If label already exists in given coordinates, it will be updated

Author: yurii-litvinov

trikControl/include/trikControl/display.h

@@ -40,9 +40,11 @@ public slots:
 	/// supported formats, but .jpg, .png, .bmp, .gif are supported.
 	void showImage(QString const &fileName);
 
-	/// Add a label to the specific position of the screen.
+	/// Add a label to the specific position of the screen. If there already is a label in these coordinates, its
+	/// contents will be updated.
 	/// @param text - label text.
-	/// @param x @param y - label coordinates.
+	/// @param x - label x coordinate.
+	/// @param y - label y coordinate.
 	void addLabel(QString const &text, int x, int y);
 
 	/// Remove all labels from the screen.

trikControl/src/display.cpp

@@ -52,7 +52,7 @@ void trikControl::Display::showImage(QString const &fileName)
 	emit threadShowImage(fileName);
 }
 
-void Display::addLabel(const QString &text, int x, int y)
+void Display::addLabel(QString const &text, int x, int y)
 {
 	emit threadAddLabel(text, x, y);
 }

trikControl/src/guiWorker.cpp

@@ -52,22 +52,27 @@ void GuiWorker::showImage(QString const &fileName)
 	mImageWidget.show();
 }
 
-void GuiWorker::addLabel(const QString &text, int x, int y)
+void GuiWorker::addLabel(QString const &text, int x, int y)
 {
-	QLabel *label = new QLabel(&mImageWidget);
+	QLabel *label = findLabel(x, y);
+	label = label ? label : new QLabel(&mImageWidget);
 	label->setText(text);
 	label->setGeometry(x, y, label->width(), label->height());
 	label->show();
-	mLabels.append(label);
+	if (!mLabels.contains(x ^ y, label)) {
+		mLabels.insertMulti(x ^ y, label);
+	}
+
 	mImageWidget.show();
 }
 
 void GuiWorker::removeLabels()
 {
-	foreach (QLabel *label, mLabels) {
+	foreach (QLabel * const label, mLabels.values()) {
 		label->close();
 		delete label;
 	}
+
 	mLabels.clear();
 }
 
@@ -127,3 +132,13 @@ void GuiWorker::hide()
 	mImageWidget.hide();
 }
 
+QLabel *GuiWorker::findLabel(int x, int y) const
+{
+	foreach (QLabel * const label, mLabels.values(x ^ y)) {
+		if (label->x() == x && label->y() == y) {
+			return label;
+		}
+	}
+
+	return NULL;
+}

trikControl/src/guiWorker.h

@@ -15,7 +15,7 @@
 #pragma once
 
 #include <QtCore/qglobal.h>
-#include <QtCore/QHash>
+#include <QtCore/QMultiHash>
 #include <QtCore/QList>
 #include <QtGui/QPixmap>
 
@@ -29,6 +29,7 @@
 
 namespace trikControl {
 
+/// Works in GUI thread and is responsible for all output to display.
 class GuiWorker : public QObject
 {
 	Q_OBJECT
@@ -37,21 +38,38 @@ class GuiWorker : public QObject
 	GuiWorker();
 
 public slots:
+	/// Shows image with given filename on display. Image is scaled to fill the screen and is cached on first read
+	/// for better performance.
 	void showImage(QString const &fileName);
+
+	/// Add a label to the specific position of the screen. If there already is a label in these coordinates, its
+	/// contents will be updated.
+	/// @param text - label text.
+	/// @param x - label x coordinate.
+	/// @param y - label y coordinate.
 	void addLabel(QString const &text, int x, int y);
+
+	/// Remove all labels from the screen.
 	void removeLabels();
+
+	/// Queues worker object for deletion. It is actually deleted when control flow returns to event loop.
 	void deleteWorker();
+
+	/// Hides image widget.
 	void hide();
 
 	/// Sets background for a picture.
 	/// @param color - color of a background.
 	void setBackground(QString const &color);
 
 private:
+	/// Returns existing label with given coordinates or NULL if no such label exists.
+	QLabel *findLabel(int x, int y) const;
+
 	QWidget mImageWidget;
 	QLabel mImageLabel;
 	QHash<QString, QPixmap> mImagesCache;
-	QList<QLabel *> mLabels; // Has ownership.
+	QMultiHash<int, QLabel *> mLabels; // Has ownership.
 };
 
 }