FileDocCategorySizeDatePackage
PlainView.javaAPI DocJava SE 5 API23780Fri Aug 26 14:58:16 BST 2005javax.swing.text

PlainView

public class PlainView extends View implements TabExpander
Implements View interface for a simple multi-line text view that has text in one font and color. The view represents each child element as a line of text.
author
Timothy Prinzing
version
1.74 04/15/04
see
View

Fields Summary
protected FontMetrics
metrics
Font metrics for the current font.
Element
longLine
The current longest line. This is used to calculate the preferred width of the view. Since the calculation is potentially expensive we try to avoid it by stashing which line is currently the longest.
Font
font
Font used to calculate the longest line... if this changes we need to recalculate the longest line
Segment
lineBuffer
int
tabSize
int
tabBase
int
sel0
int
sel1
Color
unselected
Color
selected
int
firstLineOffset
Offset of where to draw the first character on the first line. This is a hack and temporary until we can better address the problem of text measuring. This field is actually never set directly in PlainView, but by FieldView.
Constructors Summary
public PlainView(Element elem)
Constructs a new PlainView wrapped on an element.

param
elem the element

        super(elem);
    
Methods Summary
java.awt.ShapeadjustPaintRegion(java.awt.Shape a)
Should return a shape ideal for painting based on the passed in Shape a. This is useful if painting in a different region. The default implementation returns a.

	return a;
    
private voidcalculateLongestLine()
Iterate over the lines represented by the child elements of the element this view represents, looking for the line that is the longest. The longLine variable is updated to represent the longest line contained. The font variable is updated to indicate the font used to calculate the longest line.

	Component c = getContainer();
	font = c.getFont();
	metrics = c.getFontMetrics(font);
	Document doc = getDocument();
	Element lines = getElement();
	int n = lines.getElementCount();
	int maxWidth = -1;
	for (int i = 0; i < n; i++) {
	    Element line = lines.getElement(i);
	    int w = getLineWidth(line);
	    if (w > maxWidth) {
		maxWidth = w;
		longLine = line;
	    }
	}
    
public voidchangedUpdate(javax.swing.event.DocumentEvent changes, java.awt.Shape a, javax.swing.text.ViewFactory f)
Gives notification from the document that attributes were changed in a location that this view is responsible for.

param
changes the change information from the associated document
param
a the current allocation of the view
param
f the factory to use to rebuild if the view has children
see
View#changedUpdate

        updateDamage(changes, a, f);
    
protected voiddamageLineRange(int line0, int line1, java.awt.Shape a, java.awt.Component host)
Repaint the given line range.

param
host the component hosting the view (used to call repaint)
param
a the region allocated for the view to render into
param
line0 the starting line number to repaint. This must be a valid line number in the model.
param
line1 the ending line number to repaint. This must be a valid line number in the model.
since
1.4

        if (a != null) {
            Rectangle area0 = lineToRect(a, line0);
            Rectangle area1 = lineToRect(a, line1);
            if ((area0 != null) && (area1 != null)) {
                Rectangle damage = area0.union(area1);
                host.repaint(damage.x, damage.y, damage.width, damage.height);
            } else {
                host.repaint();
            }
        }
    
private intdrawElement(int lineIndex, javax.swing.text.Element elem, java.awt.Graphics g, int x, int y)

	int p0 = elem.getStartOffset();
        int p1 = elem.getEndOffset();
        p1 = Math.min(getDocument().getLength(), p1);

