Lowyat.NET: Latest topics by Palindrome

Serial port (to USB), LAN/ WiFi, Bluetooth easier?

Palindrome — Fri, 15 May 2020 23:36:33 +0800

There is a documentation defines the communication protocol such as STX, LEN, MSG, ETX, LRC....and ACK if received. It also documented two communication methods: Serial port & Socket (LAN).

Which one is the:

1. Easier to code

2. More stable (less error in transmission)

I am using .NET, which includes Bluetooth class as well. (Not well versed in it though)

The smart payment terminal can use RS232-USB cable, or WiFi, or Bluetooth to perform request and response.

I mean if using serial port, no need to do pairing like Bluetooth, correct? My concern is serial port must use a cable to connect, whereas Bluetooth and WiFi do not.

Please advise.... Thanks.

Google Kickstart Round C

Palindrome — Fri, 15 May 2020 21:56:10 +0800

Maybe you are interested, may be you are not.

I paste the email in here anyway... A coding competition by Google.

QUOTE

We hope you’re well and staying safe during this challenging time. If you’re looking for a way to stay connected, brush up on some skills, or have a little fun, #KickStart 2020 Round C starts in less than 48 hours on May 17 at 11:00 UTC (add the round to your calendar). You will have 3 hours to solve a series of algorithmic challenges designed by Google engineers.

As a reminder, we have some platform updates if you’re joining us for Round C or a future round:

We’ve refreshed the user interface a bit. But, don't worry, viewing problems and submitting solutions haven't changed! You can now view scoreboards by location and by people you choose to follow. Try out these new features on past scoreboards in the archive before the round. We removed Hidden Verdict Test Sets, so all test sets will be visible during the round. Having only Visible Verdict Test Sets means you receive instant feedback — if your solution is correct, great! If not, try again and resubmit your code. Read more about Visible Verdict Test sets on our FAQ. You'll see a fourth problem added to each round. We don't expect you to solve all four of the problems — solve what you can and enjoy the greater variety of problems. There's something for everyone to solve!

Want to practice before the round?

Try your hand at past problems and review the preparing section in our FAQ. Join our Facebook group — ask questions and get helpful tips from fellow coders! Check out our YouTube playlist where you’ll find helpful prep videos hosted by Google engineers.

Have questions? Visit our FAQ and Terms and Rules pages. During the round, be sure to use the "Ask a Question" feature.

Hope to see you in Round C. Best of luck!
-The Kick Start Team

ESC/POS Print Utility

Palindrome — Mon, 11 May 2020 19:40:48 +0800

I have spent at least two months working for someone to build a ESC/POS solution in C# with portion of it dependent on good open-source code.

However, I have my unique solution to ESC/POS printing. (Pause a second. What is ESC/POS? Umm. It is a printer commands for receipt printer used in supermarkets and restaurants. Normally the printer commands are prefixed with escape code)

To name a few:
1. Multi-column with multi-line receipt printing

2. B/W picture printing with screen preview, Black : White ratio adjustment, or invert

3. Banner printing (either horizontally or vertically)

4. CJK character printing support

5. Large character size (up to x8 width and x8 height) printing support

As usual, it comes with barcode (1D or 2D) printing as documented in ESC/POS commands specification.

---

Actually I have done a WinForms app which features 1, 2 & 4, but I am hesitate to include 3 & 5, because it might be a waste of time if I further develop it.

What is the demand in the market for such receipt printing utility? I can make it open-source as well if needed to.

One thing for sure, this print utility definitely not for home users. It targets business owners.

How to improve this C# code?

Palindrome — Tue, 25 Feb 2020 17:24:11 +0800

This piece of code is working, though I feel it is not optimized , but don't know where to improve (Both readability and code efficiency).

