DolphinQt: cache icons instead of single pixmaps

Fixes dynamically changing dpi scaling.
Load resources from svg if possible.
Currently svg support is not in Qt build in Externals,
and image files need to be added later.

Source/Core/DolphinQt/Resources.cpp

@@ -3,53 +3,58 @@
 
 #include "DolphinQt/Resources.h"
 
-#include <QGuiApplication>
+#include <QFileInfo>
 #include <QIcon>
+#include <QImageReader>
 #include <QPixmap>
-#include <QScreen>
 
+#include "Common/Assert.h"
 #include "Common/FileUtil.h"
 
 #include "Core/Config/MainSettings.h"
 
 #include "DolphinQt/Settings.h"
 
-#ifdef _WIN32
-#include "DolphinQt/QtUtils/WinIconHelper.h"
-#endif
+bool Resources::m_svg_supported;
+QList<QIcon> Resources::m_platforms;
+QList<QIcon> Resources::m_countries;
+QList<QIcon> Resources::m_misc;
 
-QList<QPixmap> Resources::m_platforms;
-QList<QPixmap> Resources::m_countries;
-QList<QPixmap> Resources::m_misc;
-
-QIcon Resources::GetIcon(std::string_view name, const QString& dir)
+QIcon Resources::LoadNamedIcon(std::string_view name, const QString& dir)
 {
-  QString name_owned = QString::fromLatin1(name.data(), static_cast<int>(name.size()));
-  QString base_path = dir + QLatin1Char{'/'} + name_owned;
+  const QString base_path = dir + QLatin1Char{'/'} + QString::fromLatin1(name);
+  const QString svg_path = base_path + QStringLiteral(".svg");
 
-  const auto dpr = QGuiApplication::primaryScreen()->devicePixelRatio();
+  // Prefer svg
+  if (m_svg_supported && QFileInfo(svg_path).exists())
+    return QIcon(svg_path);
 
-  QIcon icon(base_path.append(QStringLiteral(".png")));
+  QIcon icon;
 
-  if (dpr > 2)
-  {
-    QPixmap pixmap(base_path.append(QStringLiteral("@4x.png")));
+  auto load_png = [&](int scale) {
+    QString suffix = QStringLiteral(".png");
+    if (scale > 1)
+      suffix = QString::fromLatin1("@%1x.png").arg(scale);
+
+    QPixmap pixmap(base_path + suffix);
     if (!pixmap.isNull())
     {
-      pixmap.setDevicePixelRatio(4.0);
+      pixmap.setDevicePixelRatio(scale);
       icon.addPixmap(pixmap);
     }
-  }
+  };
+
+  // Since we are caching the files, we need to try and load all known sizes up-front.
+  // Otherwise, a dynamic change of devicePixelRatio could result in use of non-ideal image from
+  // cache while a better one exists on disk.
+  for (auto scale : {1, 2, 4})
+    load_png(scale);
+
+  ASSERT(icon.availableSizes().size() > 0);
 
   return icon;
 }
 
-QPixmap Resources::GetPixmap(std::string_view name, const QString& dir)
-{
-  const auto icon = GetIcon(name, dir);
-  return icon.pixmap(icon.availableSizes()[0]);
-}
-
 static QString GetCurrentThemeDir()
 {
   return QString::fromStdString(File::GetThemeDir(Config::Get(Config::MAIN_THEME_NAME)));
@@ -60,27 +65,24 @@ static QString GetResourcesDir()
   return QString::fromStdString(File::GetSysDirectory() + "Resources");
 }
 
-QIcon Resources::GetScaledIcon(std::string_view name)
+QIcon Resources::GetResourceIcon(std::string_view name)
 {
-  return GetIcon(name, GetResourcesDir());
+  return LoadNamedIcon(name, GetResourcesDir());
 }
 
-QIcon Resources::GetScaledThemeIcon(std::string_view name)
+QIcon Resources::GetThemeIcon(std::string_view name)
 {
-  return GetIcon(name, GetCurrentThemeDir());
-}
-
-QPixmap Resources::GetScaledPixmap(std::string_view name)
-{
-  return GetPixmap(name, GetResourcesDir());
+  return LoadNamedIcon(name, GetCurrentThemeDir());
 }
 
 void Resources::Init()
 {
+  m_svg_supported = QImageReader::supportedImageFormats().contains("svg");
+
   for (std::string_view platform :
        {"Platform_Gamecube", "Platform_Wii", "Platform_Wad", "Platform_File"})
   {
-    m_platforms.append(GetScaledPixmap(platform));
+    m_platforms.append(GetResourceIcon(platform));
   }
 
   for (std::string_view country :
@@ -88,39 +90,29 @@ void Resources::Init()
         "Flag_Italy", "Flag_Korea", "Flag_Netherlands", "Flag_Russia", "Flag_Spain", "Flag_Taiwan",
         "Flag_International", "Flag_Unknown"})
   {
-    m_countries.append(GetScaledPixmap(country));
+    m_countries.append(GetResourceIcon(country));
   }
 
-  m_misc.append(GetScaledPixmap("nobanner"));
-  m_misc.append(GetScaledPixmap("dolphin_logo"));
-  m_misc.append(GetScaledPixmap("Dolphin"));
+  m_misc.append(GetResourceIcon("nobanner"));
+  m_misc.append(GetResourceIcon("dolphin_logo"));
 }
 
-QPixmap Resources::GetPlatform(DiscIO::Platform platform)
+QIcon Resources::GetPlatform(DiscIO::Platform platform)
 {
   return m_platforms[static_cast<int>(platform)];
 }
 
-QPixmap Resources::GetCountry(DiscIO::Country country)
+QIcon Resources::GetCountry(DiscIO::Country country)
 {
   return m_countries[static_cast<int>(country)];
 }
 
-QPixmap Resources::GetMisc(MiscID id)
+QIcon Resources::GetMisc(MiscID id)
 {
   return m_misc[static_cast<int>(id)];
 }
 
 QIcon Resources::GetAppIcon()
 {
-  QIcon icon;
-
-#ifdef _WIN32
-  icon = WinIconHelper::GetNativeIcon();
-#else
-  icon.addPixmap(GetScaledPixmap("dolphin_logo"));
-  icon.addPixmap(GetScaledPixmap("Dolphin"));
-#endif
-
-  return icon;
+  return GetMisc(MiscID::Logo);
 }