        if (lineIndex == 0) {
            x += firstLineOffset;
        }
	AttributeSet attr = elem.getAttributes();
	if (Utilities.isComposedTextAttributeDefined(attr)) {
	    g.setColor(unselected);
	    x = Utilities.drawComposedText(this, attr, g, x, y, 
					p0-elem.getStartOffset(), 
					p1-elem.getStartOffset());
	} else {
	    if (sel0 == sel1 || selected == unselected) {
		// no selection, or it is invisible
		x = drawUnselectedText(g, x, y, p0, p1);
	    } else if ((p0 >= sel0 && p0 <= sel1) && (p1 >= sel0 && p1 <= sel1)) {
		x = drawSelectedText(g, x, y, p0, p1);
	    } else if (sel0 >= p0 && sel0 <= p1) {
		if (sel1 >= p0 && sel1 <= p1) {
		    x = drawUnselectedText(g, x, y, p0, sel0);
		    x = drawSelectedText(g, x, y, sel0, sel1);
		    x = drawUnselectedText(g, x, y, sel1, p1);
		} else {
		    x = drawUnselectedText(g, x, y, p0, sel0);
		    x = drawSelectedText(g, x, y, sel0, p1);
		}
	    } else if (sel1 >= p0 && sel1 <= p1) {
		x = drawSelectedText(g, x, y, p0, sel1);
		x = drawUnselectedText(g, x, y, sel1, p1);
	    } else {
		x = drawUnselectedText(g, x, y, p0, p1);
	    }
	}
        
        return x;
    
protected voiddrawLine(int lineIndex, java.awt.Graphics g, int x, int y)
Renders a line of text, suppressing whitespace at the end and expanding any tabs. This is implemented to make calls to the methods drawUnselectedText and drawSelectedText so that the way selected and unselected text are rendered can be customized.

param
lineIndex the line to draw >= 0
param
g the Graphics context
param
x the starting X position >= 0
param
y the starting Y position >= 0
see
#drawUnselectedText
see
#drawSelectedText

        Element line = getElement().getElement(lineIndex);
	Element elem;
	
	try {
	    if (line.isLeaf()) {
                drawElement(lineIndex, line, g, x, y);
	    } else {
	        // this line contains the composed text.
	        int count = line.getElementCount();
		for(int i = 0; i < count; i++) {
		    elem = line.getElement(i);
		    x = drawElement(lineIndex, elem, g, x, y);
		}
	    }
        } catch (BadLocationException e) {
            throw new StateInvariantError("Can't render line: " + lineIndex);
        }
    
protected intdrawSelectedText(java.awt.Graphics g, int x, int y, int p0, int p1)
Renders the given range in the model as selected text. This is implemented to render the text in the color specified in the hosting component. It assumes the highlighter will render the selected background.

param
g the graphics context
param
x the starting X coordinate >= 0
param
y the starting Y coordinate >= 0
param
p0 the beginning position in the model >= 0
param
p1 the ending position in the model >= 0
return
the location of the end of the range
exception
BadLocationException if the range is invalid

        g.setColor(selected);
        Document doc = getDocument();
        Segment s = SegmentCache.getSharedSegment();
        doc.getText(p0, p1 - p0, s);
        int ret = Utilities.drawTabbedText(this, s, x, y, g, this, p0);
        SegmentCache.releaseSharedSegment(s);
        return ret;
    
protected intdrawUnselectedText(java.awt.Graphics g, int x, int y, int p0, int p1)
Renders the given range in the model as normal unselected text. Uses the foreground or disabled color to render the text.

param
g the graphics context
param
x the starting X coordinate >= 0
param
y the starting Y coordinate >= 0
param
p0 the beginning position in the model >= 0
param
p1 the ending position in the model >= 0
return
the X location of the end of the range >= 0
exception
BadLocationException if the range is invalid

        g.setColor(unselected);
        Document doc = getDocument();
        Segment s = SegmentCache.getSharedSegment();
        doc.getText(p0, p1 - p0, s);
        int ret = Utilities.drawTabbedText(this, s, x, y, g, this, p0);
        SegmentCache.releaseSharedSegment(s);
        return ret;
    
protected final javax.swing.text.SegmentgetLineBuffer()
Gives access to a buffer that can be used to fetch text from the associated document.

return
the buffer

        if (lineBuffer == null) {
            lineBuffer = new Segment();
        }
        return lineBuffer;
    
private intgetLineWidth(javax.swing.text.Element line)
Calculate the width of the line represented by the given element. It is assumed that the font and font metrics are up-to-date.