The module is supposed to work with ESC/POS printing command. (80mm, which means if use FontA, that is 48 characters each line)

Basically it has two parts:

1. To enable multi-line for each column, bilingual (accept CJK character):

(the following is repeated 2 times for 2 columns, 3 times for 3 columns, etc)

CODE

for (int i = 0; i < A.Length; i++)
{
if (IsReadable(A[i]))
{
runLenA++;
arrA[countA] = arrA[countA] + A[i];
}
else
{
runLenA += 2;

if (runLenA > lenA * (countA + 1))
{
runLenA--;
i--;
}
else
arrA[countA] = arrA[countA] + A[i];
}

if (runLenA == lenA * (countA + 1))
{
lenArrA[countA] = GetActualLength(arrA[countA]);
countA++;
}
}
lenArrA[countA] = GetActualLength(arrA[countA]);

There must be better way to code it. (The code logic also will evaluate if a CJK char is at the end of current line, it will jump to next line, because every CJK char is equivalent to 2x normal char)

2. Then perform space padding
(the following, again, is repeated 2 times for 2 columns, 3 times for 3 columns, etc)

CODE

int countMax = (countA > countB) ? countA : countB;
countMax = (countMax > countC) ? countMax : countC;

for (int j = 0; j <= countMax; j++)
{
if (alignA == Align.Right)
{
for (int i = 0; i < (lenA - lenArrA[j]); i++)
arrA[j] = " " + arrA[j];
}
else if (alignA == Align.Left)
{
for (int i = 0; i < (lenA - lenArrA[j]); i++)
arrA[j] = arrA[j] + " ";
}
}

While I am sharing this working code on here, at the same time I ask for code optimization, I do not think it is a good code to be shared on GitHub.

The original working code:

» Click to show Spoiler - click again to hide... «

CODE

namespace MULTICOL
{
public static class Methods
{
public static int maxLines = 48;
public static byte[] PrintColumns(string A, string B, string C, int widthA = 50, int widthB = 25, int widthC = 25, Align alignA = Align.Left, Align alignB = Align.Right, Align alignC = Align.Right, bool bold = false, bool underLine = false)
{
byte[] cmd = new byte[] { };

int lenA = widthA * 48 / 100;
int lenB = widthB * 48 / 100;
int lenC = widthC * 48 / 100;

int runLenA = 0;
int runLenB = 0;
int runLenC = 0;

var arrA = new string[maxLines];
var arrB = new string[maxLines];
var arrC = new string[maxLines];

int[] lenArrA = new int[maxLines];
int[] lenArrB = new int[maxLines];
int[] lenArrC = new int[maxLines];

int countA = 0;
int countB = 0;
int countC = 0;

for (int i = 0; i < A.Length; i++)
{
if (IsReadable(A[i]))
{
runLenA++;
arrA[countA] = arrA[countA] + A[i];
}
else
{
runLenA += 2;

if (runLenA > lenA * (countA + 1))
{
runLenA--;
i--;
}
else
arrA[countA] = arrA[countA] + A[i];
}

if (runLenA == lenA * (countA + 1))
{
lenArrA[countA] = GetActualLength(arrA[countA]);
countA++;
}
}
lenArrA[countA] = GetActualLength(arrA[countA]);

for (int i = 0; i < B.Length; i++)
{
if (IsReadable(B[i]))
{
runLenB++;
arrB[countB] = arrB[countB] + B[i];
}
else
{
runLenB += 2;

if (runLenB > lenB * (countB + 1))
{
runLenB--;
i--;
}
else
arrB[countB] = arrB[countB] + B[i];
}

if (runLenB == lenB * (countB + 1))
{
lenArrB[countB] = GetActualLength(arrB[countB]);
countB++;
}
}
lenArrB[countB] = GetActualLength(arrB[countB]);

for (int i = 0; i < C.Length; i++)
{
if (IsReadable(C[i]))
{
runLenC++;
arrC[countC] = arrC[countC] + C[i];
}
else
{
runLenC += 2;

if (runLenC > lenC * (countC + 1))
{
runLenC--;
i--;
}
else
arrC[countC] = arrC[countC] + C[i];
}

if (runLenC == lenC * (countC + 1))
{
lenArrC[countC] = GetActualLength(arrC[countC]);
countC++;
}
}
lenArrC[countC] = GetActualLength(arrC[countC]);

int countMax = (countA > countB) ? countA : countB;
countMax = (countMax > countC) ? countMax : countC;

