我正在尝试将自定义绘制的图形与jSlider的比例对齐（滑块为图形提供X轴比例）。我需要滑块旋钮来设置与图形相关的值，所以它确实需要是一个jSlider。
问题是，如果刻度标签的长度发生变化，那么刻度的第一个（和最后一个）刻度标记的起始位置将会不同，这需要我手动更改图形的位置以匹配。
是否可以设置滑块的比例，然后确定第一个刻度线的像素位置，以便我可以设置图形的开头以匹配？
BasicSliderUI的trackRect.x将为我提供正确的X点位置，但我无法访问它。我继续使用以下代码获取trackRect上的空指针;我显然遗漏了一些非常基本的东西，因为我通过扩展BasicSliderUI看到了RangeSlider访问trackRect.x。我根本不会压倒任何类似的东西：访问trackRect.x值的类：
import javax.swing.JSlider;
import javax.swing.plaf.basic.BasicSliderUI;
public class ExtendedBasicSliderUI extends BasicSliderUI
{
public ExtendedBasicSliderUI(JSlider b)
{
super(b);
}
public int getScaleStartPosition()
{
return trackRect.x;
}
}
在包含滑块的视图的构造函数中：
initComponents();
extendedUI = new ExtendedBasicSliderUI(jSlider1);
jSlider1.setUI(extendedUI);
criteriaModel.setGraphAlignmentIntervalRatio(extendedUI.getScaleStartPosition());
答案 0 :(得分：0)
我应该在很久以前回答过，因为我最终找到了解决方法 我从这里修改了范围滑块的代码：http://ernienotes.wordpress.com/2010/12/27/creating-a-java-swing-range-slider/ 抱歉，我必须删除Java Doc注释以使其符合3000个字符限制。
滑块类代码如下：
import javax.swing.JSlider;
public class RangeSlider extends JSlider
{
RangeSliderUI rangeUI;
public RangeSlider()
{
initSlider();
}
public RangeSlider(int min, int max)
{
super(min, max);
initSlider();
}
private void initSlider()
{
setOrientation(HORIZONTAL);
}
@Override
public void updateUI()
{
rangeUI = new RangeSliderUI(this);
setUI(rangeUI);
// Update UI for slider labels. This must be called after updating the
// UI of the slider. Refer to JSlider.updateUI().
updateLabelUIs();
}
@Override
public int getValue()
{
return super.getValue();
}
public RangeSliderUI getRangeUI()
{
return rangeUI;
}
@Override
public void setValue(int value)
{
int oldValue = getValue();
if (oldValue == value)
{
return;
}
// Compute new value and extent to maintain upper value.
int oldExtent = getExtent();
int newValue = Math.min(Math.max(getMinimum(), value), oldValue + oldExtent);
int newExtent = oldExtent + oldValue - newValue;
// Set new value and extent, and fire a single change event.
getModel().setRangeProperties(newValue, newExtent, getMinimum(),
getMaximum(), getValueIsAdjusting());
}
public int getUpperValue()
{
return getValue() + getExtent();
}
/**
* Sets the upper value in the range.
*/
public void setUpperValue(int value)
{
// Compute new extent.
int lowerValue = getValue();
int newExtent = Math.min(Math.max(0, value - lowerValue), getMaximum() - lowerValue);
// Set extent to set upper value.
setExtent(newExtent);
}
public boolean isRangeSlider()
{
return rangeUI.isRangeSlider();
}
/**
* Sets whether this is currently a range slider or not. (true is range slider, false is not range slider)
*/
public void setRangeSlider(boolean rangeSlider)
{
this.rangeUI.setRangeSlider(rangeSlider);
}
}
UI类是：
package YourPackage;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Polygon;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.event.MouseEvent;
import javax.swing.JComponent;
import javax.swing.JSlider;
import javax.swing.SwingUtilities;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.plaf.basic.BasicSliderUI;
/**
* UI delegate for the RangeSlider component. RangeSliderUI paints two thumbs,
* one for the lower value and one for the upper value.
