Performing Overlap Detection of 2 Bitmaps

Question

I have a custom picturebox control that allows dragging 2 bitmaps separately on the Main image,thus allowing the user to select the location of the 2 bitmaps.

For First Bitmap

Point src = e.Location;
PointF ratio = new PointF((float)src.X / ClientSize.Width, (float)src.Y / ClientSize.Height);
LaunchOrigin.textratio = ratio;
Point origin = new Point((int)(backupbit1.Width * ratio.X), (int)(backupbit1.Height * ratio.Y));
LaunchOrigin.textorigin = origin;
point.X = src.X - origin.X;
point.Y = src.Y - origin.Y;

For Second Bitmap

Point src = e.Location;
PointF ratio = new PointF((float)src.X / Width, (float)src.Y / Height);
LaunchOrigin.logoratio = ratio;
Point origin = new Point((int)(backupbit2.Width * ratio.X), (int)(backupbit2.Height * ratio.Y));
LaunchOrigin.logoorigin = origin;
point2.X = src.X - origin.X;
point2.Y = src.Y - origin.Y;

This is location is returned to the Main form which contains the full resolution image.In order to properly translate the 2 points (of the 2 bitmaps) i do the following.

Point origin = new Point((int)(bitmap.Width * textratio.X), (int)(bitmap.Height * textratio.Y));
Point pos2 = new Point((int)(textratio.X * img.Width), (int)(textratio.Y * img.Height));
cpoint.X = pos2.X - (int)(origin.X);
cpoint.Y = pos2.Y - (int)(origin.Y);

Point origin = new Point((int)(worktag.Width * logoratio.X), (int)(worktag.Height * logoratio.Y));
Point logopositionpoint = new Point((int)(logoratio.X * img.Width), (int)(logoratio.Y * img.Height));
imgpoint.X = logopositionpoint.X - origin.X;
imgpoint.Y = logopositionpoint.Y - origin.Y;

This works pretty fine when the 2 Bitmaps are placed at distant locations.But when the 2 bitmaps are placed closer to each other and the full resolution image becomes lesser in height than the reference image used for placing the bitmaps these 2 bitmaps overlap.

I'm i doing something wrong? Or do i need to do some overlap detection?

Please advice..

Answer 1

I crated a sample code which works on form. The form has picturebox that gets the image from the button. You can change it if the solution works. The Form has the componenets ( pictureBox, btnImage)

Here is the complete code

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        Image img1;
        Image img2;
        public Form1()
        {
            InitializeComponent();

            Image img = Image.FromFile(@"C:\pics\1.jpg");
            this.btnImage.Image = img;
            this.pcitureBox.AllowDrop = true;                
        }

        private void btnImage_MouseDown(object sender, MouseEventArgs e)
        {
            Button btnPic = (Button)sender;
            btnPic.DoDragDrop(btnPic.Image, DragDropEffects.Copy);
        }

        private void picBox_DragEnter(object sender, DragEventArgs e)
        {
            if (e.Data.GetDataPresent(DataFormats.Bitmap))
            {
                e.Effect = DragDropEffects.Copy;
            }
            else
            {
                e.Effect = DragDropEffects.None;
            }
        }

        int img1X = 0;
        int img1Y = 0;
        private void picBox_DragDrop(object sender, DragEventArgs e)
        {
            var point = this.PointToClient(new Point(e.X, e.Y));
            int X = point.X - pcitureBox.Left;
            int Y = point.Y - pcitureBox.Top;



                PictureBox picbox = (PictureBox)sender;
                Graphics g = picbox.CreateGraphics();
                if (img1 == null)
                {
                    img1 = (Image)e.Data.GetData(DataFormats.Bitmap);
                    img1X=X;
                    img1Y = Y;
                    g.DrawImage(img1, new Point(img1X, img1Y));

                    return;
                }
                else
                {
                    #region add img2
                    img2 = (Image)e.Data.GetData(DataFormats.Bitmap);

                    //img1 has standart 0,0 point u can change
                    Rectangle r1 = new Rectangle(img1X, img1Y,     img1.Width, img1.Height);
                    Rectangle r2 = new Rectangle(X, Y, img2.Width,   img2.Height);
                    Rectangle overlapRect = Rectangle.Intersect(r1, r2);

                    int img2X = X;
                    int img2Y = Y;
                    if (overlapRect.Width > 0 || overlapRect.Height > 0)
                    {
                        bool betweenX = overlapRect.X >= r1.X &&         overlapRect.X <= (r1.X + r1.Height);
                        bool betweenY = overlapRect.Y >= r1.Y &&     overlapRect.Y <= (r1.Y + r1.Width);

                        if (betweenX)
                        {
                            img2X = GetNewX(r1, r2);
                        }
                        else if (betweenY)
                        {
                            img2Y = GetNewY(r1, r2);
                        }
                        else
                        {
                            if (overlapRect.Width <= overlapRect.Height)
                            {
                                img2X = GetNewX(r1, r2);
                            }
                            else
                            {
                                img2Y = GetNewY(r1, r2);
                            }
                        }
                    }
                    g.DrawImage(img1, new Point(img2X, img2Y));
                    #endregion
                }

        }

        private int GetNewX(Rectangle r1, Rectangle r2)
        {
            if (r2.X < r1.X)
            {
                return r1.X - r2.Width;
            }
            else
            {
                return r1.X + r1.Width;
            }
        }
        private int GetNewY(Rectangle r1, Rectangle r2)
        {
            if (r2.Y < r1.Y)
            {
                return r1.Y - r2.Height;
            }
            else
            {
                return r1.Y + r1.Height;
            }
        }

    }
}