Merge pull request #18 from mike42/feature/14-indexed-raster

Implement indexed raster image
mike42 · Apr 28, 2018 · 2d39a1d · 2d39a1d
2 parents cdf329a + 4c04051
commit 2d39a1d
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Showing 8 changed files with 442 additions and 33 deletions.
diff --git a/src/Mike42/ImagePhp/BlackAndWhiteRasterImage.php b/src/Mike42/ImagePhp/BlackAndWhiteRasterImage.php
@@ -156,9 +156,23 @@ public function toGrayscale() : GrayscaleRasterImage
         }
         return $img;
     }
-        
+
     public function toBlackAndWhite() : BlackAndWhiteRasterImage
     {
          return clone $this;
     }
+
+    public function toIndexed(): IndexedRasterImage
+    {
+        $width = $this -> width;
+        $height = $this -> height;
+        $pixelData = array_fill(0, $width * $height, 0);
+        for ($y = 0; $y < $height; $y++) {
+            for ($x = 0; $x < $width; $x++) {
+                $pixelData[$y * $width + $x] = $this -> getPixel($x, $y);
+            }
+        }
+        $colorTable = PaletteGenerator::blackAndWhitePalette();
+        return IndexedRasterImage::create($width, $height, $pixelData, $colorTable, 255);
+    }
 }
diff --git a/src/Mike42/ImagePhp/Codec/GifCodec.php b/src/Mike42/ImagePhp/Codec/GifCodec.php
@@ -1,24 +1,26 @@
 <?php
 namespace Mike42\ImagePhp\Codec;
 
-use Mike42\ImagePhp\GrayscaleRasterImage;
 use Mike42\ImagePhp\RasterImage;
 use Mike42\ImagePhp\Util\LzwCompression;
+use Mike42\ImagePhp\IndexedRasterImage;
 
 class GifCodec implements ImageEncoder
 {
     protected static $instance = null;
 
     public function encode(RasterImage $image, string $format): string
     {
-        if (!($image instanceof GrayscaleRasterImage)) {
+        if (!($image instanceof IndexedRasterImage)) {
             // Convert if necessary
-            $image = $image -> toGrayscale();
-        } else {
-            if ($image -> getMaxVal() != 256) {
-                // Scaling has the side-effect of mapping to 256 colors
-                $image = $image -> scale($image -> getWidth(), $image -> getHeight());
-            }
+            $image = $image -> toIndexed();
+        }
+        $palette = $image -> getPalette();
+        if ($image -> getMaxVal() > 256) {
+            // Color count is too large, clone the image and drop the color depth
+            $image = $image -> toIndexed();
+            $image -> setMaxVal(255);
+            $palette = $image -> getPalette();
         }
         // GIF signature
         $signature = pack("c6", 0x47, 0x49, 0x46, 0x38, 0x39, 0x61);
@@ -28,14 +30,31 @@ public function encode(RasterImage $image, string $format): string
         $header = pack('v2c3', $width, $height, 0xF7, 0, 0);
         // Color table of grayscale
         $colorTable = [];
-        for ($i = 0; $i < 256; $i++) {
-            $colorTable[] = $i;
-            $colorTable[] = $i;
-            $colorTable[] = $i;
+        $paletteSize = count($palette);
+        for ($i = 0; $i < $paletteSize; $i++) {
+            $entry = $palette[$i];
+            $colorTable[] = $entry[0];
+            $colorTable[] = $entry[1];
+            $colorTable[] = $entry[2];
+        }
+        // Padding to 256 color entries
+        for ($i = $paletteSize; $i < 256; $i++) {
+            $colorTable[] = 0;
+            $colorTable[] = 0;
+            $colorTable[] = 0;
         }
+
         $gct = pack("C*", ... $colorTable);
+        // Transparent color for graphic control
+        $transparentColorFlag = 0x00;
+        $transparentColor = 0;
+        if ($image -> getTransparentColor() !== null) {
+            $transparentColor = $image -> getTransparentColor() & 0xFF;
+            $transparentColorFlag = 0x01;
+        }
         // Graphic control
-        $gce = pack("C4vC2", 0x21, 0xF9, 0x04, 0x01, 0x00, 0x10, 0x00);
+        // TODO one of these flags does not do what you think it does.
+        $gce = pack("C4vC2", 0x21, 0xF9, 0x04, 0x00 | $transparentColorFlag, 0x00, $transparentColor, 0x00);
         // Image
         $imageDescriptor = pack('Cv4C', 0x2C, 0, 0, $width, $height, 0);
         $raster = $image -> getRasterData();

diff --git a/src/Mike42/ImagePhp/Codec/PnmCodec.php b/src/Mike42/ImagePhp/Codec/PnmCodec.php
@@ -72,7 +72,7 @@ public function decode(string $blob): RasterImage
                 $next_line_end = strpos($blob, "\n", $line_end + 1);
                 $maxValLine = substr($blob, $line_end + 1, ($next_line_end - $line_end) - 1);
                 $maxVal = (int)$maxValLine;
-                $depth = $maxVal >= 255 ? 2 : 1;
+                $depth = $maxVal > 255 ? 2 : 1;
                 $line_end = $next_line_end;
                 // Extract data
                 $expectedBytes = $width * $height * $depth;
@@ -93,7 +93,7 @@ public function decode(string $blob): RasterImage
                 $next_line_end = strpos($blob, "\n", $line_end + 1);
                 $maxValLine = substr($blob, $line_end + 1, ($next_line_end - $line_end) - 1);
                 $maxVal = (int)$maxValLine;
-                $depth = $maxVal >= 255 ? 2 : 1;
+                $depth = $maxVal > 255 ? 2 : 1;
                 $line_end = $next_line_end;
                 $expectedBytes = $width * $height * $depth * 3;
                 $data = substr($blob, $line_end + 1);

diff --git a/src/Mike42/ImagePhp/GrayscaleRasterImage.php b/src/Mike42/ImagePhp/GrayscaleRasterImage.php
@@ -20,7 +20,7 @@ public function getHeight() : int
     {
         return $this -> height;
     }
-
+    
     public function setPixel(int $x, int $y, int $value)
     {
         if ($x < 0 || $x >= $this -> width) {
@@ -110,7 +110,7 @@ public function toGrayscale() : GrayscaleRasterImage
     {
         return clone $this;
     }
-        
+
     public function toBlackAndWhite() : BlackAndWhiteRasterImage
     {
         $img = BlackAndWhiteRasterImage::create($this -> width, $this -> height);
@@ -123,4 +123,16 @@ public function toBlackAndWhite() : BlackAndWhiteRasterImage
         }
         return $img;
     }
+
+    public function toIndexed(): IndexedRasterImage
+    {
+        if ($this -> maxVal > 255) {
+            // Making use of how scale() uses default values to make a new canvas, which has the
+            // side-effect of creating an 8-bit image.
+            return $this -> scale($this -> width, $this -> height) -> toIndexed();
+        }
+        $data = $this -> data;
+        $colorTable = PaletteGenerator::monochromePalette();
+        return IndexedRasterImage::create($this -> width, $this -> height, $data, $colorTable, 255);
+    }
 }