mirror of
https://github.com/labwc/labwc.git
synced 2026-04-13 08:21:15 -04:00
4fa51b950c
After a roundabout discussion[1] with wlroots devs, it's become apparent that subpixel text rendering (a.k.a. "ClearType") does not work properly when rendering over a transparent background, as labwc currently does. Basically it comes down to the fact that the color of semi-transparent pixels (which is adjusted redder or bluer to compensate for RGB subpixel alignment) depends somewhat on background color. When rendering over transparency, the text engine doesn't know the intended background color and can't adjust the pixel colors correctly. With Pango/Cairo, the end result can range from grayscale rendering (no subpixel rendering at all) to wrong/oversaturated colors (for example, bright pink pixels when rendering white text on blue background). This change solves the issue by first filling the text buffer with an opaque background color before rendering the text over it. Currently, this is easy since the background is always a solid color. It may be a little more complex (but doable) if we implement gradients in future. Note that GTK 4 (and to some degree, recent versions of Microsoft Windows) avoid this issue by disabling subpixel rendering altogether. I would much prefer that labwc NOT do this -- it results in noticeably blurrier text on non-retina LCD screens, which are still common. [1] https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/3822
102 lines
2.7 KiB
C
102 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
#define _POSIX_C_SOURCE 200809L
|
|
#include <assert.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <wayland-server-core.h>
|
|
#include <wlr/util/log.h>
|
|
#include "buffer.h"
|
|
#include "common/font.h"
|
|
#include "common/mem.h"
|
|
#include "common/scaled_scene_buffer.h"
|
|
#include "common/scaled_font_buffer.h"
|
|
|
|
static struct lab_data_buffer *
|
|
_create_buffer(struct scaled_scene_buffer *scaled_buffer, double scale)
|
|
{
|
|
struct lab_data_buffer *buffer;
|
|
struct scaled_font_buffer *self = scaled_buffer->data;
|
|
|
|
/* Buffer gets free'd automatically along the backing wlr_buffer */
|
|
font_buffer_create(&buffer, self->max_width, self->text,
|
|
&self->font, self->color, self->bg_color, self->arrow, scale);
|
|
|
|
self->width = buffer ? buffer->unscaled_width : 0;
|
|
self->height = buffer ? buffer->unscaled_height : 0;
|
|
return buffer;
|
|
}
|
|
|
|
static void
|
|
_destroy(struct scaled_scene_buffer *scaled_buffer)
|
|
{
|
|
struct scaled_font_buffer *self = scaled_buffer->data;
|
|
scaled_buffer->data = NULL;
|
|
|
|
zfree(self->text);
|
|
zfree(self->font.name);
|
|
zfree(self->arrow);
|
|
free(self);
|
|
}
|
|
|
|
static const struct scaled_scene_buffer_impl impl = {
|
|
.create_buffer = _create_buffer,
|
|
.destroy = _destroy
|
|
};
|
|
|
|
/* Public API */
|
|
struct scaled_font_buffer *
|
|
scaled_font_buffer_create(struct wlr_scene_tree *parent)
|
|
{
|
|
assert(parent);
|
|
struct scaled_font_buffer *self = znew(*self);
|
|
struct scaled_scene_buffer *scaled_buffer =
|
|
scaled_scene_buffer_create(parent, &impl, /* drop_buffer */ true);
|
|
if (!scaled_buffer) {
|
|
free(self);
|
|
return NULL;
|
|
}
|
|
|
|
scaled_buffer->data = self;
|
|
self->scaled_buffer = scaled_buffer;
|
|
self->scene_buffer = scaled_buffer->scene_buffer;
|
|
return self;
|
|
}
|
|
|
|
void
|
|
scaled_font_buffer_update(struct scaled_font_buffer *self, const char *text,
|
|
int max_width, struct font *font, const float *color,
|
|
const float *bg_color, const char *arrow)
|
|
{
|
|
assert(self);
|
|
assert(text);
|
|
assert(font);
|
|
assert(color);
|
|
|
|
/* Clean up old internal state */
|
|
zfree(self->text);
|
|
zfree(self->font.name);
|
|
zfree(self->arrow);
|
|
|
|
/* Update internal state */
|
|
self->text = xstrdup(text);
|
|
self->max_width = max_width;
|
|
if (font->name) {
|
|
self->font.name = xstrdup(font->name);
|
|
}
|
|
self->font.size = font->size;
|
|
self->font.slant = font->slant;
|
|
self->font.weight = font->weight;
|
|
memcpy(self->color, color, sizeof(self->color));
|
|
memcpy(self->bg_color, bg_color, sizeof(self->bg_color));
|
|
self->arrow = arrow ? xstrdup(arrow) : NULL;
|
|
|
|
/* Invalidate cache and force a new render */
|
|
scaled_scene_buffer_invalidate_cache(self->scaled_buffer);
|
|
}
|
|
|
|
void
|
|
scaled_font_buffer_set_max_width(struct scaled_font_buffer *self, int max_width)
|
|
{
|
|
self->max_width = max_width;
|
|
scaled_scene_buffer_invalidate_cache(self->scaled_buffer);
|
|
}
|