Add compilation flag for HIDPI workaround

The HIDPI workaround is enabled by default. Expose a flag to be able to
disable it.

app/meson.build

@@ -109,15 +109,15 @@ conf.set('DEFAULT_MAX_SIZE', '0')  # 0: unlimited
 # overridden by option --bit-rate
 conf.set('DEFAULT_BIT_RATE', '8000000')  # 8Mbps
 
-# enable High DPI support
-conf.set('HIDPI_SUPPORT', get_option('hidpi_support'))
-
 # disable console on Windows
 conf.set('WINDOWS_NOCONSOLE', get_option('windows_noconsole'))
 
 # run a server debugger and wait for a client to be attached
 conf.set('SERVER_DEBUGGER', get_option('server_debugger'))
 
+# enable a workaround for bug #15
+conf.set('HIDPI_WORKAROUND', get_option('hidpi_workaround'))
+
 configure_file(configuration: conf, output: 'config.h')
 
 src_dir = include_directories('src')

app/src/scrcpy.c

@@ -145,9 +145,11 @@ handle_event(SDL_Event *event, bool control) {
         case SDL_WINDOWEVENT:
             switch (event->window.event) {
                 case SDL_WINDOWEVENT_EXPOSED:
-                case SDL_WINDOWEVENT_SIZE_CHANGED:
                     screen_render(&screen);
                     break;
+                case SDL_WINDOWEVENT_SIZE_CHANGED:
+                    screen_window_resized(&screen);
+                    break;
             }
             break;
         case SDL_TEXTINPUT:

app/src/screen.c

@@ -134,16 +134,57 @@ create_texture(SDL_Renderer *renderer, struct size frame_size) {
                              frame_size.width, frame_size.height);
 }
 
+#ifdef HIDPI_WORKAROUND
+static void
+screen_get_sizes(struct screen *screen, struct screen_sizes *out) {
+    int ww, wh, dw, dh;
+    SDL_GetWindowSize(screen->window, &ww, &wh);
+    SDL_GL_GetDrawableSize(screen->window, &dw, &dh);
+    out->window.width = ww;
+    out->window.height = wh;
+    out->window.width = dw;
+    out->window.height = dh;
+}
+#endif
+
+// This may be called more than once to work around SDL bugs
+static bool
+screen_init_renderer_and_texture(struct screen *screen) {
+    screen->renderer = SDL_CreateRenderer(screen->window, -1,
+                                          SDL_RENDERER_ACCELERATED);
+    if (!screen->renderer) {
+        LOGC("Could not create renderer: %s", SDL_GetError());
+        return false;
+    }
+
+    if (SDL_RenderSetLogicalSize(screen->renderer, screen->frame_size.width,
+                                 screen->frame_size.height)) {
+        LOGE("Could not set renderer logical size: %s", SDL_GetError());
+        return false;
+    }
+
+    screen->texture = create_texture(screen->renderer, screen->frame_size);
+    if (!screen->texture) {
+        LOGC("Could not create texture: %s", SDL_GetError());
+        return false;
+    }
+
+#ifdef HIDPI_WORKAROUND
+    screen_get_sizes(screen, &screen->sizes);
+#endif
+
+    return true;
+}
+
 bool
 screen_init_rendering(struct screen *screen, const char *window_title,
                       struct size frame_size, bool always_on_top) {
     screen->frame_size = frame_size;
 
     struct size window_size = get_initial_optimal_size(frame_size);
-    uint32_t window_flags = SDL_WINDOW_HIDDEN | SDL_WINDOW_RESIZABLE;
-#ifdef HIDPI_SUPPORT
-    window_flags |= SDL_WINDOW_ALLOW_HIGHDPI;
-#endif
+    uint32_t window_flags = SDL_WINDOW_HIDDEN
+                          | SDL_WINDOW_RESIZABLE
+                          | SDL_WINDOW_ALLOW_HIGHDPI;
     if (always_on_top) {
 #ifdef SCRCPY_SDL_HAS_WINDOW_ALWAYS_ON_TOP
         window_flags |= SDL_WINDOW_ALWAYS_ON_TOP;
@@ -162,21 +203,6 @@ screen_init_rendering(struct screen *screen, const char *window_title,
         return false;
     }
 