*
* Setting rangeSlider = false; causes the slider to revert to being a normal slider
* rather than a range slider.
*/
class RangeSliderUI extends BasicSliderUI
{
/** Color of selected range. */
private Color rangeColor = Color.darkGray;
/** Location and size of thumb for upper value. */
private Rectangle upperThumbRect;
/** Indicator that determines whether upper thumb is selected. */
private boolean upperThumbSelected;
/** Indicator that determines whether lower thumb is being dragged. */
private transient boolean lowerDragging;
/** Indicator that determines whether upper thumb is being dragged. */
private transient boolean upperDragging;
// Range/single slider (true is range slider/ false is single slider)
private boolean rangeSlider = false;
public RangeSliderUI(RangeSlider b)
{
super(b);
}
public int getTrackRect()
{
return trackRect.x;
}
public boolean isRangeSlider()
{
return rangeSlider;
}
public void setRangeSlider(boolean rangeSlider)
{
this.rangeSlider = rangeSlider;
}
@Override
public void installUI(JComponent c)
{
upperThumbRect = new Rectangle();
super.installUI(c);
}
@Override
protected TrackListener createTrackListener(JSlider slider)
{
return new RangeTrackListener();
}
@Override
protected ChangeListener createChangeListener(JSlider slider)
{
return new ChangeHandler();
}
@Override
protected void calculateThumbSize()
{
// Call superclass method for lower thumb size.
super.calculateThumbSize();
// Set upper thumb size.
upperThumbRect.setSize(thumbRect.width, thumbRect.height);
}
@Override
protected void calculateThumbLocation()
{
// Call superclass method for lower thumb location.
super.calculateThumbLocation();
// Adjust upper value to snap to ticks if necessary.
if (slider.getSnapToTicks())
{
int upperValue = slider.getValue() + slider.getExtent();
int snappedValue = upperValue;
int majorTickSpacing = slider.getMajorTickSpacing();
int minorTickSpacing = slider.getMinorTickSpacing();
int tickSpacing = 0;
if (minorTickSpacing > 0)
{
tickSpacing = minorTickSpacing;
}
else if (majorTickSpacing > 0)
{
tickSpacing = majorTickSpacing;
}
if (tickSpacing != 0)
{
// If it's not on a tick, change the value
if ((upperValue - slider.getMinimum()) % tickSpacing != 0)
{
float temp = (float) (upperValue - slider.getMinimum()) / (float) tickSpacing;
int whichTick = Math.round(temp);
snappedValue = slider.getMinimum() + (whichTick * tickSpacing);
}
if (snappedValue != upperValue)
{
slider.setExtent(snappedValue - slider.getValue());
}
}
}
// Calculate upper thumb location. The thumb is centered over its value on the track.
if (slider.getOrientation() == JSlider.HORIZONTAL)
{
int upperPosition = xPositionForValue(slider.getValue() + slider.getExtent());
upperThumbRect.x = upperPosition - (upperThumbRect.width / 2);
upperThumbRect.y = trackRect.y;
}
else
{
int upperPosition = yPositionForValue(slider.getValue() + slider.getExtent());
upperThumbRect.x = trackRect.x;
upperThumbRect.y = upperPosition - (upperThumbRect.height / 2);
}
}
@Override
protected Dimension getThumbSize()
{
return new Dimension(12, 12);
}
@Override
public void paint(Graphics g, JComponent c)
{
super.paint(g, c);
}
@Override
public void paintTrack(Graphics g)
{
// Draw track.
super.paintTrack(g);
Rectangle trackBounds = trackRect;
if (rangeSlider)
{
if (slider.getOrientation() == JSlider.HORIZONTAL)
{
// Determine position of selected range by moving from the middle
// of one thumb to the other.
int lowerX = thumbRect.x + (thumbRect.width / 2);
int upperX = upperThumbRect.x + (upperThumbRect.width / 2);
// Determine track position.
int cy = (trackBounds.height / 2) - 2;
// Save color and shift position.
