Author: Tony Soong (2012011271)

Time: 8/28/2013

All the source for RST implementations can be found on RST/lib. Since this is an outdated project, I will not provide other support. The code should be correct.

This is the document for my project for the Qt class. It is used to display Rectilinear Steiner Trees using a Qt Application.

• Help(Ctrl+H): Displays help for the project.
• File->Read(Ctrl+R): Reads some point data from a file, and displays them.
• File->Refresh(Ctrl+E): Clears all the lines on the window, and resets the view point.
• File->Clean(Ctrl+C): Clears everything on the window.
• Algorithm->SMST(Ctrl+S): Displays the Minimum Spanning Tree of the points.
• Algorithm->LMST(Ctrl+L): Displays the RST obtained by algorithm of LMST.
• Algorithm->ZMST(Ctrl+Z): Displays the RST obtained by algorithm of ZMST.
• Add Point: Use Add Point(Ctrl+N) or Right Click on a place without points.
• Delete Point: Right Click on a point to delete that point.
• Drag Point: Left Click on a point and drag the point to replace the point.
• Move Viewpoint: Use Arrow Keys or Right Click & Drag to move the whole canvas.
• Zoom In/Zoom Out: Use Zoom In(Ctrl+>), Zoom Out(Ctrl+<), or the mouse wheel.

• MainWindow: the main window for the application.
• SketchPad: the class for painting and stores the data of points and lines.
• AddPoint: (inherited from QDialog) the class used to manually add a point.

The MainWindow class mainly creates the overall environment of the class, such as the menu bars, tool bars, and status bars. The first two contains the actions connected to the SketchPad class pointer, namely MainWindow.sketchpad, which further operates the data and displays the points.

The SketchPad class gets input from files or manually, deals with the algorithms(SMST, LMST, ZMST) and paints the points by using QPainter and paintEvent(). Whenever we change the points or lines in SketchPad, it will call update() and renews the picture.

Note that the MainWindow also deals with keyborad inputs as the MainWindow.sketchpad cannot be selected by keyborad input, while mouse inputs are dealt in SketchPad class, since we need to further information on the exact positions of the points, and doing it in MainWindow will cause deviations(for about (0px, -40px) on my computer).

AddPoint is a simple QDialog class which uses hard-coded layouts, and deals with input points.

Event handling is largely used. In this project, wheelEvent(), mouseMoveEvent(), mousePressEvent(), mouseReleaseEvent(), keyPressEvent() and paintEvent() are used. They mainly serve to change the data points and repaint the picture. Private variables are used for them to temporarily store the data generated by previous events, so that posterior events can use them for calculation, such as:

void SketchPad::mousePressEvent(QMouseEvent *event) {
    if (event->button() == Qt::RightButton) {
        rightStartPos = event->pos();
        rightDragged = false;
        rightSelected = -1;
		//...
	}
	//...
}

Painting is very essential for correct event handling. This implementation uses three variables to calculate the display position of points, namely (xView, yView), (xFocus, yFocus), and scale. xView and yView adjusts the view point of the canvas and is largely used in transition; scale adjusts the size of the canvas which is used in zooming; xFocus and yFocus adjusts the central point for zooming. The function to derive the painting point from the original point(and vice versa) are as follows:

Point SketchPad::calculatePaintPoint(int x, int y) {
    int xx = (x - xFocus) * scale + xFocus + xView;
    int yy = (y - yFocus) * scale + yFocus + yView;
    return Point(xx, yy);
}

Point SketchPad::calculateOriginalPoint(int x, int y) {
    int xx = (x - xFocus - xView) / scale + xFocus;
    int yy = (y - yFocus - yView) / scale + yFocus;
    return Point(xx, yy);
}

These are very simple actions for us to connect with Qt predefined classes, and we don't need them between our classes.

readAction = new QAction(tr("&Read"), this);
readAction -> setShortcut(tr("Ctrl+R"));
//...
connect(readAction, SIGNAL(triggered()), this, SLOT(read()));