add brightness controls (#888)

Closes #860

libs/canvas.py

@@ -23,6 +23,7 @@ CURSOR_GRAB = Qt.OpenHandCursor
 
 class Canvas(QWidget):
     zoomRequest = pyqtSignal(int)
+    lightRequest = pyqtSignal(int)
     scrollRequest = pyqtSignal(int, int)
     newShape = pyqtSignal()
     selectionChanged = pyqtSignal(bool)
@@ -47,6 +48,7 @@ class Canvas(QWidget):
         self.prev_point = QPointF()
         self.offsets = QPointF(), QPointF()
         self.scale = 1.0
+        self.overlay_color = None
         self.label_font_size = 8
         self.pixmap = QPixmap()
         self.visible = {}
@@ -503,7 +505,15 @@ class Canvas(QWidget):
         p.scale(self.scale, self.scale)
         p.translate(self.offset_to_center())
 
-        p.drawPixmap(0, 0, self.pixmap)
+        temp = self.pixmap
+        if self.overlay_color:
+            temp = QPixmap(self.pixmap)
+            painter = QPainter(temp)
+            painter.setCompositionMode(painter.CompositionMode_Overlay)
+            painter.fillRect(temp.rect(), self.overlay_color)
+            painter.end()
+
+        p.drawPixmap(0, 0, temp)
         Shape.scale = self.scale
         Shape.label_font_size = self.label_font_size
         for shape in self.shapes:
@@ -607,7 +617,9 @@ class Canvas(QWidget):
             v_delta = delta.y()
 
         mods = ev.modifiers()
-        if Qt.ControlModifier == int(mods) and v_delta:
+        if int(Qt.ControlModifier) | int(Qt.ShiftModifier) == int(mods) and v_delta:
+            self.lightRequest.emit(v_delta)
+        elif Qt.ControlModifier == int(mods) and v_delta:
             self.zoomRequest.emit(v_delta)
         else:
             v_delta and self.scrollRequest.emit(v_delta, Qt.Vertical)

libs/lightWidget.py

@@ -0,0 +1,33 @@
+try:
+    from PyQt5.QtGui import *
+    from PyQt5.QtCore import *
+    from PyQt5.QtWidgets import *
+except ImportError:
+    from PyQt4.QtGui import *
+    from PyQt4.QtCore import *
+
+
+class LightWidget(QSpinBox):
+
+    def __init__(self, title, value=50):
+        super(LightWidget, self).__init__()
+        self.setButtonSymbols(QAbstractSpinBox.NoButtons)
+        self.setRange(0, 100)
+        self.setSuffix(' %')
+        self.setValue(value)
+        self.setToolTip(title)
+        self.setStatusTip(self.toolTip())
+        self.setAlignment(Qt.AlignCenter)
+
+    def minimumSizeHint(self):
+        height = super(LightWidget, self).minimumSizeHint().height()
+        fm = QFontMetrics(self.font())
+        width = fm.width(str(self.maximum()))
+        return QSize(width, height)
+
+    def color(self):
+        if self.value() == 50:
+            return None
+
+        strength = int(self.value()/100 * 255 + 0.5)
+        return QColor(strength, strength, strength)