[PATCH RFC] Run create_plot_info in a separate thread

[Anton Lundin]

This is a crude attempt to reduce the gui lag while we are calculating
things for the plot, as tts/deco.

This will delay the whole plot a while, but the gui won't freeze
meanwhile.

This is more a rough cut of what could be done than whats a real
solution.
---
 qt-ui/profilegraphics.cpp | 65 ++++++++++++++++++++++++++++++++++++-----------
 qt-ui/profilegraphics.h   |  8 ++++++
 2 files changed, 58 insertions(+), 15 deletions(-)

diff --git a/qt-ui/profilegraphics.cpp b/qt-ui/profilegraphics.cpp
index f2d8e74..8912624 100644
--- a/qt-ui/profilegraphics.cpp
+++ b/qt-ui/profilegraphics.cpp
@@ -19,6 +19,7 @@
 #include <qtextdocument.h>
 #include <QMessageBox>
 #include <limits>
+#include <QtGui>
 
 #include "../color.h"
 #include "../display.h"
@@ -365,9 +366,54 @@ void ProfileGraphicsView::plot(struct dive *d, bool forceRedraw)
 		dc = fake_dc(dc);
 	}
 
-	QString nick = get_dc_nickname(dc->model, dc->deviceid);
+	/*
+	 * Set up limits that are independent of
+	 * the dive computer
+	 */
+	calculate_max_limits(dive, diveDC, &gc);
+
+	QRectF profile_grid_area = scene()->sceneRect();
+	gc.maxx = (profile_grid_area.width() - 2 * profile_grid_area.x());
+	gc.maxy = (profile_grid_area.height() - 2 * profile_grid_area.y());
+
+
+	/* Hack tu run create_plot_info async */
+	if (future.isRunning()) {
+		printf("future is running\n");
+		future.cancel();
+		future.waitForFinished();
+	}
+	if (watcher != NULL) {
+		printf("watcher not NULL!\n");
+		delete watcher;
+		watcher = NULL;
+	}
+	printf("Scheduling\n");
+	watcher = new QFutureWatcher<struct plot_info *>();
+	future = QtConcurrent::run(create_plot_info, dive, dc, &gc);
+	watcher->setFuture(future);
+	QObject::connect(watcher, SIGNAL(finished()), this, SLOT(plot2()));
+}
+
+void ProfileGraphicsView::plot2()
+{
+	delete watcher;
+	watcher = NULL;
+
+	/* This is per-dive-computer */
+	gc.pi = *future.result();
+
+	/* Did we cancel? */
+	if (future.isCanceled())
+		return;
+
+	gc.pi = *create_plot_info(dive, diveDC, &gc);
+
+	printf("future returned a pi\n");
+
+	QString nick = get_dc_nickname(diveDC->model, diveDC->deviceid);
 	if (nick.isEmpty())
-		nick = QString(dc->model);
+		nick = QString(diveDC->model);
 
 	if (nick.isEmpty())
 		nick = tr("unknown divecomputer");
@@ -378,18 +424,7 @@ void ProfileGraphicsView::plot(struct dive *d, bool forceRedraw)
 		mode = DIVE;
 	}
 
-	/*
-	 * Set up limits that are independent of
-	 * the dive computer
-	 */
-	calculate_max_limits(dive, dc, &gc);
-
 	QRectF profile_grid_area = scene()->sceneRect();
-	gc.maxx = (profile_grid_area.width() - 2 * profile_grid_area.x());
-	gc.maxy = (profile_grid_area.height() - 2 * profile_grid_area.y());
-
-	/* This is per-dive-computer */
-	gc.pi = *create_plot_info(dive, dc, &gc);
 
 	/* Bounding box */
 	QPen pen = defaultPen;
@@ -400,7 +435,7 @@ void ProfileGraphicsView::plot(struct dive *d, bool forceRedraw)
 
 	/* Depth profile */
 	plot_depth_profile();
-	plot_events(dc);
+	plot_events(diveDC);
 
 	if (rulerEnabled && !printMode)
 		create_ruler();
@@ -458,7 +493,7 @@ void ProfileGraphicsView::plot(struct dive *d, bool forceRedraw)
 	}
 
 	if (!printMode)
-		addControlItems(d);
+		addControlItems(dive);
 
 	if (rulerEnabled && !printMode)
 		add_ruler();
diff --git a/qt-ui/profilegraphics.h b/qt-ui/profilegraphics.h
index 059b667..e4d8140 100644
--- a/qt-ui/profilegraphics.h
+++ b/qt-ui/profilegraphics.h
@@ -9,6 +9,8 @@
 #include <QDoubleSpinBox>
 #include <QPushButton>
 #include <QGraphicsProxyWidget>
+#include <QFuture>
+#include <QFutureWatcher>
 
 struct text_render_options;
 struct graphics_context;
@@ -154,6 +156,8 @@ public slots:
 	void hideEvents();
 	void removeEvent();
 	void addBookmark();
+private slots:
+	void plot2();
 private:
 	void plot_depth_profile();
 	QGraphicsItemGroup *plot_text(text_render_options_t *tro, const QPointF& pos, const QString &text, QGraphicsItem *parent = 0);
@@ -211,6 +215,10 @@ private:
 	GraphicsTextEditor *timeEditor;
 
 	enum Mode mode;
+
+	//Used to call plot2
+	QFutureWatcher<struct plot_info *> *watcher = NULL;
+	QFuture<struct plot_info *> future;
 };
 
 #endif
-- 
1.8.3.2