Color oldColor = g.getColor();
g.translate(trackBounds.x, trackBounds.y + cy);
// Draw selected range.
g.setColor(rangeColor);
for (int y = 0; y <= 3; y++)
{
g.drawLine(lowerX - trackBounds.x, y, upperX - trackBounds.x, y);
}
// Restore position and color.
g.translate(-trackBounds.x, -(trackBounds.y + cy));
g.setColor(oldColor);
}
else
{
// Determine position of selected range by moving from the middle
// of one thumb to the other.
int lowerY = thumbRect.x + (thumbRect.width / 2);
int upperY = upperThumbRect.x + (upperThumbRect.width / 2);
// Determine track position.
int cx = (trackBounds.width / 2) - 2;
// Save color and shift position.
Color oldColor = g.getColor();
g.translate(trackBounds.x + cx, trackBounds.y);
// Draw selected range.
g.setColor(rangeColor);
for (int x = 0; x <= 3; x++)
{
g.drawLine(x, lowerY - trackBounds.y, x, upperY - trackBounds.y);
}
// Restore position and color.
g.translate(-(trackBounds.x + cx), -trackBounds.y);
g.setColor(oldColor);
}
}
// Shifted the knob painting to here so it is painted with the track or not.
Rectangle clipRect = g.getClipBounds();
if (upperThumbSelected)
{
// Paint lower thumb first, then upper thumb.
if (clipRect.intersects(thumbRect))
{
paintLowerThumb(g);
}
if (clipRect.intersects(upperThumbRect))
{
paintUpperThumb(g);
}
}
else
{
// Paint upper thumb first, then lower thumb.
if (clipRect.intersects(upperThumbRect))
{
paintUpperThumb(g);
}
if (clipRect.intersects(thumbRect))
{
paintLowerThumb(g);
}
}
}
@Override
public void paintThumb(Graphics g)
{
}
private void paintLowerThumb(Graphics g)
{
Rectangle knobBounds = thumbRect;
int w = knobBounds.width;
int h = knobBounds.height;
// Create graphics copy.
Graphics2D g2d = (Graphics2D) g.create();
// Create default thumb shape.
Shape thumbShape = createThumbShape(w - 1, h - 1);
// Draw thumb.
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.translate(knobBounds.x, knobBounds.y);
g2d.setColor(Color.CYAN);
g2d.fill(thumbShape);
g2d.setColor(Color.BLUE);
g2d.draw(thumbShape);
// Dispose graphics.
g2d.dispose();
}
private void paintUpperThumb(Graphics g)
{
if (rangeSlider)
{
Rectangle knobBounds = upperThumbRect;
int w = knobBounds.width;
int h = knobBounds.height;
// Create graphics copy.
Graphics2D g2d = (Graphics2D) g.create();
// Create default thumb shape.
Shape thumbShape = createThumbShape(w - 1, h - 1);
// Draw thumb.
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.translate(knobBounds.x, knobBounds.y);
g2d.setColor(Color.orange);
g2d.fill(thumbShape);
g2d.setColor(Color.orange.darker().darker());
g2d.draw(thumbShape);
// Dispose graphics.
