Skip to content

linux: render at the fractional output scale instead of the integer scale factor #359

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
Reliacrt wants to merge 1 commit into
base: main
Choose a base branch
from
Open

linux: render at the fractional output scale instead of the integer scale factor #359

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
57 changes: 50 additions & 7 deletions src/platform/linux/gtk_host.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -229,6 +229,7 @@ typedef struct native_sdk_gtk_native_view {
double gpu_emitted_scale;
int gpu_nonblank;
uint32_t gpu_sample_color;
gulong gpu_scale_notify_id;
int gpu_pointer_down;
double gpu_pointer_x;
double gpu_pointer_y;
Expand Down Expand Up @@ -1046,6 +1047,30 @@ static int native_sdk_gpu_surface_sync_geometry(native_sdk_gtk_native_view_t *vi
return 1;
}

/* Fractional-scale-aware surface scale. GDK 4.12+ reports the exact
* fractional scale (1.5 on a 150% output) via gdk_surface_get_scale;
* gtk_widget_get_scale_factor rounds to the integer wl_output scale,
* which makes the canvas render at 2x while the compositor displays
* 1.5x — a resampling mismatch that softens/jags every curve. */
static double native_sdk_gtk_fractional_scale(GtkWidget *widget) {
if (!widget) return 1.0;
GtkWidget *root = GTK_WIDGET(gtk_widget_get_root(widget));
GdkSurface *surface = (root && GTK_IS_NATIVE(root)) ? gtk_native_get_surface(GTK_NATIVE(root)) : NULL;
#if defined(GDK_VERSION_4_12)
if (surface) return gdk_surface_get_scale(surface);
Comment thread
vercel[bot] marked this conversation as resolved.
#endif
return (double)gtk_widget_get_scale_factor(widget);
}

/* Scale of an already-resolved surface: the exact fractional value on
* GDK >= 4.12, the integer factor otherwise. */
static double native_sdk_gtk_surface_scale(GdkSurface *surface) {
#if defined(GDK_VERSION_4_12)
if (surface) return gdk_surface_get_scale(surface);
#endif
return surface ? (double)gdk_surface_get_scale_factor(surface) : 1.0;
}

/* notify::scale-factor on the drawing area (e.g. the window moved to a
* monitor with a different device scale): report the new scale immediately
* instead of waiting for the next frame tick, so the runtime can rebuild its
Expand All @@ -1058,7 +1083,7 @@ static void native_sdk_gpu_surface_scale_changed(GObject *object, GParamSpec *ps
const double width = native_sdk_gpu_surface_width(view);
const double height = native_sdk_gpu_surface_height(view);
if (width <= 0 || height <= 0) return;
const double scale = (double)gtk_widget_get_scale_factor(view->widget);
const double scale = native_sdk_gtk_fractional_scale(view->widget);
if (native_sdk_gpu_surface_sync_geometry(view, width, height, scale)) {
gtk_widget_queue_draw(view->widget);
}
Expand Down Expand Up @@ -1098,7 +1123,7 @@ static void native_sdk_gpu_surface_emit_frame(native_sdk_gtk_native_view_t *view

const double width = native_sdk_gpu_surface_width(view);
const double height = native_sdk_gpu_surface_height(view);
const double scale = (double)gtk_widget_get_scale_factor(view->widget);
const double scale = native_sdk_gtk_fractional_scale(view->widget);
if (width <= 0 || height <= 0) return;

(void)native_sdk_gpu_surface_sync_geometry(view, width, height, scale);
Expand Down Expand Up @@ -1208,10 +1233,19 @@ static void native_sdk_gpu_surface_resized(GtkDrawingArea *area, int width, int
const double logical_width = native_sdk_gpu_surface_width(view);
const double logical_height = native_sdk_gpu_surface_height(view);
if (logical_width <= 0 || logical_height <= 0) return;
const double scale = (double)gtk_widget_get_scale_factor(view->widget);
const double scale = native_sdk_gtk_fractional_scale(view->widget);
if (native_sdk_gpu_surface_sync_geometry(view, logical_width, logical_height, scale)) {
gtk_widget_queue_draw(view->widget);
}
/* Fractional scale changes (window moved to an output with a
* different 150%-style scale) fire notify::scale on the surface,
* not the widget's integer scale-factor. Harmless if the property
* is absent; the notify path re-syncs geometry with the new scale. */
GtkWidget *root = GTK_WIDGET(gtk_widget_get_root(view->widget));
GdkSurface *surface = (root && GTK_IS_NATIVE(root)) ? gtk_native_get_surface(GTK_NATIVE(root)) : NULL;
if (surface && view->gpu_scale_notify_id == 0) {
view->gpu_scale_notify_id = g_signal_connect(surface, "notify::scale", G_CALLBACK(native_sdk_gpu_surface_scale_changed), view);
}
}

