I am writing a tool in Java using Apache POI API to convert an XML to MS Excel. In my XML input, I receive the column width in points. But the Apache POI API has a slightly queer logic for setting column width based on font size etc. (refer API docs)
Is there a formula for converting points to the width as expected by Excel? Has anyone done this before?
There is a setRowHeightInPoints() method though :( but none for column.
P.S.: The input XML is in ExcelML format which I have to convert to MS Excel.
Unfortunately there is only the function setColumnWidth(int columnIndex,
int width) from class Sheet; in which width is a number of characters in the standard font (first font in the workbook) if your fonts are changing you cannot use it.
There is explained how to calculate the width in function of a font size. The formula is:
width = Truncate([{NumOfVisibleChar} * {MaxDigitWidth} + {5PixelPadding}] / {MaxDigitWidth}*256) / 256
You can always use autoSizeColumn(int column, boolean useMergedCells) after inputting the data in your Sheet.
Please be carefull with the usage of autoSizeColumn(). It can be used without problems on small files but please take care that the method is called only once (at the end) for each column and not called inside a loop which would make no sense.
Please avoid using autoSizeColumn() on large Excel files. The method generates a performance problem.
We used it on a 110k rows/11 columns file. The method took ~6m to autosize all columns.
For more details have a look at: How to speed up autosizing columns in apache POI?
You can use also util methods mentioned in this blog: Getting cell witdth and height from excel with Apache POI. It can solve your problem.
Copy & paste from that blog:
static public class PixelUtil {
public static final short EXCEL_COLUMN_WIDTH_FACTOR = 256;
public static final short EXCEL_ROW_HEIGHT_FACTOR = 20;
public static final int UNIT_OFFSET_LENGTH = 7;
public static final int[] UNIT_OFFSET_MAP = new int[] { 0, 36, 73, 109, 146, 182, 219 };
public static short pixel2WidthUnits(int pxs) {
short widthUnits = (short) (EXCEL_COLUMN_WIDTH_FACTOR * (pxs / UNIT_OFFSET_LENGTH));
widthUnits += UNIT_OFFSET_MAP[(pxs % UNIT_OFFSET_LENGTH)];
return widthUnits;
}
public static int widthUnits2Pixel(short widthUnits) {
int pixels = (widthUnits / EXCEL_COLUMN_WIDTH_FACTOR) * UNIT_OFFSET_LENGTH;
int offsetWidthUnits = widthUnits % EXCEL_COLUMN_WIDTH_FACTOR;
pixels += Math.floor((float) offsetWidthUnits / ((float) EXCEL_COLUMN_WIDTH_FACTOR / UNIT_OFFSET_LENGTH));
return pixels;
}
public static int heightUnits2Pixel(short heightUnits) {
int pixels = (heightUnits / EXCEL_ROW_HEIGHT_FACTOR);
int offsetWidthUnits = heightUnits % EXCEL_ROW_HEIGHT_FACTOR;
pixels += Math.floor((float) offsetWidthUnits / ((float) EXCEL_ROW_HEIGHT_FACTOR / UNIT_OFFSET_LENGTH));
return pixels;
}
}
So when you want to get cell width and height you can use this to get value in pixel, values are approximately.
PixelUtil.heightUnits2Pixel((short) row.getHeight())
PixelUtil.widthUnits2Pixel((short) sh.getColumnWidth(columnIndex));
With Scala there is a nice Wrapper spoiwo
You can do it like this:
Workbook(mySheet.withColumns(
Column(autoSized = true),
Column(width = new Width(100, WidthUnit.Character)),
Column(width = new Width(100, WidthUnit.Character)))
)
I answered my problem with a default width for all columns and cells, like below:
int width = 15; // Where width is number of caracters
sheet.setDefaultColumnWidth(width);
Related
Please, refer to this article.
I have implemented the section 4.1 (Pre-processing).
The preprocessing step aims to enhance image features along a set of
chosen directions. First, image is grey-scaled and filtered with a
sharpening filter (we subtract from the image its local-mean filtered
version), thus eliminating the DC component.
We selected 12 not overlapping filters, to analyze 12 different
directions, rotated with respect to 15° each other.
GitHub Repositiry is here.
Since, the given formula in the article is incorrect, I have tried two sets of different formulas.
