lavu/opt: extend AVOptionRange by extra values

AVOptionRange is not flexible enough to store AV_OPT_TYPE_IMAGE_SIZE
ranges. Current implementation can only store pixel count.
This patch aims to keep backward compatibility and extend
AVOptionRange with possibility to store width/height ranges.

Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>

1 files changed, 65 insertions, 6 deletions

diff --git a/libavutil/opt.h b/libavutil/opt.h
index cd1b18e4c0..6a1ae4354a 100644
--- a/libavutil/opt.h
+++ b/libavutil/opt.h
@@ -313,17 +313,67 @@ typedef struct AVOption {
  */
 typedef struct AVOptionRange {
     const char *str;
-    double value_min, value_max;             ///< For string ranges this represents the min/max length, for dimensions this represents the min/max pixel count
-    double component_min, component_max;     ///< For string this represents the unicode range for chars, 0-127 limits to ASCII
-    int is_range;                            ///< if set to 1 the struct encodes a range, if set to 0 a single value
+    /**
+     * Value range.
+     * For string ranges this represents the min/max length.
+     * For dimensions this represents the min/max pixel count or width/height in multi-component case.
+     */
+    double value_min, value_max;
+    /**
+     * Value's component range.
+     * For string this represents the unicode range for chars, 0-127 limits to ASCII.
+     */
+    double component_min, component_max;
+    /**
+     * Range flag.
+     * If set to 1 the struct encodes a range, if set to 0 a single value.
+     */
+    int is_range;
 } AVOptionRange;
 
 /**
- * List of AVOptionRange structs
+ * List of AVOptionRange structs.
  */
 typedef struct AVOptionRanges {
+    /**
+     * Array of option ranges.
+     *
+     * Most of option types use just one component.
+     * Following describes multi-component option types:
+     *
+     * AV_OPT_TYPE_IMAGE_SIZE:
+     * component index 0: range of pixel count (width * height).
+     * component index 1: range of width.
+     * component index 2: range of height.
+     *
+     * @note To obtain multi-component version of this structure, user must
+     *       provide AV_OPT_MULTI_COMPONENT_RANGE to av_opt_query_ranges or
+     *       av_opt_query_ranges_default function.
+     *
+     * Multi-component range can be read as in following example:
+     *
+     * @code
+     * int range_index, component_index;
+     * AVOptionRanges *ranges;
+     * AVOptionRange *range[3]; //may require more than 3 in the future.
+     * av_opt_query_ranges(&ranges, obj, key, AV_OPT_MULTI_COMPONENT_RANGE);
+     * for (range_index = 0; range_index < ranges->nb_ranges; range_index++) {
+     *     for (component_index = 0; component_index < ranges->nb_components; component_index++)
+     *         range[component_index] = ranges->range[ranges->nb_ranges * component_index + range_index];
+     *     //do something with range here.
+     * }
+     * av_opt_freep_ranges(&ranges);
+     * @endcode
+     */
     AVOptionRange **range;
+    /**
+     * Number of ranges per component.
+     */
     int nb_ranges;
+    /**
+     * Number of componentes.
+     */
+    int nb_components;
 } AVOptionRanges;
 
 
@@ -559,6 +609,13 @@ int av_opt_eval_q     (void *obj, const AVOption *o, const char *val, AVRational
 #define AV_OPT_SEARCH_FAKE_OBJ   0x0002
 
 /**
+ *  Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than
+ *  one component for certain option types.
+ *  @see AVOptionRanges for details.
+ */
+#define AV_OPT_MULTI_COMPONENT_RANGE 0x1000
+
+/**
  * Look for an option in an object. Consider only options which
  * have all the specified flags set.
  *
@@ -739,10 +796,11 @@ void av_opt_freep_ranges(AVOptionRanges **ranges);
  *
  * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
  *              AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
+ *              AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
  *
  * The result must be freed with av_opt_freep_ranges.
  *
- * @return >= 0 on success, a negative errro code otherwise
+ * @return number of compontents returned on success, a negative errro code otherwise
  */
 int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags);
 
@@ -754,10 +812,11 @@ int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags
  *
  * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
  *              AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
+ *              AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
  *
  * The result must be freed with av_opt_free_ranges.
  *
- * @return >= 0 on success, a negative errro code otherwise
+ * @return number of compontents returned on success, a negative errro code otherwise
  */
 int av_opt_query_ranges_default(AVOptionRanges **, void *obj, const char *key, int flags);