graph: flatten edges that fuse with their right neighbor
When a merge commit is printed and its final parent is the same commit that occupies the column to the right of the merge, this results in a kink in the displayed edges: * | |\ \ | |/ | * Graphs containing these shapes can be hard to read, as the expansion to the right followed immediately by collapsing back to the left creates a lot of zig-zagging edges, especially when many columns are present. We can improve this by eliminating the zig-zag and having the merge's final parent edge fuse immediately with its neighbor: * | |\| | * This reduces the horizontal width for the current commit by 2, and requires one less row, making the graph display more compact. Taken in combination with other graph-smoothing enhancements, it greatly compresses the space needed to display certain histories: * |\ | * * | |\ |\ | | * | * | | | | |\ | | \ | | * | *-. \ | * | | |\ \ \ => |/|\| |/ / / / | | * | | | / | * | | | |/ | |/ | | * * / | * | |/ | |/ * * | |/ * One of the test cases here cannot be correctly rendered in Git v2.23.0; it produces this output following commit E: | | *-. \ 5_E | | |\ \ \ | |/ / / / | | | / _ | |_|/ |/| | The new implementation makes sure that the rightmost edge in this history is not left dangling as above. Signed-off-by: James Coglan <jcoglan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:

committed by
Junio C Hamano

parent
479db18bc0
commit
92beecc136
34
graph.c
34
graph.c
@ -557,8 +557,24 @@ static void graph_insert_into_new_columns(struct git_graph *graph,
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shift = (dist > 1) ? 2 * dist - 3 : 1;
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graph->merge_layout = (dist > 0) ? 0 : 1;
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graph->edges_added = graph->num_parents + graph->merge_layout - 2;
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mapping_idx = graph->width + (graph->merge_layout - 1) * shift;
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graph->width += 2 * graph->merge_layout;
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} else if (graph->edges_added > 0 && i == graph->mapping[graph->width - 2]) {
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/*
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* If some columns have been added by a merge, but this commit
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* was found in the last existing column, then adjust the
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* numbers so that the two edges immediately join, i.e.:
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*
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* * | * |
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* |\ \ => |\|
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* | |/ | *
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* | *
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*/
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mapping_idx = graph->width - 2;
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graph->edges_added = -1;
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} else {
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mapping_idx = graph->width;
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graph->width += 2;
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@ -604,6 +620,8 @@ static void graph_update_columns(struct git_graph *graph)
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graph->mapping[i] = -1;
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graph->width = 0;
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graph->prev_edges_added = graph->edges_added;
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graph->edges_added = 0;
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/*
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* Populate graph->new_columns and graph->mapping
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@ -731,9 +749,6 @@ void graph_update(struct git_graph *graph, struct commit *commit)
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*/
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graph_update_columns(graph);
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graph->prev_edges_added = graph->edges_added;
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graph->edges_added = graph->num_parents + graph->merge_layout - 2;
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graph->expansion_row = 0;
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/*
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@ -1041,7 +1056,7 @@ const char merge_chars[] = {'/', '|', '\\'};
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static void graph_output_post_merge_line(struct git_graph *graph, struct graph_line *line)
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{
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int seen_this = 0;
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int i;
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int i, j;
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struct commit_list *first_parent = first_interesting_parent(graph);
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int seen_parent = 0;
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@ -1073,16 +1088,19 @@ static void graph_output_post_merge_line(struct git_graph *graph, struct graph_l
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char c;
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seen_this = 1;
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for (; parents; parents = next_interesting_parent(graph, parents)) {
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for (j = 0; j < graph->num_parents; j++) {
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par_column = graph_find_new_column_by_commit(graph, parents->item);
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assert(par_column >= 0);
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c = merge_chars[idx];
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graph_line_write_column(line, &graph->new_columns[par_column], c);
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if (idx == 2)
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graph_line_addch(line, ' ');
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else
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if (idx == 2) {
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if (graph->edges_added > 0 || j < graph->num_parents - 1)
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graph_line_addch(line, ' ');
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} else {
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idx++;
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}
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parents = next_interesting_parent(graph, parents);
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}
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if (graph->edges_added == 0)
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graph_line_addch(line, ' ');
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