The first set of formula,
The second set of formula,
The expected output should be,
Neither of them are giving proper results.
Can anyone suggest me any modification?
GitHub Repository is here.
Most relevalt part of the source code is here:
public List<Bitmap> Apply(Bitmap bitmap)
{
Kernels = new List<KassWitkinKernel>();
double degrees = FilterAngle;
KassWitkinKernel kernel;
for (int i = 0; i < NoOfFilters; i++)
{
kernel = new KassWitkinKernel();
kernel.Width = KernelDimension;
kernel.Height = KernelDimension;
kernel.CenterX = (kernel.Width) / 2;
kernel.CenterY = (kernel.Height) / 2;
kernel.Du = 2;
kernel.Dv = 2;
kernel.ThetaInRadian = Tools.DegreeToRadian(degrees);
kernel.Compute();
//SleuthEye
kernel.Pad(kernel.Width, kernel.Height, WidthWithPadding, HeightWithPadding);
Kernels.Add(kernel);
degrees += degrees;
}
List<Bitmap> list = new List<Bitmap>();
Bitmap image = (Bitmap)bitmap.Clone();
//PictureBoxForm f = new PictureBoxForm(image);
//f.ShowDialog();
Complex[,] cImagePadded = ImageDataConverter.ToComplex(image);
Complex[,] fftImage = FourierTransform.ForwardFFT(cImagePadded);
foreach (KassWitkinKernel k in Kernels)
{
Complex[,] cKernelPadded = k.ToComplexPadded();
Complex[,] convolved = Convolution.ConvolveInFrequencyDomain(fftImage, cKernelPadded);
Bitmap temp = ImageDataConverter.ToBitmap(convolved);
list.Add(temp);
}
return list;
}
Perhaps the first thing that should be mentioned is that the filters should be generated with angles which should increase in FilterAngle (in your case 15 degrees) increments. This can be accomplished by modifying KassWitkinFilterBank.Apply as follow (see this commit):
public List<Bitmap> Apply(Bitmap bitmap)
{
// ...
// The generated template filter from the equations gives a line at 45 degrees.
// To get the filter to highlight lines starting with an angle of 90 degrees
// we should start with an additional 45 degrees offset.
double degrees = 45;
KassWitkinKernel kernel;
for (int i = 0; i < NoOfFilters; i++)
{
// ... setup filter (unchanged)
// Now increment the angle by FilterAngle
// (not "+= degrees" which doubles the value at each step)
degrees += FilterAngle;
}
This should give you the following result:
It is not quite the result from the paper and the differences between the images are still quite subtle, but you should be able to notice that the scratch line is most intense in the 8th figure (as would be expected since the scratch angle is approximately 100-105 degrees).
To improve the result, we should feed the filters with a pre-processed image in the same way as described in the paper:
First, image is grey-scaled and filtered with a sharpening filter (we subtract from the image its local-mean filtered version), thus eliminating the DC component
When you do so, you will get a matrix of values, some of which will be negative. As a result this intermediate processing result is not suitable to be stored as a Bitmap. As a general rule when performing image processing, you should keep all intermediate results in double or Complex as appropriate, and only convert back the final result to Bitmap for visualization.
Integrating your changes to add image sharpening from your GitHub repository while keeping intermediate results as doubles can be achieve by changing the input bitmap and temporary image variables to use double[,] datatype instead of Bitmap in the KassWitkinFilterBank.Apply method (see this commit):
public List<Bitmap> Apply(double[,] bitmap)
{
// [...]
double[,] image = (double[,])bitmap.Clone();
// [...]
}
which should give you the following result:
Or to better highlight the difference, here is figure 1 (0 degrees) on the left, next to figure 8 (105 degrees) on the right:
I am using the following code to convert a Bitmap to Complex and vice versa.
