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[PATCH 09/11] graph: smooth appearance of collapsing edges on commit lines

From
James Coglan via GitGitGadget <gitgitgadget@gmail.com>
Date
Oct 10, 2019, 16:13 UTC
Message-ID
<f9ced9090d0b5fb46e4ffbd31ec57a5eefeaf5e4.1570724021.git.gitgitgadget@gmail.com>
In-Reply-To
<pull.383.git.gitgitgadget@gmail.com>
From: James Coglan <jcoglan@gmail.com>

When a graph contains edges that are in the process of collapsing to the left, but those edges cross a commit line, the effect is that the edges have a jagged appearance:

        *
        |\
        | *
        |  \
        *-. \
        |\ \ \
        | | * |
        | * | |
        | |/ /
        * | |
        |/ /
        * |
        |/
        *

We already takes steps to smooth edges like this when they're expanding; when an edge appears to the right of a merge commit marker on a GRAPH_COMMIT line immediately following a GRAPH_POST_MERGE line, we render it as a `\`:

        * \
        |\ \
        | * \
        | |\ \

We can make a similar improvement to collapsing edges, making them easier to follow and giving the overall graph a feeling of increased symmetry:

        *
        |\
        | *
        |  \
        *-. \
        |\ \ \
        | | * |
        | * | |
        | |/ /
        * / /
        |/ /
        * /
        |/
        *

To do this, we introduce a new special case for edges on GRAPH_COMMIT lines that immediately follow a GRAPH_COLLAPSING line. By retaining a copy of the `mapping` array used to render the GRAPH_COLLAPSING line in the `old_mapping` array, we can determine that an edge is collapsing through the GRAPH_COMMIT line and should be smoothed.

Signed-off-by: James Coglan <jcoglan@gmail.com>
---
 graph.c                                    | 17 +++++++++++++----
 t/t3430-rebase-merges.sh                   |  2 +-
 t/t4202-log.sh                             |  2 +-
 t/t4214-log-graph-octopus.sh               | 16 ++++++++--------
 t/t4215-log-skewed-merges.sh               |  2 +-
 t/t6016-rev-list-graph-simplify-history.sh |  4 ++--
 6 files changed, 26 insertions(+), 17 deletions(-)
diff --git a/graph.c b/graph.c
index b0e31e23ca..6391e393ec 100644
--- a/graph.c
+++ b/graph.c
@@ -278,10 +278,10 @@ struct git_graph {
 	 */
 	int *mapping;
 	/*
-	 * A temporary array for computing the next mapping state
-	 * while we are outputting a mapping line.  This is stored as part
-	 * of the git_graph simply so we don't have to allocate a new
-	 * temporary array each time we have to output a collapsing line.
+	 * A copy of the contents of the mapping array from the last commit,
+	 * which we use to improve the display of columns that are tracking
+	 * from right to left through a commit line.  We also use this to
+	 * avoid allocating a fresh array when we compute the next mapping.
 	 */
 	int *old_mapping;
 	/*
@@ -1011,6 +1011,10 @@ static void graph_output_commit_line(struct git_graph *graph, struct strbuf *sb)
 				strbuf_write_column(sb, col, '\\');
 			else
 				strbuf_write_column(sb, col, '|');
+		} else if (graph->prev_state == GRAPH_COLLAPSING &&
+			   graph->old_mapping[2 * i + 1] == i &&
+			   graph->mapping[2 * i] < i) {
+			strbuf_write_column(sb, col, '/');
 		} else {
 			strbuf_write_column(sb, col, '|');
 		}
@@ -1211,6 +1215,11 @@ static void graph_output_collapsing_line(struct git_graph *graph, struct strbuf
 		}
 	}
 
