Added support for scaling the output

* Added "Scale" user option, which can either by "Auto" or an explicit
  scaling factor. Its maximum value depends on the current resolution.

  The "Auto" factor is based on keeping the logical resolution on at
  least 800x600, wheres the maximum scale is based on keeping the
  logical resolution on at least 640x480.

* Enabled support for High DPI. This means the rendering target can now
  have a different resolution than the window size, which can happen on
  macOS, Windows and Wayland. The resulting scale is multiplied by the
  above user-controlled scale.

  Currently, this looks ugly for non-integer scales, which are not used
  on macOS and can only be configured on some Wayland compositors.

  Has not been tested on Windows.

* Simplified OpenGL initialization (moved out of _beginDraw).

* Made sure _beginDraw/_endDraw sets a clip area also for SDLGraphics.

1 files changed, 12 insertions, 3 deletions

diff --git a/src/sdlgraphics.h b/src/sdlgraphics.h
index 6685fc83..ab6407f0 100644
--- a/src/sdlgraphics.h
+++ b/src/sdlgraphics.h
@@ -24,15 +24,22 @@
 
 #include "graphics.h"
 
+#include <memory>
+
+class VideoSettings;
+
 class SDLGraphics final : public Graphics
 {
 public:
-    SDLGraphics(SDL_Window *window, SDL_Renderer *renderer);
+    static std::unique_ptr<Graphics> create(SDL_Window *window,
+                                            const VideoSettings &settings);
+
+    SDLGraphics(SDL_Renderer *renderer);
     ~SDLGraphics() override;
 
     void setVSync(bool sync) override;
 
-    void videoResized(int w, int h) override;
+    void updateSize(int windowWidth, int windowHeight, float scale) override;
 
     bool drawRescaledImage(Image *image,
                            int srcX, int srcY,
@@ -49,6 +56,9 @@ public:
 
     void updateScreen() override;
 
+    void windowToLogical(int windowX, int windowY,
+                         float &logicalX, float &logicalY) const override;
+
     SDL_Surface *getScreenshot() override;
 
     bool pushClipArea(gcn::Rectangle area) override;
@@ -66,7 +76,6 @@ public:
 private:
     void updateSDLClipRect();
 
-    SDL_Window *mWindow = nullptr;
     SDL_Renderer *mRenderer = nullptr;
 };