Re: Strange Behaviour with scaled fonts.

From:
Knute Johnson <nospam@rabbitbrush.frazmtn.com>
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 11 Jun 2008 20:24:21 -0700
Message-ID:
<485096e5$0$4071$b9f67a60@news.newsdemon.com>
RichT wrote:

Hi all,
I am experiencing some strange behaviour when scaling and drawing fonts.

Firstly the font is scaled and is drawn to the canvas positioning is
fine and behaviour as expected, I am using font =
font.deriveFont(affineTransform) on the font to scale it.

Text is typed into a text area and displayed in the canvas.

The problem is when I write this font to an image, the font seems
different but worse it draws the test slightly to the top and right of
the original text.

To clarify, text is typed into a text area, and font size colour and
type can be changed and this is reflected on the text being drawn to the
canvas.

When I draw the text to the image it moves slightly top and right but
only if the fnt is scaled <> 1:1

I have included the code which draws the text to the canvas and to the
image, so hopefully someone can pinpoint what I am doing wrong :)

public void drawTextToCanvas(Graphics g, Rectangle rect) {
       
        // number of lines of text
        int count = 0;
        Graphics2D g2d = (Graphics2D) g;

        g2d.setColor(textArea.getForeground());

//
            Font font = new Font(textArea.getFont().getFontName(),
textArea.getFont().getStyle(),

(int)(textArea.getFont().getSize()));
            // scale font to match image scale.
            g2d.setFont(font.deriveFont(transformToClient));

        saveFont = g2d.getFont();

            FontMetrics fm = g2d.getFontMetrics();

            int textHeight = fm.getHeight()
            String textToWrite = textArea.getText();

        maxWidth = (int)((fm.stringWidth(textToWrite);

                rect.width = (int)((maxWidth));
                    g2d.drawString(textToWrite, rect.x + 5, (rect.y + +
(fm.getHeight() - 5)));

                }
            }

            g2d.dispose();
        }
    }

public void drawTextToImage(Graphics g, Rectangle rect) {
       
       
        Graphics2D g2d = (Graphics2D) getImage().getGraphics();

        g2d.setFont(saveFont);
        FontMetrics fm = g2d.getFontMetrics();
    textToWrite = textArea.getText()

                    g2d.drawString(textToWrite, rect.x + 5, (rect.y +
(fm.getHeight() - 5)));

                }
            }

            g2d.dispose();
        }
    }

these two methods are called by paintComponent depending if text is
being written to canvas (it is being typed in text area) or button
pressed to draw it to the image.

Hope someone can help
Cheers
Rich


Fonts do not scale perfectly.

You should use the same rendering code for both, that may solve some of
your problems. Have paintComponent() call the rendering method and when
you are ready to draw on the image, call render with the image's Graphics.

--

Knute Johnson
email s/nospam/knute2008/

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