::update_image(const QImage& img)
         return;
     freshp = true;
 
-    const unsigned nbytes = unsigned(img.bytesPerLine() * img.height());
-    vec.resize(nbytes);
+    unsigned nbytes = unsigned(img.bytesPerLine() * img.height());
+    vec.resize(nbytes); vec.shrink_to_fit();
     std::memcpy(vec.data(), img.constBits(), nbytes);
 
-    texture = QImage((const unsigned char*) vec.data(), img.width(), img.height(), img.format());
+    texture = QImage((const unsigned char*) vec.data(), img.width(), img.height(), img.bytesPerLine(), img.format());
     texture.setDevicePixelRatio(devicePixelRatioF());
 }
 
 void cv_video_widget::paintEvent(QPaintEvent*)
 {
     QMutexLocker foo(&mtx);
-
     QPainter painter(this);
 
     double dpr = devicePixelRatioF();
@@ -106,10 +120,8 @@ void cv_video_widget::paintEvent(QPaintEvent*)
     if (texture.width() != W || texture.height() != H)
     {
         texture = QImage(W, H, QImage::Format_ARGB32);
+        texture.fill(Qt::gray);
         texture.setDevicePixelRatio(dpr);
-
-        frame2 = cv::Mat();
-        frame3 = cv::Mat();
     }
 }