	int p0 = line.getStartOffset();
	int p1 = line.getEndOffset();
	int w;
        Segment s = SegmentCache.getSharedSegment();
	try {
	    line.getDocument().getText(p0, p1 - p0, s);
	    w = Utilities.getTabbedTextWidth(s, metrics, tabBase, this, p0);
	} catch (BadLocationException ble) {
	    w = 0;
	}
        SegmentCache.releaseSharedSegment(s);
	return w;
    
public floatgetPreferredSpan(int axis)
Determines the preferred span for this view along an axis.

param
axis may be either View.X_AXIS or View.Y_AXIS
return
the span the view would like to be rendered into >= 0. Typically the view is told to render into the span that is returned, although there is no guarantee. The parent may choose to resize or break the view.
exception
IllegalArgumentException for an invalid axis

	updateMetrics();
        switch (axis) {
        case View.X_AXIS:
	    return getLineWidth(longLine);
        case View.Y_AXIS:
            return getElement().getElementCount() * metrics.getHeight();
        default:
            throw new IllegalArgumentException("Invalid axis: " + axis);
        }
    
protected intgetTabSize()
Returns the tab size set for the document, defaulting to 8.

return
the tab size

        Integer i = (Integer) getDocument().getProperty(PlainDocument.tabSizeAttribute);
        int size = (i != null) ? i.intValue() : 8;
        return size;
    
public voidinsertUpdate(javax.swing.event.DocumentEvent changes, java.awt.Shape a, javax.swing.text.ViewFactory f)
Gives notification that something was inserted into the document in a location that this view is responsible for.

param
changes the change information from the associated document
param
a the current allocation of the view
param
f the factory to use to rebuild if the view has children
see
View#insertUpdate

	updateDamage(changes, a, f);
    
protected java.awt.RectanglelineToRect(java.awt.Shape a, int line)
Determine the rectangle that represents the given line.

param
a the region allocated for the view to render into
param
line the line number to find the region of. This must be a valid line number in the model.
since
1.4

        Rectangle r = null;
	updateMetrics();
        if (metrics != null) {
            Rectangle alloc = a.getBounds();
            if (line == 0) {
                alloc.x += firstLineOffset;
                alloc.width -= firstLineOffset;
            }
            r = new Rectangle(alloc.x, alloc.y + (line * metrics.getHeight()),
                              alloc.width, metrics.getHeight());
        }
        return r;
    
public java.awt.ShapemodelToView(int pos, java.awt.Shape a, javax.swing.text.Position$Bias b)
Provides a mapping from the document model coordinate space to the coordinate space of the view mapped to it.

param
pos the position to convert >= 0
param
a the allocated region to render into
return
the bounding box of the given position
exception
BadLocationException if the given position does not represent a valid location in the associated document
see
View#modelToView

        // line coordinates
        Document doc = getDocument();
        Element map = getElement();
        int lineIndex = map.getElementIndex(pos);
        Rectangle lineArea = lineToRect(a, lineIndex);
        
        // determine span from the start of the line
        tabBase = lineArea.x;
        Element line = map.getElement(lineIndex);
        int p0 = line.getStartOffset();
        Segment s = SegmentCache.getSharedSegment();
        doc.getText(p0, pos - p0, s);
        int xOffs = Utilities.getTabbedTextWidth(s, metrics, tabBase, this,p0);
        SegmentCache.releaseSharedSegment(s);

        // fill in the results and return
        lineArea.x += xOffs;
        lineArea.width = 1;
        lineArea.height = metrics.getHeight();
        return lineArea;
    
public floatnextTabStop(float x, int tabOffset)
Returns the next tab stop position after a given reference position. This implementation does not support things like centering so it ignores the tabOffset argument.

param
x the current position >= 0
param
tabOffset the position within the text stream that the tab occurred at >= 0.
return
the tab stop, measured in points >= 0

	if (tabSize == 0) {
	    return x;
	}
        int ntabs = (((int) x) - tabBase) / tabSize;
        return tabBase + ((ntabs + 1) * tabSize);
    
public voidpaint(java.awt.Graphics g, java.awt.Shape a)
Renders using the given rendering surface and area on that surface. The view may need to do layout and create child views to enable itself to render into the given allocation.

