Merge branch 'diagonal-dpi'

Closes #47.

CHANGELOG.md

@@ -73,6 +73,8 @@
 * Crash when a **pipe-visible** or **pipe-scrollback** command
   contained an unclosed quote
   (https://codeberg.org/dnkl/foot/issues/49).
+* Improved font size consistency across multiple monitors with
+  different DPI (https://codeberg.org/dnkl/foot/issues/47).
 
 
 ### Contributors

terminal.c

@@ -559,7 +559,7 @@ term_set_fonts(struct terminal *term, struct fcft_font *fonts[static 4])
     return true;
 }
 
-static unsigned
+static float
 get_font_dpi(const struct terminal *term)
 {
     /*
@@ -584,24 +584,24 @@ get_font_dpi(const struct terminal *term)
      */
 
     /* Use highest DPI from outputs we're mapped on */
-    unsigned dpi = 0;
+    double dpi = 0.0;
     assert(term->window != NULL);
     tll_foreach(term->window->on_outputs, it) {
-        if (it->item->ppi.scaled.y > dpi)
-            dpi = it->item->ppi.scaled.y * term->scale;
+        if (it->item->dpi > dpi)
+            dpi = it->item->dpi;
     }
 
     /* If we're not mapped, use DPI from first monitor. Hopefully this is where we'll get mapped later... */
-    if (dpi == 0) {
+    if (dpi == 0.) {
         tll_foreach(term->wl->monitors, it) {
-            dpi = it->item.ppi.scaled.y * term->scale;
+            dpi = it->item.dpi;
             break;
         }
     }
 
     if (dpi == 0) {
         /* No monitors? */
-        dpi = 96;
+        dpi = 96.;
     }
 
     return dpi;
@@ -692,10 +692,10 @@ reload_fonts(struct terminal *term)
     }
 
     char attrs0[256], attrs1[256], attrs2[256], attrs3[256];
-    snprintf(attrs0, sizeof(attrs0), "dpi=%u", term->font_dpi);
-    snprintf(attrs1, sizeof(attrs1), "dpi=%u:weight=bold", term->font_dpi);
-    snprintf(attrs2, sizeof(attrs2), "dpi=%u:slant=italic", term->font_dpi);
-    snprintf(attrs3, sizeof(attrs3), "dpi=%u:weight=bold:slant=italic", term->font_dpi);
+    snprintf(attrs0, sizeof(attrs0), "dpi=%.2f", term->font_dpi);
+    snprintf(attrs1, sizeof(attrs1), "dpi=%.2f:weight=bold", term->font_dpi);
+    snprintf(attrs2, sizeof(attrs2), "dpi=%.2f:slant=italic", term->font_dpi);
+    snprintf(attrs3, sizeof(attrs3), "dpi=%.2f:weight=bold:slant=italic", term->font_dpi);
 
     struct fcft_font *fonts[4];
     struct font_load_data data[4] = {
@@ -836,7 +836,7 @@ term_init(const struct config *conf, struct fdm *fdm, struct reaper *reaper,
         .ptmx = ptmx,
         .ptmx_buffer = tll_init(),
         .font_sizes = malloc(sizeof(term->font_sizes[0]) * tll_length(conf->fonts)),
-        .font_dpi = 0,
+        .font_dpi = 0.,
         .font_subpixel = (conf->colors.alpha == 0xffff  /* Can't do subpixel rendering on transparent background */
                           ? FCFT_SUBPIXEL_DEFAULT
                           : FCFT_SUBPIXEL_NONE),
@@ -1490,11 +1490,11 @@ term_font_size_reset(struct terminal *term)
 bool
 term_font_dpi_changed(struct terminal *term)
 {
-    unsigned dpi = get_font_dpi(term);
+    float dpi = get_font_dpi(term);
     if (dpi == term->font_dpi)
         return true;
 
-    LOG_DBG("DPI changed (%u -> %u): reloading fonts", term->font_dpi, dpi);
+    LOG_DBG("DPI changed (%.2f -> %.2f): reloading fonts", term->font_dpi, dpi);
     term->font_dpi = dpi;
 
     return reload_fonts(term);

terminal.h

@@ -224,7 +224,7 @@ struct terminal {
 
     struct fcft_font *fonts[4];
     struct config_font *font_sizes;
-    int font_dpi;
+    float font_dpi;
     enum fcft_subpixel font_subpixel;
 
     tll(struct ptmx_buffer) ptmx_buffer;

wayland.c

@@ -294,11 +294,18 @@ output_update_ppi(struct monitor *mon)
 
     int x_inches = mon->dim.mm.width * 0.03937008;
     int y_inches = mon->dim.mm.height * 0.03937008;
+
     mon->ppi.real.x = mon->dim.px_real.width / x_inches;
     mon->ppi.real.y = mon->dim.px_real.height / y_inches;
 
     mon->ppi.scaled.x = mon->dim.px_scaled.width / x_inches;
     mon->ppi.scaled.y = mon->dim.px_scaled.height / y_inches;
+
+    float px_diag = sqrt(
+        pow(mon->dim.px_scaled.width, 2) +
+        pow(mon->dim.px_scaled.height, 2));
+
+    mon->dpi = px_diag / mon->inch * mon->scale;
 }
 
 static void
@@ -343,6 +350,7 @@ output_scale(void *data, struct wl_output *wl_output, int32_t factor)
 {
     struct monitor *mon = data;
     mon->scale = factor;
+    output_update_ppi(mon);
 }
 
 static const struct wl_output_listener output_listener = {
@@ -1029,13 +1037,14 @@ wayl_init(const struct config *conf, struct fdm *fdm)
 
     tll_foreach(wayl->monitors, it) {
         LOG_INFO(
-            "%s: %dx%d+%dx%d@%dHz %s %.2f\" scale=%d PPI=%dx%d (physical) PPI=%dx%d (logical)",
+            "%s: %dx%d+%dx%d@%dHz %s %.2f\" scale=%d PPI=%dx%d (physical) PPI=%dx%d (logical), DPI=%.2f",
             it->item.name, it->item.dim.px_real.width, it->item.dim.px_real.height,
             it->item.x, it->item.y, (int)round(it->item.refresh),
             it->item.model != NULL ? it->item.model : it->item.description,
             it->item.inch, it->item.scale,
             it->item.ppi.real.x, it->item.ppi.real.y,
-            it->item.ppi.scaled.x, it->item.ppi.scaled.y);
+            it->item.ppi.scaled.x, it->item.ppi.scaled.y,
+            it->item.dpi);
     }
 
     wayl->fd = wl_display_get_fd(wayl->display);

wayland.h

@@ -236,6 +236,8 @@ struct monitor {
         } scaled;
     } ppi;
 
+    float dpi;
+
     int scale;
     float refresh;
     enum wl_output_subpixel subpixel;