1 files changed, 171 insertions, 74 deletions

diff --git a/ui/gtk.c b/ui/gtk.c
index 982037b..8c4a94c 100644
--- a/ui/gtk.c
+++ b/ui/gtk.c
@@ -387,16 +387,16 @@ static void *gd_win32_get_hwnd(VirtualConsole *vc)
 /** DisplayState Callbacks **/
 
 static void gd_update(DisplayChangeListener *dcl,
-                      int x, int y, int w, int h)
+                      int fbx, int fby, int fbw, int fbh)
 {
     VirtualConsole *vc = container_of(dcl, VirtualConsole, gfx.dcl);
     GdkWindow *win;
-    int x1, x2, y1, y2;
-    int mx, my;
-    int fbw, fbh;
-    int ww, wh;
+    int wx1, wx2, wy1, wy2;
+    int wx_offset, wy_offset;
+    int ww_surface, wh_surface;
+    int ww_widget, wh_widget;
 
-    trace_gd_update(vc->label, x, y, w, h);
+    trace_gd_update(vc->label, fbx, fby, fbw, fbh);
 
     if (!gtk_widget_get_realized(vc->gfx.drawing_area)) {
         return;
@@ -405,35 +405,36 @@ static void gd_update(DisplayChangeListener *dcl,
     if (vc->gfx.convert) {
         pixman_image_composite(PIXMAN_OP_SRC, vc->gfx.ds->image,
                                NULL, vc->gfx.convert,
-                               x, y, 0, 0, x, y, w, h);
+                               fbx, fby, 0, 0, fbx, fby, fbw, fbh);
     }
 
-    x1 = floor(x * vc->gfx.scale_x);
-    y1 = floor(y * vc->gfx.scale_y);
+    wx1 = floor(fbx * vc->gfx.scale_x);
+    wy1 = floor(fby * vc->gfx.scale_y);
 
-    x2 = ceil(x * vc->gfx.scale_x + w * vc->gfx.scale_x);
-    y2 = ceil(y * vc->gfx.scale_y + h * vc->gfx.scale_y);
+    wx2 = ceil(fbx * vc->gfx.scale_x + fbw * vc->gfx.scale_x);
+    wy2 = ceil(fby * vc->gfx.scale_y + fbh * vc->gfx.scale_y);
 
-    fbw = surface_width(vc->gfx.ds) * vc->gfx.scale_x;
-    fbh = surface_height(vc->gfx.ds) * vc->gfx.scale_y;
+    ww_surface = surface_width(vc->gfx.ds) * vc->gfx.scale_x;
+    wh_surface = surface_height(vc->gfx.ds) * vc->gfx.scale_y;
 
     win = gtk_widget_get_window(vc->gfx.drawing_area);
     if (!win) {
         return;
     }
-    ww = gdk_window_get_width(win);
-    wh = gdk_window_get_height(win);
+    ww_widget = gdk_window_get_width(win);
+    wh_widget = gdk_window_get_height(win);
 
-    mx = my = 0;
-    if (ww > fbw) {
-        mx = (ww - fbw) / 2;
+    wx_offset = wy_offset = 0;
+    if (ww_widget > ww_surface) {
+        wx_offset = (ww_widget - ww_surface) / 2;
     }
-    if (wh > fbh) {
-        my = (wh - fbh) / 2;
+    if (wh_widget > wh_surface) {
+        wy_offset = (wh_widget - wh_surface) / 2;
     }
 
     gtk_widget_queue_draw_area(vc->gfx.drawing_area,
-                               mx + x1, my + y1, (x2 - x1), (y2 - y1));
+                               wx_offset + wx1, wy_offset + wy1,
+                               (wx2 - wx1), (wy2 - wy1));
 }
 
 static void gd_refresh(DisplayChangeListener *dcl)
@@ -771,8 +772,21 @@ static void gd_resize_event(GtkGLArea *area,
                             gint width, gint height, gpointer *opaque)
 {
     VirtualConsole *vc = (void *)opaque;
+    double pw = width, ph = height;
+    double sx = vc->gfx.scale_x, sy = vc->gfx.scale_y;
+    GdkWindow *window = gtk_widget_get_window(GTK_WIDGET(area));
+    const int gs = gdk_window_get_scale_factor(window);
 