-    screen->renderer = SDL_CreateRenderer(screen->window, -1,
-                                          SDL_RENDERER_ACCELERATED);
-    if (!screen->renderer) {
-        LOGC("Could not create renderer: %s", SDL_GetError());
-        screen_destroy(screen);
-        return false;
-    }
-
-    if (SDL_RenderSetLogicalSize(screen->renderer, frame_size.width,
-                                 frame_size.height)) {
-        LOGE("Could not set renderer logical size: %s", SDL_GetError());
-        screen_destroy(screen);
-        return false;
-    }
-
     SDL_Surface *icon = read_xpm(icon_xpm);
     if (icon) {
         SDL_SetWindowIcon(screen->window, icon);
@@ -187,9 +213,7 @@ screen_init_rendering(struct screen *screen, const char *window_title,
 
     LOGI("Initial texture: %" PRIu16 "x%" PRIu16, frame_size.width,
                                                   frame_size.height);
-    screen->texture = create_texture(screen->renderer, frame_size);
-    if (!screen->texture) {
-        LOGC("Could not create texture: %s", SDL_GetError());
+    if (!screen_init_renderer_and_texture(screen)) {
         screen_destroy(screen);
         return false;
     }
@@ -278,6 +302,43 @@ screen_update_frame(struct screen *screen, struct video_buffer *vb) {
     return true;
 }
 
+#ifdef HIDPI_WORKAROUND
+// workaround for <https://github.com/Genymobile/scrcpy/issues/15>
+static inline bool
+screen_fix_hidpi(struct screen *screen) {
+    struct screen_sizes cur;
+    screen_get_sizes(screen, &cur);
+
+    struct screen_sizes *prev = &screen->sizes;
+
+    bool width_ratio_changed = cur.window.width * prev->drawable.width !=
+                               cur.drawable.width * prev->window.width;
+    bool height_ratio_changed = cur.window.height * prev->drawable.height !=
+                                cur.drawable.height * prev->window.height;
+    if (width_ratio_changed || height_ratio_changed) {
+        SDL_DestroyTexture(screen->texture);
+        SDL_DestroyRenderer(screen->renderer);
+        if (!screen_init_renderer_and_texture(screen)) {
+            screen->texture = NULL;
+            screen->renderer = NULL;
+            return false;
+        }
+
+        LOGI("Renderer reset after hidpi scaling changed");
+    }
+
+    return true;
+}
+#endif
+
+void
+screen_window_resized(struct screen *screen) {
+#ifdef HIDPI_WORKAROUND
+    screen_fix_hidpi(screen);
+#endif
+    screen_render(screen);
+}
+
 void
 screen_render(struct screen *screen) {
     SDL_RenderClear(screen->renderer);

app/src/screen.h

@@ -20,6 +20,12 @@ struct screen {
     bool has_frame;
     bool fullscreen;
     bool no_window;
+#ifdef HIDPI_WORKAROUND
+    struct screen_sizes {
+        struct size window;
+        struct size drawable;
+    } sizes;
+#endif
 };
 
 #define SCREEN_INITIALIZER {  \
@@ -60,6 +66,10 @@ screen_destroy(struct screen *screen);
 bool
 screen_update_frame(struct screen *screen, struct video_buffer *vb);
 
+// update content after window resizing
+void
+screen_window_resized(struct screen *screen);
+
 // render the texture to the renderer
 void
 screen_render(struct screen *screen);

meson_options.txt

@@ -4,5 +4,5 @@ option('crossbuild_windows', type: 'boolean', value: false, description: 'Build
 option('windows_noconsole', type: 'boolean', value: false, description: 'Disable console on Windows (pass -mwindows flag)')
 option('prebuilt_server', type: 'string', description: 'Path of the prebuilt server')
 option('portable', type: 'boolean', value: false, description: 'Use scrcpy-server from the same directory as the scrcpy executable')
-option('hidpi_support', type: 'boolean', value: true, description: 'Enable High DPI support')
 option('server_debugger', type: 'boolean', value: false, description: 'Run a server debugger and wait for a client to be attached')
+option('hidpi_workaround', type: 'boolean', value: true, description: 'Enable a workaround for bug #15')