Justifying text using DrawString in C#

Question

I'm drawing text on a System.Drawing.Graphics object. I'm using the DrawString method, with the text string, a Font, a Brush, a bounding RectangleF, and a StringFormat as arguments.

Looking into StringFormat, I've found that I can set it's Alignment property to Near, Center or Far. However I haven't found a way to set it to Justified. How can I achieve this?

Thank you for your help!

Answer 1

There is no built-in way to do it. Some work-arounds are mentioned on this thread:

http://social.msdn.microsoft.com/Forums/zh/winforms/thread/aebc7ac3-4732-4175-a95e-623fda65140e

They suggest using an overridden RichTextBox, overriding the SelectionAlignment property (see this page for how) and setting it to Justify.

The guts of the override revolve around this pInvoke call:

PARAFORMAT fmt = new PARAFORMAT();
fmt.cbSize = Marshal.SizeOf(fmt);
fmt.dwMask = PFM_ALIGNMENT;
fmt.wAlignment = (short)value;

SendMessage(new HandleRef(this, Handle), // "this" is the RichTextBox
    EM_SETPARAFORMAT,
    SCF_SELECTION, ref fmt);

Not sure how well this can be integrated into your existing model (since I assume you're drawing more than text), but it might be your only option.

Answer 2

I FOUND IT :)

http://csharphelper.com/blog/2014/10/fully-justify-a-line-of-text-in-c/

in brief - you can justify text in each separate line when you know the given width of the entire paragraph:

float extra_space = rect.Width - total_width; // where total_width is the sum of all measured width for each word
int num_spaces = words.Length - 1; // where words is the array of all words in a line
if (words.Length > 1) extra_space /= num_spaces; // now extra_space has width (in px) for each space between words

the rest is pretty intuitive:

float x = rect.Left;
float y = rect.Top;
for (int i = 0; i < words.Length; i++)
{
    gr.DrawString(words[i], font, brush, x, y);

    x += word_width[i] + extra_space; // move right to draw the next word.
}