+	/*
+	 * Copy the current mapping array into old_mapping
+	 */
+	COPY_ARRAY(graph->old_mapping, graph->mapping, graph->mapping_size);
+
 	/*
 	 * The new mapping may be 1 smaller than the old mapping
 	 */
diff --git a/t/t3430-rebase-merges.sh b/t/t3430-rebase-merges.sh
index 7b6c4847ad..051351ecdf 100755
--- a/t/t3430-rebase-merges.sh
+++ b/t/t3430-rebase-merges.sh
@@ -402,7 +402,7 @@ test_expect_success 'octopus merges' '
 	| | * three
 	| * | two
 	| |/
-	* | one
+	* / one
 	|/
 	o before-octopus
 	EOF
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index c20209324c..c7aa0532c1 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -667,7 +667,7 @@ cat > expect <<\EOF
 * | | fifth
 * | | fourth
 |/ /
-* | third
+* / third
 |/
 * second
 * initial
diff --git a/t/t4214-log-graph-octopus.sh b/t/t4214-log-graph-octopus.sh
index 40f420877b..9ada687628 100755
--- a/t/t4214-log-graph-octopus.sh
+++ b/t/t4214-log-graph-octopus.sh
@@ -12,9 +12,9 @@ test_expect_success 'set up merge history' '
 	| | | * 4
 	| | * | 3
 	| | |/
-	| * | 2
+	| * / 2
 	| |/
-	* | 1
+	* / 1
 	|/
 	* initial
 	EOF
@@ -25,9 +25,9 @@ test_expect_success 'set up merge history' '
 	<RED>|<RESET> <YELLOW>|<RESET> <BLUE>|<RESET> * 4
 	<RED>|<RESET> <YELLOW>|<RESET> * <MAGENTA>|<RESET> 3
 	<RED>|<RESET> <YELLOW>|<RESET> <MAGENTA>|<RESET><MAGENTA>/<RESET>
-	<RED>|<RESET> * <MAGENTA>|<RESET> 2
+	<RED>|<RESET> * <MAGENTA>/<RESET> 2
 	<RED>|<RESET> <MAGENTA>|<RESET><MAGENTA>/<RESET>
-	* <MAGENTA>|<RESET> 1
+	* <MAGENTA>/<RESET> 1
 	<MAGENTA>|<RESET><MAGENTA>/<RESET>
 	* initial
 	EOF
@@ -68,9 +68,9 @@ test_expect_success 'log --graph with normal octopus merge, no color' '
 	| | | * 4
 	| | * | 3
 	| | |/
-	| * | 2
+	| * / 2
 	| |/
-	* | 1
+	* / 1
 	|/
 	* initial
 	EOF
@@ -86,9 +86,9 @@ test_expect_success 'log --graph with normal octopus merge with colors' '
 	<RED>|<RESET> <GREEN>|<RESET> <YELLOW>|<RESET> * 4
 	<RED>|<RESET> <GREEN>|<RESET> * <BLUE>|<RESET> 3
 	<RED>|<RESET> <GREEN>|<RESET> <BLUE>|<RESET><BLUE>/<RESET>
-	<RED>|<RESET> * <BLUE>|<RESET> 2
+	<RED>|<RESET> * <BLUE>/<RESET> 2
 	<RED>|<RESET> <BLUE>|<RESET><BLUE>/<RESET>
-	* <BLUE>|<RESET> 1
+	* <BLUE>/<RESET> 1
 	<BLUE>|<RESET><BLUE>/<RESET>
 	* initial
 	EOF
diff --git a/t/t4215-log-skewed-merges.sh b/t/t4215-log-skewed-merges.sh
index e479d6e676..b739268e5e 100755
--- a/t/t4215-log-skewed-merges.sh
+++ b/t/t4215-log-skewed-merges.sh
@@ -62,7 +62,7 @@ cat > expect <<\EOF
 | * | 1_D
 * | | 1_C
 |/ /
-* | 1_B
+* / 1_B
 |/
 * 1_A
 EOF
diff --git a/t/t6016-rev-list-graph-simplify-history.sh b/t/t6016-rev-list-graph-simplify-history.sh
index f7181d1d6a..ca1682f29b 100755
--- a/t/t6016-rev-list-graph-simplify-history.sh
+++ b/t/t6016-rev-list-graph-simplify-history.sh
@@ -154,7 +154,7 @@ test_expect_success '--graph --full-history -- bar.txt' '
 	echo "* |   $A4" >> expected &&
 	echo "|\\ \\  " >> expected &&
 	echo "| |/  " >> expected &&
-	echo "* | $A3" >> expected &&
+	echo "* / $A3" >> expected &&
 	echo "|/  " >> expected &&
 	echo "* $A2" >> expected &&
 	git rev-list --graph --full-history --all -- bar.txt > actual &&
@@ -255,7 +255,7 @@ test_expect_success '--graph --boundary ^C3' '
 	echo "* | | | $A3" >> expected &&
 	echo "o | | | $A2" >> expected &&
 	echo "|/ / /  " >> expected &&
-	echo "o | | $A1" >> expected &&
+	echo "o / / $A1" >> expected &&
 	echo " / /  " >> expected &&
 	echo "| o $C3" >> expected &&
 	echo "|/  " >> expected &&

