Recently, I researched and implemented the iText PDF library for Java in order to automatically generate some pretty PDFs. I ran into an issue, however, when I realized that cells can only be given rounded corners through packaged routines via the PdfContentByte.roundRectangle() method, which only allows for all corners to be rounded at once. This was going to be a problem, since I only needed certain corners to be rounded on certain cells. Here is the solution I came up with:
/**
* Cell event class for applying rounded corners and gradient backgrounds to
* table cells.
*/
public class PdfRoundCorners implements PdfPCellEvent {
private BaseColor[] colorFill;
private boolean topLeft;
private boolean topRight;
private boolean bottomRight;
private boolean bottomLeft;
/**
* Create a new PdfRoundCorners event while specifying a single fill color
* and which corners will be rounded.
*
* @param colorFill The BaseColor to use as the fill color.
* @param topLeft If true, top left corner will be rounded.
* @param topRight If true, top right corner will be rounded.
* @param bottomRight If true, bottom right corner will be rounded.
* @param bottomLeft If true, bottom left corner will be rounded.
*/
public PdfRoundCorners(
BaseColor colorFill,
boolean topLeft,
boolean topRight,
boolean bottomRight,
boolean bottomLeft) {
this.colorFill = new BaseColor[]{colorFill};
this.topLeft = topLeft;
this.topRight = topRight;
this.bottomRight = bottomRight;
this.bottomLeft = bottomLeft;
}
/**
* Create a new PdfRoundCorners event while specifying a vertical background
* gradient and which corners will be rounded.
*
* @param colorFill An array of two BaseColors which will be used to create
* the gradient.
* @param topLeft If true, top left corner will be rounded.
* @param topRight If true, top right corner will be rounded.
* @param bottomRight If true, bottom right corner will be rounded.
* @param bottomLeft If true, bottom left corner will be rounded.
*/
public PdfRoundCorners(
BaseColor[] colorFill,
boolean topLeft,
boolean topRight,
boolean bottomRight,
boolean bottomLeft) {
this.colorFill = colorFill;
this.topLeft = topLeft;
this.topRight = topRight;
this.bottomRight = bottomRight;
this.bottomLeft = bottomLeft;
}
/**
* Interface method for drawing the background fill pattern.
*/
@Override
public void cellLayout(PdfPCell cell, Rectangle rect, PdfContentByte[] canvas) {
// Get the cell's background canvas.
PdfContentByte cb = canvas[PdfPTable.BACKGROUNDCANVAS];
// Adjust left and right positions to fix visible gaps.
float left = rect.getLeft() - (PdfStyle.CELL_BORDER_WIDTH / 2);
float top = rect.getTop();
float right = rect.getRight() + (PdfStyle.CELL_BORDER_WIDTH / 2);
float bottom = rect.getBottom();
// Set the fill color or gradient.
if(colorFill.length < 2) {
cb.setColorFill(colorFill[0]);
} else {
PdfShading shading = PdfShading.simpleAxial(
cb.getPdfWriter(), left, top, left, bottom, colorFill[0], colorFill[1]);
PdfShadingPattern shadingPattern = new PdfShadingPattern(shading);
cb.setShadingFill(shadingPattern);
}
// Define the background box including rounded corners.
if(topLeft) {
cb.moveTo(left, top - PdfStyle.CELL_CORNER_RADIUS);
cb.curveTo(left, top, left + PdfStyle.CELL_CORNER_RADIUS, top);
} else cb.moveTo(left, top);
if(topRight) {
cb.lineTo(right - PdfStyle.CELL_CORNER_RADIUS, top);
cb.curveTo(right, top, right, top - PdfStyle.CELL_CORNER_RADIUS);
} else cb.lineTo(right, top);
if(bottomRight) {
cb.lineTo(right, bottom + PdfStyle.CELL_CORNER_RADIUS);
cb.curveTo(right, bottom, right - PdfStyle.CELL_CORNER_RADIUS, bottom);
} else cb.lineTo(right, bottom);
if(bottomLeft) {
cb.lineTo(left + PdfStyle.CELL_CORNER_RADIUS, bottom);
cb.curveTo(left, bottom, left, bottom + PdfStyle.CELL_CORNER_RADIUS);
} else cb.lineTo(left, bottom);
if(topLeft) cb.lineTo(left, top - PdfStyle.CELL_CORNER_RADIUS);
else cb.lineTo(left, top);
cb.closePath();
// Fill it up!
cb.fill();
}
}
I literally had to trace out a rounded rectangle using a stroke path. What's special about this event class is that you can specify either a single fill color, or two colors to represent a gradient. You can also mark specifically which corners should be rounded. Of course it goes without saying, but it's all vector based. So no scaling issues! Here's an example of how it looks:
I couldn't find anything else like this out there, so I hope someone else can get some use out of it!