Even though those were directly copied from Accord.NET framework, while testing these static methods, I have discovered that, repeated use of these static methods cause 'data-loss'. As a result, the end output/result becomes distorted.
public partial class ImageDataConverter
{
#region private static Complex[,] FromBitmapData(BitmapData bmpData)
private static Complex[,] ToComplex(BitmapData bmpData)
{
Complex[,] comp = null;
if (bmpData.PixelFormat == PixelFormat.Format8bppIndexed)
{
int width = bmpData.Width;
int height = bmpData.Height;
int offset = bmpData.Stride - (width * 1);//1 === 1 byte per pixel.
if ((!Tools.IsPowerOf2(width)) || (!Tools.IsPowerOf2(height)))
{
throw new Exception("Imager width and height should be n of 2.");
}
comp = new Complex[width, height];
unsafe
{
byte* src = (byte*)bmpData.Scan0.ToPointer();
for (int y = 0; y < height; y++)
{
for (int x = 0; x < width; x++, src++)
{
comp[y, x] = new Complex((float)*src / 255,
comp[y, x].Imaginary);
}
src += offset;
}
}
}
else
{
throw new Exception("EightBppIndexedImageRequired");
}
return comp;
}
#endregion
public static Complex[,] ToComplex(Bitmap bmp)
{
Complex[,] comp = null;
if (bmp.PixelFormat == PixelFormat.Format8bppIndexed)
{
BitmapData bmpData = bmp.LockBits( new Rectangle(0, 0, bmp.Width, bmp.Height),
ImageLockMode.ReadOnly,
PixelFormat.Format8bppIndexed);
try
{
comp = ToComplex(bmpData);
}
finally
{
bmp.UnlockBits(bmpData);
}
}
else
{
throw new Exception("EightBppIndexedImageRequired");
}
return comp;
}
public static Bitmap ToBitmap(Complex[,] image, bool fourierTransformed)
{
int width = image.GetLength(0);
int height = image.GetLength(1);
Bitmap bmp = Imager.CreateGrayscaleImage(width, height);
BitmapData bmpData = bmp.LockBits(
new Rectangle(0, 0, width, height),
ImageLockMode.ReadWrite,
PixelFormat.Format8bppIndexed);
int offset = bmpData.Stride - width;
double scale = (fourierTransformed) ? Math.Sqrt(width * height) : 1;
unsafe
{
byte* address = (byte*)bmpData.Scan0.ToPointer();
for (int y = 0; y < height; y++)
{
for (int x = 0; x < width; x++, address++)
{
double min = System.Math.Min(255, image[y, x].Magnitude * scale * 255);
*address = (byte)System.Math.Max(0, min);
}
address += offset;
}
}
bmp.UnlockBits(bmpData);
return bmp;
}
}
(The DotNetFiddle link of the complete source code)
(ImageDataConverter)
Output:
As you can see, FFT is working correctly, but, I-FFT isn't.
That is because bitmap to complex and vice versa isn't working as expected.
What could be done to correct the ToComplex() and ToBitmap() functions so that they don't loss data?
I do not code in C# so handle this answer with extreme prejudice!
Just from a quick look I spotted few problems:
ToComplex()
Is converting BMP into 2D complex matrix. When you are converting you are leaving imaginary part unchanged, but at the start of the same function you have:
Complex[,] complex2D = null;
complex2D = new Complex[width, height];
So the imaginary parts are either undefined or zero depends on your complex class constructor. This means you are missing half of the data needed for reconstruction !!! You should restore the original complex matrix from 2 images one for real and second for imaginary part of the result.
ToBitmap()
You are saving magnitude which is I think sqrt( Re*Re + Im*Im ) so it is power spectrum not the original complex values and so you can not reconstruct back... You should store Re,Im in 2 separate images.
8bit per pixel
That is not much and can cause significant round off errors after FFT/IFFT so reconstruction can be really distorted.
[Edit1] Remedy
There are more options to repair this for example:
use floating complex matrix for computations and bitmap only for visualization.
This is the safest way because you avoid additional conversion round offs. This approach has the best precision. But you need to rewrite your DIP/CV algorithms to support complex domain matrices instead of bitmaps which require not small amount of work.
rewrite your conversions to support real and imaginary part images
Your conversion is really bad as it does not store/restore Real and Imaginary parts as it should and also it does not account for negative values (at least I do not see it instead they are cut down to zero which is WRONG). I would rewrite the conversion to this:
// conversion scales
float Re_ofset=256.0,Re_scale=512.0/255.0;
float Im_ofset=256.0,Im_scale=512.0/255.0;
private static Complex[,] ToComplex(BitmapData bmpRe,BitmapData bmpIm)
{
//...
byte* srcRe = (byte*)bmpRe.Scan0.ToPointer();
byte* srcIm = (byte*)bmpIm.Scan0.ToPointer();
complex c = new Complex(0.0,0.0);
// for each line
for (int y = 0; y < height; y++)
{
// for each pixel
for (int x = 0; x < width; x++, src++)
{
complex2D[y, x] = c;
c.Real = (float)*(srcRe*Re_scale)-Re_ofset;
c.Imaginary = (float)*(srcIm*Im_scale)-Im_ofset;
}
src += offset;
}
//...
