Implements #2635: Draws a transparent rectangle in the loop area (plus CSS exposure) (#2657)

* Draws a transparent rectangle in the loop area (plus CSS exposure)

The color for the rectangle can be defined in the style CSS for the
active and inactive case. The following properties of the TimeLineWidget
are exposed through the CSS:
- The color of the lines that are drawn for each bar
- The color of the bar numbers
- The font size (given in pt)
- The minimum and the maximum height of the widget (given in em so that it scales with the font size). Set both to the same value to set a fixed size.
- The background of the widget
- A loop color: The color for the main rectangle's pen
- A loop brush: The brush used to fill the main rectangle
- An inner loop color: The color used for the pen that draws the inner border.
- loopRectangleVerticalPadding: specifies the padding used for the loop indicator rectangle.

The bar numbers are drawn conditionally like the bar lines. The
numbers are drawn with a constant distance to the tact line. This gives
a more consistent picture at different zoom levels and also fixes the
broken look at very small zoom sizes like for example 12.5%.

The bar numbers are drawn with hinting so that they show up less blurry on low DPI displays.

Remove the pixmaps that have been used up to now to draw the loop
boundaries.

Removes the unused "TimeLine" from style.css.

Document the style sheet properties for the loop indicator rectangle.

data/themes/classic/style.css

@@ -533,8 +533,28 @@ Fader {
 	qproperty-peakRed: rgb( 255, 100, 100);
 }
 
-TimeLine {
-	font-size: 8px;
+TimeLineWidget {
+        /* font-size only supports px and pt. */
+	font-size: 7pt;
+	/* lengths also support em. This will make sure that the height
+	   will always change in the same proportion as the font size
+	   defined above.
+	   If you want a fixed size set min and max to the same value. */
+	min-height: 1.5em;
+	max-height: 1.5em;
+
+        background-color: qlineargradient( x1: 0, y1: 0, x2: 0, y2: 1,
+	                                   stop: 0 #8796a7, stop: 1.0 #3e454e );
+
+        qproperty-inactiveLoopColor: rgba( 52, 63, 53, 64 );
+	qproperty-inactiveLoopBrush: rgba( 255, 255, 255, 32 );
+	qproperty-inactiveLoopInnerColor: rgba( 255, 255, 255, 32 );
+	qproperty-activeLoopColor: rgba( 52, 63, 53, 255 );
+	qproperty-activeLoopBrush: qlineargradient( x1: 0, y1: 0, x2: 0, y2: 1,
+	                                            stop: 0 #378d59, stop: 1.0 #297e36 );
+	qproperty-activeLoopInnerColor: rgba( 74, 155, 100, 255 );
+	qproperty-barLineColor: rgb( 192, 192, 192 );
+	qproperty-barNumberColor: rgb( 192, 192, 192 );
 }
 
 QTreeView {

data/themes/default/style.css

@@ -536,8 +536,36 @@ Fader {
 	qproperty-peakRed: #660505;
 }
 
-TimeLine {
-	font-size: 8px;
+TimeLineWidget {
+	/* font-size only supports px and pt. */
+	font-size: 7pt;
+	/* lengths also support em. This will make sure that the height
+	   will always change in the same proportion as the font size
+	   defined above.
+	   If you want a fixed size set min and max to the same value. */
+	min-height: 1.5em;
+	max-height: 1.5em;
+
+	/* Properties for the loop indicator rectangle in inactive state:
+	    - LoopColor: Color of the outermost border
+	    - LoopBrush: Brush to paint the main portion of the rectangle
+	    - LoopInnerColor: Color used to paint the inlayed border */
+	qproperty-inactiveLoopColor: #3B424A;
+	qproperty-inactiveLoopBrush: #3B424A;
+	qproperty-inactiveLoopInnerColor: #3B424A;
+
+	/* Properties for the loop indicator rectangle in active state.
+	   See above for detailed description. */
+	qproperty-activeLoopColor: #21A14F;
+	qproperty-activeLoopBrush: #21A14F;
+	qproperty-activeLoopInnerColor: #21A14F;
+
+	/* Vertical padding for the loop indicator rectangle.
+	   A value of zero draws the rectangle at the full height of the widget. */
+	qproperty-loopRectangleVerticalPadding: 1;
+
+	qproperty-barLineColor: rgb( 192, 192, 192 );
+	qproperty-barNumberColor: rgb( 192, 192, 192 );
 }
 
 QTreeView {