[FFmpeg-devel] [PATCH v5 1/3] lavu/display: Add scaling functions to the display matrix

[Thilo Borgmann]

---
 doc/APIchanges      |  3 +++
 libavutil/display.c | 21 +++++++++++++++++++++
 libavutil/display.h | 15 +++++++++++++++
 libavutil/version.h |  4 ++--
 4 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/doc/APIchanges b/doc/APIchanges
index 729f56be7b..42e3391b72 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -14,6 +14,9 @@ libavutil:     2021-04-27
 
 API changes, most recent first:
 
+2022-09-25 - xxxxxxxxxx - lavu 57.37.100 - display.h
+  Add av_display_matrix_scale(), av_display_scale_get()
+
 2022-09-03 - xxxxxxxxxx - lavu 57.36.100 - pixfmt.h
   Add AV_PIX_FMT_P012, AV_PIX_FMT_Y212, AV_PIX_FMT_XV30, AV_PIX_FMT_XV36
 
diff --git a/libavutil/display.c b/libavutil/display.c
index d31061283c..90758656e3 100644
--- a/libavutil/display.c
+++ b/libavutil/display.c
@@ -48,6 +48,19 @@ double av_display_rotation_get(const int32_t matrix[9])
     return -rotation;
 }
 
+double av_display_scale_get(const int32_t matrix[9])
+{
+    double scale[2];
+
+    scale[0] = hypot(CONV_FP(matrix[0]), CONV_FP(matrix[3]));
+    scale[1] = hypot(CONV_FP(matrix[1]), CONV_FP(matrix[4]));
+
+    if (scale[0] == 0.0 || scale[1] == 0.0)
+        return NAN;
+
+    return scale[0];
+}
+
 void av_display_rotation_set(int32_t matrix[9], double angle)
 {
     double radians = -angle * M_PI / 180.0f;
@@ -72,3 +85,11 @@ void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip)
         for (i = 0; i < 9; i++)
             matrix[i] *= flip[i % 3];
 }
+
+void av_display_matrix_scale(int32_t matrix[9], double scale)
+{
+    matrix[0] = CONV_DB(CONV_FP(matrix[0]) * scale);
+    matrix[1] = CONV_DB(CONV_FP(matrix[1]) * scale);
+    matrix[3] = CONV_DB(CONV_FP(matrix[3]) * scale);
+    matrix[4] = CONV_DB(CONV_FP(matrix[4]) * scale);
+}
diff --git a/libavutil/display.h b/libavutil/display.h
index 31d8bef361..73767b3a71 100644
--- a/libavutil/display.h
+++ b/libavutil/display.h
@@ -86,6 +86,14 @@
  */
 double av_display_rotation_get(const int32_t matrix[9]);
 
+/**
+ * Extract the scaling component of the transformation matrix.
+ *
+ * @param matrix the transformation matrix
+ * @return the scaling by which the transformation matrix scales the frame
+ */
+double av_display_scale_get(const int32_t matrix[9]);
+
 /**
  * Initialize a transformation matrix describing a pure clockwise
  * rotation by the specified angle (in degrees).
@@ -105,6 +113,13 @@ void av_display_rotation_set(int32_t matrix[9], double angle);
  */
 void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip);
 
+/**
+ * Scale the input matrix.
+ *
+ * @param matrix an allocated transformation matrix
+ * @param scale scale factor by which the matrix should be scaled
+ */
+void av_display_matrix_scale(int32_t matrix[9], double scale);
 /**
  * @}
  * @}
diff --git a/libavutil/version.h b/libavutil/version.h
index 0585fa7b80..9c44cef6aa 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,8 +79,8 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  57
-#define LIBAVUTIL_VERSION_MINOR  36
-#define LIBAVUTIL_VERSION_MICRO 102
+#define LIBAVUTIL_VERSION_MINOR  37
+#define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
                                                LIBAVUTIL_VERSION_MINOR, \
-- 
2.20.1 (Apple Git-117)