From: Shamus Hammons <jlhamm@acm.org>
Date: Sat, 23 Jan 2021 02:55:26 +0000 (-0600)
Subject: Fix scrollwheel zooming from walking all over the screen.
X-Git-Url: http://shamusworld.gotdns.org/cgi-bin/gitweb.cgi?p=architektonas;a=commitdiff_plain;h=e34f829de8f46c03e74f75e46438433153f6b96d

Fix scrollwheel zooming from walking all over the screen.

Turns out that Global::zoom was being unnecessarily updated by
SetGridSize(), causing zooming to walk all over the screen.  :-P
---

diff --git a/src/drawingview.cpp b/src/drawingview.cpp
index d35bd14..dc68532 100644
--- a/src/drawingview.cpp
+++ b/src/drawingview.cpp
@@ -145,7 +145,8 @@ void DrawingView::SetGridSize(uint32_t size)
 	pmp.end();
 
 	// Set up new BG brush & zoom level (pixels per base unit)
-	Global::zoom = gridPixels / Global::gridSpacing;
+// This shouldn't be done here, because it fucks up the scrollwheel zooming...
+//	Global::zoom = gridPixels / Global::gridSpacing;
 	UpdateGridBackground();
 }
 
@@ -1783,6 +1784,13 @@ void DrawingView::mousePressEvent(QMouseEvent * event)
 
 void DrawingView::mouseMoveEvent(QMouseEvent * event)
 {
+	// It seems that wheelEvent() triggers this for some reason...
+	if (scrollWheelSeen)
+	{
+		scrollWheelSeen = false;
+		return;
+	}
+
 	Vector point = Painter::QtToCartesianCoords(Vector(event->x(), event->y()));
 	Global::selection.setBottomRight(QPointF(point.x, point.y));
 	// Only needs to be done here, as mouse down is always preceded by movement
@@ -1989,32 +1997,31 @@ void DrawingView::mouseReleaseEvent(QMouseEvent * event)
 void DrawingView::wheelEvent(QWheelEvent * event)
 {
 	double zoomFactor = 1.25;
-	QSize sizeWin = size();
-	Vector center(sizeWin.width() / 2.0, sizeWin.height() / 2.0);
-	center = Painter::QtToCartesianCoords(center);
+	scrollWheelSeen = true;
 
-	// This is not centering for some reason. Need to figure out why. :-/
-	if (event->delta() > 0)
+	if (event->delta() < 0)
 	{
 		if (Global::zoom > 20.0)
 			return;
 
-		Vector newOrigin = center - ((center - Global::origin) / zoomFactor);
-		Global::origin = newOrigin;
 		Global::zoom *= zoomFactor;
+//		Point np = Painter::QtToCartesianCoords(oldScrollPoint);
+//		Global::origin += (oldPoint - np);
 	}
 	else
 	{
 		if (Global::zoom < 0.25)
 			return;
 
-		Vector newOrigin = center + ((-center + Global::origin) * zoomFactor);
-		Global::origin = newOrigin;
 		Global::zoom /= zoomFactor;
+//		Point np = Painter::QtToCartesianCoords(oldScrollPoint);
+//		Global::origin += (oldPoint - np);
 	}
 
+	Point np = Painter::QtToCartesianCoords(oldScrollPoint);
+	Global::origin += (oldPoint - np);
+
 //	Global::gridSpacing = gridPixels / Painter::zoom;
-//	UpdateGridBackground();
 	SetGridSize(Global::gridSpacing * Global::zoom);
 	update();
 //	zoomIndicator->setText(QString("Grid: %1\", BU: Inch").arg(Global::gridSpacing));
diff --git a/src/drawingview.h b/src/drawingview.h
index 9d543c4..d252ffc 100644
--- a/src/drawingview.h
+++ b/src/drawingview.h
@@ -109,6 +109,7 @@ class DrawingView: public QWidget
 		bool draggingObject;
 		bool angleSnap;
 		bool dirty;
+		bool scrollWheelSeen;
 };
 
 #endif	// __DRAWINGVIEW_H__