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eeshow/gui/history.c (hover_history): compensate jump on dehover

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This commit is contained in:
Werner Almesberger 2016-08-21 23:02:57 -03:00
parent b844bbfed2
commit 328ddd9ca7
1 changed files with 37 additions and 1 deletions
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38
eeshow/gui/history.c
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@ -15,6 +15,7 @@
#include <stdlib.h>
#include <gtk/gtk.h>
#include <pango/pangocairo.h>
#include "misc/util.h"
#include "file/git-hist.h"
@ -82,12 +83,38 @@ static void set_history_style(struct gui_hist *h, bool current)
}
/*
* One difficulty with resizing (enlarging, in this case) list items on hover
* is that, if we only change the size but not the position, hovering towards
* the next item will cause the previous item to shrink and thus move the next
* item up - possibly even above the mouse pointer. This can be confusing.
*
* We could adjust the mouse pointer, but manipulating the pointer position is
* not universally popular.
*
* Instead, we move the list such that the bottom edge of the item we're
* leaving remains stationary. Thus the list moves down when mousing over items
* from the top towards the bottom.
*
* To prevent this movement from being overly pronounced, we try to predict the
* direction in which an item will be left (i.e., in the same direction from
* which it was entered), and compensate for the likely list movement on
* departure on entry.
*
* These heuristics can still sometimes fail, but by and large, they produce
* the desired result without introducing too much list movement.
*/
static bool hover_history(void *user, bool on, int dx, int dy)
{
struct gui_hist *h = user;
struct gui_ctx *ctx = h->ctx;
char *s;
int before, after;
if (dy)
overlay_size(h->over, gtk_widget_get_pango_context(ctx->da),
NULL, &before);
if (on) {
s = vcs_git_long_for_pango(h->vcs_hist, fmt_pango);
overlay_text_raw(h->over, s);
@ -97,6 +124,15 @@ static bool hover_history(void *user, bool on, int dx, int dy)
vcs_git_summary(h->vcs_hist));
}
set_history_style(h, on);
if (dy)
overlay_size(h->over, gtk_widget_get_pango_context(ctx->da),
NULL, &after);
if (dy < 0 && on)
ctx->hist_y_offset -= after - before;
if (dy > 0 && !on)
ctx->hist_y_offset -= after - before;
redraw(ctx);
return 1;
}
@ -274,8 +310,8 @@ void show_history(struct gui_ctx *ctx, enum selecting sel)
h = skip_history(ctx, h);
h->over = overlay_add(&ctx->hist_overlays, &ctx->aois,
hover_history, click_history, h);
hover_history(h, 0, 0, 0);
set_history_style(h, 0);
hover_history(h, 0, 0, 0);
}
redraw(ctx);
}