LibGFX/PAM: Allow reading CMYK .pam files

These are written by `mutool extract` for CMYK images.

They don't contain color profiles so they're not super convenient.
But `image` can convert them (*) to sRGB as long as you use it with
`--assign-color-profile` pointing to some CMYK icc profile of your
choice.

*: Once #22922 is merged.

Userland/Libraries/LibGfx/ImageFormats/PAMLoader.cpp

@@ -19,30 +19,41 @@ ErrorOr<void> read_image_data(PAMLoadingContext& context)
     bool is_rgb = context.format_details.depth == 3 && context.format_details.tupl_type == "RGB"sv;
     bool is_rgba = context.format_details.depth == 4 && context.format_details.tupl_type == "RGB_ALPHA"sv;
 
-    if (!is_gray && !is_gray_alpha && !is_rgb && !is_rgba)
+    bool is_cmyk = context.format_details.depth == 4 && context.format_details.tupl_type == "CMYK"sv;
-        return Error::from_string_view("Unsupported PAM depth"sv);
 
-    TRY(create_bitmap(context));
+    if (!is_gray && !is_gray_alpha && !is_rgb && !is_rgba && !is_cmyk)
+        return Error::from_string_view("Unsupported PAM depth"sv);
 
     auto& stream = *context.stream;
 
-    for (u64 i = 0; i < context.width * context.height; ++i) {
+    if (is_cmyk) {
-        if (is_gray) {
+        context.format_details.cmyk_bitmap = TRY(CMYKBitmap::create_with_size({ context.width, context.height }));
-            Array<u8, 1> pixel;
+        CMYK* data = context.format_details.cmyk_bitmap.value()->begin();
-            TRY(stream.read_until_filled(pixel));
+        for (u64 i = 0; i < context.width * context.height; ++i) {
-            context.bitmap->set_pixel(i % context.width, i / context.width, { pixel[0], pixel[0], pixel[0] });
-        } else if (is_gray_alpha) {
-            Array<u8, 2> pixel;
-            TRY(stream.read_until_filled(pixel));
-            context.bitmap->set_pixel(i % context.width, i / context.width, { pixel[0], pixel[0], pixel[0], pixel[1] });
-        } else if (is_rgb) {
-            Array<u8, 3> pixel;
-            TRY(stream.read_until_filled(pixel));
-            context.bitmap->set_pixel(i % context.width, i / context.width, { pixel[0], pixel[1], pixel[2] });
-        } else if (is_rgba) {
             Array<u8, 4> pixel;
             TRY(stream.read_until_filled(pixel));
-            context.bitmap->set_pixel(i % context.width, i / context.width, { pixel[0], pixel[1], pixel[2], pixel[3] });
+            data[i] = { pixel[0], pixel[1], pixel[2], pixel[3] };
+        }
+    } else {
+        TRY(create_bitmap(context));
+        for (u64 i = 0; i < context.width * context.height; ++i) {
+            if (is_gray) {
+                Array<u8, 1> pixel;
+                TRY(stream.read_until_filled(pixel));
+                context.bitmap->set_pixel(i % context.width, i / context.width, { pixel[0], pixel[0], pixel[0] });
+            } else if (is_gray_alpha) {
+                Array<u8, 2> pixel;
+                TRY(stream.read_until_filled(pixel));
+                context.bitmap->set_pixel(i % context.width, i / context.width, { pixel[0], pixel[0], pixel[0], pixel[1] });
+            } else if (is_rgb) {
+                Array<u8, 3> pixel;
+                TRY(stream.read_until_filled(pixel));
+                context.bitmap->set_pixel(i % context.width, i / context.width, { pixel[0], pixel[1], pixel[2] });
+            } else if (is_rgba) {
+                Array<u8, 4> pixel;
+                TRY(stream.read_until_filled(pixel));
+                context.bitmap->set_pixel(i % context.width, i / context.width, { pixel[0], pixel[1], pixel[2], pixel[3] });
+            }
         }
     }
 

Userland/Libraries/LibGfx/ImageFormats/PAMLoader.h

@@ -18,6 +18,7 @@ struct PAM {
     u16 max_val { 0 };
     u16 depth { 0 };
     String tupl_type {};
+    Optional<NonnullRefPtr<CMYKBitmap>> cmyk_bitmap {};
 };
 
 using PAMLoadingContext = PortableImageMapLoadingContext<PAM>;

Userland/Libraries/LibGfx/ImageFormats/PortableImageMapLoader.h

@@ -62,6 +62,9 @@ public:
 
     virtual ErrorOr<ImageFrameDescriptor> frame(size_t index, Optional<IntSize> ideal_size = {}) override;
 
+    virtual NaturalFrameFormat natural_frame_format() const override;
+    virtual ErrorOr<NonnullRefPtr<CMYKBitmap>> cmyk_frame() override;
+
 private:
     PortableImageDecoderPlugin(NonnullOwnPtr<SeekableStream> stream);
 
@@ -126,8 +129,45 @@ ErrorOr<ImageFrameDescriptor> PortableImageDecoderPlugin<TContext>::frame(size_t
         }
     }
 
+    if constexpr (requires { TContext::FormatDetails::cmyk_bitmap; }) {
+        if (m_context->format_details.cmyk_bitmap.has_value())
+            m_context->bitmap = TRY(m_context->format_details.cmyk_bitmap.value()->to_low_quality_rgb());
+    }
+
     VERIFY(m_context->bitmap);
     return ImageFrameDescriptor { m_context->bitmap, 0 };
 }
 
+template<typename TContext>
+NaturalFrameFormat PortableImageDecoderPlugin<TContext>::natural_frame_format() const
+{
+    if constexpr (requires { TContext::FormatDetails::cmyk_bitmap; }) {
+        if (m_context->format_details.depth == 4 && m_context->format_details.tupl_type == "CMYK"sv)
+            return NaturalFrameFormat::CMYK;
+    }
+
+    return NaturalFrameFormat::RGB;
+}
+
+template<typename TContext>
+ErrorOr<NonnullRefPtr<CMYKBitmap>> PortableImageDecoderPlugin<TContext>::cmyk_frame()
+{
+    if constexpr (requires { TContext::FormatDetails::cmyk_bitmap; }) {
+        VERIFY(natural_frame_format() == NaturalFrameFormat::CMYK);
+        if (m_context->state == TContext::State::Error)
+            return Error::from_string_literal("PortableImageDecoderPlugin: Decoding failed");
+
+        if (m_context->state < TContext::State::BitmapDecoded) {
+            if (decode(*m_context).is_error()) {
+                m_context->state = TContext::State::Error;
+                return Error::from_string_literal("PortableImageDecoderPlugin: Decoding failed");
+            }
+        }
+
+        return *m_context->format_details.cmyk_bitmap.value();
+    }
+
+    VERIFY_NOT_REACHED();
+}
+
 }