-    gd_set_ui_size(vc, width, height);
+    if (!vc->s->free_scale && !vc->s->full_screen) {
+        pw /= sx;
+        ph /= sy;
+    }
+
+    /**
+     * width and height here are in pixel coordinate, so we must divide it
+     * by global window scale (gs)
+     */
+    gd_set_ui_size(vc, pw / gs, ph / gs);
 }
 
 #endif
@@ -800,12 +814,95 @@ void gd_update_monitor_refresh_rate(VirtualConsole *vc, GtkWidget *widget)
 #endif
 }
 
+void gd_update_scale(VirtualConsole *vc, int ww, int wh, int fbw, int fbh)
+{
+    if (!vc) {
+        return;
+    }
+
+    if (vc->s->full_screen) {
+        vc->gfx.scale_x = (double)ww / fbw;
+        vc->gfx.scale_y = (double)wh / fbh;
+    } else if (vc->s->free_scale) {
+        double sx, sy;
+
+        sx = (double)ww / fbw;
+        sy = (double)wh / fbh;
+
+        vc->gfx.scale_x = vc->gfx.scale_y = MIN(sx, sy);
+    }
+}
+/**
+ * DOC: Coordinate handling.
+ *
+ * We are coping with sizes and positions in various coordinates and the
+ * handling of these coordinates is somewhat confusing. It would benefit us
+ * all if we define these coordinates explicitly and clearly. Besides, it's
+ * also helpful to follow the same naming convention for variables
+ * representing values in different coordinates.
+ *
+ * I. Definitions
+ *
+ * - (guest) buffer coordinate: this is the coordinates that the guest will
+ *   see. The x/y offsets and width/height specified in commands sent by
+ *   guest is basically in buffer coordinate.
+ *
+ * - (host) pixel coordinate: this is the coordinate in pixel level on the
+ *   host destop. A window/widget of width 300 in pixel coordinate means it
+ *   occupies 300 pixels horizontally.
+ *
+ * - (host) logical window coordinate: the existence of global scaling
+ *   factor in desktop level makes this kind of coordinate play a role. It
+ *   always holds that (logical window size) * (global scale factor) =
+ *   (pixel size).
+ *
+ * - global scale factor: this is specified in desktop level and is
+ *   typically invariant during the life cycle of the process. Users with
+ *   high-DPI monitors might set this scale, for example, to 2, in order to
+ *   make the UI look larger.
+ *
+ * - zooming scale: this can be freely controlled by the QEMU user to zoom
+ *   in/out the guest content.
+ *
+ * II. Representation
+ *
+ * We'd like to use consistent representation for variables in different
+ * coordinates:
+ * - buffer coordinate: prefix fb
+ * - pixel coordinate: prefix p
+ * - logical window coordinate: prefix w
+ *
+ * For scales:
+ * - global scale factor: prefix gs
+ * - zooming scale: prefix scale/s
+ *
+ * Example: fbw, pw, ww for width in different coordinates
+ *
+ * III. Equation
+ *
+ * - fbw * gs * scale_x = pw
+ * - pw = gs * ww
+ *
+ * Consequently we have
+ *
+ * - fbw * scale_x = ww
+ *
+ * Example: assuming we are running QEMU on a 3840x2160 screen and have set
+ * global scaling factor to 2, if the guest buffer size is 1920x1080 and the
+ * zooming scale is 0.5, then we have:
+ * - fbw = 1920, fbh = 1080
+ * - pw  = 1920, ph  = 1080
+ * - ww  = 960,  wh  = 540
+ * A bonus of this configuration is that we can achieve pixel to pixel
+ * presentation of the guest content.
+ */
+
 static gboolean gd_draw_event(GtkWidget *widget, cairo_t *cr, void *opaque)
 {
     VirtualConsole *vc = opaque;
     GtkDisplayState *s = vc->s;
-    int mx, my;
-    int ww, wh;
+    int wx_offset, wy_offset;
+    int ww_widget, wh_widget, ww_surface, wh_surface;
     int fbw, fbh;
 
