Move all compat ifdefs definitions to compat.h

This allows to give a proper name to features requirements.

app/src/compat.h

@@ -0,0 +1,44 @@
+#ifndef COMPAT_H
+#define COMPAT_H
+
+#include <libavformat/version.h>
+#include <SDL2/SDL_version.h>
+
+// In ffmpeg/doc/APIchanges:
+// 2016-04-11 - 6f69f7a / 9200514 - lavf 57.33.100 / 57.5.0 - avformat.h
+//   Add AVStream.codecpar, deprecate AVStream.codec.
+#if    (LIBAVFORMAT_VERSION_MICRO >= 100 /* FFmpeg */ && \
+        LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(57, 33, 100)) \
+    || (LIBAVFORMAT_VERSION_MICRO < 100 && /* Libav */ \
+        LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(57, 5, 0))
+# define SCRCPY_LAVF_HAS_NEW_CODEC_PARAMS_API
+#endif
+
+// In ffmpeg/doc/APIchanges:
+// 2018-02-06 - 0694d87024 - lavf 58.9.100 - avformat.h
+//   Deprecate use of av_register_input_format(), av_register_output_format(),
+//   av_register_all(), av_iformat_next(), av_oformat_next().
+//   Add av_demuxer_iterate(), and av_muxer_iterate().
+#if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(58, 9, 100)
+# define SCRCPY_LAVF_HAS_NEW_MUXER_ITERATOR_API
+#else
+# define SCRCPY_LAVF_REQUIRES_REGISTER_ALL
+#endif
+
+// In ffmpeg/doc/APIchanges:
+// 2016-04-21 - 7fc329e - lavc 57.37.100 - avcodec.h
+//   Add a new audio/video encoding and decoding API with decoupled input
+//   and output -- avcodec_send_packet(), avcodec_receive_frame(),
+//   avcodec_send_frame() and avcodec_receive_packet().
+#if LIBAVCODEC_VERSION_INT >= AV_VERSION_INT(57, 37, 100)
+# define SCRCPY_LAVF_HAS_NEW_ENCODING_DECODING_API
+#endif
+
+#if SDL_VERSION_ATLEAST(2, 0, 5)
+// <https://wiki.libsdl.org/SDL_HINT_MOUSE_FOCUS_CLICKTHROUGH>
+# define SCRCPY_SDL_HAS_HINT_MOUSE_FOCUS_CLICKTHROUGH
+// <https://wiki.libsdl.org/SDL_GetDisplayUsableBounds>
+# define SCRCPY_SDL_HAS_GET_DISPLAY_USABLE_BOUNDS
+#endif
+
+#endif

app/src/decoder.c

@@ -8,6 +8,7 @@
 #include <SDL2/SDL_thread.h>
 #include <unistd.h>
 
+#include "compat.h"
 #include "config.h"
 #include "buffer_util.h"
 #include "events.h"
@@ -220,7 +221,7 @@ static int run_decoder(void *data) {
     while (!av_read_frame(format_ctx, &packet)) {
 // the new decoding/encoding API has been introduced by:
 // <http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=7fc329e2dd6226dfecaa4a1d7adf353bf2773726>
-#if LIBAVCODEC_VERSION_INT >= AV_VERSION_INT(57, 37, 0)
+#ifdef SCRCPY_LAVF_HAS_NEW_ENCODING_DECODING_API
         int ret;
         if ((ret = avcodec_send_packet(codec_ctx, &packet)) < 0) {
             LOGE("Could not send video packet: %d", ret);

app/src/main.c

@@ -5,6 +5,7 @@
 #include <libavformat/avformat.h>
 #include <SDL2/SDL.h>
 
+#include "compat.h"
 #include "config.h"
 #include "log.h"
 #include "recorder.h"
@@ -371,7 +372,7 @@ int main(int argc, char *argv[]) {
         return 0;
     }
 
