Use stb scaling if we don't necessarily have to link SWS.

SWS is huge, and brings a lot of dependencies not necessarily
desired when we disable video decoding. In that case, just use
STB resizing.

Issue: #140

src/CMakeLists.txt

@@ -76,17 +76,13 @@ if(WITH_TURBOJPEG)
   target_compile_definitions(timg PUBLIC WITH_TIMG_JPEG)
   target_link_libraries(timg
     PkgConfig::TURBOJPEG
-    PkgConfig::EXIF
-    PkgConfig::AVUTIL
-    PkgConfig::SWSCALE)
+    PkgConfig::EXIF)
 endif()
 
 if(WITH_OPENSLIDE_SUPPORT)
   target_sources(timg PUBLIC openslide-source.h openslide-source.cc)
   target_compile_definitions(timg PUBLIC WITH_TIMG_OPENSLIDE_SUPPORT)
-  target_link_libraries(timg PkgConfig::OPENSLIDE
-    PkgConfig::AVUTIL
-    PkgConfig::SWSCALE)
+  target_link_libraries(timg PkgConfig::OPENSLIDE)
 endif()
 
 if(WITH_VIDEO_DECODING)
@@ -100,26 +96,37 @@ if(WITH_VIDEO_DECODING)
     target_link_libraries(timg PkgConfig::LIBAV_DEVICE)
     add_definitions(-DHAVE_AVDEVICE)
   endif()
+  set(SHOULD_SCALE_SWS ON)  # we link it anyway
 endif()
 
 if(WITH_STB_IMAGE)
   # STB usuall does not come with pkg-config. Just check if we see the include
+  # Always want image resize2, if not, use third_party/
   include(CheckIncludeFileCXX)
-  CHECK_INCLUDE_FILE_CXX(stb/stb_image.h HAVE_STB)
+  CHECK_INCLUDE_FILE_CXX(stb/stb_image.h HAVE_SYSTEM_STB)
   target_sources(timg PUBLIC stb-image-source.h stb-image-source.cc)
-  if(NOT HAVE_STB)
-    message("--> Using STB from third_party/ instead")
+  if(NOT HAVE_SYSTEM_STB)
+    message("--> Using STB from third_party/")
     target_include_directories(timg PRIVATE ${CMAKE_SOURCE_DIR}/third_party)
-    set(STB_RESIZE_VERSION2 true)  # distributing resize2 in third_party/
-  else()
-    CHECK_INCLUDE_FILE_CXX(stb/stb_image_resize2.h STB_RESIZE_VERSION2)
-  endif()
-  if(STB_RESIZE_VERSION2)
-    target_compile_definitions(timg PUBLIC STB_RESIZE_VERSION2)
   endif()
   target_compile_definitions(timg PUBLIC WITH_TIMG_STB)
 endif()
 
+# TODO: for scaling, there is also zimg to explore
+if(SHOULD_SCALE_SWS)
+  target_link_libraries(timg
+    PkgConfig::AVUTIL
+    PkgConfig::SWSCALE)
+  target_compile_definitions(timg PUBLIC WITH_TIMG_SWS_RESIZE)
+else()
+  CHECK_INCLUDE_FILE_CXX(stb/stb_image_resize2.h HAVE_SYSTEM_STB_RESIZE2)
+  if(NOT HAVE_SYSTEM_STB_RESIZE2)
+    message("--> Using STB resize2 from third_party/")
+    target_include_directories(timg PRIVATE ${CMAKE_SOURCE_DIR}/third_party)
+  endif()
+  target_compile_definitions(timg PUBLIC WITH_TIMG_STB_RESIZE)
+endif()
+
 if(WITH_QOI_IMAGE)
   include(CheckIncludeFileCXX)
   CHECK_INCLUDE_FILE_CXX(qoi.h HAVE_QOI)
@@ -129,9 +136,6 @@ if(WITH_QOI_IMAGE)
     target_include_directories(timg PRIVATE ${CMAKE_SOURCE_DIR}/third_party/qoi)
   endif()
   target_compile_definitions(timg PUBLIC WITH_TIMG_QOI)
-  target_link_libraries(timg
-    PkgConfig::AVUTIL
-    PkgConfig::SWSCALE)
 endif()
 
