如何基于列/行输入和边距变量以及保留图像的高宽比将最大图像放置在空白位图中

Question

This might be a tricky question.

I will just cut to the chase. First i make a blank Bitmap image:

Bitmap MasterImage = new Bitmap(PageSize.Width, PageSize.Height, PixelFormat.Format32bppArgb);
System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(MasterImage);

Afterwards: I get a parameter of how much images i want to place in the Blank Bitmap (page) based on columns and rows:

int numOfColumns=2; //(could be any value)
int numOfRows=4;

So we should get something like this:

I also get a parameter if i have some margin at top image and left image:

int PagetopMargin=0; //(could be any value)
int PageLeftMargin=0;

Than i have a variable called: imagesPath which is type of List<String> it contains full path of images.

Now i loop through images:

  while (imagesPath.Count > 0)
   {
      Image image = Image.FromFile(imagesPath[0]);
    //Logic comes here. 
    //after finishing processing and drawing images in Bitmap i remove image from list
      imagesPath.RemoveAt(0);
    }

What i am trying to achieve is how to place maximum images in that Bitmap page based on column/row and margin variables and preserving aspect ratio of images. (so images wont get distorted). if some images are left behind, its okey, i will continue next blank Bitmap to place them. just need to fill the Bitmap blank image to the full.

Answer 1

Here is a function to fit a rectangle into another, either centered or uncentered (aligned top-left):

Rectangle FitToBox(Rectangle scr, Rectangle dest, bool centered)
{
    var ratioX = (double)dest.Width / scr.Width;
    var ratioY = (double)dest.Height / scr.Height;
    var ratio = Math.Min(ratioX, ratioY);

    var newWidth = (int)(scr.Width * ratio);
    var newHeight = (int)(scr.Height * ratio);

    if (!centered)
        return new Rectangle(0, 0, newWidth, newHeight);
    else
        return new Rectangle((dest.Width - newWidth) / 2, 
                             (dest.Height - newHeight) / 2, newWidth, newHeight);
}

Its basic math is taken form this post .

Here is a test bed, centered and uncentered using different random values:

Random rnd = new Random();

int cols = rnd.Next(3) + 2;
int rows = rnd.Next(4) + 3;

int w = pan_dest.Width / cols;
int h = pan_dest.Height / rows;
using (Graphics G = pan_dest.CreateGraphics())
{
    G.Clear(Color.White);
    for (int c = 0; c < cols; c++)
        for (int r = 0; r < rows; r++)
        {
            Rectangle rDest = new Rectangle(c * w, r * h, w, h);
            Rectangle rSrc = new Rectangle(0, 0, rnd.Next(200) + 10, rnd.Next(200) + 10);
            Rectangle rResult = FitToBox(rSrc, rDest, checkBox1.Checked);
            Rectangle rDestPlaced = new Rectangle(c * w + (int)rResult.X, 
                                        r * h + rResult.Y, rResult.Width, rResult.Height);

            using (Pen pen2 = new Pen(Color.SlateGray, 4f))
                G.DrawRectangle(pen2, Rectangle.Round(rDest));
            G.DrawRectangle(Pens.Red, rDestPlaced);
            G.FillEllipse(Brushes.LightPink, rDestPlaced);
        }
}

You would then draw your images like this:

  G.DrawImage(someImageimg, rDestPlaced, rSrc, GraphicsUnit.Pixel);

This maximizes the image sizes , not the number of images you can fit on a page, as specified in your comment. For the latter you should look into something like 2-dimensional packing ..