-#if LIBAVCODEC_VERSION_INT < AV_VERSION_INT(58, 9, 100)
+#ifdef SCRCPY_LAVF_REQUIRES_REGISTER_ALL
     av_register_all();
 #endif
 

app/src/recorder.c

@@ -3,28 +3,19 @@
 #include <libavutil/time.h>
 #include <SDL2/SDL_assert.h>
 
+#include "compat.h"
 #include "config.h"
 #include "log.h"
 
-// In ffmpeg/doc/APIchanges:
-// 2016-04-11 - 6f69f7a / 9200514 - lavf 57.33.100 / 57.5.0 - avformat.h
-//   Add AVStream.codecpar, deprecate AVStream.codec.
-#if    (LIBAVFORMAT_VERSION_MICRO >= 100 /* FFmpeg */ && \
-        LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(57, 33, 100)) \
-    || (LIBAVFORMAT_VERSION_MICRO < 100 && /* Libav */ \
-        LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(57, 5, 0))
-# define LAVF_NEW_CODEC_API
-#endif
-
 static const AVRational SCRCPY_TIME_BASE = {1, 1000000}; // timestamps in us
 
 static const AVOutputFormat *find_muxer(const char *name) {
-#if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(58, 9, 100)
+#ifdef SCRCPY_LAVF_HAS_NEW_MUXER_ITERATOR_API
     void *opaque = NULL;
 #endif
     const AVOutputFormat *oformat = NULL;
     do {
-#if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(58, 9, 100)
+#ifdef SCRCPY_LAVF_HAS_NEW_MUXER_ITERATOR_API
         oformat = av_muxer_iterate(&opaque);
 #else
         oformat = av_oformat_next(oformat);
@@ -91,7 +82,7 @@ SDL_bool recorder_open(struct recorder *recorder, AVCodec *input_codec) {
         return SDL_FALSE;
     }
 
-#ifdef LAVF_NEW_CODEC_API
+#ifdef SCRCPY_LAVF_HAS_NEW_CODEC_PARAMS_API
     ostream->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
     ostream->codecpar->codec_id = input_codec->id;
     ostream->codecpar->format = AV_PIX_FMT_YUV420P;
@@ -144,7 +135,7 @@ recorder_write_header(struct recorder *recorder, AVPacket *packet) {
     // copy the first packet to the extra data
     memcpy(extradata, packet->data, packet->size);
 
-#ifdef LAVF_NEW_CODEC_API
+#ifdef SCRCPY_LAVF_HAS_NEW_CODEC_PARAMS_API
     ostream->codecpar->extradata = extradata;
     ostream->codecpar->extradata_size = packet->size;
 #else

app/src/screen.c

@@ -3,6 +3,7 @@
 #include <SDL2/SDL.h>
 #include <string.h>
 
+#include "compat.h"
 #include "icon.xpm"
 #include "lock_util.h"
 #include "log.h"
@@ -23,7 +24,7 @@ SDL_bool sdl_init_and_configure(void) {
         LOGW("Could not enable bilinear filtering");
     }
 
-#if SDL_VERSION_ATLEAST(2, 0, 5)
+#ifdef SCRCPY_SDL_HAS_HINT_MOUSE_FOCUS_CLICKTHROUGH
     // Handle a click to gain focus as any other click
     if (!SDL_SetHint(SDL_HINT_MOUSE_FOCUS_CLICKTHROUGH, "1")) {
         LOGW("Could not enable mouse focus clickthrough");
@@ -71,7 +72,7 @@ static void set_window_size(struct screen *screen, struct size new_size) {
 // get the preferred display bounds (i.e. the screen bounds with some margins)
 static SDL_bool get_preferred_display_bounds(struct size *bounds) {
     SDL_Rect rect;
-#if SDL_VERSION_ATLEAST(2, 0, 5)
+#ifdef SCRCPY_SDL_HAS_GET_DISPLAY_USABLE_BOUNDS
 # define GET_DISPLAY_BOUNDS(i, r) SDL_GetDisplayUsableBounds((i), (r))
 #else
 # define GET_DISPLAY_BOUNDS(i, r) SDL_GetDisplayBounds((i), (r))