static void native_sdk_gpu_surface_draw(GtkDrawingArea *area, cairo_t *cr, int width, int height, gpointer data) {
Expand All @@ -1233,7 +1267,7 @@ static void native_sdk_gpu_surface_draw(GtkDrawingArea *area, cairo_t *cr, int w
const double device_scale_x = (double)view->gpu_buf_width / (double)width;
const double device_scale_y = (double)view->gpu_buf_height / (double)height;
cairo_surface_set_device_scale(surface, device_scale_x, device_scale_y);
const double widget_scale = (double)gtk_widget_get_scale_factor(GTK_WIDGET(area));
const double widget_scale = native_sdk_gtk_fractional_scale(GTK_WIDGET(area));
const int exact = device_scale_x == widget_scale && device_scale_y == widget_scale;
cairo_set_source_surface(cr, surface, 0, 0);
cairo_pattern_set_filter(cairo_get_source(cr), exact ? CAIRO_FILTER_NEAREST : CAIRO_FILTER_BILINEAR);
Expand Down Expand Up @@ -1636,6 +1670,15 @@ static void native_sdk_teardown_gpu_surface_view(native_sdk_gtk_native_view_t *v
gtk_drawing_area_set_draw_func(GTK_DRAWING_AREA(view->widget), NULL, NULL, NULL);
g_signal_handlers_disconnect_by_data(view->widget, view);
}
if (view->gpu_scale_notify_id != 0) {
/* The surface outlives the view (it belongs to the window), so a
* handler connected there must be disconnected explicitly before
* the view memory goes away. */
GtkWidget *root = view->widget ? GTK_WIDGET(gtk_widget_get_root(view->widget)) : NULL;
GdkSurface *surface = (root && GTK_IS_NATIVE(root)) ? gtk_native_get_surface(GTK_NATIVE(root)) : NULL;
if (surface) g_signal_handler_disconnect(surface, view->gpu_scale_notify_id);
view->gpu_scale_notify_id = 0;
}
if (view->gpu_im_context) {
g_signal_handlers_disconnect_by_data(view->gpu_im_context, view);
gtk_im_context_set_client_widget(view->gpu_im_context, NULL);
Expand Down Expand Up @@ -2509,7 +2552,7 @@ static void native_sdk_emit_window_frame(native_sdk_gtk_host_t *host, native_sdk
int w = 0, h = 0;
native_sdk_window_content_size(win, &w, &h);
GdkSurface *surface = gtk_native_get_surface(GTK_NATIVE(win->gtk_window));
double scale = surface ? gdk_surface_get_scale_factor(surface) : 1.0;
double scale = native_sdk_gtk_surface_scale(surface);
int focused = gtk_window_is_active(win->gtk_window) ? 1 : 0;
native_sdk_emit(host, (native_sdk_gtk_event_t){
.kind = NATIVE_SDK_GTK_EVENT_WINDOW_FRAME,
Expand All @@ -2532,7 +2575,7 @@ static void native_sdk_emit_resize(native_sdk_gtk_host_t *host, native_sdk_gtk_w
int w = 0, h = 0;
native_sdk_window_content_size(win, &w, &h);
GdkSurface *surface = gtk_native_get_surface(GTK_NATIVE(win->gtk_window));
double scale = surface ? gdk_surface_get_scale_factor(surface) : 1.0;
double scale = native_sdk_gtk_surface_scale(surface);
native_sdk_emit(host, (native_sdk_gtk_event_t){
.kind = NATIVE_SDK_GTK_EVENT_RESIZE,
.window_id = win->id,
Expand Down Expand Up @@ -2677,7 +2720,7 @@ static gboolean native_sdk_frame_tick(gpointer data) {
const double w = (double)gtk_widget_get_width(GTK_WIDGET(win->gtk_window));
const double h = (double)gtk_widget_get_height(GTK_WIDGET(win->gtk_window));
GdkSurface *surface = gtk_native_get_surface(GTK_NATIVE(win->gtk_window));
const double scale = surface ? gdk_surface_get_scale_factor(surface) : 1.0;
const double scale = native_sdk_gtk_surface_scale(surface);
if (w > 0 && h > 0 && (w != win->emitted_width || h != win->emitted_height || scale != win->emitted_scale)) {
win->emitted_width = w;
win->emitted_height = h;
Expand Down