g2d.dispose();
}
}
private Shape createThumbShape(int width, int height)
{
Point p1 = new Point(0, 0);
Point p2 = new Point(width, 0);
Point p3 = new Point(width, (height / 2) + 1);
Point p4 = new Point((width / 2) + 1, height);
Point p5 = new Point(0, (height / 2) + 1);
int[] xs =
{
p1.x, p2.x, p3.x, p4.x, p5.x
};
int[] ys =
{
p1.y, p2.y, p3.y, p4.y, p5.y
};
Polygon thumb = new Polygon(xs, ys, xs.length);
return thumb;
}
private void setUpperThumbLocation(int x, int y)
{
Rectangle upperUnionRect = new Rectangle();
upperUnionRect.setBounds(upperThumbRect);
upperThumbRect.setLocation(x, y);
SwingUtilities.computeUnion(upperThumbRect.x, upperThumbRect.y, upperThumbRect.width, upperThumbRect.height, upperUnionRect);
slider.repaint(upperUnionRect.x, upperUnionRect.y, upperUnionRect.width, upperUnionRect.height);
}
@Override
public void scrollByBlock(int direction)
{
synchronized (slider)
{
int blockIncrement = (slider.getMaximum() - slider.getMinimum()) / 10;
if (blockIncrement <= 0 && slider.getMaximum() > slider.getMinimum())
{
blockIncrement = 1;
}
int delta = blockIncrement * ((direction > 0) ? POSITIVE_SCROLL : NEGATIVE_SCROLL);
if (upperThumbSelected)
{
int oldValue = ((RangeSlider) slider).getUpperValue();
((RangeSlider) slider).setUpperValue(oldValue + delta);
}
else
{
int oldValue = slider.getValue();
slider.setValue(oldValue + delta);
}
}
}
@Override
public void scrollByUnit(int direction)
{
synchronized (slider)
{
int delta = 1 * ((direction > 0) ? POSITIVE_SCROLL : NEGATIVE_SCROLL);
if (upperThumbSelected)
{
int oldValue = ((RangeSlider) slider).getUpperValue();
((RangeSlider) slider).setUpperValue(oldValue + delta);
}
else
{
int oldValue = slider.getValue();
slider.setValue(oldValue + delta);
}
}
}
public class ChangeHandler implements ChangeListener
{
public void stateChanged(ChangeEvent arg0)
{
if (!lowerDragging && !upperDragging)
{
calculateThumbLocation();
slider.repaint();
}
}
}
public class RangeTrackListener extends TrackListener
{
@Override
public void mousePressed(MouseEvent e)
{
if (!slider.isEnabled())
{
return;
}
currentMouseX = e.getX();
currentMouseY = e.getY();
if (slider.isRequestFocusEnabled())
{
slider.requestFocus();
}
// Determine which thumb is pressed. If the upper thumb is selected (last one dragged), then check its position first;
// otherwise check the position of the lower thumb first.
boolean lowerPressed = false;
boolean upperPressed = false;
if (upperThumbSelected)
{
// Only enable upper slider movement if in range mode.
if (upperThumbRect.contains(currentMouseX, currentMouseY) && rangeSlider)
{
upperPressed = true;
}
else
{
if (thumbRect.contains(currentMouseX, currentMouseY))
{
lowerPressed = true;
}
}
}
else
{
if (thumbRect.contains(currentMouseX, currentMouseY))
{
lowerPressed = true;
}
else
{
// Only enable if in range mode.
if (upperThumbRect.contains(currentMouseX, currentMouseY) && rangeSlider)
{
upperPressed = true;
}
}
}
// Handle lower thumb pressed.
if (lowerPressed)
{
switch (slider.getOrientation())
{
case JSlider.VERTICAL:
offset = currentMouseY - thumbRect.y;
break;
case JSlider.HORIZONTAL:
offset = currentMouseX - thumbRect.x;
break;
}
upperThumbSelected = false;
lowerDragging = true;
return;
}
lowerDragging = false;
// Handle upper thumb pressed.
if (upperPressed)
{
switch (slider.getOrientation())
{
case JSlider.VERTICAL:
offset = currentMouseY - upperThumbRect.y;
break;
case JSlider.HORIZONTAL:
offset = currentMouseX - upperThumbRect.x;
break;
}
upperThumbSelected = true;
upperDragging = true;
return;
}
upperDragging = false;
}
@Override
public void mouseReleased(MouseEvent e)
{
lowerDragging = false;
upperDragging = false;
slider.setValueIsAdjusting(false);
super.mouseReleased(e);
}
@Override
public void mouseDragged(MouseEvent e)
{
if (!slider.isEnabled())
{
return;
}
currentMouseX = e.getX();
currentMouseY = e.getY();
if (lowerDragging)
{
slider.setValueIsAdjusting(true);
moveLowerThumb();
}
else if (upperDragging)
{
slider.setValueIsAdjusting(true);
moveUpperThumb();
}
}
@Override
public boolean shouldScroll(int direction)
{
return false;
}
private void moveLowerThumb()
{
int thumbMiddle = 0;
switch (slider.getOrientation())
{
case JSlider.VERTICAL:
int halfThumbHeight = thumbRect.height / 2;
int thumbTop = currentMouseY - offset;
int trackTop = trackRect.y;
int trackBottom = trackRect.y + (trackRect.height - 1);
int vMax = yPositionForValue(slider.getValue() + slider.getExtent());
// Apply bounds to thumb position.