}
public static Bitmap ToBitmapRe(Complex[,] complex2D)
{
//...
float Re = (complex2D[y, x].Real+Re_ofset)/Re_scale;
Re = min(Re,255.0);
Re = max(Re, 0.0);
*address = (byte)Re;
//...
}
public static Bitmap ToBitmapIm(Complex[,] complex2D)
{
//...
float Im = (complex2D[y, x].Imaginary+Im_ofset)/Im_scale;
Re = min(Im,255.0);
Re = max(Im, 0.0);
*address = (byte)Im;
//...
}
Where:
Re_ofset = min(complex2D[,].Real);
Im_ofset = min(complex2D[,].Imaginary);
Re_scale = (max(complex2D[,].Real )-min(complex2D[,].Real ))/255.0;
Im_scale = (max(complex2D[,].Imaginary)-min(complex2D[,].Imaginary))/255.0;
or cover bigger interval then the complex matrix values.
You can also encode both Real and Imaginary parts to single image for example first half of image could be Real and next the Imaginary part. In that case you do not need to change the function headers nor names at all .. but you would need to handle the images as 2 joined squares each with different meaning ...
You can also use RGB images where R = Real, B = Imaginary or any other encoding that suites you.
[Edit2] some examples to make my points more clear
example of approach #1
The image is in form of floating point 2D complex matrix and the images are created only for visualization. There is little rounding error this way. The values are not normalized so the range is <0.0,255.0> per pixel/cell at first but after transforms and scaling it could change greatly.
As you can see I added scaling so all pixels are multiplied by 315 to actually see anything because the FFT output values are small except of few cells. But only for visualization the complex matrix is unchanged.
example of approach #2
Well as I mentioned before you do not handle negative values, normalize values to range <0,1> and back by scaling and rounding off and using only 8 bits per pixel to store the sub results. I tried to simulate that with my code and here is what I got (using complex domain instead of wrongly used power spectrum like you did). Here C++ source only as an template example as you do not have the functions and classes behind it:
transform t;
cplx_2D c;
rgb2i(bmp0);
c.ld(bmp0,bmp0);
null_im(c);
c.mul(1.0/255.0);
c.mul(255.0); c.st(bmp0,bmp1); c.ld(bmp0,bmp1); i2iii(bmp0); i2iii(bmp1); c.mul(1.0/255.0);
bmp0->SaveToFile("_out0_Re.bmp");
bmp1->SaveToFile("_out0_Im.bmp");
t. DFFT(c,c);
c.wrap();
c.mul(255.0); c.st(bmp0,bmp1); c.ld(bmp0,bmp1); i2iii(bmp0); i2iii(bmp1); c.mul(1.0/255.0);
bmp0->SaveToFile("_out1_Re.bmp");
bmp1->SaveToFile("_out1_Im.bmp");
c.wrap();
t.iDFFT(c,c);
c.mul(255.0); c.st(bmp0,bmp1); c.ld(bmp0,bmp1); i2iii(bmp0); i2iii(bmp1); c.mul(1.0/255.0);
bmp0->SaveToFile("_out2_Re.bmp");
bmp1->SaveToFile("_out2_Im.bmp");
And here the sub results:
As you can see after the DFFT and wrap the image is really dark and most of the values are rounded off. So the result after unwrap and IDFFT is really pure.
Here some explanations to code:
c.st(bmpre,bmpim) is the same as your ToBitmap
c.ld(bmpre,bmpim) is the same as your ToComplex
c.mul(scale) multiplies complex matrix c by scale
rgb2i converts RGB to grayscale intensity <0,255>
i2iii converts grayscale intensity ro grayscale RGB image
I'm not really good in this puzzles but double check this dividing.
comp[y, x] = new Complex((float)*src / 255, comp[y, x].Imaginary);
You can loose precision as it is described here
Complex class definition in Remarks section.
