[FFmpeg-devel] [PATCH v4 4/6] lavu/display: Add horizontal and vertical scaling to the display matrix

[Thilo Borgmann]

---
 doc/APIchanges      |  3 +++
 libavutil/display.c | 35 +++++++++++++++++++++++++++++++++++
 libavutil/display.h | 26 ++++++++++++++++++++++++++
 libavutil/version.h |  2 +-
 4 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/doc/APIchanges b/doc/APIchanges
index e4b2fc8799..9dc393d999 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -14,6 +14,9 @@ libavutil:     2021-04-27
 
 API changes, most recent first:
 
+2022-09-19 - xxxxxxxxxx - lavu 57.38.100 - display.h
+  Add av_display_matrix_scale(), av_display_{h,v}scale_get()
+
 2022-09-19 - xxxxxxxxxx - lavu 57.37.100 - opt.h
   Add AV_OPT_FLAG_ARGUMENT.
   Add av_arg_show() to print arguments to options.
diff --git a/libavutil/display.c b/libavutil/display.c
index d31061283c..434ed50104 100644
--- a/libavutil/display.c
+++ b/libavutil/display.c
@@ -48,6 +48,30 @@ double av_display_rotation_get(const int32_t matrix[9])
     return -rotation;
 }
 
+double av_display_hscale_get(const int32_t matrix[9])
+{
+    double scale;
+
+    scale = hypot(CONV_FP(matrix[0]), CONV_FP(matrix[1]));
+
+    if (scale == 0.0)
+        return NAN;
+
+    return scale;
+}
+
+double av_display_vscale_get(const int32_t matrix[9])
+{
+    double scale;
+
+    scale = hypot(CONV_FP(matrix[3]), CONV_FP(matrix[4]));
+
+    if (scale == 0.0)
+        return NAN;
+
+    return scale;
+}
+
 void av_display_rotation_set(int32_t matrix[9], double angle)
 {
     double radians = -angle * M_PI / 180.0f;
@@ -72,3 +96,14 @@ 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 hscale, double vscale)
+{
+    // hscale
+    matrix[0] = CONV_DB(CONV_FP(matrix[0]) * hscale);
+    matrix[1] = CONV_DB(CONV_FP(matrix[1]) * hscale);
+
+    // vscale
+    matrix[3] = CONV_DB(CONV_FP(matrix[3]) * vscale);
+    matrix[4] = CONV_DB(CONV_FP(matrix[4]) * vscale);
+}
diff --git a/libavutil/display.h b/libavutil/display.h
index 31d8bef361..ef507eb521 100644
--- a/libavutil/display.h
+++ b/libavutil/display.h
@@ -86,6 +86,24 @@
  */
 double av_display_rotation_get(const int32_t matrix[9]);
 
+/**
+ * Extract the horizontal scaling component of the transformation matrix.
+ *
+ * @param matrix the transformation matrix
+ * @return the horizontal scaling by which the transformation matrix scales the frame
+ *         in the horizontal direction.
+ */
+double av_display_hscale_get(const int32_t matrix[9]);
+
+/**
+ * Extract the vertical scaling component of the transformation matrix.
+ *
+ * @param matrix the transformation matrix
+ * @return the vertical scaling by which the transformation matrix scales the frame
+ *         in the vertical direction.
+ */
+double av_display_vscale_get(const int32_t matrix[9]);
+
 /**
  * Initialize a transformation matrix describing a pure clockwise
  * rotation by the specified angle (in degrees).
@@ -105,6 +123,14 @@ 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 horizontally and/or vertically.
+ *
+ * @param matrix an allocated transformation matrix
+ * @param hscale scale factor by which the matrix should be scaled horizontally
+ * @param vscale scale factor by which the matrix should be scaled vertically
+ */
+void av_display_matrix_scale(int32_t matrix[9], double hscale, double vscale);
 /**
  * @}
  * @}
diff --git a/libavutil/version.h b/libavutil/version.h
index 9c44cef6aa..5aca550f45 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  57
-#define LIBAVUTIL_VERSION_MINOR  37
+#define LIBAVUTIL_VERSION_MINOR  38
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
-- 
2.20.1 (Apple Git-117)