if (drawInverted())
{
trackBottom = vMax;
}
else
{
trackTop = vMax;
}
thumbTop = Math.max(thumbTop, trackTop - halfThumbHeight);
thumbTop = Math.min(thumbTop, trackBottom - halfThumbHeight);
setThumbLocation(thumbRect.x, thumbTop);
// Update slider value.
thumbMiddle = thumbTop + halfThumbHeight;
slider.setValue(valueForYPosition(thumbMiddle));
break;
case JSlider.HORIZONTAL:
int halfThumbWidth = thumbRect.width / 2;
int thumbLeft = currentMouseX - offset;
int trackLeft = trackRect.x;
int trackRight = trackRect.x + (trackRect.width - 1);
int hMax = xPositionForValue(slider.getValue() + slider.getExtent());
// Apply bounds to thumb position.
if (drawInverted())
{
trackLeft = hMax;
}
else
{
trackRight = hMax;
}
thumbLeft = Math.max(thumbLeft, trackLeft - halfThumbWidth);
thumbLeft = Math.min(thumbLeft, trackRight - halfThumbWidth);
setThumbLocation(thumbLeft, thumbRect.y);
// Update slider value.
thumbMiddle = thumbLeft + halfThumbWidth;
slider.setValue(valueForXPosition(thumbMiddle));
break;
default:
return;
}
}
private void moveUpperThumb()
{
int thumbMiddle = 0;
switch (slider.getOrientation())
{
case JSlider.VERTICAL:
int halfThumbHeight = thumbRect.height / 2;
int thumbTop = currentMouseY - offset;
int trackTop = trackRect.y;
int trackBottom = trackRect.y + (trackRect.height - 1);
int vMin = yPositionForValue(slider.getValue());
// Apply bounds to thumb position.
if (drawInverted())
{
trackTop = vMin;
}
else
{
trackBottom = vMin;
}
thumbTop = Math.max(thumbTop, trackTop - halfThumbHeight);
thumbTop = Math.min(thumbTop, trackBottom - halfThumbHeight);
setUpperThumbLocation(thumbRect.x, thumbTop);
// Update slider extent.
thumbMiddle = thumbTop + halfThumbHeight;
slider.setExtent(valueForYPosition(thumbMiddle) - slider.getValue());
break;
case JSlider.HORIZONTAL:
int halfThumbWidth = thumbRect.width / 2;
int thumbLeft = currentMouseX - offset;
int trackLeft = trackRect.x;
int trackRight = trackRect.x + (trackRect.width - 1);
int hMin = xPositionForValue(slider.getValue());
// Apply bounds to thumb position.
if (drawInverted())
{
trackRight = hMin;
}
else
{
trackLeft = hMin;
}
thumbLeft = Math.max(thumbLeft, trackLeft - halfThumbWidth);
thumbLeft = Math.min(thumbLeft, trackRight - halfThumbWidth);
setUpperThumbLocation(thumbLeft, thumbRect.y);
// Update slider extent.
thumbMiddle = thumbLeft + halfThumbWidth;
slider.setExtent(valueForXPosition(thumbMiddle) - slider.getValue());
break;
default:
return;
}
}
}
}
通过调用以下方式获取轨道矩形的x位置（也是第一个刻度线的位置），以使图形与滑块对齐：
rangeSlider1.getRangeUI().getTrackRect()
我也不喜欢他们的圆形旋钮，并将它们改成更传统的形状。