98 lines
2.7 KiB
C
98 lines
2.7 KiB
C
/*
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* vim:ts=4:sw=4:expandtab
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*
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* i3 - an improved dynamic tiling window manager
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* © 2009 Michael Stapelberg and contributors (see also: LICENSE)
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*
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*/
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#include "libi3.h"
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#include <math.h>
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#include <stdlib.h>
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#include <xcb/xcb_xrm.h>
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static long dpi;
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static long init_dpi_fallback(void) {
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return (double)root_screen->height_in_pixels * 25.4 / (double)root_screen->height_in_millimeters;
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}
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/*
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* Initialize the DPI setting.
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* This will use the 'Xft.dpi' X resource if available and fall back to
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* guessing the correct value otherwise.
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*/
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void init_dpi(void) {
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xcb_xrm_database_t *database = NULL;
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if (conn == NULL) {
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goto init_dpi_end;
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}
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database = xcb_xrm_database_from_default(conn);
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if (database == NULL) {
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ELOG("Failed to open the resource database.\n");
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goto init_dpi_end;
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}
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char *resource;
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xcb_xrm_resource_get_string(database, "Xft.dpi", NULL, &resource);
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if (resource == NULL) {
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DLOG("Resource Xft.dpi not specified, skipping.\n");
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goto init_dpi_end;
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}
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char *endptr;
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dpi = strtol(resource, &endptr, 10);
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if (dpi == LONG_MAX || dpi == LONG_MIN || dpi < 0 || *endptr != '\0' || endptr == resource) {
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ELOG("Xft.dpi = %s is an invalid number and couldn't be parsed.\n", resource);
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dpi = 0;
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goto init_dpi_end;
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}
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DLOG("Found Xft.dpi = %ld.\n", dpi);
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init_dpi_end:
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if (database != NULL) {
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xcb_xrm_database_free(database);
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}
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if (dpi == 0) {
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DLOG("Using fallback for calculating DPI.\n");
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dpi = init_dpi_fallback();
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DLOG("Using dpi = %ld\n", dpi);
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}
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}
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/*
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* This function returns the value of the DPI setting.
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*
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*/
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long get_dpi_value(void) {
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return dpi;
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}
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/*
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* Convert a logical amount of pixels (e.g. 2 pixels on a “standard” 96 DPI
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* screen) to a corresponding amount of physical pixels on a standard or retina
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* screen, e.g. 5 pixels on a 227 DPI MacBook Pro 13" Retina screen.
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*
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*/
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int logical_px(const int logical) {
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if (root_screen == NULL) {
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/* Dpi info may not be available when parsing a config without an X
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* server, such as for config file validation. */
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return logical;
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}
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/* There are many misconfigurations out there, i.e. systems with screens
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* whose dpi is in fact higher than 96 dpi, but not significantly higher,
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* so software was never adapted. We could tell people to reconfigure their
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* systems to 96 dpi in order to get the behavior they expect/are used to,
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* but since we can easily detect this case in code, let’s do it for them.
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*/
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if ((dpi / 96.0) < 1.25)
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return logical;
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return ceil((dpi / 96.0) * logical);
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}
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