Add QRPbm output format for Portable BitMap outputs #323

wgevaert · 2025-12-11T19:02:46Z

Proposed changes

See #322

Types of changes

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Bugfix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to not work as expected)
Documentation fix or enhancement (no code was touched)
Other (CI, dependencies, etc., please describe)

Checklist:

I have checked to ensure there aren't other open Issues or Pull Requests for the same update/change
I have added tests that prove my fix is effective or that my feature works
I have added necessary documentation (if appropriate)
~~Any dependent changes have been merged and published in downstream modules~~ There are none
Static analysis and unit tests pass locally with my changes

codemasher · 2025-12-12T17:37:10Z

Hey, I haven't had a close look at the specification yet, but I see that there are multiple formats, so I'm thinking what the best way to abstract is (QRNetpbmAbstract -> QRPbm, ...). I'll add my thoughts to the code.

codemasher · 2025-12-12T17:38:10Z

src/Output/QRPbm.php

+
+class QRPbm extends QROutputAbstract {
+
+	private const LIGHT_DARK = [ '0', '1' ];


This is unnecessary when we handle integers instead.

codemasher · 2025-12-12T17:38:51Z

src/Output/QRPbm.php

+	private const LIGHT_DARK = [ '0', '1' ];
+
+	protected function prepareModuleValue( mixed $value ): mixed {
+		return $value;


This method should cast/clamp the allowed values, and the return type can be narrowed to int then.

I think I will use bool instead

I was thinking beyond the implementation of the b/w PBM format - int is certainly the more flexible and consistent choice.

The b/w PBM format is fundamentally different from the other formats: In PBM, 0/false is white, in PGM/PPM, 0 is black. To prevent confusion, I think I will handle PBM as a special case and use booleans for those.

In that case you can just completely ignore the module values setting. If you're going to abstract the classes as I recommended, you can override the setModuleValues() method from the parent to do nothing and be done with it for this particular format.

codemasher · 2025-12-12T17:43:24Z

src/Output/QRPbm.php

+	}
+
+	protected function getDefaultModuleValue( bool $isDark ): mixed {
+		return $isDark ? self::LIGHT_DARK[1] : self::LIGHT_DARK[0];


this can return (int)$isDark for the b/w PBM, 0 and 255 (or 65535?) for grayscale PGM, and for the RGB formats PPM/PAM it could return an array similar to the GD output class.

That's not entirely true; For P1 image format, 0 is white so we'd have to return (int)!$isDark instead. Confusingly, for P2 image format, 0 is black so we'd have to return $isDark ? 0 : $this->getMaxValue().

codemasher · 2025-12-12T17:49:40Z

src/Output/QRPbm.php

+	}
+
+	public static function moduleValueIsValid( mixed $value): bool {
+		return is_string( $value ) && in_array( $value, self::LIGHT_DARK, true );


A simple is_int() here would suffice for grayscale, for RGB formats see

php-qrcode/src/Output/RGBArrayModuleValueTrait.php

Lines 28 to 48 in c55c64d

public static function moduleValueIsValid(mixed $value):bool{

if(!is_array($value) || count($value) < 3){

return false;

}

// check the first 3 values of the array

foreach(array_values($value) as $i => $val){

if($i > 2){

break;

}

if(!is_numeric($val)){

return false;

}

}

return true;

}

codemasher · 2025-12-12T17:52:13Z

src/Output/QRPbm.php

+	}
+
+	public function dump( string|null $file = null ): mixed {
+		$size = $this->matrix->getSize();


This call is unnecessary, the size is already available in the parent class as $this->size.

codemasher · 2025-12-12T17:58:30Z

src/Output/QRPbm.php

+	public function dump( string|null $file = null ): mixed {
+		$size = $this->matrix->getSize();
+		$qrString = "P1\n"
+                    .$size.' '.$size."\n";


This implementation does not yet take into account the module scaling. From what I understand, the Netpbm formats are raster images, so the output size would be 1 pixel per QR module, which is very small. The parent class also holds the calculated matrix size as $this->length as well as the current scale as $this->scale, which could be used to repeat the rows/columns accordingly. The return type can be narrowed to string.

codemasher · 2025-12-12T18:02:55Z

src/Output/QRPbm.php

+                    .$size.' '.$size."\n";
+		foreach($this->matrix->getBooleanMatrix() as $row) {
+			foreach ($row as $isDark) {
+				$qrString .= $this->getDefaultModuleValue( $isDark );


The method getDefaultModuleValue() is supposed to only be called when you really need the default value - while it doesn't matter in this case, it can lead to unexpected results in extended classes. In the case of the b/w PBM format, a simple (int)$isDark will suffice.

I'm also thinking of adding an option like netpbmBinary or so, to allow saving in the binary format as the raw plaintext format can grow excessively large.

codemasher · 2025-12-12T18:05:20Z

src/Output/QRPbm.php

+		if ( is_string($file) ) {
+			$writeResult = file_put_contents($file,$qrString);
+			if ( $writeResult === false ) {
+				throw new QRCodeOutputException('Cannot write data to cache file: '.$file);
+			}
+		}


This entire block can be replaced by $this->saveToFile($qrString, $file); from the parent - it does all necessary error handling.

codemasher · 2025-12-12T18:07:52Z

tests/Output/QRPbmTest.php

+			$this->assertStringContainsString('1', $data);
+			$this->assertStringContainsString('0', $data);


You had this right before, we do call static methods statically :)

README.md

codemasher · 2025-12-15T14:06:53Z

src/Output/QRNetpbmBitmapBinary.php

+
+namespace chillerlan\QRCode\Output;
+
+use chillerlan\QRCode\Output\QRNetpbmBitmapAbstract;


I don't think we need separate classes for ASCII and binary here - it's quite excessive for a file format that's barely used. My initial recommendation was an abstract class for all netpbm based formats with child classes for each PBM, PGM, PPM and PAM. The conversion to binary can be done in the loop that creates the body (avoiding to loop over the same data 3 times), with a switch in the options, same goes for the header.

wgevaert added 5 commits December 11, 2025 19:58

Add QRPbm output format for Portable BitMap outputs

0a069c3

Add pbm output to readme

e70a744

Actually run tests against new class

f5a2d2b

Formatting

aa748d2

Call instance methods non-statically

9b94cfe

codemasher requested changes Dec 12, 2025

View reviewed changes

wgevaert added 5 commits December 15, 2025 14:04

Also support binary bitmaps

aff03cc

Missing import

78ae3a3

Formatting

03802e8

Formatting

ddef97d

Remove superseded QRPbm class

e5f60fd

codemasher requested changes Dec 15, 2025

View reviewed changes


		class QRPbm extends QROutputAbstract {

		private const LIGHT_DARK = [ '0', '1' ];

	public static function moduleValueIsValid(mixed $value):bool{

	if(!is_array($value) \|\| count($value) < 3){
	return false;
	}

	// check the first 3 values of the array
	foreach(array_values($value) as $i => $val){

	if($i > 2){
	break;
	}

	if(!is_numeric($val)){
	return false;
	}

	}

	return true;
	}

		$this->assertStringContainsString('1', $data);
		$this->assertStringContainsString('0', $data);


		namespace chillerlan\QRCode\Output;

		use chillerlan\QRCode\Output\QRNetpbmBitmapAbstract;

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Add QRPbm output format for Portable BitMap outputs #323

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wgevaert commented Dec 11, 2025

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codemasher commented Dec 12, 2025

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codemasher Dec 12, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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codemasher Dec 12, 2025 •

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