[freetype2-demos] master 448cc83 2/3: [ftinspect] Prepare zoom for drawing pixel center.

[Werner LEMBERG]

branch: master
commit 448cc839c2c186e5009cab8f8186c3af3b27076b
Author: Werner Lemberg <address@hidden>
Commit: Werner Lemberg <address@hidden>

    [ftinspect] Prepare zoom for drawing pixel center.
    
    This change makes the zoom use only even values larger than a given
    threshold; it also implements (kind of) logarithmic zooming.
    
    * src/ftinspect.h (QSpinBoxx): New class, derived from `QSpinBox'.
    (MainGUI): Updated.
    
    * src/ftinspect.cpp (MainGUI::createLayout): Updated.
    (QSpinBoxx::valueFromText, QSpinBoxx::stepBy): New methods.
---
 ChangeLog         |   13 ++++++++
 src/ftinspect.cpp |   88 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 src/ftinspect.h   |   14 ++++++++-
 3 files changed, 111 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 7d95d02..f109371 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2016-05-29  Werner Lemberg  <address@hidden>
+
+       [ftinspect] Prepare zoom for drawing pixel center.
+
+       This change makes the zoom use only even values larger than a given
+       threshold; it also implements (kind of) logarithmic zooming.
+
+       * src/ftinspect.h (QSpinBoxx): New class, derived from `QSpinBox'.
+       (MainGUI): Updated.
+
+       * src/ftinspect.cpp (MainGUI::createLayout): Updated.
+       (QSpinBoxx::valueFromText, QSpinBoxx::stepBy): New methods.
+
 2016-05-26  Werner Lemberg  <address@hidden>
 
        [ftbench] Add support for third TrueType interpreter version.
diff --git a/src/ftinspect.cpp b/src/ftinspect.cpp
index e56785b..edec05c 100644
--- a/src/ftinspect.cpp
+++ b/src/ftinspect.cpp
@@ -2138,10 +2138,10 @@ MainGUI::createLayout()
 
   zoomLabel = new QLabel(tr("Zoom Factor"));
   zoomLabel->setAlignment(Qt::AlignRight);
-  zoomSpinBox = new QSpinBox;
+  zoomSpinBox = new QSpinBoxx;
   zoomSpinBox->setAlignment(Qt::AlignRight);
-  zoomSpinBox->setRange(1, 1000);
-  zoomSpinBox->setSingleStep(1);
+  zoomSpinBox->setRange(1, 1000 - 1000 % 64);
+  zoomSpinBox->setKeyboardTracking(false);
   zoomLabel->setBuddy(zoomSpinBox);
 
   previousFontButton = new QPushButton(tr("Previous Font"));
@@ -2511,6 +2511,88 @@ QGraphicsViewx::resizeEvent(QResizeEvent* event)
 
 /////////////////////////////////////////////////////////////////////////////
 //
+// QSpinBoxx
+//
+/////////////////////////////////////////////////////////////////////////////
+
+// we want to mark the center of a pixel square with a single dot or a small
+// cross; starting with a certain magnification we thus only use even values
+// so that we can do that symmetrically
+
+int
+QSpinBoxx::valueFromText(const QString& text) const
+{
+  int val = QSpinBox::valueFromText(text);
+
+  if (val > 640)
+    val = val - (val % 64);
+  else if (val > 320)
+    val = val - (val % 32);
+  else if (val > 160)
+    val = val - (val % 16);
+  else if (val > 80)
+    val = val - (val % 8);
+  else if (val > 40)
+    val = val - (val % 4);
+  else if (val > 20)
+    val = val - (val % 2);
+
+  return val;
+}
+
+
+void
+QSpinBoxx::stepBy(int steps)
+{
+  int val = value();
+
+  if (steps > 0)
+  {
+    for (int i = 0; i < steps; i++)
+    {
+      if (val >= 640)
+        val = val + 64;
+      else if (val >= 320)
+        val = val + 32;
+      else if (val >= 160)
+        val = val + 16;
+      else if (val >= 80)
+        val = val + 8;
+      else if (val >= 40)
+        val = val + 4;
+      else if (val >= 20)
+        val = val + 2;
+      else
+        val++;
+    }
+  }
+  else if (steps < 0)
+  {
+    for (int i = 0; i < -steps; i++)
+    {
+      if (val > 640)
+        val = val - 64;
+      else if (val > 320)
+        val = val - 32;
+      else if (val > 160)
+        val = val - 16;
+      else if (val > 80)
+        val = val - 8;
+      else if (val > 40)
+        val = val - 4;
+      else if (val > 20)
+        val = val - 2;
+      else
+        val--;
+    }
+  }
+
+  setValue(val);
+}
+
+
+/////////////////////////////////////////////////////////////////////////////
+//
 // QComboBoxx
 //
 /////////////////////////////////////////////////////////////////////////////
diff --git a/src/ftinspect.h b/src/ftinspect.h
index 789f8b3..bf6e9af 100644
--- a/src/ftinspect.h
+++ b/src/ftinspect.h
@@ -285,6 +285,18 @@ private:
 };
 
 
+// we want to have our own `stepBy' function for the zoom spin box
+class QSpinBoxx
+: public QSpinBox
+{
+  Q_OBJECT
+
+public:
+  void stepBy(int);
+  int valueFromText(const QString&) const;
+};
+
+
 // we want to grey out items in a combo box;
 // since Qt doesn't provide a function for this we derive a class
 class QComboBoxx
@@ -482,7 +494,7 @@ private:
   QSlider *gammaSlider;
 
   QSpinBox *dpiSpinBox;
-  QSpinBox *zoomSpinBox;
+  QSpinBoxx *zoomSpinBox;
 
   QTabWidget *tabWidget;