 # We always take the manpage from the checkout currently so that we don't

src/image-scaler.cc

@@ -15,14 +15,26 @@
 
 #include "image-scaler.h"
 
+#ifdef WITH_TIMG_SWS_RESIZE
 extern "C" {  // avutil is missing extern "C"
 #include <libavutil/log.h>
 #include <libavutil/pixfmt.h>
 #include <libswscale/swscale.h>
 }
+#endif
+
+#ifdef WITH_TIMG_STB_RESIZE
+#define STB_IMAGE_RESIZE_IMPLEMENTATION
+// Least amount of fuzziness on upscaling
+#define STBIR_DEFAULT_FILTER_UPSAMPLE STBIR_FILTER_BOX
+#include "stb/stb_image_resize2.h"
+#endif
+
+// TODO: there is also zimg.
 
 namespace timg {
 namespace {
+#if WITH_TIMG_SWS_RESIZE
 static void dummy_log(void *, int, const char *, va_list) {}
 
 class SWSImageScaler final : public ImageScaler {
@@ -53,13 +65,47 @@ class SWSImageScaler final : public ImageScaler {
 
     SwsContext *const sws_context_;
 };
+#endif
+#if WITH_TIMG_STB_RESIZE
+class STBImageScaler final : public ImageScaler {
+public:
+    static STBImageScaler *Create(int in_width, int in_height,
+                                  ColorFmt in_color_format, int out_width,
+                                  int out_height) {
+        return new STBImageScaler(in_color_format);
+    }
+
+    void Scale(Framebuffer &in, Framebuffer *out) final {
+        struct STBIR_RESIZE context {};
+        stbir_resize_init(&context, (uint8_t *)in.begin(), in.width(),
+                          in.height(), 0, (uint8_t *)out->begin(), out->width(),
+                          out->height(), 0, STBIR_RGBA, STBIR_TYPE_UINT8);
+        stbir_set_pixel_layouts(
+            &context, in_fmt_ == ColorFmt::kRGBA ? STBIR_RGBA : STBIR_BGRA,
+            STBIR_RGBA);
+        stbir_resize_extended(&context);
+    }
+
+private:
+    explicit STBImageScaler(ColorFmt in_fmt) : in_fmt_(in_fmt) {}
+    const ColorFmt in_fmt_;
+};
+#endif
 }  // namespace
 
 std::unique_ptr<ImageScaler> ImageScaler::Create(int in_width, int in_height,
                                                  ColorFmt in_color_format,
                                                  int out_width,
                                                  int out_height) {
+#if WITH_TIMG_SWS_RESIZE
     return std::unique_ptr<ImageScaler>(SWSImageScaler::Create(
         in_width, in_height, in_color_format, out_width, out_height));
+#elif WITH_TIMG_STB_RESIZE
+    return std::unique_ptr<ImageScaler>(STBImageScaler::Create(
+        in_width, in_height, in_color_format, out_width, out_height));
+#else
+#error "Configure issue: no image scaler available"
+    return nullptr;
+#endif
 }
 }  // namespace timg

src/stb-image-source.cc

@@ -26,40 +26,12 @@
 #include "buffered-write-sequencer.h"
 #include "display-options.h"
 #include "framebuffer.h"
+#include "image-scaler.h"
 #include "image-source.h"
 #include "renderer.h"
 #include "stb/stb_image.h"
 #include "timg-time.h"
 
