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c9eef95492
Instead of guesstimating the values of the scrollbars adjustments after a change in zoom level, connect callbacks to the "changed" GtkAdjustment event (which is emitted when the bounds or page_size of the adjustment change, e.g. when the zoom level changes), and compute the new values from there. The previous adjustment values are tracked in zathura->ui.hadjustment and zathura->ui.vadjustment (and updated by signal handlers as well), so that the view's position can be maintained while zooming. cb_view_hadjustment_changed() centers the page horizontally if a "best-fit" or "width" zoom is being performed, or if "zoom-center" is true; otherwise, it keeps the view horizontally centered around the same area of the page. cb_view_vadjustment_changed() always keeps the view vertically centered around the same area of the page. Many thanks to Marwan Tanager for thoroughly reviewing the various stages of this patch, and actually coming up with a working solution. Signed-off-by: Sebastian Ramacher <sebastian+dev@ramacher.at>
56 lines
1.9 KiB
C
56 lines
1.9 KiB
C
/* See LICENSE file for license and copyright information */
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#include "adjustment.h"
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#include "utils.h"
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GtkAdjustment*
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zathura_adjustment_clone(GtkAdjustment* adjustment)
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{
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gdouble value = gtk_adjustment_get_value(adjustment);
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gdouble lower = gtk_adjustment_get_lower(adjustment);
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gdouble upper = gtk_adjustment_get_upper(adjustment);
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gdouble step_increment = gtk_adjustment_get_step_increment(adjustment);
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gdouble page_increment = gtk_adjustment_get_page_increment(adjustment);
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gdouble page_size = gtk_adjustment_get_page_size(adjustment);
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return GTK_ADJUSTMENT(gtk_adjustment_new(value, lower, upper, step_increment,
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page_increment, page_size));
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}
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void
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zathura_adjustment_set_value(GtkAdjustment* adjustment, gdouble value)
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{
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gtk_adjustment_set_value(adjustment,
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MAX(gtk_adjustment_get_lower(adjustment),
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MIN(gtk_adjustment_get_upper(adjustment) -
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gtk_adjustment_get_page_size(adjustment),
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value)));
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}
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gdouble
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zathura_adjustment_get_ratio(GtkAdjustment* adjustment)
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{
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gdouble lower = gtk_adjustment_get_lower(adjustment);
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gdouble upper = gtk_adjustment_get_upper(adjustment);
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gdouble page_size = gtk_adjustment_get_page_size(adjustment);
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gdouble value = gtk_adjustment_get_value(adjustment);
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return (value - lower + page_size / 2.0) / (upper - lower);
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}
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void
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zathura_adjustment_set_value_from_ratio(GtkAdjustment* adjustment,
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gdouble ratio)
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{
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if (ratio == 0.0)
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return;
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gdouble lower = gtk_adjustment_get_lower(adjustment);
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gdouble upper = gtk_adjustment_get_upper(adjustment);
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gdouble page_size = gtk_adjustment_get_page_size(adjustment);
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gdouble value = (upper - lower) * ratio + lower - page_size / 2.0;
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zathura_adjustment_set_value(adjustment, value);
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}
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