-- 
gitgitgadget
Previous: James Coglan via GitGitGadgetNext: James Coglan via GitGitGadget
Message 21 of 83 in “Improve the readability of log --graph output”
  1. 00/11 Improve the readability of log --graph outputJames Coglan via GitGitGadget, Oct 10, 2019
  2. 01/11 graph: automatically track visible width of `strbuf`James Coglan via GitGitGadget, Oct 10, 2019
  3. Johannes SchindelinOct 10, 2019
  4. Denton LiuOct 10, 2019
  5. Derrick StoleeOct 11, 2019
  6. Junio C HamanoOct 11, 2019
  7. Denton LiuOct 11, 2019
  8. Johannes SchindelinOct 11, 2019
  9. James CoglanOct 11, 2019
  10. Junio C HamanoOct 12, 2019
  11. Johannes SchindelinOct 12, 2019
  12. James CoglanOct 14, 2019
  13. James CoglanOct 14, 2019
  14. Junio C HamanoOct 16, 2019
  15. Junio C HamanoOct 11, 2019
  16. James CoglanOct 11, 2019
  17. 03/11 graph: reduce duplication in `graph_insert_into_new_columns()`James Coglan via GitGitGadget, Oct 10, 2019
  18. 02/11 graph: reuse `find_new_column_by_commit()`James Coglan via GitGitGadget, Oct 10, 2019
  19. 04/11 graph: remove `mapping_idx` and `graph_update_width()`James Coglan via GitGitGadget, Oct 10, 2019
  20. 05/11 graph: extract logic for moving to GRAPH_PRE_COMMIT stateJames Coglan via GitGitGadget, Oct 10, 2019
  21. 09/11 graph: smooth appearance of collapsing edges on commit linesJames Coglan via GitGitGadget, Oct 10, 2019
  22. 08/11 graph: rename `new_mapping` to `old_mapping`James Coglan via GitGitGadget, Oct 10, 2019
  23. 11/11 graph: fix coloring of octopus dashesJames Coglan via GitGitGadget, Oct 10, 2019
  24. Denton LiuOct 10, 2019
  25. Denton LiuOct 10, 2019
  26. Jeff KingOct 13, 2019
  27. 07/11 graph: commit and post-merge lines for left-skewed mergesJames Coglan via GitGitGadget, Oct 10, 2019
  28. Derrick StoleeOct 10, 2019
  29. James CoglanOct 11, 2019
  30. Jeff KingOct 13, 2019
  31. James CoglanOct 14, 2019
  32. Derrick StoleeOct 14, 2019
  33. Johannes SchindelinOct 14, 2019
  34. 06/11 graph: tidy up display of left-skewed mergesJames Coglan via GitGitGadget, Oct 10, 2019
  35. Derrick StoleeOct 10, 2019
  36. James CoglanOct 11, 2019
  37. Derrick StoleeOct 12, 2019
  38. James CoglanOct 14, 2019
  39. 10/11 graph: flatten edges that join to their right neighborJames Coglan via GitGitGadget, Oct 10, 2019
  40. Derrick StoleeOct 10, 2019
  41. Jeff KingOct 13, 2019
  42. James CoglanOct 14, 2019
  43. 00/13 Improve the readability of log --graph outputJames Coglan via GitGitGadget, Oct 15, 2019
  44. 03/13 graph: reuse `find_new_column_by_commit()`James Coglan via GitGitGadget, Oct 15, 2019
  45. 02/13 graph: handle line padding in `graph_next_line()`James Coglan via GitGitGadget, Oct 15, 2019
  46. 05/13 graph: remove `mapping_idx` and `graph_update_width()`James Coglan via GitGitGadget, Oct 15, 2019
  47. 01/13 graph: automatically track display width of graph linesJames Coglan via GitGitGadget, Oct 15, 2019
  48. 04/13 graph: reduce duplication in `graph_insert_into_new_columns()`James Coglan via GitGitGadget, Oct 15, 2019
