Zooming the selected rectangle of an image

Question

I am working on zooming selected rectangle of an image. But for some reason the selected area has not been displayed in the picture box. I do want only zoom the selected area. But the following code does not work properly. What could be the problem? Thanks for any help.

   private void Form1_MouseDown(object sender,
        System.Windows.Forms.MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
           if (popupMenuZoomOptionSelected)
           {
                    isDrag = true;
                    Control control = (Control)sender;

                    ptLast.X = -1;
                    ptLast.Y = -1;
                    ptOriginal.X = -1;
                    ptOriginal.Y = -1;
                    // Make a note that we "have the mouse".
                    bHaveMouse = true;

                    ptOriginal.X = e.X;
                    ptOriginal.Y = e.Y;

                    ptLast.X = -1;
                    ptLast.Y = -1;

                    startPoint = control.PointToScreen(new Point(e.X, e.Y));


           }
        }
    }

    private void Form1_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
    {

        if (isDrag)

       {

           Point endPoint = ((Control)sender).PointToScreen(new Point(e.X, e.Y));
            int width = endPoint.X - startPoint.X;
            int height = endPoint.Y - startPoint.Y;

            if (bHaveMouse)
            {
                if (endPoint.X > this.pbImage.Width)
                {
                    endPoint.X = this.pbImage.Width;
                }

                if (endPoint.X < 0)
                {
                    endPoint.X = 0;
                }

                if (endPoint.Y < 0)
                {
                    endPoint.Y = 0;
                }

                if (endPoint.Y > this.pbImage.Height)
                {
                    endPoint.Y = this.pbImage.Height;
                }

                // Update last point.
                ptLast = endPoint;


            ControlPaint.DrawReversibleFrame(theRectangle,
                this.BackColor, FrameStyle.Dashed);

             }


            theRectangle = new Rectangle(startPoint.X,
                startPoint.Y, width, height);

            // Draw the new rectangle by calling DrawReversibleFrame
            // again.  
            ControlPaint.DrawReversibleFrame(theRectangle,
                this.BackColor, FrameStyle.Dashed);

        }
    }


    private void Form1_MouseUp(object sender,
        System.Windows.Forms.MouseEventArgs e)
    {

        // If the MouseUp event occurs, the user is not dragging.
        isDrag = false;

        // Draw the rectangle to be evaluated. Set a dashed frame style 
        // using the FrameStyle enumeration.
        ControlPaint.DrawReversibleFrame(theRectangle,
            this.BackColor, FrameStyle.Dashed);

        bHaveMouse = false;

        Rectangle controlRectangle;
        for (int i = 0; i < Controls.Count; i++)
        {
            controlRectangle = Controls[i].RectangleToScreen
                (Controls[i].ClientRectangle);
            if (controlRectangle.IntersectsWith(theRectangle))
            {
                Controls[i].BackColor = Color.BurlyWood;
            }
        }

        if (ptLast.X > ptOriginal.X)
        {
            selectedAreaWidth = ptLast.X - ptOriginal.X;
            selectedAreaStartingPointX = ptOriginal.X;
        }
        else
        {
            selectedAreaWidth = ptOriginal.X - ptLast.X;
            selectedAreaStartingPointX = ptLast.X;
        };

        if (ptLast.Y > ptOriginal.Y)
        {
            selectedAreaStartingPointY = ptOriginal.Y;
            selectedAreaHeight = ptLast.Y - ptOriginal.Y;
        }
        else
        {
            selectedAreaStartingPointY = ptLast.Y;
            selectedAreaHeight = ptOriginal.Y - ptLast.Y;
        }

        // Set flags to know that there is no "previous" line to reverse.
        ptLast.X = -1;
        ptLast.Y = -1;
        ptOriginal.X = -1;
        ptOriginal.Y = -1;

        int _ZoomFactor = 2;
        int zoomWidth = pbImage.Width / _ZoomFactor;
        int zoomHeight = pbImage.Height / _ZoomFactor;

        int halfWidth = zoomWidth / 2;
        int halfHeight = zoomHeight / 2;

        // Create a new temporary bitmap to fit inside the picZoom picturebox
        Bitmap tempBitmap = new Bitmap(zoomWidth, zoomHeight, PixelFormat.Format24bppRgb);

       Graphics bmGraphics = Graphics.FromImage(tempBitmap);


        bmGraphics.InterpolationMode = InterpolationMode.HighQualityBicubic;

        bmGraphics.DrawImage(pbImage.Image,
                             new Rectangle(0, 0, zoomWidth, zoomHeight),
                             new Rectangle(e.X - halfWidth, e.Y - halfHeight, zoomWidth, zoomHeight),
                             GraphicsUnit.Pixel);

        // Draw the bitmap on the picZoom picturebox
        pbImage.Image = tempBitmap;


        ptLast.X = -1;
        ptLast.Y = -1;
       // Reset the rectangle.
        theRectangle = new Rectangle(0, 0, 0, 0);
    }

Answer 1

Perhaps this will help you:

http://www.bobpowell.net/zoompicbox.htm