 #if defined(CONFIG_OPENGL)
@@ -839,46 +936,37 @@ static gboolean gd_draw_event(GtkWidget *widget, cairo_t *cr, void *opaque)
     fbw = surface_width(vc->gfx.ds);
     fbh = surface_height(vc->gfx.ds);
 
-    ww = gdk_window_get_width(gtk_widget_get_window(widget));
-    wh = gdk_window_get_height(gtk_widget_get_window(widget));
+    ww_widget = gdk_window_get_width(gtk_widget_get_window(widget));
+    wh_widget = gdk_window_get_height(gtk_widget_get_window(widget));
 
-    if (s->full_screen) {
-        vc->gfx.scale_x = (double)ww / fbw;
-        vc->gfx.scale_y = (double)wh / fbh;
-    } else if (s->free_scale) {
-        double sx, sy;
+    gd_update_scale(vc, ww_widget, wh_widget, fbw, fbh);
 
-        sx = (double)ww / fbw;
-        sy = (double)wh / fbh;
+    ww_surface = fbw * vc->gfx.scale_x;
+    wh_surface = fbh * vc->gfx.scale_y;
 
-        vc->gfx.scale_x = vc->gfx.scale_y = MIN(sx, sy);
+    wx_offset = wy_offset = 0;
+    if (ww_widget > ww_surface) {
+        wx_offset = (ww_widget - ww_surface) / 2;
     }
-
-    fbw *= vc->gfx.scale_x;
-    fbh *= vc->gfx.scale_y;
-
-    mx = my = 0;
-    if (ww > fbw) {
-        mx = (ww - fbw) / 2;
-    }
-    if (wh > fbh) {
-        my = (wh - fbh) / 2;
+    if (wh_widget > wh_surface) {
+        wy_offset = (wh_widget - wh_surface) / 2;
     }
 
-    cairo_rectangle(cr, 0, 0, ww, wh);
+    cairo_rectangle(cr, 0, 0, ww_widget, wh_widget);
 
     /* Optionally cut out the inner area where the pixmap
        will be drawn. This avoids 'flashing' since we're
        not double-buffering. Note we're using the undocumented
        behaviour of drawing the rectangle from right to left
        to cut out the whole */
-    cairo_rectangle(cr, mx + fbw, my,
-                    -1 * fbw, fbh);
+    cairo_rectangle(cr, wx_offset + ww_surface, wy_offset,
+                    -1 * ww_surface, wh_surface);
     cairo_fill(cr);
 
     cairo_scale(cr, vc->gfx.scale_x, vc->gfx.scale_y);
     cairo_set_source_surface(cr, vc->gfx.surface,
-                             mx / vc->gfx.scale_x, my / vc->gfx.scale_y);
+                             wx_offset / vc->gfx.scale_x,
+                             wy_offset / vc->gfx.scale_y);
     cairo_paint(cr);
 
     return TRUE;
@@ -889,19 +977,19 @@ static gboolean gd_motion_event(GtkWidget *widget, GdkEventMotion *motion,
 {
     VirtualConsole *vc = opaque;
     GtkDisplayState *s = vc->s;
-    int x, y;
-    int mx, my;
-    int fbh, fbw;
-    int ww, wh;
+    int fbx, fby;
+    int wx_offset, wy_offset;
+    int wh_surface, ww_surface;
+    int ww_widget, wh_widget;
 
     if (!vc->gfx.ds) {
         return TRUE;
     }
 
-    fbw = surface_width(vc->gfx.ds) * vc->gfx.scale_x;
-    fbh = surface_height(vc->gfx.ds) * vc->gfx.scale_y;
-    ww = gtk_widget_get_allocated_width(widget);
-    wh = gtk_widget_get_allocated_height(widget);
+    ww_surface = surface_width(vc->gfx.ds) * vc->gfx.scale_x;
+    wh_surface = surface_height(vc->gfx.ds) * vc->gfx.scale_y;
+    ww_widget = gtk_widget_get_allocated_width(widget);
+    wh_widget = gtk_widget_get_allocated_height(widget);
 
