LibGfx/PortableFormat: Simplify `read_number` signature

The function signature goes from:
`bool read_number(Streamer& streamer, TValue* value)`
to
`ErrorOr<u16> read_number(Streamer& streamer)`

It allows us to, on one hand use `ErrorOr` for error propagation,
removing an out parameter in the meantime, and on the other hand remove
the useless template.

3 files changed, 26 insertions, 29 deletions

diff --git a/Userland/Libraries/LibGfx/ImageFormats/PGMLoader.cpp b/Userland/Libraries/LibGfx/ImageFormats/PGMLoader.cpp
index 0240548013..2ee82006b8 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/PGMLoader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/PGMLoader.cpp
@@ -33,11 +33,11 @@ bool read_image_data(PGMLoadingContext& context, Streamer& streamer)
     Vector<Gfx::Color> color_data;
 
     if (context.type == PGMLoadingContext::Type::ASCII) {
-        u16 value;
-
         while (true) {
-            if (!read_number(streamer, &value))
+            auto number_or_error = read_number(streamer);
+            if (number_or_error.is_error())
                 break;
+            auto value = number_or_error.value();
 
             if (!read_whitespace(context, streamer))
                 break;
diff --git a/Userland/Libraries/LibGfx/ImageFormats/PPMLoader.cpp b/Userland/Libraries/LibGfx/ImageFormats/PPMLoader.cpp
index c662e76b87..c8859350af 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/PPMLoader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/PPMLoader.cpp
@@ -22,30 +22,29 @@ bool read_image_data(PPMLoadingContext& context, Streamer& streamer)
     color_data.ensure_capacity(context.width * context.height);
 
     if (context.type == PPMLoadingContext::Type::ASCII) {
-        u16 red;
-        u16 green;
-        u16 blue;
-
         while (true) {
-            if (!read_number(streamer, &red))
+            auto const red_or_error = read_number(streamer);
+            if (red_or_error.is_error())
                 break;
 
             if (!read_whitespace(context, streamer))
                 break;
 
-            if (!read_number(streamer, &green))
+            auto const green_or_error = read_number(streamer);
+            if (green_or_error.is_error())
                 break;
 
             if (!read_whitespace(context, streamer))
                 break;
 
-            if (!read_number(streamer, &blue))
+            auto const blue_or_error = read_number(streamer);
+            if (blue_or_error.is_error())
                 break;
 
             if (!read_whitespace(context, streamer))
                 break;
 
-            Color color { (u8)red, (u8)green, (u8)blue };
+            Color color { (u8)red_or_error.value(), (u8)green_or_error.value(), (u8)blue_or_error.value() };
             if (context.format_details.max_val < 255)
                 color = adjust_color(context.format_details.max_val, color);
             color_data.append(color);
diff --git a/Userland/Libraries/LibGfx/ImageFormats/PortableImageLoaderCommon.h b/Userland/Libraries/LibGfx/ImageFormats/PortableImageLoaderCommon.h
index a17b6c1921..8ab778c555 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/PortableImageLoaderCommon.h
+++ b/Userland/Libraries/LibGfx/ImageFormats/PortableImageLoaderCommon.h
@@ -11,6 +11,7 @@
 #include <AK/DeprecatedString.h>
 #include <AK/Endian.h>
 #include <AK/ScopeGuard.h>
+#include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <AK/Types.h>
 #include <AK/Vector.h>
@@ -30,8 +31,7 @@ static constexpr Color adjust_color(u16 max_val, Color color)
     return color;
 }
 
-template<typename TValue>
-static bool read_number(Streamer& streamer, TValue* value)
+static inline ErrorOr<u16> read_number(Streamer& streamer)
 {
     u8 byte {};
     StringBuilder sb {};
@@ -45,14 +45,11 @@ static bool read_number(Streamer& streamer, TValue* value)
         sb.append(byte);
     }
 
-    auto const opt_value = sb.to_deprecated_string().to_uint();
-    if (!opt_value.has_value()) {
-        *value = 0;
-        return false;
-    }
+    auto const maybe_value = TRY(sb.to_string()).to_number<u16>();
+    if (!maybe_value.has_value())
+        return Error::from_string_literal("Can't convert bytes to a number");
 
-    *value = static_cast<u16>(opt_value.value());
-    return true;
+    return *maybe_value;
 }
 
 template<typename TContext>
@@ -133,11 +130,11 @@ static bool read_whitespace(TContext& context, Streamer& streamer)
 template<typename TContext>
 static bool read_width(TContext& context, Streamer& streamer)
 {
-    if (bool const result = read_number(streamer, &context.width);
-        !result || context.width == 0) {
+    auto number_or_error = read_number(streamer);
+    if (number_or_error.is_error())
         return false;
-    }
 
+    context.width = number_or_error.value();
     context.state = TContext::State::Width;
     return true;
 }
@@ -145,11 +142,11 @@ static bool read_width(TContext& context, Streamer& streamer)
 template<typename TContext>
 static bool read_height(TContext& context, Streamer& streamer)
 {
-    if (bool const result = read_number(streamer, &context.height);
-        !result || context.height == 0) {
+    auto number_or_error = read_number(streamer);
+    if (number_or_error.is_error())
         return false;
-    }
 
+    context.height = number_or_error.value();
     context.state = TContext::State::Height;
     return true;
 }
@@ -157,10 +154,11 @@ static bool read_height(TContext& context, Streamer& streamer)
 template<typename TContext>
 static bool read_max_val(TContext& context, Streamer& streamer)
 {
-    if (bool const result = read_number(streamer, &context.format_details.max_val);
-        !result || context.format_details.max_val == 0) {
+    auto number_or_error = read_number(streamer);
+    if (number_or_error.is_error())
         return false;
-    }
+
+    context.format_details.max_val = number_or_error.value();
 
     if (context.format_details.max_val > 255) {
         dbgln_if(PORTABLE_IMAGE_LOADER_DEBUG, "We can't parse 2 byte color for {}", TContext::FormatDetails::image_type);