ggpujpeg_reader_get_image_info: pixfmt sel to fn

factor out pixel format deduction to a separate function

refactor only

Author: MartinPulec

src/gpujpeg_reader.c

@@ -1490,6 +1490,71 @@ static _Bool sampling_factor_compare(int count, struct gpujpeg_component_samplin
     return 1;
 }
 
+static int
+gcd(int a, int b)
+{
+    assert(b != 0);
+    int c = a % b;
+    while (c != 0) {
+        a = b;
+        b = c;
+        c = a % b;
+    }
+
+    return (b);
+}
+
+static enum gpujpeg_pixel_format
+get_native_pixel_format(struct gpujpeg_parameters* param)
+{
+    if ( param->comp_count == 1 ) {
+        return GPUJPEG_U8;
+    }
+    if ( param->comp_count == 3 ) {
+        // reduce [2, 2; 1, 2; 1, 2] (FFmpeg) to [2, 1; 1, 1; 1, 1]
+        int horizontal_gcd = param->sampling_factor[0].horizontal;
+        int vertical_gcd = param->sampling_factor[0].vertical;
+        for (int i = 1; i < 3; ++i) {
+            horizontal_gcd = gcd(horizontal_gcd, param->sampling_factor[i].horizontal);
+            vertical_gcd = gcd(vertical_gcd, param->sampling_factor[i].vertical);
+        }
+        for (int i = 0; i < 3; ++i) {
+            param->sampling_factor[i].horizontal /= horizontal_gcd;
+            param->sampling_factor[i].vertical /= vertical_gcd;
+        }
+
+        if ( param->sampling_factor[1].horizontal == 1 && param->sampling_factor[1].vertical == 1 &&
+             param->sampling_factor[2].horizontal == 1 && param->sampling_factor[2].vertical == 1 ) {
+            int sum = param->interleaved << 16 | param->sampling_factor[0].horizontal << 8 |
+                      param->sampling_factor[0].vertical; // NOLINT
+            switch (sum) {
+                case 1<<16 | 1<<8 | 1: return GPUJPEG_444_U8_P012; break;   // NOLINT
+                case 0<<16 | 1<<8 | 1: return GPUJPEG_444_U8_P0P1P2; break; // NOLINT
+                case 1<<16 | 2<<8 | 1: return GPUJPEG_422_U8_P1020; break;  // NOLINT
+                case 0<<16 | 2<<8 | 1: return GPUJPEG_422_U8_P0P1P2; break; // NOLINT
+                case 1<<16 | 2<<8 | 2: // we have only one pixfmt for 420, so use for both          NOLINT
+                case 0<<16 | 2<<8 | 2: return GPUJPEG_420_U8_P0P1P2; break; // NOLINT
+                default: break;
+            }
+        }
+    }
+
+    if ( param->comp_count == 4 ) {
+        _Bool subsampling_is4444 = 1;
+        for (int i = 1; i < 4; ++i) {
+            if (param->sampling_factor[i].horizontal != param->sampling_factor[0].horizontal
+                    || param->sampling_factor[i].vertical != param->sampling_factor[0].vertical) {
+                subsampling_is4444 = 0;
+                break;
+            }
+        }
+        if (subsampling_is4444) {
+            return GPUJPEG_4444_U8_P0123;
+        }
+    }
+    return GPUJPEG_PIXFMT_NONE;
+}
+
 static enum gpujpeg_pixel_format
 adjust_pixel_format(struct gpujpeg_parameters * param, struct gpujpeg_image_parameters * param_image) {
     assert(param_image->pixel_format == GPUJPEG_PIXFMT_AUTODETECT || param_image->pixel_format == GPUJPEG_PIXFMT_STD);
@@ -1661,20 +1726,6 @@ gpujpeg_reader_read_image(struct gpujpeg_decoder* decoder, uint8_t* image, size_
     return 0;
 }
 
-static int
-gcd(int a, int b)
-{
-    assert(b != 0);
-    int c = a % b;
-    while (c != 0) {
-        a = b;
-        b = c;
-        c = a % b;
-    }
-
-    return (b);
-}
-
 /* Documented at declaration */
 int
 gpujpeg_reader_get_image_info(uint8_t *image, size_t image_size, struct gpujpeg_image_info *info, int verbose, unsigned flags)
@@ -1801,56 +1852,11 @@ gpujpeg_reader_get_image_info(uint8_t *image, size_t image_size, struct gpujpeg_
 
     info->param = reader.param;
     info->param_image = reader.param_image;
-    info->param_image.pixel_format = GPUJPEG_PIXFMT_NONE;
     info->segment_count = segments;
     info->header_type = reader.header_type;
     info->comment = reader.comment;
 
-    if ( info->param.comp_count == 1 ) {
-        info->param_image.pixel_format = GPUJPEG_U8;
-    }
-    if ( info->param.comp_count == 3 ) {
-        // reduce [2, 2; 1, 2; 1, 2] (FFmpeg) to [2, 1; 1, 1; 1, 1]
-        int horizontal_gcd = info->param.sampling_factor[0].horizontal;
-        int vertical_gcd = info->param.sampling_factor[0].vertical;
-        for (int i = 1; i < 3; ++i) {
-            horizontal_gcd = gcd(horizontal_gcd, info->param.sampling_factor[i].horizontal);
-            vertical_gcd = gcd(vertical_gcd, info->param.sampling_factor[i].vertical);
-        }
-        for (int i = 0; i < 3; ++i) {
-            info->param.sampling_factor[i].horizontal /= horizontal_gcd;
-            info->param.sampling_factor[i].vertical /= vertical_gcd;
-        }
-
-        if (info->param.sampling_factor[1].horizontal == 1 && info->param.sampling_factor[1].vertical == 1
-                && info->param.sampling_factor[2].horizontal == 1 && info->param.sampling_factor[2].vertical == 1) {
-            int sum = info->param.interleaved << 16 | info->param.sampling_factor[0].horizontal << 8 |
-                      info->param.sampling_factor[0].vertical; // NOLINT
-            switch (sum) {
-                case 1<<16 | 1<<8 | 1: info->param_image.pixel_format = GPUJPEG_444_U8_P012; break;   // NOLINT
-                case 0<<16 | 1<<8 | 1: info->param_image.pixel_format = GPUJPEG_444_U8_P0P1P2; break; // NOLINT
-                case 1<<16 | 2<<8 | 1: info->param_image.pixel_format = GPUJPEG_422_U8_P1020; break;  // NOLINT
-                case 0<<16 | 2<<8 | 1: info->param_image.pixel_format = GPUJPEG_422_U8_P0P1P2; break; // NOLINT
-                case 1<<16 | 2<<8 | 2: // we have only one pixfmt for 420, so use for both          NOLINT
-                case 0<<16 | 2<<8 | 2: info->param_image.pixel_format = GPUJPEG_420_U8_P0P1P2; break; // NOLINT
-                default: break;
-            }
-        }
-    }
-
-    if ( info->param.comp_count == 4 ) {
-        _Bool subsampling_is4444 = 1;
-        for (int i = 1; i < 4; ++i) {
-            if (info->param.sampling_factor[i].horizontal != info->param.sampling_factor[0].horizontal
-                    || info->param.sampling_factor[i].vertical != info->param.sampling_factor[0].vertical) {
-                subsampling_is4444 = 0;
-                break;
-            }
-        }
-        if (subsampling_is4444) {
-            info->param_image.pixel_format = GPUJPEG_4444_U8_P0123;
-        }
-    }
+    info->param_image.pixel_format = get_native_pixel_format(&reader.param);
 
     return 0;
 }