May be this happens in your case.
Hope this helps.
How to autofit content in cell using jxl api?
I know this is an old question at this point, but I was looking for the solution to this and thought I would post it in case someone else needs it.
CellView Auto-Size
I'm not sure why the FAQ doesn't mention this, because it very clearly exists in the docs.
My code looked like the following:
for(int x=0;x<c;x++)
{
cell=sheet.getColumnView(x);
cell.setAutosize(true);
sheet.setColumnView(x, cell);
}
c stores the number of columns created
cell is just a temporary place holder for the returned CellView object
sheet is my WriteableSheet object
The Api warns that this is a processor intensive function, so it's probably not ideal for large files. But for a small file like mine (<100 rows) it took no noticeable time.
Hope this helps someone.
The method is self explanatory and commented:
private void sheetAutoFitColumns(WritableSheet sheet) {
for (int i = 0; i < sheet.getColumns(); i++) {
Cell[] cells = sheet.getColumn(i);
int longestStrLen = -1;
if (cells.length == 0)
continue;
/* Find the widest cell in the column. */
for (int j = 0; j < cells.length; j++) {
if ( cells[j].getContents().length() > longestStrLen ) {
String str = cells[j].getContents();
if (str == null || str.isEmpty())
continue;
longestStrLen = str.trim().length();
}
}
/* If not found, skip the column. */
if (longestStrLen == -1)
continue;
/* If wider than the max width, crop width */
if (longestStrLen > 255)
longestStrLen = 255;
CellView cv = sheet.getColumnView(i);
cv.setSize(longestStrLen * 256 + 100); /* Every character is 256 units wide, so scale it. */
sheet.setColumnView(i, cv);
}
}
for(int x=0;x<c;x++)
{
cell=sheet.getColumnView(x);
cell.setAutosize(true);
sheet.setColumnView(x, cell);
}
It is fine, instead of scanning all the columns. Pass the column as a parameter.
void display(column)
{
Cell = sheet.getColumnView(column);
cell.setAutosize(true);
sheet.setColumnView(column, cell);
}
So when you wiill be displaying your text you can set the particular length. Can be helpfull for huge excel files.
From the JExcelApi FAQ
How do I do the equivilent of Excel's "Format/Column/Auto Fit Selection"?
There is no API function to do this for you. You'll need to write code that scans the cells in each column, calculates the maximum length, and then calls setColumnView() accordingly. This will get you close to what Excel does but not exactly. Since most fonts have variable width characters, to get the exact same value, you would need to use FontMetrics to calculate the maximum width of each string in the column. No one has posted code on how to do this yet. Feel free to post code to the Yahoo! group or send it directly to the FAQ author's listed at the bottom of this page.
FontMetrics presumably refers to java.awt.FontMetrics. You should be able to work something out with the getLineMetrics(String, Graphics) method I would have though.
CellView's autosize method doesn't work for me all the time. My way of doing this is by programatically set the size(width) of the column based on the highest length of data in the column. Then perform some mathematical operations.
CellView cv = excelSheet.getColumnView(0);
cv.setSize((highest + ((highest/2) + (highest/4))) * 256);
where highest is an int that holds the longest length of data in the column.
setAutosize() method WILL NOT WORK if your cell has over 255 characters. This is related to the Excel 2003 max column width specification: http://office.microsoft.com/en-us/excel-help/excel-specifications-and-limits-HP005199291.aspx
You will need to write your own autosize method to handle this case.