  49. 06/13 graph: extract logic for moving to GRAPH_PRE_COMMIT stateJames Coglan via GitGitGadget, Oct 15, 2019
  50. 09/13 graph: commit and post-merge lines for left-skewed mergesJames Coglan via GitGitGadget, Oct 15, 2019
  51. 07/13 graph: example of graph output that can be simplifiedJames Coglan via GitGitGadget, Oct 15, 2019
  52. 11/13 graph: smooth appearance of collapsing edges on commit linesJames Coglan via GitGitGadget, Oct 15, 2019
  53. 08/13 graph: tidy up display of left-skewed mergesJames Coglan via GitGitGadget, Oct 15, 2019
  54. 12/13 graph: flatten edges that fuse with their right neighborJames Coglan via GitGitGadget, Oct 15, 2019
  55. 10/13 graph: rename `new_mapping` to `old_mapping`James Coglan via GitGitGadget, Oct 15, 2019
  56. 13/13 graph: fix coloring of octopus dashesJames Coglan via GitGitGadget, Oct 15, 2019
  57. 00/13 Improve the readability of log --graph outputJames Coglan via GitGitGadget, Oct 15, 2019
  58. 03/13 graph: reuse `find_new_column_by_commit()`James Coglan via GitGitGadget, Oct 15, 2019
  59. 02/13 graph: handle line padding in `graph_next_line()`James Coglan via GitGitGadget, Oct 15, 2019
  60. Junio C HamanoOct 16, 2019
  61. 01/13 graph: automatically track display width of graph linesJames Coglan via GitGitGadget, Oct 15, 2019
  62. Junio C HamanoOct 16, 2019
  63. Junio C HamanoOct 16, 2019
  64. 04/13 graph: reduce duplication in `graph_insert_into_new_columns()`James Coglan via GitGitGadget, Oct 15, 2019
  65. 06/13 graph: extract logic for moving to GRAPH_PRE_COMMIT stateJames Coglan via GitGitGadget, Oct 15, 2019
  66. 05/13 graph: remove `mapping_idx` and `graph_update_width()`James Coglan via GitGitGadget, Oct 15, 2019
  67. 07/13 graph: example of graph output that can be simplifiedJames Coglan via GitGitGadget, Oct 15, 2019
  68. Derrick StoleeOct 17, 2019
  69. SZEDER GáborOct 18, 2019
  70. t4215: don't put git commands upstream of pipeDenton Liu, Nov 12, 2019
  71. Junio C HamanoNov 12, 2019
  72. SZEDER GáborNov 12, 2019
  73. t4215: use helper function to check outputDenton Liu, Nov 12, 2019
  74. Junio C HamanoNov 13, 2019
  75. 09/13 graph: commit and post-merge lines for left-skewed mergesJames Coglan via GitGitGadget, Oct 15, 2019
  76. 13/13 graph: fix coloring of octopus dashesJames Coglan via GitGitGadget, Oct 15, 2019
  77. 08/13 graph: tidy up display of left-skewed mergesJames Coglan via GitGitGadget, Oct 15, 2019
  78. Junio C HamanoOct 16, 2019
  79. Derrick StoleeOct 17, 2019
  80. Junio C HamanoOct 18, 2019
  81. 10/13 graph: rename `new_mapping` to `old_mapping`James Coglan via GitGitGadget, Oct 15, 2019
  82. 12/13 graph: flatten edges that fuse with their right neighborJames Coglan via GitGitGadget, Oct 15, 2019
  83. 11/13 graph: smooth appearance of collapsing edges on commit linesJames Coglan via GitGitGadget, Oct 15, 2019

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