[FFmpeg-devel] [PATCH v2 1/2] lavu/display: add av_display_rotation_hflip_get and bump version

[Jun Li]

Add av_display_rotation_hflip_get to get information whether the
matrix indicates horizontal flip.
---
 doc/APIchanges            |  3 +++
 libavutil/display.c       | 14 ++++++++++++++
 libavutil/display.h       | 14 ++++++++++++++
 libavutil/tests/display.c |  8 ++++++++
 libavutil/version.h       |  2 +-
 tests/ref/fate/display    |  4 ++++
 6 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/doc/APIchanges b/doc/APIchanges
index e75c4044ce..73c6809563 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -15,6 +15,9 @@ libavutil:     2017-10-21
 
 API changes, most recent first:
 
+2019-05-13 - XXXXXXXXXX - lavu 56.28.100 - display.h
+  Add av_display_rotation_hflip_get
+
 2019-04-20 - 3153a6502a - lavc 58.52.100 - avcodec.h
   Add AV_CODEC_FLAG_DROPCHANGED to allow avcodec_receive_frame to drop
   frames whose parameters differ from first decoded frame in stream.
diff --git a/libavutil/display.c b/libavutil/display.c
index a0076e067b..f5a6a4a08d 100644
--- a/libavutil/display.c
+++ b/libavutil/display.c
@@ -71,3 +71,17 @@ void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip)
         for (i = 0; i < 9; i++)
             matrix[i] *= flip[i % 3];
 }
+
+double av_display_rotation_hflip_get(const int32_t matrix[9], int *hflip)
+{
+    int32_t m[9];
+    *hflip = 0;
+    memcpy(m, matrix, sizeof(m));
+    
+    if (m[0] > 0 && m[4] < 0 || m[0] < 0 && m[4] > 0 ||
+        m[1] > 0 && m[3] > 0 || m[1] < 0 && m[3] < 0) {
+        *hflip = 1;
+        av_display_matrix_flip(m, 1, 0);
+    }
+    return av_display_rotation_get(m);
+}
diff --git a/libavutil/display.h b/libavutil/display.h
index 515adad795..c37d10c741 100644
--- a/libavutil/display.h
+++ b/libavutil/display.h
@@ -106,6 +106,20 @@ void av_display_rotation_set(int32_t matrix[9], double angle);
  */
 void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip);
 
+/**
+ * Extract the rotation component and hflip status of the transformation matrix.
+ *
+ * @param matrix the transformation matrix
+ * @param hflip will be set to 1 if the matrix indicates horizontal flip
+ * @return the angle (in degrees) by which the transformation rotates the frame
+ *         counterclockwise. The angle will be in range [-180.0, 180.0],
+ *         or NaN if the matrix is singular.
+ * 
+ * @note floating point numbers are inherently inexact, so callers are
+ *       recommended to round the return value to nearest integer before use.
+ */
+double av_display_rotation_hflip_get(const int32_t matrix[9], int* hflip);
+
 /**
  * @}
  * @}
diff --git a/libavutil/tests/display.c b/libavutil/tests/display.c
index 893ebb5543..65a0971e7b 100644
--- a/libavutil/tests/display.c
+++ b/libavutil/tests/display.c
@@ -35,6 +35,8 @@ static void print_matrix(int32_t matrix[9])
 int main(void)
 {
     int32_t matrix[9];
+    int hflip = 0;
+    double degree;
 
     // Set the matrix to 90 degrees
     av_display_rotation_set(matrix, 90);
@@ -56,6 +58,12 @@ int main(void)
     print_matrix(matrix);
     printf("degrees: %f\n", av_display_rotation_get(matrix));
 
+    // flip vertical
+    av_display_matrix_flip(matrix, 0, 1);
+    print_matrix(matrix);
+    degree = av_display_rotation_hflip_get(matrix, &hflip);
+    printf("degrees: %f, hflip: %i\n", degree, hflip);
+
     return 0;
 
 }
diff --git a/libavutil/version.h b/libavutil/version.h
index 12b4f9fc3a..91ab71604b 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  56
-#define LIBAVUTIL_VERSION_MINOR  27
+#define LIBAVUTIL_VERSION_MINOR  28
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
diff --git a/tests/ref/fate/display b/tests/ref/fate/display
index 251e7e0cdf..14b4c7db7c 100644
--- a/tests/ref/fate/display
+++ b/tests/ref/fate/display
@@ -14,3 +14,7 @@ degrees: 135.000000
 -46340 -46340 0
 0 0 1073741824
 degrees: -135.000000
+-46340 -46340 0
+-46340 46340 0
+0 0 1073741824
+degrees: 45.000000, hflip: 1
-- 
2.17.1