Automation Editor - Straighten out draw line function (#3997)

Fixes:
  AutomationEditor::drawLine(..) - quantize input
  AutomationEditor::drawLine(..) - Adjust line level.

Author: zonkmachine

src/gui/editors/AutomationEditor.cpp

@@ -434,9 +434,11 @@ void AutomationEditor::leaveEvent(QEvent * e )
 }
 
 
-void AutomationEditor::drawLine( int x0, float y0, int x1, float y1 )
+void AutomationEditor::drawLine( int x0In, float y0, int x1In, float y1 )
 {
-	int deltax = qRound( qAbs<float>( x1 - x0 ) );
+	int x0 = Note::quantized( x0In, AutomationPattern::quantization() );
+	int x1 = Note::quantized( x1In, AutomationPattern::quantization() );
+	int deltax = qAbs( x1 - x0 );
 	float deltay = qAbs<float>( y1 - y0 );
 	int x = x0;
 	float y = y0;
@@ -452,7 +454,7 @@ void AutomationEditor::drawLine( int x0, float y0, int x1, float y1 )
 
 	float yscale = deltay / ( deltax );
 
-	if( x0 < x1)
+	if( x0 < x1 )
 	{
 		xstep = AutomationPattern::quantization();
 	}
@@ -461,19 +463,22 @@ void AutomationEditor::drawLine( int x0, float y0, int x1, float y1 )
 		xstep = -( AutomationPattern::quantization() );
 	}
 
+	float lineAdjust;
 	if( y0 < y1 )
 	{
 		ystep = 1;
+		lineAdjust = yscale;
 	}
 	else
 	{
 		ystep = -1;
+		lineAdjust = -( yscale );
 	}
 
 	int i = 0;
 	while( i < deltax )
 	{
-		y = y0 + ( ystep * yscale * i );
+		y = y0 + ( ystep * yscale * i ) + lineAdjust;
 
 		x += xstep;
 		i += 1;