-#define STB_IMAGE_RESIZE_IMPLEMENTATION
-// Least amount of fuzziness on upscaling
-#define STBIR_DEFAULT_FILTER_UPSAMPLE STBIR_FILTER_BOX
-
-// There is an old and a new version of stb resize. Prefer newer if available
-// (tested for in CMake), and provide adapter functions to use either.
-#if STB_RESIZE_VERSION2
-#include "stb/stb_image_resize2.h"
-inline void stb_resize_image(const unsigned char *input_pixels, int input_w,
-                             int input_h, unsigned char *output_pixels,
-                             int output_w, int output_h) {
-    static constexpr stbir_pixel_layout kFramebufferFormat = STBIR_RGBA;
-    stbir_resize_uint8_linear(input_pixels, input_w, input_h, 0,  //
-                              output_pixels, output_w, output_h, 0,
-                              kFramebufferFormat);
-}
-
-#else
-#include "stb/stb_image_resize.h"
-inline void stb_resize_image(const unsigned char *input_pixels, int input_w,
-                             int input_h, unsigned char *output_pixels,
-                             int output_w, int output_h) {
-    static constexpr int kFramebufferFormat = 4;              // RGBA.
-    stbir_resize_uint8(input_pixels, input_w, input_h, 0,     //
-                       output_pixels, output_w, output_h, 0,  //
-                       kFramebufferFormat);
-}
-#endif
-
 // TODO: preprocessed frame and SendFrames() are similar to
 // image-display.cc. Maybe things can be consolidated.
 
@@ -71,8 +43,15 @@ class STBImageSource::PreprocessedFrame {
                       int target_w, int target_h, const Duration &delay,
                       const DisplayOptions &opt)
         : delay_(delay), framebuffer_(target_w, target_h) {
-        stb_resize_image(image_data, source_w, source_h,
-                         (uint8_t *)framebuffer_.begin(), target_w, target_h);
+        const size_t len = source_w * source_h * 4;
+        Framebuffer source_img(source_w, source_h);  // TODO: avoid copy.
+        std::copy(image_data, image_data + len, (uint8_t *)source_img.begin());
+        auto scaler = ImageScaler::Create(source_w, source_h,
+                                          ImageScaler::ColorFmt::kRGBA,
+                                          target_w, target_h);
+        if (scaler) {
+            scaler->Scale(source_img, &framebuffer_);
+        }
         framebuffer_.AlphaComposeBackground(
             opt.bgcolor_getter, opt.bg_pattern_color,
             opt.pattern_size * opt.cell_x_px,

src/timg-print-version.cc

@@ -43,7 +43,10 @@
 #include <jconfig.h>
 #endif
 #include <libdeflate.h>
+
+#ifdef WITH_TIMG_SWS_RESIZE
 #include <libswscale/swscale.h>  // NOLINT used for version.
+#endif
 
 #include "timg-version.h"  // generated.
 #ifndef TIMG_VERSION
@@ -95,20 +98,22 @@ int PrintComponentVersions(FILE *stream) {
 #endif
 #ifdef WITH_TIMG_STB
     fprintf(stream,
-            "STB image loading; STB resize v"
-#ifdef STB_RESIZE_VERSION2
-            "2"
-#else
-            "1"
-#endif
+            "STB image loading"
+
 #ifdef WITH_TIMG_GRPAPHICSMAGICK
             // If we have graphics magic, that will take images first,
             // so STB will only really be called as fallback.
             " (fallback)"
 #endif
             "\n");
 #endif
-    fprintf(stream, "swscale %s\n", AV_STRINGIFY(LIBSWSCALE_VERSION));
+
+#ifdef WITH_TIMG_SWS_RESIZE
+    fprintf(stream, "Resize: swscale %s\n", AV_STRINGIFY(LIBSWSCALE_VERSION));
+#else
+    fprintf(stream, "Resize: STB resize\n");
+#endif
+
 #ifdef WITH_TIMG_VIDEO
     fprintf(stream, "Video decoding %s\n", timg::VideoSource::VersionInfo());
 #endif