add image interface, remove lodepng from video_core/core, address more comments, fix comments

remove unnecessary conversion

src/citra_qt/CMakeLists.txt

@@ -142,6 +142,8 @@ add_executable(citra-qt
     multiplayer/validation.h
     uisettings.cpp
     uisettings.h
+    qt_image_interface.cpp
+    qt_image_interface.h
     updater/updater.cpp
     updater/updater.h
     updater/updater_p.h

src/citra_qt/main.cpp

@@ -51,6 +51,7 @@
 #include "citra_qt/main.h"
 #include "citra_qt/multiplayer/state.h"
 #include "citra_qt/uisettings.h"
+#include "citra_qt/qt_image_interface.h"
 #include "citra_qt/updater/updater.h"
 #include "citra_qt/util/clickable_label.h"
 #include "common/common_paths.h"
@@ -2059,6 +2060,9 @@ int main(int argc, char* argv[]) {
     Core::System::GetInstance().RegisterMiiSelector(std::make_shared<QtMiiSelector>(main_window));
     Core::System::GetInstance().RegisterSoftwareKeyboard(std::make_shared<QtKeyboard>(main_window));
 
+    // Register Qt image interface
+    Core::System::GetInstance().RegisterImageInterface(std::make_shared<QtImageInterface>());
+
     main_window.show();
 
     QObject::connect(&app, &QGuiApplication::applicationStateChanged, &main_window,

src/citra_qt/qt_image_interface.cpp

@@ -0,0 +1,46 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <QBuffer>
+#include <QImage>
+#include <QString>
+#include "common/logging/log.h"
+#include "core/frontend/image_interface.h"
+#include "qt_image_interface.h"
+
+bool QtImageInterface::DecodePNG(std::vector<u8>& dst, u32& width, u32& height,
+                                 const std::string& path) {
+    QImage image(QString::fromStdString(path));
+
+    if (image.isNull()) {
+        LOG_ERROR(Frontend, "Failed to open {} for decoding", path);
+        return false;
+    }
+    width = image.width();
+    height = image.height();
+
+    // Write RGBA8 to vector
+    for (u32 y = 1; y < image.height() + 1; y++) {
+        for (u32 x = 1; x < image.width() + 1; x++) {
+            const QColor pixel(image.pixel(y, x));
+            dst.push_back(pixel.red());
+            dst.push_back(pixel.green());
+            dst.push_back(pixel.blue());
+            dst.push_back(pixel.alpha());
+        }
+    }
+
+    return true;
+}
+
+bool QtImageInterface::EncodePNG(const std::string& path, const std::vector<u8>& src, u32 width,
+                                 u32 height) {
+    QImage image(src.data(), width, height, QImage::Format_RGBA8888);
+
+    if (!image.save(QString::fromStdString(path))) {
+        LOG_ERROR(Frontend, "Failed to save {}", path);
+        return false;
+    }
+    return true;
+}

src/citra_qt/qt_image_interface.h

@@ -0,0 +1,14 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "core/frontend/image_interface.h"
+
+class QtImageInterface final : public Frontend::ImageInterface {
+public:
+    bool DecodePNG(std::vector<u8>& dst, u32& width, u32& height, const std::string& path) override;
+    bool EncodePNG(const std::string& path, const std::vector<u8>& src, u32 width,
+                   u32 height) override;
+};