for (int j = 0; j <= countMax; j++)
{
if (alignA == Align.Right)
{
for (int i = 0; i < (lenA - lenArrA[j]); i++)
arrA[j] = " " + arrA[j];
}
else if (alignA == Align.Left)
{
for (int i = 0; i < (lenA - lenArrA[j]); i++)
arrA[j] = arrA[j] + " ";
}
}
for (int j = 0; j <= countMax; j++)
{
if (alignB == Align.Right)
{
for (int i = 0; i < (lenB - lenArrB[j]); i++)
arrB[j] = " " + arrB[j];
}
else if (alignB == Align.Left)
{
for (int i = 0; i < (lenB - lenArrB[j]); i++)
arrB[j] = arrB[j] + " ";
}
}
for (int j = 0; j <= countMax; j++)
{
if (alignC == Align.Right)
{
for (int i = 0; i < (lenC - lenArrC[j]); i++)
arrC[j] = " " + arrC[j];
}
else if (alignC == Align.Left)
{
for (int i = 0; i < (lenC - lenArrC[j]); i++)
arrC[j] = arrC[j] + " ";
}
}

for (int i = 0; i <= countMax; i++)
cmd = cmd.Add(PrintChineseLine(arrA[i] + arrB[i] + arrC[i], Align.Left, bold, underLine));

return cmd;
}
public static byte[] PrintColumns(string A, string B, int widthA = 50, int widthB = 50, Align alignA = Align.Left, Align alignB = Align.Right, bool bold = false, bool underLine = false)
{
byte[] cmd = new byte[] { };

int lenA = widthA * 48 / 100;
int lenB = widthB * 48 / 100;

if ((100 - widthA) < widthB)
lenB = (100 - widthA) / 100 * 48;

int runLenA = 0;
int runLenB = 0;

var arrA = new string[maxLines];
var arrB = new string[maxLines];

int[] lenArrA = new int[maxLines];
int[] lenArrB = new int[maxLines];

int countA = 0;
int countB = 0;

for (int i = 0; i < A.Length; i++)
{
if (IsReadable(A[i]))
{
runLenA++;
arrA[countA] = arrA[countA] + A[i];
}
else
{
runLenA += 2;

if (runLenA > lenA * (countA + 1))
{
runLenA--;
i--;
}
else
arrA[countA] = arrA[countA] + A[i];
}

if (runLenA == lenA * (countA + 1))
{
lenArrA[countA] = GetActualLength(arrA[countA]);
countA++;
}
}
lenArrA[countA] = GetActualLength(arrA[countA]);

for (int i = 0; i < B.Length; i++)
{
if (IsReadable(B[i]))
{
runLenB++;
arrB[countB] = arrB[countB] + B[i];
}
else
{
runLenB += 2;

if (runLenB > lenB * (countB + 1))
{
runLenB--;
i--;
}
else
arrB[countB] = arrB[countB] + B[i];
}

if (runLenB == lenB * (countB + 1))
{
lenArrB[countB] = GetActualLength(arrB[countB]);
countB++;
}
}
lenArrB[countB] = GetActualLength(arrB[countB]);

int countMax = (countA > countB) ? countA : countB;

for (int j = 0; j <= countMax; j++)
{
if (alignA == Align.Right)
{
for (int i = 0; i < (lenA - lenArrA[j]); i++)
arrA[j] = " " + arrA[j];
}
else if (alignA == Align.Left)
{
for (int i = 0; i < (lenA - lenArrA[j]); i++)
arrA[j] = arrA[j] + " ";
}
}
for (int j = 0; j <= countMax; j++)
{
if (alignB == Align.Right)
{
for (int i = 0; i < (lenB - lenArrB[j]); i++)
arrB[j] = " " + arrB[j];
}
else if (alignB == Align.Left)
{
for (int i = 0; i < (lenB - lenArrB[j]); i++)
arrB[j] = arrB[j] + " ";
}
}

for (int i = 0; i <= countMax; i++)
cmd = cmd.Add(PrintChineseLine(arrA[i] + arrB[i], Align.Left, bold, underLine));

return cmd;
}

#region internal
private static bool IsReadable(char input)
{
return ((input >= 32) & (input <= 127));
}

private static int GetActualLength(string input)
{
int lenInput = 0;

if (input is null)
return 0;

for (int i = 0; i < input.Length; i++)
{
if (IsReadable(input[i]))
lenInput++;
else
lenInput += 2;
}
return lenInput;
}
#endregion
}
}