start on libncsixel #2383

CMakeLists.txt

@@ -213,7 +213,7 @@ file(GLOB COMPATSRC CONFIGURE_DEPENDS src/compat/*.c)
 
 ############################################################################
 # libnotcurses-core (core shared library, core static library)
-file(GLOB NCCORESRCS CONFIGURE_DEPENDS src/lib/*.c src/lib/*.cpp)
+file(GLOB NCCORESRCS CONFIGURE_DEPENDS src/lib/*.c)
 add_library(notcurses-core SHARED ${NCCORESRCS} ${COMPATSRC})
 if(${USE_STATIC})
 add_library(notcurses-core-static STATIC ${NCCORESRCS} ${COMPATSRC})
@@ -408,6 +408,57 @@ target_link_directories(notcurses PRIVATE ${OIIO_LIBRARY_DIRS})
 target_link_directories(notcurses-static PRIVATE ${OIIO_STATIC_LIBRARY_DIRS})
 endif()
 
+############################################################################
+# libncsixel (sixel library built atop notcurses)
+file(GLOB NCSIXSRCS CONFIGURE_DEPENDS src/sixel/*.c)
+add_library(ncsixel SHARED ${NCSIXSRCS} ${COMPATSRC})
+if(${USE_STATIC})
+add_library(ncsixel-static STATIC ${NCSIXSRCS})
+else()
+add_library(ncsixel-static STATIC EXCLUDE_FROM_ALL ${NCSIXSRCS})
+endif()
+set_target_properties(ncsixel PROPERTIES
+  VERSION ${PROJECT_VERSION}
+  SOVERSION ${PROJECT_VERSION_MAJOR}
+)
+set_target_properties(ncsixel-static PROPERTIES
+  VERSION ${PROJECT_VERSION}
+  OUTPUT_NAME ncsixel
+)
+target_include_directories(ncsixel
+  BEFORE
+  PRIVATE
+    include
+    src
+    "${CMAKE_REQUIRED_INCLUDES}"
+    "${PROJECT_BINARY_DIR}/include"
+    "${TERMINFO_INCLUDE_DIRS}"
+)
+target_include_directories(ncsixel-static
+  BEFORE
+  PRIVATE
+    include
+    src
+    "${CMAKE_REQUIRED_INCLUDES}"
+    "${PROJECT_BINARY_DIR}/include"
+    "${TERMINFO_INCLUDE_DIRS}"
+)
+target_compile_definitions(ncsixel
+  PRIVATE
+   _GNU_SOURCE _DEFAULT_SOURCE
+)
+target_compile_definitions(ncsixel-static
+  PRIVATE
+   _GNU_SOURCE _DEFAULT_SOURCE
+)
+target_link_libraries(ncsixel
+  PUBLIC
+    notcurses
+)
+target_link_libraries(ncsixel-static
+  PUBLIC
+    notcurses-static
+)
 ############################################################################
 if(${USE_CXX})
 # libnotcurses++ (C++ wrappers)

include/sixel/sixel.h

@@ -1,6 +1,9 @@
 #ifndef NOTCURSES_SIXEL_SIXEL
 #define NOTCURSES_SIXEL_SIXEL
 
+// a library built atop Notcurses suitable for working with sixels outside
+// the Notcurses framework--a replacement for libsixel.
+
 #ifdef __cplusplus
 extern "C" {
 #define RESTRICT
@@ -15,7 +18,19 @@ extern "C" {
 #endif
 #define ALLOC __attribute__((malloc)) __attribute__((warn_unused_result))
 
-// FIXME libsixel-like API
+struct sixel;
+struct sixelctx;
+
+API ALLOC struct sixelctx* libncsixel_init(void);
+
+// load the file and encode the first frame as a sixel. if |colorregs| is 0,
+// use the number supported by the terminal, or 256 if the terminal does not
+// support sixel.
+API ALLOC __attribute__ ((nonnull (1, 2)))
+struct sixel* libncsixel_encode(struct sixelctx* sctx, const char* file,
+                                unsigned colorregs);
+
+API void libncsixel_stop(struct sixelctx* sctx);
 
 #undef API
 #undef ALLOC

src/sixel/sixel.c

@@ -0,0 +1,51 @@
+#include "sixel/sixel.h"
+#include <notcurses/notcurses.h>
+
+// represents a sixel generated from some image
+typedef struct sixel {
+  char* escape; // nul-terminated escape suitable for writing to the terminal
+  // there is both the true pixel geometry, and the sprixel-padded pixel
+  // geometry--the latter always has a height which is a multiple of six.
+  unsigned pixy, pixx;           // original pixel geometry
+  unsigned sprixpixy, sprixpixx; // sprixel-padded pixel geometry
+  // we might only occupy a portion of the final column and row of cells.
+  unsigned celly, cellx;         // cell geometry
+  unsigned colorregs_avail;      // color registers available
+  unsigned colorregs_used;       // color registers used
+} sixel;
+
+typedef struct sixelctx {
+  struct notcurses* nc;
+} sixelctx;
+
+sixelctx* libncsixel_init(void){
+  sixelctx* sctx = malloc(sizeof(*sctx));
+  if(sctx == NULL){
+    return NULL;
+  }
+  struct notcurses_options nopts = {
+    .flags = NCOPTION_NO_ALTERNATE_SCREEN |
+             NCOPTION_PRESERVE_CURSOR |
+             NCOPTION_SUPPRESS_BANNERS |
+             NCOPTION_DRAIN_INPUT,
+  };
+  if((sctx->nc = notcurses_init(&nopts, NULL)) == NULL){
+    free(sctx);
+    return NULL;
+  }
+  return sctx;
+}
+
+sixel* libncsixel_encode(sixelctx* sctx, const char* file, unsigned colorregs){
+  (void)sctx;
+  (void)file;
+  (void)colorregs;
+  return NULL;
+}
+
+void libncsixel_stop(sixelctx* sctx){
+  if(sctx){
+    notcurses_stop(sctx->nc);
+    free(sctx);
+  }
+}