     /*
      * `widget` may not have the same size with the frame buffer.
@@ -909,41 +997,42 @@ static gboolean gd_motion_event(GtkWidget *widget, GdkEventMotion *motion,
      * To achieve that, `vc` will be displayed at (mx, my)
      * so that it is displayed at the center of the widget.
      */
-    mx = my = 0;
-    if (ww > fbw) {
-        mx = (ww - fbw) / 2;
+    wx_offset = wy_offset = 0;
+    if (ww_widget > ww_surface) {
+        wx_offset = (ww_widget - ww_surface) / 2;
     }
-    if (wh > fbh) {
-        my = (wh - fbh) / 2;
+    if (wh_widget > wh_surface) {
+        wy_offset = (wh_widget - wh_surface) / 2;
     }
 
     /*
      * `motion` is reported in `widget` coordinates
      * so translating it to the coordinates in `vc`.
      */
-    x = (motion->x - mx) / vc->gfx.scale_x;
-    y = (motion->y - my) / vc->gfx.scale_y;
+    fbx = (motion->x - wx_offset) / vc->gfx.scale_x;
+    fby = (motion->y - wy_offset) / vc->gfx.scale_y;
 
-    trace_gd_motion_event(ww, wh, gtk_widget_get_scale_factor(widget), x, y);
+    trace_gd_motion_event(ww_widget, wh_widget,
+                          gtk_widget_get_scale_factor(widget), fbx, fby);
 
     if (qemu_input_is_absolute(vc->gfx.dcl.con)) {
-        if (x < 0 || y < 0 ||
-            x >= surface_width(vc->gfx.ds) ||
-            y >= surface_height(vc->gfx.ds)) {
+        if (fbx < 0 || fby < 0 ||
+            fbx >= surface_width(vc->gfx.ds) ||
+            fby >= surface_height(vc->gfx.ds)) {
             return TRUE;
         }
-        qemu_input_queue_abs(vc->gfx.dcl.con, INPUT_AXIS_X, x,
+        qemu_input_queue_abs(vc->gfx.dcl.con, INPUT_AXIS_X, fbx,
                              0, surface_width(vc->gfx.ds));
-        qemu_input_queue_abs(vc->gfx.dcl.con, INPUT_AXIS_Y, y,
+        qemu_input_queue_abs(vc->gfx.dcl.con, INPUT_AXIS_Y, fby,
                              0, surface_height(vc->gfx.ds));
         qemu_input_event_sync();
     } else if (s->last_set && s->ptr_owner == vc) {
-        qemu_input_queue_rel(vc->gfx.dcl.con, INPUT_AXIS_X, x - s->last_x);
-        qemu_input_queue_rel(vc->gfx.dcl.con, INPUT_AXIS_Y, y - s->last_y);
+        qemu_input_queue_rel(vc->gfx.dcl.con, INPUT_AXIS_X, fbx - s->last_x);
+        qemu_input_queue_rel(vc->gfx.dcl.con, INPUT_AXIS_Y, fby - s->last_y);
         qemu_input_event_sync();
     }
-    s->last_x = x;
-    s->last_y = y;
+    s->last_x = fbx;
+    s->last_y = fby;
     s->last_set = TRUE;
 
     if (!qemu_input_is_absolute(vc->gfx.dcl.con) && s->ptr_owner == vc) {
@@ -1760,8 +1849,16 @@ static gboolean gd_configure(GtkWidget *widget,
                              GdkEventConfigure *cfg, gpointer opaque)
 {
     VirtualConsole *vc = opaque;
+    const double sx = vc->gfx.scale_x, sy = vc->gfx.scale_y;
+    double width = cfg->width, height = cfg->height;
+
+    if (!vc->s->free_scale && !vc->s->full_screen) {
+        width /= sx;
+        height /= sy;
+    }
+
+    gd_set_ui_size(vc, width, height);
 
-    gd_set_ui_size(vc, cfg->width, cfg->height);
     return FALSE;
 }