Question

I need to order windows in “rectangle” form. It’s mean that when I have six windows it orders it in rectangle 2×3, when I have 5 windows it orders it 2×3 but without last window, when I have 9 windows it orders in 3×3. But I’ve got some troubles with coordinates – child windows are out of bounds of mdiparent window.(img)

I used the same algorithm as I used in my mdi application on java

for(int i=0;i<a;i++)
    for(int j=0;j<b;j++)
         try{
             indfr.get(counter).setLocation(i*theDesktop.getWidth()/a,j*theDesktop.getHeight()/b);
             indfr.get(counter).setSize(theDesktop.getWidth()/a,theDesktop.getHeight()/b);
             counter++;
            }catch (IndexOutOfBoundsException exc){ break;}

where indfr - arralist of JInternalFrames,and theDesktop - JDesktopPane

Algorithm in c#

for (int i = 0; i < a; i++)
    for (int j = 0; j < b; j++)
            try
            {
                list[counter].SetDesktopLocation(i*list[counter].MdiParent.Width/a, j*list[counter].MdiParent.Height/b);
                list[counter].Size = new Size(list[counter].MdiParent.Width/a, list[counter].MdiParent.Height/b);
                counter++;
            }
            catch (IndexOutOfRangeException)
            {
                break;
            }

where list – Form[] list = this.MdiChildern;

What is wrong with coordinates?
(P.S it is not whole algorithm but it is the main loop where windows are ordering)

Answer 1

The problem lines are those inside of your try block:

list[counter].SetDesktopLocation(i*list[counter].MdiParent.Width/a, j*list[counter].MdiParent.Height/b);
list[counter].Size = new Size(list[counter].MdiParent.Width/a, list[counter].MdiParent.Height/b);
counter++;

You’re checking Form.Width and Form.Height, which return the total size of the form on the screen, including all of the borders. You can only place child windows inside the client area of the parent form, so you need to query the ClientSize property instead. That is defined as the size of the form, minus the borders and title bar; in other words, the area of the form in which children can be placed.

Re-write your try block to this, instead:

list[counter].SetDesktopLocation(i*list[counter].MdiParent.ClientSize.Width/a, j*list[counter].MdiParent.ClientSize.Height/b);
list[counter].Size = new Size(list[counter].MdiParent.ClientSize.Width/a, list[counter].MdiParent.ClientSize.Height/b);
counter++;

And then get rid of that silly empty catch block. If all you’re doing when an exception is thrown is breaking, then there’s no point in catching the exception. It will bubble up to the next exception handler, all the way to the global one if necessary. Only catch exceptions that you know specifically how to handle. You shouldn’t be getting an IndexOutOfRangeException, and if you do, that’s a bug in your code—you want to know about it so that you can fix it. That means not swallowing the exception.

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But, if I may channel Clippy here, it looks like you’re trying to tile your MDI children.

In that case, there’s an easier method than writing a bunch of for loops and manually setting the size and position of your children. Instead, just call the Form.LayoutMdi method on your parent MDI form, and specify one of the MdiLayout enumeration values. In this case, you probably want either MdiLayout.TileHorizontal or MdiLayout.TileVertical.

WinForms will take care of arranging your child windows precisely how you want them automatically.