From dd963415de36f8e0e61e251d8ecf5c3342e5c0c1 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Wed, 8 Nov 2017 14:49:23 +0100
Subject: [PATCH] + found a solution using painter path to fix the text rending
 in image view

---
 src/Mod/Image/Gui/GLImageBox.cpp     |  4 +-
 src/Mod/Image/Gui/ImageView.cpp      |  4 +-
 src/Mod/Image/Gui/OpenGLImageBox.cpp | 88 ++++++++++++----------------
 3 files changed, 44 insertions(+), 52 deletions(-)

diff --git a/src/Mod/Image/Gui/GLImageBox.cpp b/src/Mod/Image/Gui/GLImageBox.cpp
index d7e00cc911..fc6d3c2544 100644
--- a/src/Mod/Image/Gui/GLImageBox.cpp
+++ b/src/Mod/Image/Gui/GLImageBox.cpp
@@ -84,7 +84,9 @@ GLImageBox::~GLImageBox()
 // Set up the OpenGL rendering state
 void GLImageBox::initializeGL()
 {
-    qglClearColor( Qt::black );		// Let OpenGL clear to black
+    QPalette p = this->palette();
+    qglClearColor(p.color(this->backgroundRole()));		// Let OpenGL clear to background color
+    //qglClearColor(Qt::black);		// Let OpenGL clear to black
     static bool init = false;
     if (!init) {
         init = true;
diff --git a/src/Mod/Image/Gui/ImageView.cpp b/src/Mod/Image/Gui/ImageView.cpp
index aa9dfb1e2c..9c52551e36 100644
--- a/src/Mod/Image/Gui/ImageView.cpp
+++ b/src/Mod/Image/Gui/ImageView.cpp
@@ -61,7 +61,7 @@ ImageView::ImageView(QWidget* parent)
     // In order to fix this problem we directly pass the pointer of the parent
     // of this ImageView, i.e. the main window.
     // Note:
-    // Since Qt the class QGLWidget is marked as deprecated and should be
+    // Since Qt5 the class QGLWidget is marked as deprecated and should be
     // replaced by QOpenGLWidget.
 
 #if defined(HAVE_QT5_OPENGL)
@@ -489,7 +489,7 @@ void ImageView::wheelEvent(QWheelEvent * cEvent)
 
 void ImageView::showEvent (QShowEvent *)
 {
-    //_pGLImageBox->setFocus();
+    _pGLImageBox->setFocus();
 }
 
 // Update the status bar with the image parameters for the current mouse position
diff --git a/src/Mod/Image/Gui/OpenGLImageBox.cpp b/src/Mod/Image/Gui/OpenGLImageBox.cpp
index 36c41cad15..8dd1e74886 100644
--- a/src/Mod/Image/Gui/OpenGLImageBox.cpp
+++ b/src/Mod/Image/Gui/OpenGLImageBox.cpp
@@ -139,7 +139,7 @@ void GLImageBox::initializeGL()
         connect(logger, &QOpenGLDebugLogger::messageLogged, this, &GLImageBox::handleLoggedMessage);
 
         if (logger->initialize())
-            logger->startLogging();
+            logger->startLogging(QOpenGLDebugLogger::SynchronousLogging);
     }
 #endif
 }
@@ -858,70 +858,60 @@ unsigned int GLImageBox::pixValToMapIndex(double PixVal)
     }
 }
 
+// https://learnopengl.com/?_escaped_fragment_=In-Practice/Text-Rendering#!In-Practice/Text-Rendering
 void GLImageBox::renderText(int x, int y, const QString& str, const QFont& fnt)
 {
-    // replacement for QGLWidget::renderText
-    // FIXME: The result looks very poor!
-
     if (str.isEmpty() || !isValid())
         return;
 
-    QOpenGLFunctions *f = QOpenGLContext::currentContext()->functions();
+    //glPushClientAttrib(GL_CLIENT_ALL_ATTRIB_BITS);
+    //glPushAttrib(GL_ALL_ATTRIB_BITS);
 
-    GLint view[4];
-    bool use_scissor_testing = f->glIsEnabled(GL_SCISSOR_TEST);
-    //if (!use_scissor_testing)
-        f->glGetIntegerv(GL_VIEWPORT, &view[0]);
-
-
-    glPushClientAttrib(GL_CLIENT_ALL_ATTRIB_BITS);
-    glPushAttrib(GL_ALL_ATTRIB_BITS);
-    glMatrixMode(GL_TEXTURE);
-    glPushMatrix();
-    glLoadIdentity();
-    glMatrixMode(GL_PROJECTION);
-    glPushMatrix();
-    glMatrixMode(GL_MODELVIEW);
-    glPushMatrix();
-
-    glShadeModel(GL_FLAT);
-    glDisable(GL_CULL_FACE);
-    glDisable(GL_LIGHTING);
-    glDisable(GL_STENCIL_TEST);
-    glDisable(GL_DEPTH_TEST);
+#if 0
     glEnable(GL_BLEND);
-    glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
-
-    QRect viewport(view[0], view[1], view[2], view[3]);
-    if (!use_scissor_testing && viewport != rect()) {
-        // if the user hasn't set a scissor box, we set one that
-        // covers the current viewport
-        f->glScissor(view[0], view[1], view[2], view[3]);
-        f->glEnable(GL_SCISSOR_TEST);
-    } else if (use_scissor_testing) {
-        // use the scissor box set by the user
-        f->glEnable(GL_SCISSOR_TEST);
-    }
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
     GLfloat color[4];
-    f->glGetFloatv(GL_CURRENT_COLOR, &color[0]);
+    glGetFloatv(GL_CURRENT_COLOR, &color[0]);
     QColor col;
     col.setRgbF(color[0], color[1], color[2],color[3]);
 
-    QPainter painter(this);
+    QFont font(fnt);
+    font.setStyleHint(QFont::Times, QFont::PreferAntialias);
+
+    QPainter painter;
+    painter.begin(this);
+    painter.setRenderHint(QPainter::Antialiasing);
+    painter.setRenderHint(QPainter::TextAntialiasing);
+
+    painter.setFont(font);
     painter.setPen(col);
-    painter.setFont(fnt);
     painter.drawText(x, y, str);
     painter.end();
+#else
+    GLfloat color[4];
+    glGetFloatv(GL_CURRENT_COLOR, &color[0]);
+    QColor col;
+    col.setRgbF(color[0], color[1], color[2],color[3]);
 
-    glMatrixMode(GL_TEXTURE);
-    glPopMatrix();
-    glMatrixMode(GL_PROJECTION);
-    glPopMatrix();
-    glMatrixMode(GL_MODELVIEW);
-    glPopMatrix();
-    glPopAttrib();
-    glPopClientAttrib();
+    QFont font(fnt);
+    font.setStyleHint(QFont::Times, QFont::PreferAntialias);
+
+    QPainterPath textPath;
+    textPath.addText(x, y, font, str);
+
+    QPainter painter;
+    painter.begin(this);
+    painter.setRenderHint(QPainter::Antialiasing);
+    painter.setRenderHint(QPainter::TextAntialiasing);
+
+    painter.setBrush(col);
+    painter.setPen(Qt::NoPen);
+    painter.drawPath(textPath);
+    painter.end();
+#endif
+    //glPopAttrib();
+    //glPopClientAttrib();
 }
 
 #include "moc_OpenGLImageBox.cpp"