Try this exemple:
expandColumns(sheet, 3);
workbook.write();
workbook.close();
private void expandColumn(WritableSheet sheet, int amountOfColumns){
int c = amountOfColumns;
for(int x=0;x<c;x++)
{
CellView cell = sheet.getColumnView(x);
cell.setAutosize(true);
sheet.setColumnView(x, cell);
}
}
Kotlin's implementation
private fun sheetAutoFitColumns(sheet: WritableSheet, columnsIndexesForFit: Array<Int>? = null, startFromRowWithIndex: Int = 0, excludeLastRows : Int = 0) {
for (columnIndex in columnsIndexesForFit?.iterator() ?: IntProgression.fromClosedRange(0, sheet.columns, 1).iterator()) {
val cells = sheet.getColumn(columnIndex)
var longestStrLen = -1
if (cells.isEmpty()) continue
for (j in startFromRowWithIndex until cells.size - excludeLastRows) {
if (cells[j].contents.length > longestStrLen) {
val str = cells[j].contents
if (str == null || str.isEmpty()) continue
longestStrLen = str.trim().length
}
}
if (longestStrLen == -1) continue
val newWidth = if (longestStrLen > 255) 255 else longestStrLen
sheet.setColumnView(columnIndex, newWidth)
}
}
example for use
sheetAutoFitColumns(sheet) // fit all columns by all rows
sheetAutoFitColumns(sheet, arrayOf(0, 3))// fit A and D columns by all rows
sheetAutoFitColumns(sheet, arrayOf(0, 3), 5)// fit A and D columns by rows after 5
sheetAutoFitColumns(sheet, arrayOf(0, 3), 5, 2)// fit A and D columns by rows after 5 and ignore two last rows
I'm developing a class, which allows users to create Excel spreadsheets on the fly (using OpenXML api) and I need to calculate columns width, so that they auto-fit the widest cell in the column.
I have the following code to calculate each column's width (using the formula from here and this tutorial):
private double CalculateColumnWidth(int textLength)
{
var font = new System.Drawing.Font("Calibri", 11);
float digitMaximumWidth = 0;
using(var graphics = Graphics.FromImage(new Bitmap(200, 200)))
{
for(var i = 0; i < 10; ++i)
{
var digitWidth = graphics.MeasureString(i.ToString(), font).Width;
if (digitWidth > digitMaximumWidth)
digitMaximumWidth = digitWidth;
}
}
return Math.Truncate((textLength * digitMaximumWidth + 5.0) / digitMaximumWidth * 256.0) / 256.0;
}
This works fine, the only question is:
Is there any way to get rid of the Bitmap and Graphics objects, that I don't really need to calculate the Excel's column width? Why is the Graphics object necessary to do this?
Thx in advance
"Column width measured as the number of characters of the maximum digit width of the numbers 0, 1, 2, …, 9 as rendered in the normal style's font. There are 4 pixels of margin padding (two on each side), plus 1 pixel padding for the gridlines.
Reference: http://msdn.microsoft.com/en-us/library/documentformat.openxml.spreadsheet.column.aspx
You need to calculate the width of each number 0 - 10 and determine which of those has the largest width. An easy way to accomplish this in .Net is to use MeasureString in System.Drawing.Graphics one of it's constructors requires a valid Bitmap. If your main process contains a window, i.e. you are a desktop windows app, you could construct the graphic object without a bitmap using:
Graphics graphics = Graphics.FromHwnd(Process.GetCurrentProcess().MainWindowHandle)
It is also possible to use classes in System.Windows.Media part of WPF see:http://stackoverflow.com/questions/1528525/alternatives-to-system-drawing-for-use-with-asp-net
In WPF there is the FormattedText in the System.Windows.Media namespace MSDN FormattedText that I can use like so:
private static Size GetTextSize(string txt, string font, int size, bool isBold)
{
Typeface tf = new Typeface(new System.Windows.Media.FontFamily(font),
FontStyles.Normal,
(isBold) ? FontWeights.Bold : FontWeights.Normal,
FontStretches.Normal);
FormattedText ft = new FormattedText(txt, new CultureInfo("en-us"), System.Windows.FlowDirection.LeftToRight, tf, (double)size, System.Windows.Media.Brushes.Black, null, TextFormattingMode.Display);
return new Size { Width = ft.WidthIncludingTrailingWhitespace, Height = ft.Height };
}
Is there a good approach in Silverlight to getting the width in pixels (at the moment height isn't important) besides making a call to the server?
An approach that I've seen used, that may not work in your particular instance, is to throw the text into an unstyled TextBlock, and then get the width of that control, like so:
private double GetTextWidth(string text, int fontSize)
{
TextBlock txtMeasure = new TextBlock();
txtMeasure.FontSize = fontSize;
txtMeasure.Text = text;
double width = txtMeasure.ActualWidth;
return width;
}
It's a hack, no doubt.