param
g the rendering surface to use
param
a the allocated region to render into
see
View#paint

	Shape originalA = a;
	a = adjustPaintRegion(a);
        Rectangle alloc = (Rectangle) a;
        tabBase = alloc.x;
	JTextComponent host = (JTextComponent) getContainer();
        Highlighter h = host.getHighlighter();
        g.setFont(host.getFont());
        sel0 = host.getSelectionStart();
        sel1 = host.getSelectionEnd();
        unselected = (host.isEnabled()) ? 
            host.getForeground() : host.getDisabledTextColor();
	Caret c = host.getCaret();
        selected = c.isSelectionVisible() && h != null ?
                       host.getSelectedTextColor() : unselected;
	updateMetrics();

        // If the lines are clipped then we don't expend the effort to
        // try and paint them.  Since all of the lines are the same height
        // with this object, determination of what lines need to be repainted
        // is quick.
        Rectangle clip = g.getClipBounds();
        int fontHeight = metrics.getHeight();
        int heightBelow = (alloc.y + alloc.height) - (clip.y + clip.height);
        int linesBelow = Math.max(0, heightBelow / fontHeight);
        int heightAbove = clip.y - alloc.y;
        int linesAbove = Math.max(0, heightAbove / fontHeight);
        int linesTotal = alloc.height / fontHeight;

	if (alloc.height % fontHeight != 0) {
	    linesTotal++;
	}
        // update the visible lines
        Rectangle lineArea = lineToRect(a, linesAbove);
        int y = lineArea.y + metrics.getAscent();
        int x = lineArea.x;
        Element map = getElement();
	int lineCount = map.getElementCount();
        int endLine = Math.min(lineCount, linesTotal - linesBelow);
	lineCount--;
	LayeredHighlighter dh = (h instanceof LayeredHighlighter) ?
	                   (LayeredHighlighter)h : null;
        for (int line = linesAbove; line < endLine; line++) {
	    if (dh != null) {
		Element lineElement = map.getElement(line);
		if (line == lineCount) {
		    dh.paintLayeredHighlights(g, lineElement.getStartOffset(),
					      lineElement.getEndOffset(),
					      originalA, host, this);
		}
		else {
		    dh.paintLayeredHighlights(g, lineElement.getStartOffset(),
					      lineElement.getEndOffset() - 1,
					      originalA, host, this);
		}
	    }
            drawLine(line, g, x, y);
            y += fontHeight;
            if (line == 0) {
                // This should never really happen, in so far as if
                // firstLineOffset is non 0, there should only be one
                // line of text.
                x -= firstLineOffset;
            }
        }
    
public voidremoveUpdate(javax.swing.event.DocumentEvent changes, java.awt.Shape a, javax.swing.text.ViewFactory f)
Gives notification that something was removed from the document in a location that this view is responsible for.

param
changes the change information from the associated document
param
a the current allocation of the view
param
f the factory to use to rebuild if the view has children
see
View#removeUpdate

        updateDamage(changes, a, f);
    
public voidsetSize(float width, float height)
Sets the size of the view. This should cause layout of the view along the given axis, if it has any layout duties.

param
width the width >= 0
param
height the height >= 0

        super.setSize(width, height);
        updateMetrics();
    
protected voidupdateDamage(javax.swing.event.DocumentEvent changes, java.awt.Shape a, javax.swing.text.ViewFactory f)

	Component host = getContainer();
	updateMetrics();
	Element elem = getElement();
	DocumentEvent.ElementChange ec = changes.getChange(elem);
	
