From c336cef065e631dbed8dda860ea501096f7ca93b Mon Sep 17 00:00:00 2001
From: Lucas CHOLLET <lucas.chollet@free.fr>
Date: Sun, 16 Jul 2023 21:55:07 -0400
Subject: [PATCH] LibGfx/BMP: Decode the header in `create()` and remove
 `initialize()`

This is done as a part of #19893.
---
 .../LibGfx/ImageFormats/BMPLoader.cpp         | 37 +++++--------------
 .../Libraries/LibGfx/ImageFormats/BMPLoader.h |  2 +-
 2 files changed, 11 insertions(+), 28 deletions(-)

diff --git a/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.cpp b/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.cpp
index 58b30c12eb..e81675ad96 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.cpp
@@ -191,7 +191,6 @@ enum class DIBType {
 struct BMPLoadingContext {
     enum class State {
         NotDecoded = 0,
-        HeaderDecoded,
         DIBDecoded,
         ColorTableDecoded,
         PixelDataDecoded,
@@ -494,12 +493,6 @@ static bool set_dib_bitmasks(BMPLoadingContext& context, InputStreamer& streamer
 
 static ErrorOr<void> decode_bmp_header(BMPLoadingContext& context)
 {
-    if (context.state == BMPLoadingContext::State::Error)
-        return Error::from_string_literal("Error before starting decode_bmp_header");
-
-    if (context.state >= BMPLoadingContext::State::HeaderDecoded)
-        return {};
-
     if (!context.file_bytes || context.file_size < bmp_header_size) {
         dbgln_if(BMP_DEBUG, "Missing BMP header");
         context.state = BMPLoadingContext::State::Error;
@@ -536,7 +529,6 @@ static ErrorOr<void> decode_bmp_header(BMPLoadingContext& context)
         return Error::from_string_literal("BMP data offset is beyond file end");
     }
 
-    context.state = BMPLoadingContext::State::HeaderDecoded;
     return {};
 }
 
@@ -823,7 +815,7 @@ static ErrorOr<void> decode_bmp_dib(BMPLoadingContext& context)
     if (context.state >= BMPLoadingContext::State::DIBDecoded)
         return {};
 
-    if (!context.is_included_in_ico && context.state < BMPLoadingContext::State::HeaderDecoded)
+    if (!context.is_included_in_ico)
         TRY(decode_bmp_header(context));
 
     u8 header_size = context.is_included_in_ico ? 0 : bmp_header_size;
@@ -936,9 +928,6 @@ static ErrorOr<void> decode_bmp_color_table(BMPLoadingContext& context)
     if (context.state == BMPLoadingContext::State::Error)
         return Error::from_string_literal("Error before starting decode_bmp_color_table");
 
-    if (context.state < BMPLoadingContext::State::DIBDecoded)
-        TRY(decode_bmp_dib(context));
-
     if (context.state >= BMPLoadingContext::State::ColorTableDecoded)
         return {};
 
@@ -1478,20 +1467,9 @@ BMPImageDecoderPlugin::~BMPImageDecoderPlugin() = default;
 
 IntSize BMPImageDecoderPlugin::size()
 {
-    if (m_context->state == BMPLoadingContext::State::Error)
-        return {};
-
-    if (m_context->state < BMPLoadingContext::State::DIBDecoded && decode_bmp_dib(*m_context).is_error())
-        return {};
-
     return { m_context->dib.core.width, abs(m_context->dib.core.height) };
 }
 
-ErrorOr<void> BMPImageDecoderPlugin::initialize()
-{
-    return decode_bmp_header(*m_context);
-}
-
 bool BMPImageDecoderPlugin::sniff(ReadonlyBytes data)
 {
     BMPLoadingContext context;
@@ -1500,14 +1478,21 @@ bool BMPImageDecoderPlugin::sniff(ReadonlyBytes data)
     return !decode_bmp_header(context).is_error();
 }
 
+ErrorOr<NonnullOwnPtr<BMPImageDecoderPlugin>> BMPImageDecoderPlugin::create_impl(ReadonlyBytes data, IncludedInICO included_in_ico)
+{
+    auto plugin = TRY(adopt_nonnull_own_or_enomem(new (nothrow) BMPImageDecoderPlugin(data.data(), data.size(), included_in_ico)));
+    TRY(decode_bmp_dib(*plugin->m_context));
+    return plugin;
+}
+
 ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> BMPImageDecoderPlugin::create(ReadonlyBytes data)
 {
-    return adopt_nonnull_own_or_enomem(new (nothrow) BMPImageDecoderPlugin(data.data(), data.size()));
+    return create_impl(data, IncludedInICO::No);
 }
 
 ErrorOr<NonnullOwnPtr<BMPImageDecoderPlugin>> BMPImageDecoderPlugin::create_as_included_in_ico(Badge<ICOImageDecoderPlugin>, ReadonlyBytes data)
 {
-    return adopt_nonnull_own_or_enomem(new (nothrow) BMPImageDecoderPlugin(data.data(), data.size(), IncludedInICO::Yes));
+    return create_impl(data, IncludedInICO::Yes);
 }
 
 bool BMPImageDecoderPlugin::sniff_dib()
@@ -1552,8 +1537,6 @@ ErrorOr<ImageFrameDescriptor> BMPImageDecoderPlugin::frame(size_t index, Optiona
 
 ErrorOr<Optional<ReadonlyBytes>> BMPImageDecoderPlugin::icc_data()
 {
-    TRY(decode_bmp_dib(*m_context));
-
     if (m_context->dib_type != DIBType::V5)
         return OptionalNone {};
 
diff --git a/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.h b/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.h
index bc29fed16a..b6a25ce981 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.h
+++ b/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.h
@@ -29,7 +29,6 @@ public:
 
     virtual IntSize size() override;
 
-    virtual ErrorOr<void> initialize() override;
     bool sniff_dib();
     virtual bool is_animated() override;
     virtual size_t loop_count() override;
@@ -40,6 +39,7 @@ public:
 
 private:
     BMPImageDecoderPlugin(u8 const*, size_t, IncludedInICO included_in_ico = IncludedInICO::No);
+    static ErrorOr<NonnullOwnPtr<BMPImageDecoderPlugin>> create_impl(ReadonlyBytes, IncludedInICO);
 
     OwnPtr<BMPLoadingContext> m_context;
 };