org.apache.batik.ext.awt.font.TextPathLayout Maven / Gradle / Ivy
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package org.apache.batik.ext.awt.font;
import java.awt.Shape;
import java.awt.font.GlyphMetrics;
import java.awt.font.GlyphVector;
import java.awt.geom.AffineTransform;
import java.awt.geom.GeneralPath;
import java.awt.geom.Point2D;
import org.apache.batik.ext.awt.geom.PathLength;
/**
* PathLayout can layout text along a Shape, usually a Path object.
*
* There are a number of improvements that could be made to this class.
* I'll try to list some of them:
*
* - The layout should really only modify the GlyphVector, rather
* than converting to a Shape.
*
- Maybe the functions should take a AttributedCharacterIterator
* or something? Should this class do the entire layout?
*
- The layout code works, but it's definitely not perfect.
*
* @author Dean Jackson
* @version $Id: TextPathLayout.java 1808001 2017-09-11 09:51:29Z ssteiner $
*/
public class TextPathLayout {
/**
* Align the text at the start of the path.
*/
public static final int ALIGN_START = 0;
/**
* Align the text at the middle of the path.
*/
public static final int ALIGN_MIDDLE = 1;
/**
* Align the text at the end of the path.
*/
public static final int ALIGN_END = 2;
/**
* Use the spacing between the glyphs to adjust for textLength.
*/
public static final int ADJUST_SPACING = 0;
/**
* Use the entire glyph to adjust for textLength.
*/
public static final int ADJUST_GLYPHS = 1;
/**
* Wraps the GlyphVector around the given path. The results
* are mostly quite nice but you need to be careful choosing
* the size of the font that created the GlyphVector, as
* well as the "curvyness" of the path (really dynamic curves
* don't look so great, abrupt changes/vertices look worse).
*
* @param glyphs The GlyphVector to layout.
* @param path The path (or shape) to wrap around
* @param align The text alignment to use. Should be one
* of ALIGN_START, ALIGN_MIDDLE or ALIGN_END.
* @param startOffset The offset from the start of the path for the initial
* text position.
* @param textLength The length that the text should fill.
* @param lengthAdjustMode The method used to expand or contract
* the text to meet the textLength.
* @return A shape that is the outline of the glyph vector
* wrapped along the path
*/
public static Shape layoutGlyphVector(GlyphVector glyphs,
Shape path, int align,
float startOffset,
float textLength,
int lengthAdjustMode) {
GeneralPath newPath = new GeneralPath();
PathLength pl = new PathLength(path);
float pathLength = pl.lengthOfPath();
if ( glyphs == null ){
return newPath;
}
float glyphsLength = (float) glyphs.getVisualBounds().getWidth();
// return from the ugly cases
if (path == null ||
glyphs.getNumGlyphs() == 0 ||
pl.lengthOfPath() == 0f ||
glyphsLength == 0f) {
return newPath;
}
// work out the expansion/contraction per character
float lengthRatio = textLength / glyphsLength;
// the current start point of the character on the path
float currentPosition = startOffset;
// if align is START then a currentPosition of 0f
// is correct.
// if align is END then the currentPosition should
// be enough to place the last character on the end
// of the path
// if align is MIDDLE then the currentPosition should
// be enough to center the glyphs on the path
if (align == ALIGN_END) {
currentPosition += pathLength - textLength;
} else if (align == ALIGN_MIDDLE) {
currentPosition += (pathLength - textLength) / 2;
}
// iterate through the GlyphVector placing each glyph
for (int i = 0; i < glyphs.getNumGlyphs(); i++) {
GlyphMetrics gm = glyphs.getGlyphMetrics(i);
float charAdvance = gm.getAdvance();
Shape glyph = glyphs.getGlyphOutline(i);
// if lengthAdjust was GLYPHS, then scale the glyph
// by the lengthRatio in the X direction
// FIXME: for vertical text this will be the Y direction
if (lengthAdjustMode == ADJUST_GLYPHS) {
AffineTransform scale = AffineTransform.getScaleInstance(lengthRatio, 1.0f);
glyph = scale.createTransformedShape(glyph);
// charAdvance has to scale accordingly
charAdvance *= lengthRatio;
}
float glyphWidth = (float) glyph.getBounds2D().getWidth();
// Use either of these to calculate the mid point
// of the character along the path.
// If you change this, you must also change the
// transform on the glyph down below
// In some case this gives better layout, but
// the way it is at the moment is a closer match
// to the textPath layout from the SVG spec
//float charMidPos = currentPosition + charAdvance / 2f;
float charMidPos = currentPosition + glyphWidth / 2f;
// Calculate the actual point to place the glyph around
Point2D charMidPoint = pl.pointAtLength(charMidPos);
// Check if the glyph is actually on the path
if (charMidPoint != null) {
// Calculate the normal to the path (midline of glyph)
float angle = pl.angleAtLength(charMidPos);
// Define the transform of the glyph
AffineTransform glyphTrans = new AffineTransform();
// translate to the point on the path
glyphTrans.translate(charMidPoint.getX(), charMidPoint.getY());
// rotate midline of glyph to be normal to path
glyphTrans.rotate(angle);
// translate glyph backwards so we rotate about the
// center of the glyph
// Choose one of these translations - see the comments
// in the charMidPos calculation above
glyphTrans.translate(charAdvance / -2f, 0f);
//glyphTrans.translate(glyphWidth / -2f, 0f);
glyph = glyphTrans.createTransformedShape(glyph);
newPath.append(glyph, false);
}
// move along by the advance value
// if the lengthAdjustMode was SPACING then
// we have to take this into account here
if (lengthAdjustMode == ADJUST_SPACING) {
currentPosition += (charAdvance * lengthRatio);
} else {
currentPosition += charAdvance;
}
}
return newPath;
}
/**
* Wraps the GlyphVector around the given path.
*
* @param glyphs The GlyphVector to layout.
* @param path The path (or shape) to wrap around
* @param align The text alignment to use. Should be one
* of ALIGN_START, ALIGN_MIDDLE or ALIGN_END.
* @return A shape that is the outline of the glyph vector
* wrapped along the path
*/
public static Shape layoutGlyphVector(GlyphVector glyphs,
Shape path, int align) {
return layoutGlyphVector(glyphs, path, align, 0f,
(float) glyphs.getVisualBounds().getWidth(),
ADJUST_SPACING);
}
/**
* Wraps the GlyphVector around the given path.
*
* @param glyphs The GlyphVector to layout.
* @param path The path (or shape) to wrap around
* @return A shape that is the outline of the glyph vector
* wrapped along the path
*/
public static Shape layoutGlyphVector(GlyphVector glyphs,
Shape path) {
return layoutGlyphVector(glyphs, path, ALIGN_START);
}
} // TextPathLayout