Reduce CPU usage by more than half by using QImage to do ABGR -> RGB conversion.

Now the main CPU hog is base64encoding the image data to send to Hyperion.
Don't sent signal as exit code.

CMakeLists.txt

@@ -8,9 +8,10 @@ set(CMAKE_BUILD_TYPE Desktop)
 
 find_package(Qt5Core REQUIRED)
 find_package(Qt5Network REQUIRED)
+find_package(Qt5Widgets REQUIRED)
 find_package(X11 REQUIRED)
 
 set(CMAKE_CXX_STANDARD_LIBRARIES "${CMAKE_CXX_STANDARD_LIBRARIES} -lXrender -lXdamage")
 include_directories(${X11_INCLUDE_DIR})
 add_executable(${PROJECT_NAME} "main.cpp" "hgx11.h" "hgx11.cpp" "hgx11net.h" "hgx11net.cpp" "hgx11damage.h" "hgx11damage.cpp" "hgx11grab.h" "hgx11grab.cpp")
-target_link_libraries(${PROJECT_NAME} Qt5::Core Qt5::Network ${X11_LIBRARIES})
+target_link_libraries(${PROJECT_NAME} Qt5::Core Qt5::Network Qt5::Widgets ${X11_LIBRARIES})

README.md

@@ -32,7 +32,7 @@ You should set this option so the image resolution sent to Hyperion is at least
 Ideally you want a perfect dividor, for example if your LED array is 70x39 and screen sis 3840x2160, then you get (3840/70) 54.86 for the width and (2160/39) 55.38 for the height, the nearest perfect dividor is 48 (3840/48 = 80 ; 2160/48 = 45), if you were to use 54, then there would be rounding error (3840/54 = 71.111, but is truncated to 71) and the image sent to hyperion will not be correctly scaled.
 
 
-While watching a video with a 3840x2160 60hz display, frameskip at 1 (30fps), divisor at 24 (160x90 output resolution) CPU usage is about 2% of one cpu thread, memory usage is 17.3 KB according to HTOP. CPU usage is 0% when nothing is changing on the display.
+While watching a video with a 3840x2160 60hz display, frameskip at 1 (30fps), divisor at 24 (160x90 output resolution) CPU usage is about 0.7% of one cpu thread, memory usage is 17.3 KB according to HTOP. CPU usage is 0% when nothing is changing on the display.
 
 ## Contributing
 

hgx11grab.cpp

@@ -129,28 +129,17 @@ void hgx11grab::_grabFrame()
 
     XSync(_x11Display_p, false);
 
-    XShmGetImage(_x11Display_p, _pixmap_m, _xImage_p, 0, 0, 0x00FFFFFF);
+    XShmGetImage(_x11Display_p, _pixmap_m, _xImage_p, 0, 0, 0xFFFFFFFF);
 
     if (_xImage_p == nullptr) {
         qWarning() << "Failed to get image from X11 server.";
         return;
     }
 
+    QImage qimg = *new QImage(reinterpret_cast<const uchar *>(_xImage_p->data), _destWidth_m, _destHeight_m, _xImage_p->bytes_per_line, QImage::Format_RGBA8888);
+    qimg = qimg.convertToFormat(QImage::Format_RGB888);
     imgdata_m.clear();
-
-    if (_xImage_p->byte_order == 0) { // BGR
-        for (int i = 0; i < _imgSize_m; i += 4) {
-            imgdata_m.append(_xImage_p->data[i+2]);
-            imgdata_m.append(_xImage_p->data[i+1]);
-            imgdata_m.append(_xImage_p->data[i]);
-        }
-    } else { // RGB
-        for (int i = 0; i < _imgSize_m; i += 4) {
-            imgdata_m.append(_xImage_p->data[i]);
-            imgdata_m.append(_xImage_p->data[i+1]);
-            imgdata_m.append(_xImage_p->data[i+2]);
-        }
-    }
+    imgdata_m = QByteArray::fromRawData(reinterpret_cast<const char *>(qimg.bits()), qimg.byteCount());
 
     _freeResources();
 

hgx11grab.h

@@ -3,6 +3,7 @@
 
 #include <QObject>
 #include <QDebug>
+#include <QImage>
 #include <X11/extensions/Xrender.h>
 #include <X11/extensions/XShm.h>
 #include <sys/shm.h>

main.cpp

@@ -6,12 +6,12 @@
 static hgx11 *grab;
 static QCoreApplication *qapp;
 
-static void quit(int sig)
+static void quit(int)
 {
     if (grab != nullptr) {
         grab->~hgx11();
     }
-    qapp->exit(sig);
+    qapp->exit();
 }
 
 int main(int argc, char *argv[])