	Element[] added = (ec != null) ? ec.getChildrenAdded() : null;
	Element[] removed = (ec != null) ? ec.getChildrenRemoved() : null;
	if (((added != null) && (added.length > 0)) || 
	    ((removed != null) && (removed.length > 0))) {
	    // lines were added or removed...
	    if (added != null) {
		int currWide = getLineWidth(longLine);
		for (int i = 0; i < added.length; i++) {
		    int w = getLineWidth(added[i]);
		    if (w > currWide) {
			currWide = w;
			longLine = added[i];
		    }
		}
	    }
	    if (removed != null) {
		for (int i = 0; i < removed.length; i++) {
		    if (removed[i] == longLine) {
			calculateLongestLine();
			break;
		    }
		}
	    }
	    preferenceChanged(null, true, true);
	    host.repaint();
	} else {
	    Element map = getElement();
	    int line = map.getElementIndex(changes.getOffset());
	    damageLineRange(line, line, a, host);
	    if (changes.getType() == DocumentEvent.EventType.INSERT) {
		// check to see if the line is longer than current
		// longest line.
		int w = getLineWidth(longLine);
		Element e = map.getElement(line);
		if (e == longLine) {
		    preferenceChanged(null, true, false);
		} else if (getLineWidth(e) > w) {
		    longLine = e;
		    preferenceChanged(null, true, false);
		}
	    } else if (changes.getType() == DocumentEvent.EventType.REMOVE) {
		if (map.getElement(line) == longLine) {
		    // removed from longest line... recalc
		    calculateLongestLine();
		    preferenceChanged(null, true, false);
		}			
	    }
	}
    
protected voidupdateMetrics()
Checks to see if the font metrics and longest line are up-to-date.

since
1.4

	Component host = getContainer();
	Font f = host.getFont();
	if (font != f) {
	    // The font changed, we need to recalculate the
	    // longest line.
	    calculateLongestLine();
	    tabSize = getTabSize() * metrics.charWidth('m");
	}
    
public intviewToModel(float fx, float fy, java.awt.Shape a, javax.swing.text.Position$Bias[] bias)
Provides a mapping from the view coordinate space to the logical coordinate space of the model.

param
fx the X coordinate >= 0
param
fy the Y coordinate >= 0
param
a the allocated region to render into
return
the location within the model that best represents the given point in the view >= 0
see
View#viewToModel

	// PENDING(prinz) properly calculate bias
	bias[0] = Position.Bias.Forward;

        Rectangle alloc = a.getBounds();
        Document doc = getDocument();
        int x = (int) fx;
        int y = (int) fy;
        if (y < alloc.y) {
            // above the area covered by this icon, so the the position
            // is assumed to be the start of the coverage for this view.
            return getStartOffset();
        } else if (y > alloc.y + alloc.height) {
            // below the area covered by this icon, so the the position
            // is assumed to be the end of the coverage for this view.
            return getEndOffset() - 1;
        } else {
            // positioned within the coverage of this view vertically,
            // so we figure out which line the point corresponds to.
            // if the line is greater than the number of lines contained, then
            // simply use the last line as it represents the last possible place
            // we can position to.
            Element map = doc.getDefaultRootElement();
            int lineIndex = Math.abs((y - alloc.y) / metrics.getHeight() );
            if (lineIndex >= map.getElementCount()) {
                return getEndOffset() - 1;
            }
            Element line = map.getElement(lineIndex);
            int dx = 0;
            if (lineIndex == 0) {
                alloc.x += firstLineOffset;
                alloc.width -= firstLineOffset;
            }
            if (x < alloc.x) {
                // point is to the left of the line
                return line.getStartOffset();
            } else if (x > alloc.x + alloc.width) {
                // point is to the right of the line
                return line.getEndOffset() - 1;
            } else {
                // Determine the offset into the text
                try {
                    int p0 = line.getStartOffset();
                    int p1 = line.getEndOffset() - 1;
                    Segment s = SegmentCache.getSharedSegment();
                    doc.getText(p0, p1 - p0, s);
                    tabBase = alloc.x;
                    int offs = p0 + Utilities.getTabbedTextOffset(s, metrics,
                                                                  tabBase, x, this, p0);
                    SegmentCache.releaseSharedSegment(s);
                    return offs;
                } catch (BadLocationException e) {
                    // should not happen
                    return -1;
                }
            }
        }