fix issues with themes on HiDPI screens and strict aliasing violations in byte swapping

Author: wkjarosz

src/endian-utils.h

@@ -9,6 +9,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
+#include <type_traits>
 
 //! Endianness indicator
 enum class Endian
@@ -46,24 +47,39 @@ inline Endian host_endian() { return is_little_endian() ? Endian::Little : Endia
 template <typename T>
 inline T swap_bytes(T value)
 {
+    static_assert(std::is_trivially_copyable_v<T>, "swap_bytes requires trivially copyable types");
+
     if constexpr (sizeof(T) == 1)
     {
         return value;
     }
+
     else if constexpr (sizeof(T) == 2)
     {
-        uint16_t swapped = byte_swap_16(*reinterpret_cast<uint16_t *>(&value));
-        return *reinterpret_cast<T *>(&swapped);
+        uint16_t tmp = 0;
+        std::memcpy(&tmp, &value, sizeof(tmp));
+        tmp = byte_swap_16(tmp);
+        T out;
+        std::memcpy(&out, &tmp, sizeof(tmp));
+        return out;
     }
     else if constexpr (sizeof(T) == 4)
     {
-        uint32_t swapped = byte_swap_32(*reinterpret_cast<uint32_t *>(&value));
-        return *reinterpret_cast<T *>(&swapped);
+        uint32_t tmp = 0;
+        std::memcpy(&tmp, &value, sizeof(tmp));
+        tmp = byte_swap_32(tmp);
+        T out;
+        std::memcpy(&out, &tmp, sizeof(tmp));
+        return out;
     }
     else if constexpr (sizeof(T) == 8)
     {
-        uint64_t swapped = byte_swap_64(*reinterpret_cast<uint64_t *>(&value));
-        return *reinterpret_cast<T *>(&swapped);
+        uint64_t tmp = 0;
+        std::memcpy(&tmp, &value, sizeof(tmp));
+        tmp = byte_swap_64(tmp);
+        T out;
+        std::memcpy(&out, &tmp, sizeof(tmp));
+        return out;
     }
     else
     {

src/imageio/exif.cpp

@@ -1,6 +1,5 @@
 #include "exif.h"
 #include "endian-utils.h"
-#include "fwd.h"
 #include "json.h"
 #include <cstdint>
 #include <cstdio>
@@ -96,8 +95,9 @@ static json get_value(int format, size_t components, const uint8_t *data, Endian
         vector<double> vals;
         for (unsigned int i = 0; i < components; i++)
         {
-            auto r = read_as<uint2>(&data[sizeof(uint2) * i], data_endian);
-            vals.push_back(double(r.x) / r.y);
+            auto num = read_as<uint32_t>(&data[sizeof(uint32_t) * (2 * i + 0)], data_endian);
+            auto den = read_as<uint32_t>(&data[sizeof(uint32_t) * (2 * i + 1)], data_endian);
+            vals.push_back(double(num) / den);
         }
         return vals.size() == 1 ? json(vals[0]) : json(vals);
     }
@@ -107,8 +107,9 @@ static json get_value(int format, size_t components, const uint8_t *data, Endian
         vector<double> vals;
         for (unsigned int i = 0; i < components; i++)
         {
-            auto r = read_as<int2>(&data[sizeof(int2) * i], data_endian);
-            vals.push_back(double(r.x) / r.y);
+            auto num = read_as<int32_t>(&data[sizeof(int32_t) * (2 * i + 0)], data_endian);
+            auto den = read_as<int32_t>(&data[sizeof(int32_t) * (2 * i + 1)], data_endian);
+            vals.push_back(double(num) / den);
         }
         return vals.size() == 1 ? json(vals[0]) : json(vals);
     }

src/theme.cpp

@@ -17,8 +17,6 @@ static void apply_hdrview_dark_theme()
     ImGuiStyle &style = ImGui::GetStyle();
     style             = ImGuiStyle(); // resets all fields to default values
 
-    style.FontSizeBase = 14.0f; // base font size
-    // style._NextFrameFontSizeBase = style.FontSizeBase; // FIXME: Temporary hack until we finish remaining work.
     // make things like radio buttons look nice and round
     style.CircleTessellationMaxError = 0.1f;
 
@@ -109,8 +107,6 @@ static void apply_hdrview_light_theme()
     ImGuiStyle &style = ImGui::GetStyle();
     style             = ImGuiStyle(); // resets all fields to default values
 
-    style.FontSizeBase = 14.0f; // base font size
-    // style._NextFrameFontSizeBase = style.FontSizeBase; // FIXME: Temporary hack until we finish remaining work.
     // make things like radio buttons look nice and round
     style.CircleTessellationMaxError = 0.1f;